md.c

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/*
   md.c : Multiple Devices driver for Linux
      Copyright (C) 1998, 1999, 2000 Ingo Molnar

     completely rewritten, based on the MD driver code from Marc Zyngier

   Changes:

   - RAID-1/RAID-5 extensions by Miguel de Icaza, Gadi Oxman, Ingo Molnar
   - RAID-6 extensions by H. Peter Anvin <[email protected]>
   - boot support for linear and striped mode by Harald Hoyer <[email protected]>
   - kerneld support by Boris Tobotras <[email protected]>
   - kmod support by: Cyrus Durgin
   - RAID0 bugfixes: Mark Anthony Lisher <[email protected]>
   - Devfs support by Richard Gooch <[email protected]>

   - lots of fixes and improvements to the RAID1/RAID5 and generic
     RAID code (such as request based resynchronization):

     Neil Brown <[email protected]>.

   - persistent bitmap code
     Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   You should have received a copy of the GNU General Public License
   (for example /usr/src/linux/COPYING); if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <linux/kthread.h>
#include <linux/blkdev.h>
#include <linux/sysctl.h>
#include <linux/seq_file.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/hdreg.h>
#include <linux/proc_fs.h>
#include <linux/random.h>
#include <linux/module.h>
#include <linux/reboot.h>
#include <linux/file.h>
#include <linux/compat.h>
#include <linux/delay.h>
#include <linux/raid/md_p.h>
#include <linux/raid/md_u.h>
#include <linux/slab.h>
#include "md.h"
#include "bitmap.h"

#ifndef MODULE
static void autostart_arrays(int part);
#endif

/* pers_list is a list of registered personalities protected
 * by pers_lock.
 * pers_lock does extra service to protect accesses to
 * mddev->thread when the mutex cannot be held.
 */
static LIST_HEAD(pers_list);
static DEFINE_SPINLOCK(pers_lock);

static void md_print_devices(void);

static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
static struct workqueue_struct *md_wq;
static struct workqueue_struct *md_misc_wq;

#define MD_BUG(x...) { printk("md: bug in file %s, line %d\n", __FILE__, __LINE__); md_print_devices(); }

/*
 * Default number of read corrections we'll attempt on an rdev
 * before ejecting it from the array. We divide the read error
 * count by 2 for every hour elapsed between read errors.
 */
#define MD_DEFAULT_MAX_CORRECTED_READ_ERRORS 20
/*
 * Current RAID-1,4,5 parallel reconstruction 'guaranteed speed limit'
 * is 1000 KB/sec, so the extra system load does not show up that much.
 * Increase it if you want to have more _guaranteed_ speed. Note that
 * the RAID driver will use the maximum available bandwidth if the IO
 * subsystem is idle. There is also an 'absolute maximum' reconstruction
 * speed limit - in case reconstruction slows down your system despite
 * idle IO detection.
 *
 * you can change it via /proc/sys/dev/raid/speed_limit_min and _max.
 * or /sys/block/mdX/md/sync_speed_{min,max}
 */

static int sysctl_speed_limit_min = 1000;
static int sysctl_speed_limit_max = 200000;
static inline int speed_min(struct mddev *mddev)
{
    return mddev->sync_speed_min ?
        mddev->sync_speed_min : sysctl_speed_limit_min;
}

static inline int speed_max(struct mddev *mddev)
{
    return mddev->sync_speed_max ?
        mddev->sync_speed_max : sysctl_speed_limit_max;
}

static struct ctl_table_header *raid_table_header;

static ctl_table raid_table[] = {
    {
        .procname   = "speed_limit_min",
        .data       = &sysctl_speed_limit_min,
        .maxlen     = sizeof(int),
        .mode       = S_IRUGO|S_IWUSR,
        .proc_handler   = proc_dointvec,
    },
    {
        .procname   = "speed_limit_max",
        .data       = &sysctl_speed_limit_max,
        .maxlen     = sizeof(int),
        .mode       = S_IRUGO|S_IWUSR,
        .proc_handler   = proc_dointvec,
    },
    { }
};

static ctl_table raid_dir_table[] = {
    {
        .procname   = "raid",
        .maxlen     = 0,
        .mode       = S_IRUGO|S_IXUGO,
        .child      = raid_table,
    },
    { }
};

static ctl_table raid_root_table[] = {
    {
        .procname   = "dev",
        .maxlen     = 0,
        .mode       = 0555,
        .child      = raid_dir_table,
    },
    {  }
};

static const struct block_device_operations md_fops;

static int start_readonly;

/* bio_clone_mddev
 * like bio_clone, but with a local bio set
 */

struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
                struct mddev *mddev)
{
    struct bio *b;

    if (!mddev || !mddev->bio_set)
        return bio_alloc(gfp_mask, nr_iovecs);

    b = bio_alloc_bioset(gfp_mask, nr_iovecs, mddev->bio_set);
    if (!b)
        return NULL;
    return b;
}
EXPORT_SYMBOL_GPL(bio_alloc_mddev);

struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
                struct mddev *mddev)
{
    if (!mddev || !mddev->bio_set)
        return bio_clone(bio, gfp_mask);

    return bio_clone_bioset(bio, gfp_mask, mddev->bio_set);
}
EXPORT_SYMBOL_GPL(bio_clone_mddev);

void md_trim_bio(struct bio *bio, int offset, int size)
{
    /* 'bio' is a cloned bio which we need to trim to match
     * the given offset and size.
     * This requires adjusting bi_sector, bi_size, and bi_io_vec
     */
    int i;
    struct bio_vec *bvec;
    int sofar = 0;

    size <<= 9;
    if (offset == 0 && size == bio->bi_size)
        return;

    bio->bi_sector += offset;
    bio->bi_size = size;
    offset <<= 9;
    clear_bit(BIO_SEG_VALID, &bio->bi_flags);

    while (bio->bi_idx < bio->bi_vcnt &&
           bio->bi_io_vec[bio->bi_idx].bv_len <= offset) {
        /* remove this whole bio_vec */
        offset -= bio->bi_io_vec[bio->bi_idx].bv_len;
        bio->bi_idx++;
    }
    if (bio->bi_idx < bio->bi_vcnt) {
        bio->bi_io_vec[bio->bi_idx].bv_offset += offset;
        bio->bi_io_vec[bio->bi_idx].bv_len -= offset;
    }
    /* avoid any complications with bi_idx being non-zero*/
    if (bio->bi_idx) {
        memmove(bio->bi_io_vec, bio->bi_io_vec+bio->bi_idx,
            (bio->bi_vcnt - bio->bi_idx) * sizeof(struct bio_vec));
        bio->bi_vcnt -= bio->bi_idx;
        bio->bi_idx = 0;
    }
    /* Make sure vcnt and last bv are not too big */
    bio_for_each_segment(bvec, bio, i) {
        if (sofar + bvec->bv_len > size)
            bvec->bv_len = size - sofar;
        if (bvec->bv_len == 0) {
            bio->bi_vcnt = i;
            break;
        }
        sofar += bvec->bv_len;
    }
}
EXPORT_SYMBOL_GPL(md_trim_bio);

/*
 * We have a system wide 'event count' that is incremented
 * on any 'interesting' event, and readers of /proc/mdstat
 * can use 'poll' or 'select' to find out when the event
 * count increases.
 *
 * Events are:
 *  start array, stop array, error, add device, remove device,
 *  start build, activate spare
 */
static DECLARE_WAIT_QUEUE_HEAD(md_event_waiters);
static atomic_t md_event_count;
void md_new_event(struct mddev *mddev)
{
    atomic_inc(&md_event_count);
    wake_up(&md_event_waiters);
}
EXPORT_SYMBOL_GPL(md_new_event);

/* Alternate version that can be called from interrupts
 * when calling sysfs_notify isn't needed.
 */
static void md_new_event_inintr(struct mddev *mddev)
{
    atomic_inc(&md_event_count);
    wake_up(&md_event_waiters);
}

/*
 * Enables to iterate over all existing md arrays
 * all_mddevs_lock protects this list.
 */
static LIST_HEAD(all_mddevs);
static DEFINE_SPINLOCK(all_mddevs_lock);


/*
 * iterates through all used mddevs in the system.
 * We take care to grab the all_mddevs_lock whenever navigating
 * the list, and to always hold a refcount when unlocked.
 * Any code which breaks out of this loop while own
 * a reference to the current mddev and must mddev_put it.
 */
#define for_each_mddev(_mddev,_tmp)                 \
                                    \
    for (({ spin_lock(&all_mddevs_lock);                \
        _tmp = all_mddevs.next;                 \
        _mddev = NULL;});                   \
         ({ if (_tmp != &all_mddevs)                \
            mddev_get(list_entry(_tmp, struct mddev, all_mddevs));\
        spin_unlock(&all_mddevs_lock);              \
        if (_mddev) mddev_put(_mddev);              \
        _mddev = list_entry(_tmp, struct mddev, all_mddevs);    \
        _tmp != &all_mddevs;});                 \
         ({ spin_lock(&all_mddevs_lock);                \
        _tmp = _tmp->next;})                    \
        )


/* Rather than calling directly into the personality make_request function,
 * IO requests come here first so that we can check if the device is
 * being suspended pending a reconfiguration.
 * We hold a refcount over the call to ->make_request.  By the time that
 * call has finished, the bio has been linked into some internal structure
 * and so is visible to ->quiesce(), so we don't need the refcount any more.
 */
static void md_make_request(struct request_queue *q, struct bio *bio)
{
    const int rw = bio_data_dir(bio);
    struct mddev *mddev = q->queuedata;
    int cpu;
    unsigned int sectors;

    if (mddev == NULL || mddev->pers == NULL
        || !mddev->ready) {
        bio_io_error(bio);
        return;
    }
    smp_rmb(); /* Ensure implications of  'active' are visible */
    rcu_read_lock();
    if (mddev->suspended) {
        DEFINE_WAIT(__wait);
        for (;;) {
            prepare_to_wait(&mddev->sb_wait, &__wait,
                    TASK_UNINTERRUPTIBLE);
            if (!mddev->suspended)
                break;
            rcu_read_unlock();
            schedule();
            rcu_read_lock();
        }
        finish_wait(&mddev->sb_wait, &__wait);
    }
    atomic_inc(&mddev->active_io);
    rcu_read_unlock();

    /*
     * save the sectors now since our bio can
     * go away inside make_request
     */
    sectors = bio_sectors(bio);
    mddev->pers->make_request(mddev, bio);

    cpu = part_stat_lock();
    part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
    part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], sectors);
    part_stat_unlock();

    if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
        wake_up(&mddev->sb_wait);
}

/* mddev_suspend makes sure no new requests are submitted
 * to the device, and that any requests that have been submitted
 * are completely handled.
 * Once ->stop is called and completes, the module will be completely
 * unused.
 */
void mddev_suspend(struct mddev *mddev)
{
    BUG_ON(mddev->suspended);
    mddev->suspended = 1;
    synchronize_rcu();
    wait_event(mddev->sb_wait, atomic_read(&mddev->active_io) == 0);
    mddev->pers->quiesce(mddev, 1);

    del_timer_sync(&mddev->safemode_timer);
}
EXPORT_SYMBOL_GPL(mddev_suspend);

void mddev_resume(struct mddev *mddev)
{
    mddev->suspended = 0;
    wake_up(&mddev->sb_wait);
    mddev->pers->quiesce(mddev, 0);

    set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
    md_wakeup_thread(mddev->thread);
    md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
}
EXPORT_SYMBOL_GPL(mddev_resume);

int mddev_congested(struct mddev *mddev, int bits)
{
    return mddev->suspended;
}
EXPORT_SYMBOL(mddev_congested);

/*
 * Generic flush handling for md
 */

static void md_end_flush(struct bio *bio, int err)
{
    struct md_rdev *rdev = bio->bi_private;
    struct mddev *mddev = rdev->mddev;

    rdev_dec_pending(rdev, mddev);

    if (atomic_dec_and_test(&mddev->flush_pending)) {
        /* The pre-request flush has finished */
        queue_work(md_wq, &mddev->flush_work);
    }
    bio_put(bio);
}

static void md_submit_flush_data(struct work_struct *ws);

static void submit_flushes(struct work_struct *ws)
{
    struct mddev *mddev = container_of(ws, struct mddev, flush_work);
    struct md_rdev *rdev;

    INIT_WORK(&mddev->flush_work, md_submit_flush_data);
    atomic_set(&mddev->flush_pending, 1);
    rcu_read_lock();
    rdev_for_each_rcu(rdev, mddev)
        if (rdev->raid_disk >= 0 &&
            !test_bit(Faulty, &rdev->flags)) {
            /* Take two references, one is dropped
             * when request finishes, one after
             * we reclaim rcu_read_lock
             */
            struct bio *bi;
            atomic_inc(&rdev->nr_pending);
            atomic_inc(&rdev->nr_pending);
            rcu_read_unlock();
            bi = bio_alloc_mddev(GFP_NOIO, 0, mddev);
            bi->bi_end_io = md_end_flush;
            bi->bi_private = rdev;
            bi->bi_bdev = rdev->bdev;
            atomic_inc(&mddev->flush_pending);
            submit_bio(WRITE_FLUSH, bi);
            rcu_read_lock();
            rdev_dec_pending(rdev, mddev);
        }
    rcu_read_unlock();
    if (atomic_dec_and_test(&mddev->flush_pending))
        queue_work(md_wq, &mddev->flush_work);
}

static void md_submit_flush_data(struct work_struct *ws)
{
    struct mddev *mddev = container_of(ws, struct mddev, flush_work);
    struct bio *bio = mddev->flush_bio;

    if (bio->bi_size == 0)
        /* an empty barrier - all done */
        bio_endio(bio, 0);
    else {
        bio->bi_rw &= ~REQ_FLUSH;
        mddev->pers->make_request(mddev, bio);
    }

    mddev->flush_bio = NULL;
    wake_up(&mddev->sb_wait);
}

void md_flush_request(struct mddev *mddev, struct bio *bio)
{
    spin_lock_irq(&mddev->write_lock);
    wait_event_lock_irq(mddev->sb_wait,
                !mddev->flush_bio,
                mddev->write_lock, /*nothing*/);
    mddev->flush_bio = bio;
    spin_unlock_irq(&mddev->write_lock);

    INIT_WORK(&mddev->flush_work, submit_flushes);
    queue_work(md_wq, &mddev->flush_work);
}
EXPORT_SYMBOL(md_flush_request);

void md_unplug(struct blk_plug_cb *cb, bool from_schedule)
{
    struct mddev *mddev = cb->data;
    md_wakeup_thread(mddev->thread);
    kfree(cb);
}
EXPORT_SYMBOL(md_unplug);

static inline struct mddev *mddev_get(struct mddev *mddev)
{
    atomic_inc(&mddev->active);
    return mddev;
}

static void mddev_delayed_delete(struct work_struct *ws);

static void mddev_put(struct mddev *mddev)
{
    struct bio_set *bs = NULL;

    if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
        return;
    if (!mddev->raid_disks && list_empty(&mddev->disks) &&
        mddev->ctime == 0 && !mddev->hold_active) {
        /* Array is not configured at all, and not held active,
         * so destroy it */
        list_del_init(&mddev->all_mddevs);
        bs = mddev->bio_set;
        mddev->bio_set = NULL;
        if (mddev->gendisk) {
            /* We did a probe so need to clean up.  Call
             * queue_work inside the spinlock so that
             * flush_workqueue() after mddev_find will
             * succeed in waiting for the work to be done.
             */
            INIT_WORK(&mddev->del_work, mddev_delayed_delete);
            queue_work(md_misc_wq, &mddev->del_work);
        } else
            kfree(mddev);
    }
    spin_unlock(&all_mddevs_lock);
    if (bs)
        bioset_free(bs);
}

void mddev_init(struct mddev *mddev)
{
    mutex_init(&mddev->open_mutex);
    mutex_init(&mddev->reconfig_mutex);
    mutex_init(&mddev->bitmap_info.mutex);
    INIT_LIST_HEAD(&mddev->disks);
    INIT_LIST_HEAD(&mddev->all_mddevs);
    init_timer(&mddev->safemode_timer);
    atomic_set(&mddev->active, 1);
    atomic_set(&mddev->openers, 0);
    atomic_set(&mddev->active_io, 0);
    spin_lock_init(&mddev->write_lock);
    atomic_set(&mddev->flush_pending, 0);
    init_waitqueue_head(&mddev->sb_wait);
    init_waitqueue_head(&mddev->recovery_wait);
    mddev->reshape_position = MaxSector;
    mddev->reshape_backwards = 0;
    mddev->resync_min = 0;
    mddev->resync_max = MaxSector;
    mddev->level = LEVEL_NONE;
}
EXPORT_SYMBOL_GPL(mddev_init);

static struct mddev * mddev_find(dev_t unit)
{
    struct mddev *mddev, *new = NULL;

    if (unit && MAJOR(unit) != MD_MAJOR)
        unit &= ~((1<<MdpMinorShift)-1);

 retry:
    spin_lock(&all_mddevs_lock);

    if (unit) {
        list_for_each_entry(mddev, &all_mddevs, all_mddevs)
            if (mddev->unit == unit) {
                mddev_get(mddev);
                spin_unlock(&all_mddevs_lock);
                kfree(new);
                return mddev;
            }

        if (new) {
            list_add(&new->all_mddevs, &all_mddevs);
            spin_unlock(&all_mddevs_lock);
            new->hold_active = UNTIL_IOCTL;
            return new;
        }
    } else if (new) {
        /* find an unused unit number */
        static int next_minor = 512;
        int start = next_minor;
        int is_free = 0;
        int dev = 0;
        while (!is_free) {
            dev = MKDEV(MD_MAJOR, next_minor);
            next_minor++;
            if (next_minor > MINORMASK)
                next_minor = 0;
            if (next_minor == start) {
                /* Oh dear, all in use. */
                spin_unlock(&all_mddevs_lock);
                kfree(new);
                return NULL;
            }
                
            is_free = 1;
            list_for_each_entry(mddev, &all_mddevs, all_mddevs)
                if (mddev->unit == dev) {
                    is_free = 0;
                    break;
                }
        }
        new->unit = dev;
        new->md_minor = MINOR(dev);
        new->hold_active = UNTIL_STOP;
        list_add(&new->all_mddevs, &all_mddevs);
        spin_unlock(&all_mddevs_lock);
        return new;
    }
    spin_unlock(&all_mddevs_lock);

    new = kzalloc(sizeof(*new), GFP_KERNEL);
    if (!new)
        return NULL;

    new->unit = unit;
    if (MAJOR(unit) == MD_MAJOR)
        new->md_minor = MINOR(unit);
    else
        new->md_minor = MINOR(unit) >> MdpMinorShift;

    mddev_init(new);

    goto retry;
}

static inline int mddev_lock(struct mddev * mddev)
{
    return mutex_lock_interruptible(&mddev->reconfig_mutex);
}

static inline int mddev_is_locked(struct mddev *mddev)
{
    return mutex_is_locked(&mddev->reconfig_mutex);
}

static inline int mddev_trylock(struct mddev * mddev)
{
    return mutex_trylock(&mddev->reconfig_mutex);
}

static struct attribute_group md_redundancy_group;

static void mddev_unlock(struct mddev * mddev)
{
    if (mddev->to_remove) {
        /* These cannot be removed under reconfig_mutex as
         * an access to the files will try to take reconfig_mutex
         * while holding the file unremovable, which leads to
         * a deadlock.
         * So hold set sysfs_active while the remove in happeing,
         * and anything else which might set ->to_remove or my
         * otherwise change the sysfs namespace will fail with
         * -EBUSY if sysfs_active is still set.
         * We set sysfs_active under reconfig_mutex and elsewhere
         * test it under the same mutex to ensure its correct value
         * is seen.
         */
        struct attribute_group *to_remove = mddev->to_remove;
        mddev->to_remove = NULL;
        mddev->sysfs_active = 1;
        mutex_unlock(&mddev->reconfig_mutex);

        if (mddev->kobj.sd) {
            if (to_remove != &md_redundancy_group)
                sysfs_remove_group(&mddev->kobj, to_remove);
            if (mddev->pers == NULL ||
                mddev->pers->sync_request == NULL) {
                sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
                if (mddev->sysfs_action)
                    sysfs_put(mddev->sysfs_action);
                mddev->sysfs_action = NULL;
            }
        }
        mddev->sysfs_active = 0;
    } else
        mutex_unlock(&mddev->reconfig_mutex);

    /* As we've dropped the mutex we need a spinlock to
     * make sure the thread doesn't disappear
     */
    spin_lock(&pers_lock);
    md_wakeup_thread(mddev->thread);
    spin_unlock(&pers_lock);
}

static struct md_rdev * find_rdev_nr(struct mddev *mddev, int nr)
{
    struct md_rdev *rdev;

    rdev_for_each(rdev, mddev)
        if (rdev->desc_nr == nr)
            return rdev;

    return NULL;
}

static struct md_rdev *find_rdev_nr_rcu(struct mddev *mddev, int nr)
{
    struct md_rdev *rdev;

    rdev_for_each_rcu(rdev, mddev)
        if (rdev->desc_nr == nr)
            return rdev;

    return NULL;
}

static struct md_rdev *find_rdev(struct mddev *mddev, dev_t dev)
{
    struct md_rdev *rdev;

    rdev_for_each(rdev, mddev)
        if (rdev->bdev->bd_dev == dev)
            return rdev;

    return NULL;
}

static struct md_rdev *find_rdev_rcu(struct mddev *mddev, dev_t dev)
{
    struct md_rdev *rdev;

    rdev_for_each_rcu(rdev, mddev)
        if (rdev->bdev->bd_dev == dev)
            return rdev;

    return NULL;
}

static struct md_personality *find_pers(int level, char *clevel)
{
    struct md_personality *pers;
    list_for_each_entry(pers, &pers_list, list) {
        if (level != LEVEL_NONE && pers->level == level)
            return pers;
        if (strcmp(pers->name, clevel)==0)
            return pers;
    }
    return NULL;
}

/* return the offset of the super block in 512byte sectors */
static inline sector_t calc_dev_sboffset(struct md_rdev *rdev)
{
    sector_t num_sectors = i_size_read(rdev->bdev->bd_inode) / 512;
    return MD_NEW_SIZE_SECTORS(num_sectors);
}

static int alloc_disk_sb(struct md_rdev * rdev)
{
    if (rdev->sb_page)
        MD_BUG();

    rdev->sb_page = alloc_page(GFP_KERNEL);
    if (!rdev->sb_page) {
        printk(KERN_ALERT "md: out of memory.\n");
        return -ENOMEM;
    }

    return 0;
}

void md_rdev_clear(struct md_rdev *rdev)
{
    if (rdev->sb_page) {
        put_page(rdev->sb_page);
        rdev->sb_loaded = 0;
        rdev->sb_page = NULL;
        rdev->sb_start = 0;
        rdev->sectors = 0;
    }
    if (rdev->bb_page) {
        put_page(rdev->bb_page);
        rdev->bb_page = NULL;
    }
    kfree(rdev->badblocks.page);
    rdev->badblocks.page = NULL;
}
EXPORT_SYMBOL_GPL(md_rdev_clear);

static void super_written(struct bio *bio, int error)
{
    struct md_rdev *rdev = bio->bi_private;
    struct mddev *mddev = rdev->mddev;

    if (error || !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
        printk("md: super_written gets error=%d, uptodate=%d\n",
               error, test_bit(BIO_UPTODATE, &bio->bi_flags));
        WARN_ON(test_bit(BIO_UPTODATE, &bio->bi_flags));
        md_error(mddev, rdev);
    }

    if (atomic_dec_and_test(&mddev->pending_writes))
        wake_up(&mddev->sb_wait);
    bio_put(bio);
}

void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
           sector_t sector, int size, struct page *page)
{
    /* write first size bytes of page to sector of rdev
     * Increment mddev->pending_writes before returning
     * and decrement it on completion, waking up sb_wait
     * if zero is reached.
     * If an error occurred, call md_error
     */
    struct bio *bio = bio_alloc_mddev(GFP_NOIO, 1, mddev);

    bio->bi_bdev = rdev->meta_bdev ? rdev->meta_bdev : rdev->bdev;
    bio->bi_sector = sector;
    bio_add_page(bio, page, size, 0);
    bio->bi_private = rdev;
    bio->bi_end_io = super_written;

    atomic_inc(&mddev->pending_writes);
    submit_bio(WRITE_FLUSH_FUA, bio);
}

void md_super_wait(struct mddev *mddev)
{
    /* wait for all superblock writes that were scheduled to complete */
    DEFINE_WAIT(wq);
    for(;;) {
        prepare_to_wait(&mddev->sb_wait, &wq, TASK_UNINTERRUPTIBLE);
        if (atomic_read(&mddev->pending_writes)==0)
            break;
        schedule();
    }
    finish_wait(&mddev->sb_wait, &wq);
}

static void bi_complete(struct bio *bio, int error)
{
    complete((struct completion*)bio->bi_private);
}

int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
         struct page *page, int rw, bool metadata_op)
{
    struct bio *bio = bio_alloc_mddev(GFP_NOIO, 1, rdev->mddev);
    struct completion event;
    int ret;

    rw |= REQ_SYNC;

    bio->bi_bdev = (metadata_op && rdev->meta_bdev) ?
        rdev->meta_bdev : rdev->bdev;
    if (metadata_op)
        bio->bi_sector = sector + rdev->sb_start;
    else if (rdev->mddev->reshape_position != MaxSector &&
         (rdev->mddev->reshape_backwards ==
          (sector >= rdev->mddev->reshape_position)))
        bio->bi_sector = sector + rdev->new_data_offset;
    else
        bio->bi_sector = sector + rdev->data_offset;
    bio_add_page(bio, page, size, 0);
    init_completion(&event);
    bio->bi_private = &event;
    bio->bi_end_io = bi_complete;
    submit_bio(rw, bio);
    wait_for_completion(&event);

    ret = test_bit(BIO_UPTODATE, &bio->bi_flags);
    bio_put(bio);
    return ret;
}
EXPORT_SYMBOL_GPL(sync_page_io);

static int read_disk_sb(struct md_rdev * rdev, int size)
{
    char b[BDEVNAME_SIZE];
    if (!rdev->sb_page) {
        MD_BUG();
        return -EINVAL;
    }
    if (rdev->sb_loaded)
        return 0;


    if (!sync_page_io(rdev, 0, size, rdev->sb_page, READ, true))
        goto fail;
    rdev->sb_loaded = 1;
    return 0;

fail:
    printk(KERN_WARNING "md: disabled device %s, could not read superblock.\n",
        bdevname(rdev->bdev,b));
    return -EINVAL;
}

static int uuid_equal(mdp_super_t *sb1, mdp_super_t *sb2)
{
    return  sb1->set_uuid0 == sb2->set_uuid0 &&
        sb1->set_uuid1 == sb2->set_uuid1 &&
        sb1->set_uuid2 == sb2->set_uuid2 &&
        sb1->set_uuid3 == sb2->set_uuid3;
}

static int sb_equal(mdp_super_t *sb1, mdp_super_t *sb2)
{
    int ret;
    mdp_super_t *tmp1, *tmp2;

    tmp1 = kmalloc(sizeof(*tmp1),GFP_KERNEL);
    tmp2 = kmalloc(sizeof(*tmp2),GFP_KERNEL);

    if (!tmp1 || !tmp2) {
        ret = 0;
        printk(KERN_INFO "md.c sb_equal(): failed to allocate memory!\n");
        goto abort;
    }

    *tmp1 = *sb1;
    *tmp2 = *sb2;

    /*
     * nr_disks is not constant
     */
    tmp1->nr_disks = 0;
    tmp2->nr_disks = 0;

    ret = (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4) == 0);
abort:
    kfree(tmp1);
    kfree(tmp2);
    return ret;
}


static u32 md_csum_fold(u32 csum)
{
    csum = (csum & 0xffff) + (csum >> 16);
    return (csum & 0xffff) + (csum >> 16);
}

static unsigned int calc_sb_csum(mdp_super_t * sb)
{
    u64 newcsum = 0;
    u32 *sb32 = (u32*)sb;
    int i;
    unsigned int disk_csum, csum;

    disk_csum = sb->sb_csum;
    sb->sb_csum = 0;

    for (i = 0; i < MD_SB_BYTES/4 ; i++)
        newcsum += sb32[i];
    csum = (newcsum & 0xffffffff) + (newcsum>>32);


#ifdef CONFIG_ALPHA
    /* This used to use csum_partial, which was wrong for several
     * reasons including that different results are returned on
     * different architectures.  It isn't critical that we get exactly
     * the same return value as before (we always csum_fold before
     * testing, and that removes any differences).  However as we
     * know that csum_partial always returned a 16bit value on
     * alphas, do a fold to maximise conformity to previous behaviour.
     */
    sb->sb_csum = md_csum_fold(disk_csum);
#else
    sb->sb_csum = disk_csum;
#endif
    return csum;
}


/*
 * Handle superblock details.
 * We want to be able to handle multiple superblock formats
 * so we have a common interface to them all, and an array of
 * different handlers.
 * We rely on user-space to write the initial superblock, and support
 * reading and updating of superblocks.
 * Interface methods are:
 *   int load_super(struct md_rdev *dev, struct md_rdev *refdev, int minor_version)
 *      loads and validates a superblock on dev.
 *      if refdev != NULL, compare superblocks on both devices
 *    Return:
 *      0 - dev has a superblock that is compatible with refdev
 *      1 - dev has a superblock that is compatible and newer than refdev
 *          so dev should be used as the refdev in future
 *     -EINVAL superblock incompatible or invalid
 *     -othererror e.g. -EIO
 *
 *   int validate_super(struct mddev *mddev, struct md_rdev *dev)
 *      Verify that dev is acceptable into mddev.
 *       The first time, mddev->raid_disks will be 0, and data from
 *       dev should be merged in.  Subsequent calls check that dev
 *       is new enough.  Return 0 or -EINVAL
 *
 *   void sync_super(struct mddev *mddev, struct md_rdev *dev)
 *     Update the superblock for rdev with data in mddev
 *     This does not write to disc.
 *
 */

struct super_type  {
    char            *name;
    struct module       *owner;
    int         (*load_super)(struct md_rdev *rdev,
                      struct md_rdev *refdev,
                      int minor_version);
    int         (*validate_super)(struct mddev *mddev,
                          struct md_rdev *rdev);
    void            (*sync_super)(struct mddev *mddev,
                      struct md_rdev *rdev);
    unsigned long long  (*rdev_size_change)(struct md_rdev *rdev,
                        sector_t num_sectors);
    int         (*allow_new_offset)(struct md_rdev *rdev,
                        unsigned long long new_offset);
};

/*
 * Check that the given mddev has no bitmap.
 *
 * This function is called from the run method of all personalities that do not
 * support bitmaps. It prints an error message and returns non-zero if mddev
 * has a bitmap. Otherwise, it returns 0.
 *
 */
int md_check_no_bitmap(struct mddev *mddev)
{
    if (!mddev->bitmap_info.file && !mddev->bitmap_info.offset)
        return 0;
    printk(KERN_ERR "%s: bitmaps are not supported for %s\n",
        mdname(mddev), mddev->pers->name);
    return 1;
}
EXPORT_SYMBOL(md_check_no_bitmap);

/*
 * load_super for 0.90.0 
 */
static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
{
    char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
    mdp_super_t *sb;
    int ret;

    /*
     * Calculate the position of the superblock (512byte sectors),
     * it's at the end of the disk.
     *
     * It also happens to be a multiple of 4Kb.
     */
    rdev->sb_start = calc_dev_sboffset(rdev);

    ret = read_disk_sb(rdev, MD_SB_BYTES);
    if (ret) return ret;

    ret = -EINVAL;

    bdevname(rdev->bdev, b);
    sb = page_address(rdev->sb_page);

    if (sb->md_magic != MD_SB_MAGIC) {
        printk(KERN_ERR "md: invalid raid superblock magic on %s\n",
               b);
        goto abort;
    }

    if (sb->major_version != 0 ||
        sb->minor_version < 90 ||
        sb->minor_version > 91) {
        printk(KERN_WARNING "Bad version number %d.%d on %s\n",
            sb->major_version, sb->minor_version,
            b);
        goto abort;
    }

    if (sb->raid_disks <= 0)
        goto abort;

    if (md_csum_fold(calc_sb_csum(sb)) != md_csum_fold(sb->sb_csum)) {
        printk(KERN_WARNING "md: invalid superblock checksum on %s\n",
            b);
        goto abort;
    }

    rdev->preferred_minor = sb->md_minor;
    rdev->data_offset = 0;
    rdev->new_data_offset = 0;
    rdev->sb_size = MD_SB_BYTES;
    rdev->badblocks.shift = -1;

    if (sb->level == LEVEL_MULTIPATH)
        rdev->desc_nr = -1;
    else
        rdev->desc_nr = sb->this_disk.number;

    if (!refdev) {
        ret = 1;
    } else {
        __u64 ev1, ev2;
        mdp_super_t *refsb = page_address(refdev->sb_page);
        if (!uuid_equal(refsb, sb)) {
            printk(KERN_WARNING "md: %s has different UUID to %s\n",
                b, bdevname(refdev->bdev,b2));
            goto abort;
        }
        if (!sb_equal(refsb, sb)) {
            printk(KERN_WARNING "md: %s has same UUID"
                   " but different superblock to %s\n",
                   b, bdevname(refdev->bdev, b2));
            goto abort;
        }
        ev1 = md_event(sb);
        ev2 = md_event(refsb);
        if (ev1 > ev2)
            ret = 1;
        else 
            ret = 0;
    }
    rdev->sectors = rdev->sb_start;
    /* Limit to 4TB as metadata cannot record more than that.
     * (not needed for Linear and RAID0 as metadata doesn't
     * record this size)
     */
    if (rdev->sectors >= (2ULL << 32) && sb->level >= 1)
        rdev->sectors = (2ULL << 32) - 2;

    if (rdev->sectors < ((sector_t)sb->size) * 2 && sb->level >= 1)
        /* "this cannot possibly happen" ... */
        ret = -EINVAL;

 abort:
    return ret;
}

/*
 * validate_super for 0.90.0
 */
static int super_90_validate(struct mddev *mddev, struct md_rdev *rdev)
{
    mdp_disk_t *desc;
    mdp_super_t *sb = page_address(rdev->sb_page);
    __u64 ev1 = md_event(sb);

    rdev->raid_disk = -1;
    clear_bit(Faulty, &rdev->flags);
    clear_bit(In_sync, &rdev->flags);
    clear_bit(WriteMostly, &rdev->flags);

    if (mddev->raid_disks == 0) {
        mddev->major_version = 0;
        mddev->minor_version = sb->minor_version;
        mddev->patch_version = sb->patch_version;
        mddev->external = 0;
        mddev->chunk_sectors = sb->chunk_size >> 9;
        mddev->ctime = sb->ctime;
        mddev->utime = sb->utime;
        mddev->level = sb->level;
        mddev->clevel[0] = 0;
        mddev->layout = sb->layout;
        mddev->raid_disks = sb->raid_disks;
        mddev->dev_sectors = ((sector_t)sb->size) * 2;
        mddev->events = ev1;
        mddev->bitmap_info.offset = 0;
        mddev->bitmap_info.space = 0;
        /* bitmap can use 60 K after the 4K superblocks */
        mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
        mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
        mddev->reshape_backwards = 0;

        if (mddev->minor_version >= 91) {
            mddev->reshape_position = sb->reshape_position;
            mddev->delta_disks = sb->delta_disks;
            mddev->new_level = sb->new_level;
            mddev->new_layout = sb->new_layout;
            mddev->new_chunk_sectors = sb->new_chunk >> 9;
            if (mddev->delta_disks < 0)
                mddev->reshape_backwards = 1;
        } else {
            mddev->reshape_position = MaxSector;
            mddev->delta_disks = 0;
            mddev->new_level = mddev->level;
            mddev->new_layout = mddev->layout;
            mddev->new_chunk_sectors = mddev->chunk_sectors;
        }

        if (sb->state & (1<<MD_SB_CLEAN))
            mddev->recovery_cp = MaxSector;
        else {
            if (sb->events_hi == sb->cp_events_hi && 
                sb->events_lo == sb->cp_events_lo) {
                mddev->recovery_cp = sb->recovery_cp;
            } else
                mddev->recovery_cp = 0;
        }

        memcpy(mddev->uuid+0, &sb->set_uuid0, 4);
        memcpy(mddev->uuid+4, &sb->set_uuid1, 4);
        memcpy(mddev->uuid+8, &sb->set_uuid2, 4);
        memcpy(mddev->uuid+12,&sb->set_uuid3, 4);

        mddev->max_disks = MD_SB_DISKS;

        if (sb->state & (1<<MD_SB_BITMAP_PRESENT) &&
            mddev->bitmap_info.file == NULL) {
            mddev->bitmap_info.offset =
                mddev->bitmap_info.default_offset;
            mddev->bitmap_info.space =
                mddev->bitmap_info.space;
        }

    } else if (mddev->pers == NULL) {
        /* Insist on good event counter while assembling, except
         * for spares (which don't need an event count) */
        ++ev1;
        if (sb->disks[rdev->desc_nr].state & (
                (1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)))
            if (ev1 < mddev->events) 
                return -EINVAL;
    } else if (mddev->bitmap) {
        /* if adding to array with a bitmap, then we can accept an
         * older device ... but not too old.
         */
        if (ev1 < mddev->bitmap->events_cleared)
            return 0;
    } else {
        if (ev1 < mddev->events)
            /* just a hot-add of a new device, leave raid_disk at -1 */
            return 0;
    }

    if (mddev->level != LEVEL_MULTIPATH) {
        desc = sb->disks + rdev->desc_nr;

        if (desc->state & (1<<MD_DISK_FAULTY))
            set_bit(Faulty, &rdev->flags);
        else if (desc->state & (1<<MD_DISK_SYNC) /* &&
                desc->raid_disk < mddev->raid_disks */) {
            set_bit(In_sync, &rdev->flags);
            rdev->raid_disk = desc->raid_disk;
        } else if (desc->state & (1<<MD_DISK_ACTIVE)) {
            /* active but not in sync implies recovery up to
             * reshape position.  We don't know exactly where
             * that is, so set to zero for now */
            if (mddev->minor_version >= 91) {
                rdev->recovery_offset = 0;
                rdev->raid_disk = desc->raid_disk;
            }
        }
        if (desc->state & (1<<MD_DISK_WRITEMOSTLY))
            set_bit(WriteMostly, &rdev->flags);
    } else /* MULTIPATH are always insync */
        set_bit(In_sync, &rdev->flags);
    return 0;
}

/*
 * sync_super for 0.90.0
 */
static void super_90_sync(struct mddev *mddev, struct md_rdev *rdev)
{
    mdp_super_t *sb;
    struct md_rdev *rdev2;
    int next_spare = mddev->raid_disks;


    /* make rdev->sb match mddev data..
     *
     * 1/ zero out disks
     * 2/ Add info for each disk, keeping track of highest desc_nr (next_spare);
     * 3/ any empty disks < next_spare become removed
     *
     * disks[0] gets initialised to REMOVED because
     * we cannot be sure from other fields if it has
     * been initialised or not.
     */
    int i;
    int active=0, working=0,failed=0,spare=0,nr_disks=0;

    rdev->sb_size = MD_SB_BYTES;

    sb = page_address(rdev->sb_page);

    memset(sb, 0, sizeof(*sb));

    sb->md_magic = MD_SB_MAGIC;
    sb->major_version = mddev->major_version;
    sb->patch_version = mddev->patch_version;
    sb->gvalid_words  = 0; /* ignored */
    memcpy(&sb->set_uuid0, mddev->uuid+0, 4);
    memcpy(&sb->set_uuid1, mddev->uuid+4, 4);
    memcpy(&sb->set_uuid2, mddev->uuid+8, 4);
    memcpy(&sb->set_uuid3, mddev->uuid+12,4);

    sb->ctime = mddev->ctime;
    sb->level = mddev->level;
    sb->size = mddev->dev_sectors / 2;
    sb->raid_disks = mddev->raid_disks;
    sb->md_minor = mddev->md_minor;
    sb->not_persistent = 0;
    sb->utime = mddev->utime;
    sb->state = 0;
    sb->events_hi = (mddev->events>>32);
    sb->events_lo = (u32)mddev->events;

    if (mddev->reshape_position == MaxSector)
        sb->minor_version = 90;
    else {
        sb->minor_version = 91;
        sb->reshape_position = mddev->reshape_position;
        sb->new_level = mddev->new_level;
        sb->delta_disks = mddev->delta_disks;
        sb->new_layout = mddev->new_layout;
        sb->new_chunk = mddev->new_chunk_sectors << 9;
    }
    mddev->minor_version = sb->minor_version;
    if (mddev->in_sync)
    {
        sb->recovery_cp = mddev->recovery_cp;
        sb->cp_events_hi = (mddev->events>>32);
        sb->cp_events_lo = (u32)mddev->events;
        if (mddev->recovery_cp == MaxSector)
            sb->state = (1<< MD_SB_CLEAN);
    } else
        sb->recovery_cp = 0;

    sb->layout = mddev->layout;
    sb->chunk_size = mddev->chunk_sectors << 9;

    if (mddev->bitmap && mddev->bitmap_info.file == NULL)
        sb->state |= (1<<MD_SB_BITMAP_PRESENT);

    sb->disks[0].state = (1<<MD_DISK_REMOVED);
    rdev_for_each(rdev2, mddev) {
        mdp_disk_t *d;
        int desc_nr;
        int is_active = test_bit(In_sync, &rdev2->flags);

        if (rdev2->raid_disk >= 0 &&
            sb->minor_version >= 91)
            /* we have nowhere to store the recovery_offset,
             * but if it is not below the reshape_position,
             * we can piggy-back on that.
             */
            is_active = 1;
        if (rdev2->raid_disk < 0 ||
            test_bit(Faulty, &rdev2->flags))
            is_active = 0;
        if (is_active)
            desc_nr = rdev2->raid_disk;
        else
            desc_nr = next_spare++;
        rdev2->desc_nr = desc_nr;
        d = &sb->disks[rdev2->desc_nr];
        nr_disks++;
        d->number = rdev2->desc_nr;
        d->major = MAJOR(rdev2->bdev->bd_dev);
        d->minor = MINOR(rdev2->bdev->bd_dev);
        if (is_active)
            d->raid_disk = rdev2->raid_disk;
        else
            d->raid_disk = rdev2->desc_nr; /* compatibility */
        if (test_bit(Faulty, &rdev2->flags))
            d->state = (1<<MD_DISK_FAULTY);
        else if (is_active) {
            d->state = (1<<MD_DISK_ACTIVE);
            if (test_bit(In_sync, &rdev2->flags))
                d->state |= (1<<MD_DISK_SYNC);
            active++;
            working++;
        } else {
            d->state = 0;
            spare++;
            working++;
        }
        if (test_bit(WriteMostly, &rdev2->flags))
            d->state |= (1<<MD_DISK_WRITEMOSTLY);
    }
    /* now set the "removed" and "faulty" bits on any missing devices */
    for (i=0 ; i < mddev->raid_disks ; i++) {
        mdp_disk_t *d = &sb->disks[i];
        if (d->state == 0 && d->number == 0) {
            d->number = i;
            d->raid_disk = i;
            d->state = (1<<MD_DISK_REMOVED);
            d->state |= (1<<MD_DISK_FAULTY);
            failed++;
        }
    }
    sb->nr_disks = nr_disks;
    sb->active_disks = active;
    sb->working_disks = working;
    sb->failed_disks = failed;
    sb->spare_disks = spare;

    sb->this_disk = sb->disks[rdev->desc_nr];
    sb->sb_csum = calc_sb_csum(sb);
}

/*
 * rdev_size_change for 0.90.0
 */
static unsigned long long
super_90_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
{
    if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
        return 0; /* component must fit device */
    if (rdev->mddev->bitmap_info.offset)
        return 0; /* can't move bitmap */
    rdev->sb_start = calc_dev_sboffset(rdev);
    if (!num_sectors || num_sectors > rdev->sb_start)
        num_sectors = rdev->sb_start;
    /* Limit to 4TB as metadata cannot record more than that.
     * 4TB == 2^32 KB, or 2*2^32 sectors.
     */
    if (num_sectors >= (2ULL << 32) && rdev->mddev->level >= 1)
        num_sectors = (2ULL << 32) - 2;
    md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
               rdev->sb_page);
    md_super_wait(rdev->mddev);
    return num_sectors;
}

static int
super_90_allow_new_offset(struct md_rdev *rdev, unsigned long long new_offset)
{
    /* non-zero offset changes not possible with v0.90 */
    return new_offset == 0;
}

/*
 * version 1 superblock
 */

static __le32 calc_sb_1_csum(struct mdp_superblock_1 * sb)
{
    __le32 disk_csum;
    u32 csum;
    unsigned long long newcsum;
    int size = 256 + le32_to_cpu(sb->max_dev)*2;
    __le32 *isuper = (__le32*)sb;
    int i;

    disk_csum = sb->sb_csum;
    sb->sb_csum = 0;
    newcsum = 0;
    for (i=0; size>=4; size -= 4 )
        newcsum += le32_to_cpu(*isuper++);

    if (size == 2)
        newcsum += le16_to_cpu(*(__le16*) isuper);

    csum = (newcsum & 0xffffffff) + (newcsum >> 32);
    sb->sb_csum = disk_csum;
    return cpu_to_le32(csum);
}

static int md_set_badblocks(struct badblocks *bb, sector_t s, int sectors,
                int acknowledged);
static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
{
    struct mdp_superblock_1 *sb;
    int ret;
    sector_t sb_start;
    sector_t sectors;
    char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
    int bmask;

    /*
     * Calculate the position of the superblock in 512byte sectors.
     * It is always aligned to a 4K boundary and
     * depeding on minor_version, it can be:
     * 0: At least 8K, but less than 12K, from end of device
     * 1: At start of device
     * 2: 4K from start of device.
     */
    switch(minor_version) {
    case 0:
        sb_start = i_size_read(rdev->bdev->bd_inode) >> 9;
        sb_start -= 8*2;
        sb_start &= ~(sector_t)(4*2-1);
        break;
    case 1:
        sb_start = 0;
        break;
    case 2:
        sb_start = 8;
        break;
    default:
        return -EINVAL;
    }
    rdev->sb_start = sb_start;

    /* superblock is rarely larger than 1K, but it can be larger,
     * and it is safe to read 4k, so we do that
     */
    ret = read_disk_sb(rdev, 4096);
    if (ret) return ret;


    sb = page_address(rdev->sb_page);

    if (sb->magic != cpu_to_le32(MD_SB_MAGIC) ||
        sb->major_version != cpu_to_le32(1) ||
        le32_to_cpu(sb->max_dev) > (4096-256)/2 ||
        le64_to_cpu(sb->super_offset) != rdev->sb_start ||
        (le32_to_cpu(sb->feature_map) & ~MD_FEATURE_ALL) != 0)
        return -EINVAL;

    if (calc_sb_1_csum(sb) != sb->sb_csum) {
        printk("md: invalid superblock checksum on %s\n",
            bdevname(rdev->bdev,b));
        return -EINVAL;
    }
    if (le64_to_cpu(sb->data_size) < 10) {
        printk("md: data_size too small on %s\n",
               bdevname(rdev->bdev,b));
        return -EINVAL;
    }
    if (sb->pad0 ||
        sb->pad3[0] ||
        memcmp(sb->pad3, sb->pad3+1, sizeof(sb->pad3) - sizeof(sb->pad3[1])))
        /* Some padding is non-zero, might be a new feature */
        return -EINVAL;

    rdev->preferred_minor = 0xffff;
    rdev->data_offset = le64_to_cpu(sb->data_offset);
    rdev->new_data_offset = rdev->data_offset;
    if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE) &&
        (le32_to_cpu(sb->feature_map) & MD_FEATURE_NEW_OFFSET))
        rdev->new_data_offset += (s32)le32_to_cpu(sb->new_offset);
    atomic_set(&rdev->corrected_errors, le32_to_cpu(sb->cnt_corrected_read));

    rdev->sb_size = le32_to_cpu(sb->max_dev) * 2 + 256;
    bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
    if (rdev->sb_size & bmask)
        rdev->sb_size = (rdev->sb_size | bmask) + 1;

    if (minor_version
        && rdev->data_offset < sb_start + (rdev->sb_size/512))
        return -EINVAL;
    if (minor_version
        && rdev->new_data_offset < sb_start + (rdev->sb_size/512))
        return -EINVAL;

    if (sb->level == cpu_to_le32(LEVEL_MULTIPATH))
        rdev->desc_nr = -1;
    else
        rdev->desc_nr = le32_to_cpu(sb->dev_number);

    if (!rdev->bb_page) {
        rdev->bb_page = alloc_page(GFP_KERNEL);
        if (!rdev->bb_page)
            return -ENOMEM;
    }
    if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BAD_BLOCKS) &&
        rdev->badblocks.count == 0) {
        /* need to load the bad block list.
         * Currently we limit it to one page.
         */
        s32 offset;
        sector_t bb_sector;
        u64 *bbp;
        int i;
        int sectors = le16_to_cpu(sb->bblog_size);
        if (sectors > (PAGE_SIZE / 512))
            return -EINVAL;
        offset = le32_to_cpu(sb->bblog_offset);
        if (offset == 0)
            return -EINVAL;
        bb_sector = (long long)offset;
        if (!sync_page_io(rdev, bb_sector, sectors << 9,
                  rdev->bb_page, READ, true))
            return -EIO;
        bbp = (u64 *)page_address(rdev->bb_page);
        rdev->badblocks.shift = sb->bblog_shift;
        for (i = 0 ; i < (sectors << (9-3)) ; i++, bbp++) {
            u64 bb = le64_to_cpu(*bbp);
            int count = bb & (0x3ff);
            u64 sector = bb >> 10;
            sector <<= sb->bblog_shift;
            count <<= sb->bblog_shift;
            if (bb + 1 == 0)
                break;
            if (md_set_badblocks(&rdev->badblocks,
                         sector, count, 1) == 0)
                return -EINVAL;
        }
    } else if (sb->bblog_offset == 0)
        rdev->badblocks.shift = -1;

    if (!refdev) {
        ret = 1;
    } else {
        __u64 ev1, ev2;
        struct mdp_superblock_1 *refsb = page_address(refdev->sb_page);

        if (memcmp(sb->set_uuid, refsb->set_uuid, 16) != 0 ||
            sb->level != refsb->level ||
            sb->layout != refsb->layout ||
            sb->chunksize != refsb->chunksize) {
            printk(KERN_WARNING "md: %s has strangely different"
                " superblock to %s\n",
                bdevname(rdev->bdev,b),
                bdevname(refdev->bdev,b2));
            return -EINVAL;
        }
        ev1 = le64_to_cpu(sb->events);
        ev2 = le64_to_cpu(refsb->events);

        if (ev1 > ev2)
            ret = 1;
        else
            ret = 0;
    }
    if (minor_version) {
        sectors = (i_size_read(rdev->bdev->bd_inode) >> 9);
        sectors -= rdev->data_offset;
    } else
        sectors = rdev->sb_start;
    if (sectors < le64_to_cpu(sb->data_size))
        return -EINVAL;
    rdev->sectors = le64_to_cpu(sb->data_size);
    return ret;
}

static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)
{
    struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
    __u64 ev1 = le64_to_cpu(sb->events);

    rdev->raid_disk = -1;
    clear_bit(Faulty, &rdev->flags);
    clear_bit(In_sync, &rdev->flags);
    clear_bit(WriteMostly, &rdev->flags);

    if (mddev->raid_disks == 0) {
        mddev->major_version = 1;
        mddev->patch_version = 0;
        mddev->external = 0;
        mddev->chunk_sectors = le32_to_cpu(sb->chunksize);
        mddev->ctime = le64_to_cpu(sb->ctime) & ((1ULL << 32)-1);
        mddev->utime = le64_to_cpu(sb->utime) & ((1ULL << 32)-1);
        mddev->level = le32_to_cpu(sb->level);
        mddev->clevel[0] = 0;
        mddev->layout = le32_to_cpu(sb->layout);
        mddev->raid_disks = le32_to_cpu(sb->raid_disks);
        mddev->dev_sectors = le64_to_cpu(sb->size);
        mddev->events = ev1;
        mddev->bitmap_info.offset = 0;
        mddev->bitmap_info.space = 0;
        /* Default location for bitmap is 1K after superblock
         * using 3K - total of 4K
         */
        mddev->bitmap_info.default_offset = 1024 >> 9;
        mddev->bitmap_info.default_space = (4096-1024) >> 9;
        mddev->reshape_backwards = 0;

        mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
        memcpy(mddev->uuid, sb->set_uuid, 16);

        mddev->max_disks =  (4096-256)/2;

        if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BITMAP_OFFSET) &&
            mddev->bitmap_info.file == NULL) {
            mddev->bitmap_info.offset =
                (__s32)le32_to_cpu(sb->bitmap_offset);
            /* Metadata doesn't record how much space is available.
             * For 1.0, we assume we can use up to the superblock
             * if before, else to 4K beyond superblock.
             * For others, assume no change is possible.
             */
            if (mddev->minor_version > 0)
                mddev->bitmap_info.space = 0;
            else if (mddev->bitmap_info.offset > 0)
                mddev->bitmap_info.space =
                    8 - mddev->bitmap_info.offset;
            else
                mddev->bitmap_info.space =
                    -mddev->bitmap_info.offset;
        }

        if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
            mddev->reshape_position = le64_to_cpu(sb->reshape_position);
            mddev->delta_disks = le32_to_cpu(sb->delta_disks);
            mddev->new_level = le32_to_cpu(sb->new_level);
            mddev->new_layout = le32_to_cpu(sb->new_layout);
            mddev->new_chunk_sectors = le32_to_cpu(sb->new_chunk);
            if (mddev->delta_disks < 0 ||
                (mddev->delta_disks == 0 &&
                 (le32_to_cpu(sb->feature_map)
                  & MD_FEATURE_RESHAPE_BACKWARDS)))
                mddev->reshape_backwards = 1;
        } else {
            mddev->reshape_position = MaxSector;
            mddev->delta_disks = 0;
            mddev->new_level = mddev->level;
            mddev->new_layout = mddev->layout;
            mddev->new_chunk_sectors = mddev->chunk_sectors;
        }

    } else if (mddev->pers == NULL) {
        /* Insist of good event counter while assembling, except for
         * spares (which don't need an event count) */
        ++ev1;
        if (rdev->desc_nr >= 0 &&
            rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
            le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < 0xfffe)
            if (ev1 < mddev->events)
                return -EINVAL;
    } else if (mddev->bitmap) {
        /* If adding to array with a bitmap, then we can accept an
         * older device, but not too old.
         */
        if (ev1 < mddev->bitmap->events_cleared)
            return 0;
    } else {
        if (ev1 < mddev->events)
            /* just a hot-add of a new device, leave raid_disk at -1 */
            return 0;
    }
    if (mddev->level != LEVEL_MULTIPATH) {
        int role;
        if (rdev->desc_nr < 0 ||
            rdev->desc_nr >= le32_to_cpu(sb->max_dev)) {
            role = 0xffff;
            rdev->desc_nr = -1;
        } else
            role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
        switch(role) {
        case 0xffff: /* spare */
            break;
        case 0xfffe: /* faulty */
            set_bit(Faulty, &rdev->flags);
            break;
        default:
            if ((le32_to_cpu(sb->feature_map) &
                 MD_FEATURE_RECOVERY_OFFSET))
                rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
            else
                set_bit(In_sync, &rdev->flags);
            rdev->raid_disk = role;
            break;
        }
        if (sb->devflags & WriteMostly1)
            set_bit(WriteMostly, &rdev->flags);
        if (le32_to_cpu(sb->feature_map) & MD_FEATURE_REPLACEMENT)
            set_bit(Replacement, &rdev->flags);
    } else /* MULTIPATH are always insync */
        set_bit(In_sync, &rdev->flags);

    return 0;
}

static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
{
    struct mdp_superblock_1 *sb;
    struct md_rdev *rdev2;
    int max_dev, i;
    /* make rdev->sb match mddev and rdev data. */

    sb = page_address(rdev->sb_page);

    sb->feature_map = 0;
    sb->pad0 = 0;
    sb->recovery_offset = cpu_to_le64(0);
    memset(sb->pad3, 0, sizeof(sb->pad3));

    sb->utime = cpu_to_le64((__u64)mddev->utime);
    sb->events = cpu_to_le64(mddev->events);
    if (mddev->in_sync)
        sb->resync_offset = cpu_to_le64(mddev->recovery_cp);
    else
        sb->resync_offset = cpu_to_le64(0);

    sb->cnt_corrected_read = cpu_to_le32(atomic_read(&rdev->corrected_errors));

    sb->raid_disks = cpu_to_le32(mddev->raid_disks);
    sb->size = cpu_to_le64(mddev->dev_sectors);
    sb->chunksize = cpu_to_le32(mddev->chunk_sectors);
    sb->level = cpu_to_le32(mddev->level);
    sb->layout = cpu_to_le32(mddev->layout);

    if (test_bit(WriteMostly, &rdev->flags))
        sb->devflags |= WriteMostly1;
    else
        sb->devflags &= ~WriteMostly1;
    sb->data_offset = cpu_to_le64(rdev->data_offset);
    sb->data_size = cpu_to_le64(rdev->sectors);

    if (mddev->bitmap && mddev->bitmap_info.file == NULL) {
        sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_info.offset);
        sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
    }

    if (rdev->raid_disk >= 0 &&
        !test_bit(In_sync, &rdev->flags)) {
        sb->feature_map |=
            cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET);
        sb->recovery_offset =
            cpu_to_le64(rdev->recovery_offset);
    }
    if (test_bit(Replacement, &rdev->flags))
        sb->feature_map |=
            cpu_to_le32(MD_FEATURE_REPLACEMENT);

    if (mddev->reshape_position != MaxSector) {
        sb->feature_map |= cpu_to_le32(MD_FEATURE_RESHAPE_ACTIVE);
        sb->reshape_position = cpu_to_le64(mddev->reshape_position);
        sb->new_layout = cpu_to_le32(mddev->new_layout);
        sb->delta_disks = cpu_to_le32(mddev->delta_disks);
        sb->new_level = cpu_to_le32(mddev->new_level);
        sb->new_chunk = cpu_to_le32(mddev->new_chunk_sectors);
        if (mddev->delta_disks == 0 &&
            mddev->reshape_backwards)
            sb->feature_map
                |= cpu_to_le32(MD_FEATURE_RESHAPE_BACKWARDS);
        if (rdev->new_data_offset != rdev->data_offset) {
            sb->feature_map
                |= cpu_to_le32(MD_FEATURE_NEW_OFFSET);
            sb->new_offset = cpu_to_le32((__u32)(rdev->new_data_offset
                                 - rdev->data_offset));
        }
    }

    if (rdev->badblocks.count == 0)
        /* Nothing to do for bad blocks*/ ;
    else if (sb->bblog_offset == 0)
        /* Cannot record bad blocks on this device */
        md_error(mddev, rdev);
    else {
        struct badblocks *bb = &rdev->badblocks;
        u64 *bbp = (u64 *)page_address(rdev->bb_page);
        u64 *p = bb->page;
        sb->feature_map |= cpu_to_le32(MD_FEATURE_BAD_BLOCKS);
        if (bb->changed) {
            unsigned seq;

retry:
            seq = read_seqbegin(&bb->lock);

            memset(bbp, 0xff, PAGE_SIZE);

            for (i = 0 ; i < bb->count ; i++) {
                u64 internal_bb = p[i];
                u64 store_bb = ((BB_OFFSET(internal_bb) << 10)
                        | BB_LEN(internal_bb));
                bbp[i] = cpu_to_le64(store_bb);
            }
            bb->changed = 0;
            if (read_seqretry(&bb->lock, seq))
                goto retry;

            bb->sector = (rdev->sb_start +
                      (int)le32_to_cpu(sb->bblog_offset));
            bb->size = le16_to_cpu(sb->bblog_size);
        }
    }

    max_dev = 0;
    rdev_for_each(rdev2, mddev)
        if (rdev2->desc_nr+1 > max_dev)
            max_dev = rdev2->desc_nr+1;

    if (max_dev > le32_to_cpu(sb->max_dev)) {
        int bmask;
        sb->max_dev = cpu_to_le32(max_dev);
        rdev->sb_size = max_dev * 2 + 256;
        bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
        if (rdev->sb_size & bmask)
            rdev->sb_size = (rdev->sb_size | bmask) + 1;
    } else
        max_dev = le32_to_cpu(sb->max_dev);

    for (i=0; i<max_dev;i++)
        sb->dev_roles[i] = cpu_to_le16(0xfffe);
    
    rdev_for_each(rdev2, mddev) {
        i = rdev2->desc_nr;
        if (test_bit(Faulty, &rdev2->flags))
            sb->dev_roles[i] = cpu_to_le16(0xfffe);
        else if (test_bit(In_sync, &rdev2->flags))
            sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
        else if (rdev2->raid_disk >= 0)
            sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
        else
            sb->dev_roles[i] = cpu_to_le16(0xffff);
    }

    sb->sb_csum = calc_sb_1_csum(sb);
}

static unsigned long long
super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
{
    struct mdp_superblock_1 *sb;
    sector_t max_sectors;
    if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
        return 0; /* component must fit device */
    if (rdev->data_offset != rdev->new_data_offset)
        return 0; /* too confusing */
    if (rdev->sb_start < rdev->data_offset) {
        /* minor versions 1 and 2; superblock before data */
        max_sectors = i_size_read(rdev->bdev->bd_inode) >> 9;
        max_sectors -= rdev->data_offset;
        if (!num_sectors || num_sectors > max_sectors)
            num_sectors = max_sectors;
    } else if (rdev->mddev->bitmap_info.offset) {
        /* minor version 0 with bitmap we can't move */
        return 0;
    } else {
        /* minor version 0; superblock after data */
        sector_t sb_start;
        sb_start = (i_size_read(rdev->bdev->bd_inode) >> 9) - 8*2;
        sb_start &= ~(sector_t)(4*2 - 1);
        max_sectors = rdev->sectors + sb_start - rdev->sb_start;
        if (!num_sectors || num_sectors > max_sectors)
            num_sectors = max_sectors;
        rdev->sb_start = sb_start;
    }
    sb = page_address(rdev->sb_page);
    sb->data_size = cpu_to_le64(num_sectors);
    sb->super_offset = rdev->sb_start;
    sb->sb_csum = calc_sb_1_csum(sb);
    md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
               rdev->sb_page);
    md_super_wait(rdev->mddev);
    return num_sectors;

}

static int
super_1_allow_new_offset(struct md_rdev *rdev,
             unsigned long long new_offset)
{
    /* All necessary checks on new >= old have been done */
    struct bitmap *bitmap;
    if (new_offset >= rdev->data_offset)
        return 1;

    /* with 1.0 metadata, there is no metadata to tread on
     * so we can always move back */
    if (rdev->mddev->minor_version == 0)
        return 1;

    /* otherwise we must be sure not to step on
     * any metadata, so stay:
     * 36K beyond start of superblock
     * beyond end of badblocks
     * beyond write-intent bitmap
     */
    if (rdev->sb_start + (32+4)*2 > new_offset)
        return 0;
    bitmap = rdev->mddev->bitmap;
    if (bitmap && !rdev->mddev->bitmap_info.file &&
        rdev->sb_start + rdev->mddev->bitmap_info.offset +
        bitmap->storage.file_pages * (PAGE_SIZE>>9) > new_offset)
        return 0;
    if (rdev->badblocks.sector + rdev->badblocks.size > new_offset)
        return 0;

    return 1;
}

static struct super_type super_types[] = {
    [0] = {
        .name   = "0.90.0",
        .owner  = THIS_MODULE,
        .load_super     = super_90_load,
        .validate_super     = super_90_validate,
        .sync_super     = super_90_sync,
        .rdev_size_change   = super_90_rdev_size_change,
        .allow_new_offset   = super_90_allow_new_offset,
    },
    [1] = {
        .name   = "md-1",
        .owner  = THIS_MODULE,
        .load_super     = super_1_load,
        .validate_super     = super_1_validate,
        .sync_super     = super_1_sync,
        .rdev_size_change   = super_1_rdev_size_change,
        .allow_new_offset   = super_1_allow_new_offset,
    },
};

static void sync_super(struct mddev *mddev, struct md_rdev *rdev)
{
    if (mddev->sync_super) {
        mddev->sync_super(mddev, rdev);
        return;
    }

    BUG_ON(mddev->major_version >= ARRAY_SIZE(super_types));

    super_types[mddev->major_version].sync_super(mddev, rdev);
}

static int match_mddev_units(struct mddev *mddev1, struct mddev *mddev2)
{
    struct md_rdev *rdev, *rdev2;

    rcu_read_lock();
    rdev_for_each_rcu(rdev, mddev1)
        rdev_for_each_rcu(rdev2, mddev2)
            if (rdev->bdev->bd_contains ==
                rdev2->bdev->bd_contains) {
                rcu_read_unlock();
                return 1;
            }
    rcu_read_unlock();
    return 0;
}

static LIST_HEAD(pending_raid_disks);

/*
 * Try to register data integrity profile for an mddev
 *
 * This is called when an array is started and after a disk has been kicked
 * from the array. It only succeeds if all working and active component devices
 * are integrity capable with matching profiles.
 */
int md_integrity_register(struct mddev *mddev)
{
    struct md_rdev *rdev, *reference = NULL;

    if (list_empty(&mddev->disks))
        return 0; /* nothing to do */
    if (!mddev->gendisk || blk_get_integrity(mddev->gendisk))
        return 0; /* shouldn't register, or already is */
    rdev_for_each(rdev, mddev) {
        /* skip spares and non-functional disks */
        if (test_bit(Faulty, &rdev->flags))
            continue;
        if (rdev->raid_disk < 0)
            continue;
        if (!reference) {
            /* Use the first rdev as the reference */
            reference = rdev;
            continue;
        }
        /* does this rdev's profile match the reference profile? */
        if (blk_integrity_compare(reference->bdev->bd_disk,
                rdev->bdev->bd_disk) < 0)
            return -EINVAL;
    }
    if (!reference || !bdev_get_integrity(reference->bdev))
        return 0;
    /*
     * All component devices are integrity capable and have matching
     * profiles, register the common profile for the md device.
     */
    if (blk_integrity_register(mddev->gendisk,
            bdev_get_integrity(reference->bdev)) != 0) {
        printk(KERN_ERR "md: failed to register integrity for %s\n",
            mdname(mddev));
        return -EINVAL;
    }
    printk(KERN_NOTICE "md: data integrity enabled on %s\n", mdname(mddev));
    if (bioset_integrity_create(mddev->bio_set, BIO_POOL_SIZE)) {
        printk(KERN_ERR "md: failed to create integrity pool for %s\n",
               mdname(mddev));
        return -EINVAL;
    }
    return 0;
}
EXPORT_SYMBOL(md_integrity_register);

/* Disable data integrity if non-capable/non-matching disk is being added */
void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev)
{
    struct blk_integrity *bi_rdev;
    struct blk_integrity *bi_mddev;

    if (!mddev->gendisk)
        return;

    bi_rdev = bdev_get_integrity(rdev->bdev);
    bi_mddev = blk_get_integrity(mddev->gendisk);

    if (!bi_mddev) /* nothing to do */
        return;
    if (rdev->raid_disk < 0) /* skip spares */
        return;
    if (bi_rdev && blk_integrity_compare(mddev->gendisk,
                         rdev->bdev->bd_disk) >= 0)
        return;
    printk(KERN_NOTICE "disabling data integrity on %s\n", mdname(mddev));
    blk_integrity_unregister(mddev->gendisk);
}
EXPORT_SYMBOL(md_integrity_add_rdev);

static int bind_rdev_to_array(struct md_rdev * rdev, struct mddev * mddev)
{
    char b[BDEVNAME_SIZE];
    struct kobject *ko;
    char *s;
    int err;

    if (rdev->mddev) {
        MD_BUG();
        return -EINVAL;
    }

    /* prevent duplicates */
    if (find_rdev(mddev, rdev->bdev->bd_dev))
        return -EEXIST;

    /* make sure rdev->sectors exceeds mddev->dev_sectors */
    if (rdev->sectors && (mddev->dev_sectors == 0 ||
            rdev->sectors < mddev->dev_sectors)) {
        if (mddev->pers) {
            /* Cannot change size, so fail
             * If mddev->level <= 0, then we don't care
             * about aligning sizes (e.g. linear)
             */
            if (mddev->level > 0)
                return -ENOSPC;
        } else
            mddev->dev_sectors = rdev->sectors;
    }

    /* Verify rdev->desc_nr is unique.
     * If it is -1, assign a free number, else
     * check number is not in use
     */
    if (rdev->desc_nr < 0) {
        int choice = 0;
        if (mddev->pers) choice = mddev->raid_disks;
        while (find_rdev_nr(mddev, choice))
            choice++;
        rdev->desc_nr = choice;
    } else {
        if (find_rdev_nr(mddev, rdev->desc_nr))
            return -EBUSY;
    }
    if (mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {
        printk(KERN_WARNING "md: %s: array is limited to %d devices\n",
               mdname(mddev), mddev->max_disks);
        return -EBUSY;
    }
    bdevname(rdev->bdev,b);
    while ( (s=strchr(b, '/')) != NULL)
        *s = '!';

    rdev->mddev = mddev;
    printk(KERN_INFO "md: bind<%s>\n", b);

    if ((err = kobject_add(&rdev->kobj, &mddev->kobj, "dev-%s", b)))
        goto fail;

    ko = &part_to_dev(rdev->bdev->bd_part)->kobj;
    if (sysfs_create_link(&rdev->kobj, ko, "block"))
        /* failure here is OK */;
    rdev->sysfs_state = sysfs_get_dirent_safe(rdev->kobj.sd, "state");

    list_add_rcu(&rdev->same_set, &mddev->disks);
    bd_link_disk_holder(rdev->bdev, mddev->gendisk);

    /* May as well allow recovery to be retried once */
    mddev->recovery_disabled++;

    return 0;

 fail:
    printk(KERN_WARNING "md: failed to register dev-%s for %s\n",
           b, mdname(mddev));
    return err;
}

static void md_delayed_delete(struct work_struct *ws)
{
    struct md_rdev *rdev = container_of(ws, struct md_rdev, del_work);
    kobject_del(&rdev->kobj);
    kobject_put(&rdev->kobj);
}

static void unbind_rdev_from_array(struct md_rdev * rdev)
{
    char b[BDEVNAME_SIZE];
    if (!rdev->mddev) {
        MD_BUG();
        return;
    }
    bd_unlink_disk_holder(rdev->bdev, rdev->mddev->gendisk);
    list_del_rcu(&rdev->same_set);
    printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
    rdev->mddev = NULL;
    sysfs_remove_link(&rdev->kobj, "block");
    sysfs_put(rdev->sysfs_state);
    rdev->sysfs_state = NULL;
    rdev->badblocks.count = 0;
    /* We need to delay this, otherwise we can deadlock when
     * writing to 'remove' to "dev/state".  We also need
     * to delay it due to rcu usage.
     */
    synchronize_rcu();
    INIT_WORK(&rdev->del_work, md_delayed_delete);
    kobject_get(&rdev->kobj);
    queue_work(md_misc_wq, &rdev->del_work);
}

/*
 * prevent the device from being mounted, repartitioned or
 * otherwise reused by a RAID array (or any other kernel
 * subsystem), by bd_claiming the device.
 */
static int lock_rdev(struct md_rdev *rdev, dev_t dev, int shared)
{
    int err = 0;
    struct block_device *bdev;
    char b[BDEVNAME_SIZE];

    bdev = blkdev_get_by_dev(dev, FMODE_READ|FMODE_WRITE|FMODE_EXCL,
                 shared ? (struct md_rdev *)lock_rdev : rdev);
    if (IS_ERR(bdev)) {
        printk(KERN_ERR "md: could not open %s.\n",
            __bdevname(dev, b));
        return PTR_ERR(bdev);
    }
    rdev->bdev = bdev;
    return err;
}

static void unlock_rdev(struct md_rdev *rdev)
{
    struct block_device *bdev = rdev->bdev;
    rdev->bdev = NULL;
    if (!bdev)
        MD_BUG();
    blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
}

void md_autodetect_dev(dev_t dev);

static void export_rdev(struct md_rdev * rdev)
{
    char b[BDEVNAME_SIZE];
    printk(KERN_INFO "md: export_rdev(%s)\n",
        bdevname(rdev->bdev,b));
    if (rdev->mddev)
        MD_BUG();
    md_rdev_clear(rdev);
#ifndef MODULE
    if (test_bit(AutoDetected, &rdev->flags))
        md_autodetect_dev(rdev->bdev->bd_dev);
#endif
    unlock_rdev(rdev);
    kobject_put(&rdev->kobj);
}

static void kick_rdev_from_array(struct md_rdev * rdev)
{
    unbind_rdev_from_array(rdev);
    export_rdev(rdev);
}

static void export_array(struct mddev *mddev)
{
    struct md_rdev *rdev, *tmp;

    rdev_for_each_safe(rdev, tmp, mddev) {
        if (!rdev->mddev) {
            MD_BUG();
            continue;
        }
        kick_rdev_from_array(rdev);
    }
    if (!list_empty(&mddev->disks))
        MD_BUG();
    mddev->raid_disks = 0;
    mddev->major_version = 0;
}

static void print_desc(mdp_disk_t *desc)
{
    printk(" DISK<N:%d,(%d,%d),R:%d,S:%d>\n", desc->number,
        desc->major,desc->minor,desc->raid_disk,desc->state);
}

static void print_sb_90(mdp_super_t *sb)
{
    int i;

    printk(KERN_INFO 
        "md:  SB: (V:%d.%d.%d) ID:<%08x.%08x.%08x.%08x> CT:%08x\n",
        sb->major_version, sb->minor_version, sb->patch_version,
        sb->set_uuid0, sb->set_uuid1, sb->set_uuid2, sb->set_uuid3,
        sb->ctime);
    printk(KERN_INFO "md:     L%d S%08d ND:%d RD:%d md%d LO:%d CS:%d\n",
        sb->level, sb->size, sb->nr_disks, sb->raid_disks,
        sb->md_minor, sb->layout, sb->chunk_size);
    printk(KERN_INFO "md:     UT:%08x ST:%d AD:%d WD:%d"
        " FD:%d SD:%d CSUM:%08x E:%08lx\n",
        sb->utime, sb->state, sb->active_disks, sb->working_disks,
        sb->failed_disks, sb->spare_disks,
        sb->sb_csum, (unsigned long)sb->events_lo);

    printk(KERN_INFO);
    for (i = 0; i < MD_SB_DISKS; i++) {
        mdp_disk_t *desc;

        desc = sb->disks + i;
        if (desc->number || desc->major || desc->minor ||
            desc->raid_disk || (desc->state && (desc->state != 4))) {
            printk("     D %2d: ", i);
            print_desc(desc);
        }
    }
    printk(KERN_INFO "md:     THIS: ");
    print_desc(&sb->this_disk);
}

static void print_sb_1(struct mdp_superblock_1 *sb)
{
    __u8 *uuid;

    uuid = sb->set_uuid;
    printk(KERN_INFO
           "md:  SB: (V:%u) (F:0x%08x) Array-ID:<%pU>\n"
           "md:    Name: \"%s\" CT:%llu\n",
        le32_to_cpu(sb->major_version),
        le32_to_cpu(sb->feature_map),
        uuid,
        sb->set_name,
        (unsigned long long)le64_to_cpu(sb->ctime)
               & MD_SUPERBLOCK_1_TIME_SEC_MASK);

    uuid = sb->device_uuid;
    printk(KERN_INFO
           "md:       L%u SZ%llu RD:%u LO:%u CS:%u DO:%llu DS:%llu SO:%llu"
            " RO:%llu\n"
           "md:     Dev:%08x UUID: %pU\n"
           "md:       (F:0x%08x) UT:%llu Events:%llu ResyncOffset:%llu CSUM:0x%08x\n"
           "md:         (MaxDev:%u) \n",
        le32_to_cpu(sb->level),
        (unsigned long long)le64_to_cpu(sb->size),
        le32_to_cpu(sb->raid_disks),
        le32_to_cpu(sb->layout),
        le32_to_cpu(sb->chunksize),
        (unsigned long long)le64_to_cpu(sb->data_offset),
        (unsigned long long)le64_to_cpu(sb->data_size),
        (unsigned long long)le64_to_cpu(sb->super_offset),
        (unsigned long long)le64_to_cpu(sb->recovery_offset),
        le32_to_cpu(sb->dev_number),
        uuid,
        sb->devflags,
        (unsigned long long)le64_to_cpu(sb->utime) & MD_SUPERBLOCK_1_TIME_SEC_MASK,
        (unsigned long long)le64_to_cpu(sb->events),
        (unsigned long long)le64_to_cpu(sb->resync_offset),
        le32_to_cpu(sb->sb_csum),
        le32_to_cpu(sb->max_dev)
        );
}

static void print_rdev(struct md_rdev *rdev, int major_version)
{
    char b[BDEVNAME_SIZE];
    printk(KERN_INFO "md: rdev %s, Sect:%08llu F:%d S:%d DN:%u\n",
        bdevname(rdev->bdev, b), (unsigned long long)rdev->sectors,
            test_bit(Faulty, &rdev->flags), test_bit(In_sync, &rdev->flags),
            rdev->desc_nr);
    if (rdev->sb_loaded) {
        printk(KERN_INFO "md: rdev superblock (MJ:%d):\n", major_version);
        switch (major_version) {
        case 0:
            print_sb_90(page_address(rdev->sb_page));
            break;
        case 1:
            print_sb_1(page_address(rdev->sb_page));
            break;
        }
    } else
        printk(KERN_INFO "md: no rdev superblock!\n");
}

static void md_print_devices(void)
{
    struct list_head *tmp;
    struct md_rdev *rdev;
    struct mddev *mddev;
    char b[BDEVNAME_SIZE];

    printk("\n");
    printk("md: **********************************\n");
    printk("md: * <COMPLETE RAID STATE PRINTOUT> *\n");
    printk("md: **********************************\n");
    for_each_mddev(mddev, tmp) {

        if (mddev->bitmap)
            bitmap_print_sb(mddev->bitmap);
        else
            printk("%s: ", mdname(mddev));
        rdev_for_each(rdev, mddev)
            printk("<%s>", bdevname(rdev->bdev,b));
        printk("\n");

        rdev_for_each(rdev, mddev)
            print_rdev(rdev, mddev->major_version);
    }
    printk("md: **********************************\n");
    printk("\n");
}


static void sync_sbs(struct mddev * mddev, int nospares)
{
    /* Update each superblock (in-memory image), but
     * if we are allowed to, skip spares which already
     * have the right event counter, or have one earlier
     * (which would mean they aren't being marked as dirty
     * with the rest of the array)
     */
    struct md_rdev *rdev;
    rdev_for_each(rdev, mddev) {
        if (rdev->sb_events == mddev->events ||
            (nospares &&
             rdev->raid_disk < 0 &&
             rdev->sb_events+1 == mddev->events)) {
            /* Don't update this superblock */
            rdev->sb_loaded = 2;
        } else {
            sync_super(mddev, rdev);
            rdev->sb_loaded = 1;
        }
    }
}

static void md_update_sb(struct mddev * mddev, int force_change)
{
    struct md_rdev *rdev;
    int sync_req;
    int nospares = 0;
    int any_badblocks_changed = 0;

repeat:
    /* First make sure individual recovery_offsets are correct */
    rdev_for_each(rdev, mddev) {
        if (rdev->raid_disk >= 0 &&
            mddev->delta_disks >= 0 &&
            !test_bit(In_sync, &rdev->flags) &&
            mddev->curr_resync_completed > rdev->recovery_offset)
                rdev->recovery_offset = mddev->curr_resync_completed;

    }   
    if (!mddev->persistent) {
        clear_bit(MD_CHANGE_CLEAN, &mddev->flags);
        clear_bit(MD_CHANGE_DEVS, &mddev->flags);
        if (!mddev->external) {
            clear_bit(MD_CHANGE_PENDING, &mddev->flags);
            rdev_for_each(rdev, mddev) {
                if (rdev->badblocks.changed) {
                    rdev->badblocks.changed = 0;
                    md_ack_all_badblocks(&rdev->badblocks);
                    md_error(mddev, rdev);
                }
                clear_bit(Blocked, &rdev->flags);
                clear_bit(BlockedBadBlocks, &rdev->flags);
                wake_up(&rdev->blocked_wait);
            }
        }
        wake_up(&mddev->sb_wait);
        return;
    }

    spin_lock_irq(&mddev->write_lock);

    mddev->utime = get_seconds();

    if (test_and_clear_bit(MD_CHANGE_DEVS, &mddev->flags))
        force_change = 1;
    if (test_and_clear_bit(MD_CHANGE_CLEAN, &mddev->flags))
        /* just a clean<-> dirty transition, possibly leave spares alone,
         * though if events isn't the right even/odd, we will have to do
         * spares after all
         */
        nospares = 1;
    if (force_change)
        nospares = 0;
    if (mddev->degraded)
        /* If the array is degraded, then skipping spares is both
         * dangerous and fairly pointless.
         * Dangerous because a device that was removed from the array
         * might have a event_count that still looks up-to-date,
         * so it can be re-added without a resync.
         * Pointless because if there are any spares to skip,
         * then a recovery will happen and soon that array won't
         * be degraded any more and the spare can go back to sleep then.
         */
        nospares = 0;

    sync_req = mddev->in_sync;

    /* If this is just a dirty<->clean transition, and the array is clean
     * and 'events' is odd, we can roll back to the previous clean state */
    if (nospares
        && (mddev->in_sync && mddev->recovery_cp == MaxSector)
        && mddev->can_decrease_events
        && mddev->events != 1) {
        mddev->events--;
        mddev->can_decrease_events = 0;
    } else {
        /* otherwise we have to go forward and ... */
        mddev->events ++;
        mddev->can_decrease_events = nospares;
    }

    if (!mddev->events) {
        /*
         * oops, this 64-bit counter should never wrap.
         * Either we are in around ~1 trillion A.C., assuming
         * 1 reboot per second, or we have a bug:
         */
        MD_BUG();
        mddev->events --;
    }

    rdev_for_each(rdev, mddev) {
        if (rdev->badblocks.changed)
            any_badblocks_changed++;
        if (test_bit(Faulty, &rdev->flags))
            set_bit(FaultRecorded, &rdev->flags);
    }

    sync_sbs(mddev, nospares);
    spin_unlock_irq(&mddev->write_lock);

    pr_debug("md: updating %s RAID superblock on device (in sync %d)\n",
         mdname(mddev), mddev->in_sync);

    bitmap_update_sb(mddev->bitmap);
    rdev_for_each(rdev, mddev) {
        char b[BDEVNAME_SIZE];

        if (rdev->sb_loaded != 1)
            continue; /* no noise on spare devices */

        if (!test_bit(Faulty, &rdev->flags) &&
            rdev->saved_raid_disk == -1) {
            md_super_write(mddev,rdev,
                       rdev->sb_start, rdev->sb_size,
                       rdev->sb_page);
            pr_debug("md: (write) %s's sb offset: %llu\n",
                 bdevname(rdev->bdev, b),
                 (unsigned long long)rdev->sb_start);
            rdev->sb_events = mddev->events;
            if (rdev->badblocks.size) {
                md_super_write(mddev, rdev,
                           rdev->badblocks.sector,
                           rdev->badblocks.size << 9,
                           rdev->bb_page);
                rdev->badblocks.size = 0;
            }

        } else if (test_bit(Faulty, &rdev->flags))
            pr_debug("md: %s (skipping faulty)\n",
                 bdevname(rdev->bdev, b));
        else
            pr_debug("(skipping incremental s/r ");

        if (mddev->level == LEVEL_MULTIPATH)
            /* only need to write one superblock... */
            break;
    }
    md_super_wait(mddev);
    /* if there was a failure, MD_CHANGE_DEVS was set, and we re-write super */

    spin_lock_irq(&mddev->write_lock);
    if (mddev->in_sync != sync_req ||
        test_bit(MD_CHANGE_DEVS, &mddev->flags)) {
        /* have to write it out again */
        spin_unlock_irq(&mddev->write_lock);
        goto repeat;
    }
    clear_bit(MD_CHANGE_PENDING, &mddev->flags);
    spin_unlock_irq(&mddev->write_lock);
    wake_up(&mddev->sb_wait);
    if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
        sysfs_notify(&mddev->kobj, NULL, "sync_completed");

    rdev_for_each(rdev, mddev) {
        if (test_and_clear_bit(FaultRecorded, &rdev->flags))
            clear_bit(Blocked, &rdev->flags);

        if (any_badblocks_changed)
            md_ack_all_badblocks(&rdev->badblocks);
        clear_bit(BlockedBadBlocks, &rdev->flags);
        wake_up(&rdev->blocked_wait);
    }
}

/* words written to sysfs files may, or may not, be \n terminated.
 * We want to accept with case. For this we use cmd_match.
 */
static int cmd_match(const char *cmd, const char *str)
{
    /* See if cmd, written into a sysfs file, matches
     * str.  They must either be the same, or cmd can
     * have a trailing newline
     */
    while (*cmd && *str && *cmd == *str) {
        cmd++;
        str++;
    }
    if (*cmd == '\n')
        cmd++;
    if (*str || *cmd)
        return 0;
    return 1;
}

struct rdev_sysfs_entry {
    struct attribute attr;
    ssize_t (*show)(struct md_rdev *, char *);
    ssize_t (*store)(struct md_rdev *, const char *, size_t);
};

static ssize_t
state_show(struct md_rdev *rdev, char *page)
{
    char *sep = "";
    size_t len = 0;

    if (test_bit(Faulty, &rdev->flags) ||
        rdev->badblocks.unacked_exist) {
        len+= sprintf(page+len, "%sfaulty",sep);
        sep = ",";
    }
    if (test_bit(In_sync, &rdev->flags)) {
        len += sprintf(page+len, "%sin_sync",sep);
        sep = ",";
    }
    if (test_bit(WriteMostly, &rdev->flags)) {
        len += sprintf(page+len, "%swrite_mostly",sep);
        sep = ",";
    }
    if (test_bit(Blocked, &rdev->flags) ||
        (rdev->badblocks.unacked_exist
         && !test_bit(Faulty, &rdev->flags))) {
        len += sprintf(page+len, "%sblocked", sep);
        sep = ",";
    }
    if (!test_bit(Faulty, &rdev->flags) &&
        !test_bit(In_sync, &rdev->flags)) {
        len += sprintf(page+len, "%sspare", sep);
        sep = ",";
    }
    if (test_bit(WriteErrorSeen, &rdev->flags)) {
        len += sprintf(page+len, "%swrite_error", sep);
        sep = ",";
    }
    if (test_bit(WantReplacement, &rdev->flags)) {
        len += sprintf(page+len, "%swant_replacement", sep);
        sep = ",";
    }
    if (test_bit(Replacement, &rdev->flags)) {
        len += sprintf(page+len, "%sreplacement", sep);
        sep = ",";
    }

    return len+sprintf(page+len, "\n");
}

static ssize_t
state_store(struct md_rdev *rdev, const char *buf, size_t len)
{
    /* can write
     *  faulty  - simulates an error
     *  remove  - disconnects the device
     *  writemostly - sets write_mostly
     *  -writemostly - clears write_mostly
     *  blocked - sets the Blocked flags
     *  -blocked - clears the Blocked and possibly simulates an error
     *  insync - sets Insync providing device isn't active
     *  write_error - sets WriteErrorSeen
     *  -write_error - clears WriteErrorSeen
     */
    int err = -EINVAL;
    if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
        md_error(rdev->mddev, rdev);
        if (test_bit(Faulty, &rdev->flags))
            err = 0;
        else
            err = -EBUSY;
    } else if (cmd_match(buf, "remove")) {
        if (rdev->raid_disk >= 0)
            err = -EBUSY;
        else {
            struct mddev *mddev = rdev->mddev;
            kick_rdev_from_array(rdev);
            if (mddev->pers)
                md_update_sb(mddev, 1);
            md_new_event(mddev);
            err = 0;
        }
    } else if (cmd_match(buf, "writemostly")) {
        set_bit(WriteMostly, &rdev->flags);
        err = 0;
    } else if (cmd_match(buf, "-writemostly")) {
        clear_bit(WriteMostly, &rdev->flags);
        err = 0;
    } else if (cmd_match(buf, "blocked")) {
        set_bit(Blocked, &rdev->flags);
        err = 0;
    } else if (cmd_match(buf, "-blocked")) {
        if (!test_bit(Faulty, &rdev->flags) &&
            rdev->badblocks.unacked_exist) {
            /* metadata handler doesn't understand badblocks,
             * so we need to fail the device
             */
            md_error(rdev->mddev, rdev);
        }
        clear_bit(Blocked, &rdev->flags);
        clear_bit(BlockedBadBlocks, &rdev->flags);
        wake_up(&rdev->blocked_wait);
        set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
        md_wakeup_thread(rdev->mddev->thread);

        err = 0;
    } else if (cmd_match(buf, "insync") && rdev->raid_disk == -1) {
        set_bit(In_sync, &rdev->flags);
        err = 0;
    } else if (cmd_match(buf, "write_error")) {
        set_bit(WriteErrorSeen, &rdev->flags);
        err = 0;
    } else if (cmd_match(buf, "-write_error")) {
        clear_bit(WriteErrorSeen, &rdev->flags);
        err = 0;
    } else if (cmd_match(buf, "want_replacement")) {
        /* Any non-spare device that is not a replacement can
         * become want_replacement at any time, but we then need to
         * check if recovery is needed.
         */
        if (rdev->raid_disk >= 0 &&
            !test_bit(Replacement, &rdev->flags))
            set_bit(WantReplacement, &rdev->flags);
        set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
        md_wakeup_thread(rdev->mddev->thread);
        err = 0;
    } else if (cmd_match(buf, "-want_replacement")) {
        /* Clearing 'want_replacement' is always allowed.
         * Once replacements starts it is too late though.
         */
        err = 0;
        clear_bit(WantReplacement, &rdev->flags);
    } else if (cmd_match(buf, "replacement")) {
        /* Can only set a device as a replacement when array has not
         * yet been started.  Once running, replacement is automatic
         * from spares, or by assigning 'slot'.
         */
        if (rdev->mddev->pers)
            err = -EBUSY;
        else {
            set_bit(Replacement, &rdev->flags);
            err = 0;
        }
    } else if (cmd_match(buf, "-replacement")) {
        /* Similarly, can only clear Replacement before start */
        if (rdev->mddev->pers)
            err = -EBUSY;
        else {
            clear_bit(Replacement, &rdev->flags);
            err = 0;
        }
    }
    if (!err)
        sysfs_notify_dirent_safe(rdev->sysfs_state);
    return err ? err : len;
}
static struct rdev_sysfs_entry rdev_state =
__ATTR(state, S_IRUGO|S_IWUSR, state_show, state_store);

static ssize_t
errors_show(struct md_rdev *rdev, char *page)
{
    return sprintf(page, "%d\n", atomic_read(&rdev->corrected_errors));
}

static ssize_t
errors_store(struct md_rdev *rdev, const char *buf, size_t len)
{
    char *e;
    unsigned long n = simple_strtoul(buf, &e, 10);
    if (*buf && (*e == 0 || *e == '\n')) {
        atomic_set(&rdev->corrected_errors, n);
        return len;
    }
    return -EINVAL;
}
static struct rdev_sysfs_entry rdev_errors =
__ATTR(errors, S_IRUGO|S_IWUSR, errors_show, errors_store);

static ssize_t
slot_show(struct md_rdev *rdev, char *page)
{
    if (rdev->raid_disk < 0)
        return sprintf(page, "none\n");
    else
        return sprintf(page, "%d\n", rdev->raid_disk);
}

static ssize_t
slot_store(struct md_rdev *rdev, const char *buf, size_t len)
{
    char *e;
    int err;
    int slot = simple_strtoul(buf, &e, 10);
    if (strncmp(buf, "none", 4)==0)
        slot = -1;
    else if (e==buf || (*e && *e!= '\n'))
        return -EINVAL;
    if (rdev->mddev->pers && slot == -1) {
        /* Setting 'slot' on an active array requires also
         * updating the 'rd%d' link, and communicating
         * with the personality with ->hot_*_disk.
         * For now we only support removing
         * failed/spare devices.  This normally happens automatically,
         * but not when the metadata is externally managed.
         */
        if (rdev->raid_disk == -1)
            return -EEXIST;
        /* personality does all needed checks */
        if (rdev->mddev->pers->hot_remove_disk == NULL)
            return -EINVAL;
        err = rdev->mddev->pers->
            hot_remove_disk(rdev->mddev, rdev);
        if (err)
            return err;
        sysfs_unlink_rdev(rdev->mddev, rdev);
        rdev->raid_disk = -1;
        set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
        md_wakeup_thread(rdev->mddev->thread);
    } else if (rdev->mddev->pers) {
        /* Activating a spare .. or possibly reactivating
         * if we ever get bitmaps working here.
         */

        if (rdev->raid_disk != -1)
            return -EBUSY;

        if (test_bit(MD_RECOVERY_RUNNING, &rdev->mddev->recovery))
            return -EBUSY;

        if (rdev->mddev->pers->hot_add_disk == NULL)
            return -EINVAL;

        if (slot >= rdev->mddev->raid_disks &&
            slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
            return -ENOSPC;

        rdev->raid_disk = slot;
        if (test_bit(In_sync, &rdev->flags))
            rdev->saved_raid_disk = slot;
        else
            rdev->saved_raid_disk = -1;
        clear_bit(In_sync, &rdev->flags);
        err = rdev->mddev->pers->
            hot_add_disk(rdev->mddev, rdev);
        if (err) {
            rdev->raid_disk = -1;
            return err;
        } else
            sysfs_notify_dirent_safe(rdev->sysfs_state);
        if (sysfs_link_rdev(rdev->mddev, rdev))
            /* failure here is OK */;
        /* don't wakeup anyone, leave that to userspace. */
    } else {
        if (slot >= rdev->mddev->raid_disks &&
            slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
            return -ENOSPC;
        rdev->raid_disk = slot;
        /* assume it is working */
        clear_bit(Faulty, &rdev->flags);
        clear_bit(WriteMostly, &rdev->flags);
        set_bit(In_sync, &rdev->flags);
        sysfs_notify_dirent_safe(rdev->sysfs_state);
    }
    return len;
}


static struct rdev_sysfs_entry rdev_slot =
__ATTR(slot, S_IRUGO|S_IWUSR, slot_show, slot_store);

static ssize_t
offset_show(struct md_rdev *rdev, char *page)
{
    return sprintf(page, "%llu\n", (unsigned long long)rdev->data_offset);
}

static ssize_t
offset_store(struct md_rdev *rdev, const char *buf, size_t len)
{
    unsigned long long offset;
    if (strict_strtoull(buf, 10, &offset) < 0)
        return -EINVAL;
    if (rdev->mddev->pers && rdev->raid_disk >= 0)
        return -EBUSY;
    if (rdev->sectors && rdev->mddev->external)
        /* Must set offset before size, so overlap checks
         * can be sane */
        return -EBUSY;
    rdev->data_offset = offset;
    rdev->new_data_offset = offset;
    return len;
}

static struct rdev_sysfs_entry rdev_offset =
__ATTR(offset, S_IRUGO|S_IWUSR, offset_show, offset_store);

static ssize_t new_offset_show(struct md_rdev *rdev, char *page)
{
    return sprintf(page, "%llu\n",
               (unsigned long long)rdev->new_data_offset);
}

static ssize_t new_offset_store(struct md_rdev *rdev,
                const char *buf, size_t len)
{
    unsigned long long new_offset;
    struct mddev *mddev = rdev->mddev;

    if (strict_strtoull(buf, 10, &new_offset) < 0)
        return -EINVAL;

    if (mddev->sync_thread)
        return -EBUSY;
    if (new_offset == rdev->data_offset)
        /* reset is always permitted */
        ;
    else if (new_offset > rdev->data_offset) {
        /* must not push array size beyond rdev_sectors */
        if (new_offset - rdev->data_offset
            + mddev->dev_sectors > rdev->sectors)
                return -E2BIG;
    }
    /* Metadata worries about other space details. */

    /* decreasing the offset is inconsistent with a backwards
     * reshape.
     */
    if (new_offset < rdev->data_offset &&
        mddev->reshape_backwards)
        return -EINVAL;
    /* Increasing offset is inconsistent with forwards
     * reshape.  reshape_direction should be set to
     * 'backwards' first.
     */
    if (new_offset > rdev->data_offset &&
        !mddev->reshape_backwards)
        return -EINVAL;

    if (mddev->pers && mddev->persistent &&
        !super_types[mddev->major_version]
        .allow_new_offset(rdev, new_offset))
        return -E2BIG;
    rdev->new_data_offset = new_offset;
    if (new_offset > rdev->data_offset)
        mddev->reshape_backwards = 1;
    else if (new_offset < rdev->data_offset)
        mddev->reshape_backwards = 0;

    return len;
}
static struct rdev_sysfs_entry rdev_new_offset =
__ATTR(new_offset, S_IRUGO|S_IWUSR, new_offset_show, new_offset_store);

static ssize_t
rdev_size_show(struct md_rdev *rdev, char *page)
{
    return sprintf(page, "%llu\n", (unsigned long long)rdev->sectors / 2);
}

static int overlaps(sector_t s1, sector_t l1, sector_t s2, sector_t l2)
{
    /* check if two start/length pairs overlap */
    if (s1+l1 <= s2)
        return 0;
    if (s2+l2 <= s1)
        return 0;
    return 1;
}

static int strict_blocks_to_sectors(const char *buf, sector_t *sectors)
{
    unsigned long long blocks;
    sector_t new;

    if (strict_strtoull(buf, 10, &blocks) < 0)
        return -EINVAL;

    if (blocks & 1ULL << (8 * sizeof(blocks) - 1))
        return -EINVAL; /* sector conversion overflow */

    new = blocks * 2;
    if (new != blocks * 2)
        return -EINVAL; /* unsigned long long to sector_t overflow */

    *sectors = new;
    return 0;
}

static ssize_t
rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len)
{
    struct mddev *my_mddev = rdev->mddev;
    sector_t oldsectors = rdev->sectors;
    sector_t sectors;

    if (strict_blocks_to_sectors(buf, &sectors) < 0)
        return -EINVAL;
    if (rdev->data_offset != rdev->new_data_offset)
        return -EINVAL; /* too confusing */
    if (my_mddev->pers && rdev->raid_disk >= 0) {
        if (my_mddev->persistent) {
            sectors = super_types[my_mddev->major_version].
                rdev_size_change(rdev, sectors);
            if (!sectors)
                return -EBUSY;
        } else if (!sectors)
            sectors = (i_size_read(rdev->bdev->bd_inode) >> 9) -
                rdev->data_offset;
    }
    if (sectors < my_mddev->dev_sectors)
        return -EINVAL; /* component must fit device */

    rdev->sectors = sectors;
    if (sectors > oldsectors && my_mddev->external) {
        /* need to check that all other rdevs with the same ->bdev
         * do not overlap.  We need to unlock the mddev to avoid
         * a deadlock.  We have already changed rdev->sectors, and if
         * we have to change it back, we will have the lock again.
         */
        struct mddev *mddev;
        int overlap = 0;
        struct list_head *tmp;

        mddev_unlock(my_mddev);
        for_each_mddev(mddev, tmp) {
            struct md_rdev *rdev2;

            mddev_lock(mddev);
            rdev_for_each(rdev2, mddev)
                if (rdev->bdev == rdev2->bdev &&
                    rdev != rdev2 &&
                    overlaps(rdev->data_offset, rdev->sectors,
                         rdev2->data_offset,
                         rdev2->sectors)) {
                    overlap = 1;
                    break;
                }
            mddev_unlock(mddev);
            if (overlap) {
                mddev_put(mddev);
                break;
            }
        }
        mddev_lock(my_mddev);
        if (overlap) {
            /* Someone else could have slipped in a size
             * change here, but doing so is just silly.
             * We put oldsectors back because we *know* it is
             * safe, and trust userspace not to race with
             * itself
             */
            rdev->sectors = oldsectors;
            return -EBUSY;
        }
    }
    return len;
}

static struct rdev_sysfs_entry rdev_size =
__ATTR(size, S_IRUGO|S_IWUSR, rdev_size_show, rdev_size_store);


static ssize_t recovery_start_show(struct md_rdev *rdev, char *page)
{
    unsigned long long recovery_start = rdev->recovery_offset;

    if (test_bit(In_sync, &rdev->flags) ||
        recovery_start == MaxSector)
        return sprintf(page, "none\n");

    return sprintf(page, "%llu\n", recovery_start);
}

static ssize_t recovery_start_store(struct md_rdev *rdev, const char *buf, size_t len)
{
    unsigned long long recovery_start;

    if (cmd_match(buf, "none"))
        recovery_start = MaxSector;
    else if (strict_strtoull(buf, 10, &recovery_start))
        return -EINVAL;

    if (rdev->mddev->pers &&
        rdev->raid_disk >= 0)
        return -EBUSY;

    rdev->recovery_offset = recovery_start;
    if (recovery_start == MaxSector)
        set_bit(In_sync, &rdev->flags);
    else
        clear_bit(In_sync, &rdev->flags);
    return len;
}

static struct rdev_sysfs_entry rdev_recovery_start =
__ATTR(recovery_start, S_IRUGO|S_IWUSR, recovery_start_show, recovery_start_store);


static ssize_t
badblocks_show(struct badblocks *bb, char *page, int unack);
static ssize_t
badblocks_store(struct badblocks *bb, const char *page, size_t len, int unack);

static ssize_t bb_show(struct md_rdev *rdev, char *page)
{
    return badblocks_show(&rdev->badblocks, page, 0);
}
static ssize_t bb_store(struct md_rdev *rdev, const char *page, size_t len)
{
    int rv = badblocks_store(&rdev->badblocks, page, len, 0);
    /* Maybe that ack was all we needed */
    if (test_and_clear_bit(BlockedBadBlocks, &rdev->flags))
        wake_up(&rdev->blocked_wait);
    return rv;
}
static struct rdev_sysfs_entry rdev_bad_blocks =
__ATTR(bad_blocks, S_IRUGO|S_IWUSR, bb_show, bb_store);


static ssize_t ubb_show(struct md_rdev *rdev, char *page)
{
    return badblocks_show(&rdev->badblocks, page, 1);
}
static ssize_t ubb_store(struct md_rdev *rdev, const char *page, size_t len)
{
    return badblocks_store(&rdev->badblocks, page, len, 1);
}
static struct rdev_sysfs_entry rdev_unack_bad_blocks =
__ATTR(unacknowledged_bad_blocks, S_IRUGO|S_IWUSR, ubb_show, ubb_store);

static struct attribute *rdev_default_attrs[] = {
    &rdev_state.attr,
    &rdev_errors.attr,
    &rdev_slot.attr,
    &rdev_offset.attr,
    &rdev_new_offset.attr,
    &rdev_size.attr,
    &rdev_recovery_start.attr,
    &rdev_bad_blocks.attr,
    &rdev_unack_bad_blocks.attr,
    NULL,
};
static ssize_t
rdev_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
    struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
    struct md_rdev *rdev = container_of(kobj, struct md_rdev, kobj);
    struct mddev *mddev = rdev->mddev;
    ssize_t rv;

    if (!entry->show)
        return -EIO;

    rv = mddev ? mddev_lock(mddev) : -EBUSY;
    if (!rv) {
        if (rdev->mddev == NULL)
            rv = -EBUSY;
        else
            rv = entry->show(rdev, page);
        mddev_unlock(mddev);
    }
    return rv;
}

static ssize_t
rdev_attr_store(struct kobject *kobj, struct attribute *attr,
          const char *page, size_t length)
{
    struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
    struct md_rdev *rdev = container_of(kobj, struct md_rdev, kobj);
    ssize_t rv;
    struct mddev *mddev = rdev->mddev;

    if (!entry->store)
        return -EIO;
    if (!capable(CAP_SYS_ADMIN))
        return -EACCES;
    rv = mddev ? mddev_lock(mddev): -EBUSY;
    if (!rv) {
        if (rdev->mddev == NULL)
            rv = -EBUSY;
        else
            rv = entry->store(rdev, page, length);
        mddev_unlock(mddev);
    }
    return rv;
}

static void rdev_free(struct kobject *ko)
{
    struct md_rdev *rdev = container_of(ko, struct md_rdev, kobj);
    kfree(rdev);
}
static const struct sysfs_ops rdev_sysfs_ops = {
    .show       = rdev_attr_show,
    .store      = rdev_attr_store,
};
static struct kobj_type rdev_ktype = {
    .release    = rdev_free,
    .sysfs_ops  = &rdev_sysfs_ops,
    .default_attrs  = rdev_default_attrs,
};

int md_rdev_init(struct md_rdev *rdev)
{
    rdev->desc_nr = -1;
    rdev->saved_raid_disk = -1;
    rdev->raid_disk = -1;
    rdev->flags = 0;
    rdev->data_offset = 0;
    rdev->new_data_offset = 0;
    rdev->sb_events = 0;
    rdev->last_read_error.tv_sec  = 0;
    rdev->last_read_error.tv_nsec = 0;
    rdev->sb_loaded = 0;
    rdev->bb_page = NULL;
    atomic_set(&rdev->nr_pending, 0);
    atomic_set(&rdev->read_errors, 0);
    atomic_set(&rdev->corrected_errors, 0);

    INIT_LIST_HEAD(&rdev->same_set);
    init_waitqueue_head(&rdev->blocked_wait);

    /* Add space to store bad block list.
     * This reserves the space even on arrays where it cannot
     * be used - I wonder if that matters
     */
    rdev->badblocks.count = 0;
    rdev->badblocks.shift = 0;
    rdev->badblocks.page = kmalloc(PAGE_SIZE, GFP_KERNEL);
    seqlock_init(&rdev->badblocks.lock);
    if (rdev->badblocks.page == NULL)
        return -ENOMEM;

    return 0;
}
EXPORT_SYMBOL_GPL(md_rdev_init);
/*
 * Import a device. If 'super_format' >= 0, then sanity check the superblock
 *
 * mark the device faulty if:
 *
 *   - the device is nonexistent (zero size)
 *   - the device has no valid superblock
 *
 * a faulty rdev _never_ has rdev->sb set.
 */
static struct md_rdev *md_import_device(dev_t newdev, int super_format, int super_minor)
{
    char b[BDEVNAME_SIZE];
    int err;
    struct md_rdev *rdev;
    sector_t size;

    rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
    if (!rdev) {
        printk(KERN_ERR "md: could not alloc mem for new device!\n");
        return ERR_PTR(-ENOMEM);
    }

    err = md_rdev_init(rdev);
    if (err)
        goto abort_free;
    err = alloc_disk_sb(rdev);
    if (err)
        goto abort_free;

    err = lock_rdev(rdev, newdev, super_format == -2);
    if (err)
        goto abort_free;

    kobject_init(&rdev->kobj, &rdev_ktype);

    size = i_size_read(rdev->bdev->bd_inode) >> BLOCK_SIZE_BITS;
    if (!size) {
        printk(KERN_WARNING 
            "md: %s has zero or unknown size, marking faulty!\n",
            bdevname(rdev->bdev,b));
        err = -EINVAL;
        goto abort_free;
    }

    if (super_format >= 0) {
        err = super_types[super_format].
            load_super(rdev, NULL, super_minor);
        if (err == -EINVAL) {
            printk(KERN_WARNING
                "md: %s does not have a valid v%d.%d "
                   "superblock, not importing!\n",
                bdevname(rdev->bdev,b),
                   super_format, super_minor);
            goto abort_free;
        }
        if (err < 0) {
            printk(KERN_WARNING 
                "md: could not read %s's sb, not importing!\n",
                bdevname(rdev->bdev,b));
            goto abort_free;
        }
    }
    if (super_format == -1)
        /* hot-add for 0.90, or non-persistent: so no badblocks */
        rdev->badblocks.shift = -1;

    return rdev;

abort_free:
    if (rdev->bdev)
        unlock_rdev(rdev);
    md_rdev_clear(rdev);
    kfree(rdev);
    return ERR_PTR(err);
}

/*
 * Check a full RAID array for plausibility
 */


static void analyze_sbs(struct mddev * mddev)
{
    int i;
    struct md_rdev *rdev, *freshest, *tmp;
    char b[BDEVNAME_SIZE];

    freshest = NULL;
    rdev_for_each_safe(rdev, tmp, mddev)
        switch (super_types[mddev->major_version].
            load_super(rdev, freshest, mddev->minor_version)) {
        case 1:
            freshest = rdev;
            break;
        case 0:
            break;
        default:
            printk( KERN_ERR \
                "md: fatal superblock inconsistency in %s"
                " -- removing from array\n", 
                bdevname(rdev->bdev,b));
            kick_rdev_from_array(rdev);
        }


    super_types[mddev->major_version].
        validate_super(mddev, freshest);

    i = 0;
    rdev_for_each_safe(rdev, tmp, mddev) {
        if (mddev->max_disks &&
            (rdev->desc_nr >= mddev->max_disks ||
             i > mddev->max_disks)) {
            printk(KERN_WARNING
                   "md: %s: %s: only %d devices permitted\n",
                   mdname(mddev), bdevname(rdev->bdev, b),
                   mddev->max_disks);
            kick_rdev_from_array(rdev);
            continue;
        }
        if (rdev != freshest)
            if (super_types[mddev->major_version].
                validate_super(mddev, rdev)) {
                printk(KERN_WARNING "md: kicking non-fresh %s"
                    " from array!\n",
                    bdevname(rdev->bdev,b));
                kick_rdev_from_array(rdev);
                continue;
            }
        if (mddev->level == LEVEL_MULTIPATH) {
            rdev->desc_nr = i++;
            rdev->raid_disk = rdev->desc_nr;
            set_bit(In_sync, &rdev->flags);
        } else if (rdev->raid_disk >= (mddev->raid_disks - min(0, mddev->delta_disks))) {
            rdev->raid_disk = -1;
            clear_bit(In_sync, &rdev->flags);
        }
    }
}

/* Read a fixed-point number.
 * Numbers in sysfs attributes should be in "standard" units where
 * possible, so time should be in seconds.
 * However we internally use a a much smaller unit such as 
 * milliseconds or jiffies.
 * This function takes a decimal number with a possible fractional
 * component, and produces an integer which is the result of
 * multiplying that number by 10^'scale'.
 * all without any floating-point arithmetic.
 */
int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale)
{
    unsigned long result = 0;
    long decimals = -1;
    while (isdigit(*cp) || (*cp == '.' && decimals < 0)) {
        if (*cp == '.')
            decimals = 0;
        else if (decimals < scale) {
            unsigned int value;
            value = *cp - '0';
            result = result * 10 + value;
            if (decimals >= 0)
                decimals++;
        }
        cp++;
    }
    if (*cp == '\n')
        cp++;
    if (*cp)
        return -EINVAL;
    if (decimals < 0)
        decimals = 0;
    while (decimals < scale) {
        result *= 10;
        decimals ++;
    }
    *res = result;
    return 0;
}


static void md_safemode_timeout(unsigned long data);

static ssize_t
safe_delay_show(struct mddev *mddev, char *page)
{
    int msec = (mddev->safemode_delay*1000)/HZ;
    return sprintf(page, "%d.%03d\n", msec/1000, msec%1000);
}
static ssize_t
safe_delay_store(struct mddev *mddev, const char *cbuf, size_t len)
{
    unsigned long msec;

    if (strict_strtoul_scaled(cbuf, &msec, 3) < 0)
        return -EINVAL;
    if (msec == 0)
        mddev->safemode_delay = 0;
    else {
        unsigned long old_delay = mddev->safemode_delay;
        mddev->safemode_delay = (msec*HZ)/1000;
        if (mddev->safemode_delay == 0)
            mddev->safemode_delay = 1;
        if (mddev->safemode_delay < old_delay)
            md_safemode_timeout((unsigned long)mddev);
    }
    return len;
}
static struct md_sysfs_entry md_safe_delay =
__ATTR(safe_mode_delay, S_IRUGO|S_IWUSR,safe_delay_show, safe_delay_store);

static ssize_t
level_show(struct mddev *mddev, char *page)
{
    struct md_personality *p = mddev->pers;
    if (p)
        return sprintf(page, "%s\n", p->name);
    else if (mddev->clevel[0])
        return sprintf(page, "%s\n", mddev->clevel);
    else if (mddev->level != LEVEL_NONE)
        return sprintf(page, "%d\n", mddev->level);
    else
        return 0;
}

static ssize_t
level_store(struct mddev *mddev, const char *buf, size_t len)
{
    char clevel[16];
    ssize_t rv = len;
    struct md_personality *pers;
    long level;
    void *priv;
    struct md_rdev *rdev;

    if (mddev->pers == NULL) {
        if (len == 0)
            return 0;
        if (len >= sizeof(mddev->clevel))
            return -ENOSPC;
        strncpy(mddev->clevel, buf, len);
        if (mddev->clevel[len-1] == '\n')
            len--;
        mddev->clevel[len] = 0;
        mddev->level = LEVEL_NONE;
        return rv;
    }

    /* request to change the personality.  Need to ensure:
     *  - array is not engaged in resync/recovery/reshape
     *  - old personality can be suspended
     *  - new personality will access other array.
     */

    if (mddev->sync_thread ||
        mddev->reshape_position != MaxSector ||
        mddev->sysfs_active)
        return -EBUSY;

    if (!mddev->pers->quiesce) {
        printk(KERN_WARNING "md: %s: %s does not support online personality change\n",
               mdname(mddev), mddev->pers->name);
        return -EINVAL;
    }

    /* Now find the new personality */
    if (len == 0 || len >= sizeof(clevel))
        return -EINVAL;
    strncpy(clevel, buf, len);
    if (clevel[len-1] == '\n')
        len--;
    clevel[len] = 0;
    if (strict_strtol(clevel, 10, &level))
        level = LEVEL_NONE;

    if (request_module("md-%s", clevel) != 0)
        request_module("md-level-%s", clevel);
    spin_lock(&pers_lock);
    pers = find_pers(level, clevel);
    if (!pers || !try_module_get(pers->owner)) {
        spin_unlock(&pers_lock);
        printk(KERN_WARNING "md: personality %s not loaded\n", clevel);
        return -EINVAL;
    }
    spin_unlock(&pers_lock);

    if (pers == mddev->pers) {
        /* Nothing to do! */
        module_put(pers->owner);
        return rv;
    }
    if (!pers->takeover) {
        module_put(pers->owner);
        printk(KERN_WARNING "md: %s: %s does not support personality takeover\n",
               mdname(mddev), clevel);
        return -EINVAL;
    }

    rdev_for_each(rdev, mddev)
        rdev->new_raid_disk = rdev->raid_disk;

    /* ->takeover must set new_* and/or delta_disks
     * if it succeeds, and may set them when it fails.
     */
    priv = pers->takeover(mddev);
    if (IS_ERR(priv)) {
        mddev->new_level = mddev->level;
        mddev->new_layout = mddev->layout;
        mddev->new_chunk_sectors = mddev->chunk_sectors;
        mddev->raid_disks -= mddev->delta_disks;
        mddev->delta_disks = 0;
        mddev->reshape_backwards = 0;
        module_put(pers->owner);
        printk(KERN_WARNING "md: %s: %s would not accept array\n",
               mdname(mddev), clevel);
        return PTR_ERR(priv);
    }

    /* Looks like we have a winner */
    mddev_suspend(mddev);
    mddev->pers->stop(mddev);
    
    if (mddev->pers->sync_request == NULL &&
        pers->sync_request != NULL) {
        /* need to add the md_redundancy_group */
        if (sysfs_create_group(&mddev->kobj, &md_redundancy_group))
            printk(KERN_WARNING
                   "md: cannot register extra attributes for %s\n",
                   mdname(mddev));
        mddev->sysfs_action = sysfs_get_dirent(mddev->kobj.sd, NULL, "sync_action");
    }       
    if (mddev->pers->sync_request != NULL &&
        pers->sync_request == NULL) {
        /* need to remove the md_redundancy_group */
        if (mddev->to_remove == NULL)
            mddev->to_remove = &md_redundancy_group;
    }

    if (mddev->pers->sync_request == NULL &&
        mddev->external) {
        /* We are converting from a no-redundancy array
         * to a redundancy array and metadata is managed
         * externally so we need to be sure that writes
         * won't block due to a need to transition
         *      clean->dirty
         * until external management is started.
         */
        mddev->in_sync = 0;
        mddev->safemode_delay = 0;
        mddev->safemode = 0;
    }

    rdev_for_each(rdev, mddev) {
        if (rdev->raid_disk < 0)
            continue;
        if (rdev->new_raid_disk >= mddev->raid_disks)
            rdev->new_raid_disk = -1;
        if (rdev->new_raid_disk == rdev->raid_disk)
            continue;
        sysfs_unlink_rdev(mddev, rdev);
    }
    rdev_for_each(rdev, mddev) {
        if (rdev->raid_disk < 0)
            continue;
        if (rdev->new_raid_disk == rdev->raid_disk)
            continue;
        rdev->raid_disk = rdev->new_raid_disk;
        if (rdev->raid_disk < 0)
            clear_bit(In_sync, &rdev->flags);
        else {
            if (sysfs_link_rdev(mddev, rdev))
                printk(KERN_WARNING "md: cannot register rd%d"
                       " for %s after level change\n",
                       rdev->raid_disk, mdname(mddev));
        }
    }

    module_put(mddev->pers->owner);
    mddev->pers = pers;
    mddev->private = priv;
    strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
    mddev->level = mddev->new_level;
    mddev->layout = mddev->new_layout;
    mddev->chunk_sectors = mddev->new_chunk_sectors;
    mddev->delta_disks = 0;
    mddev->reshape_backwards = 0;
    mddev->degraded = 0;
    if (mddev->pers->sync_request == NULL) {
        /* this is now an array without redundancy, so
         * it must always be in_sync
         */
        mddev->in_sync = 1;
        del_timer_sync(&mddev->safemode_timer);
    }
    pers->run(mddev);
    set_bit(MD_CHANGE_DEVS, &mddev->flags);
    mddev_resume(mddev);
    sysfs_notify(&mddev->kobj, NULL, "level");
    md_new_event(mddev);
    return rv;
}

static struct md_sysfs_entry md_level =
__ATTR(level, S_IRUGO|S_IWUSR, level_show, level_store);


static ssize_t
layout_show(struct mddev *mddev, char *page)
{
    /* just a number, not meaningful for all levels */
    if (mddev->reshape_position != MaxSector &&
        mddev->layout != mddev->new_layout)
        return sprintf(page, "%d (%d)\n",
                   mddev->new_layout, mddev->layout);
    return sprintf(page, "%d\n", mddev->layout);
}

static ssize_t
layout_store(struct mddev *mddev, const char *buf, size_t len)
{
    char *e;
    unsigned long n = simple_strtoul(buf, &e, 10);

    if (!*buf || (*e && *e != '\n'))
        return -EINVAL;

    if (mddev->pers) {
        int err;
        if (mddev->pers->check_reshape == NULL)
            return -EBUSY;
        mddev->new_layout = n;
        err = mddev->pers->check_reshape(mddev);
        if (err) {
            mddev->new_layout = mddev->layout;
            return err;
        }
    } else {
        mddev->new_layout = n;
        if (mddev->reshape_position == MaxSector)
            mddev->layout = n;
    }
    return len;
}
static struct md_sysfs_entry md_layout =
__ATTR(layout, S_IRUGO|S_IWUSR, layout_show, layout_store);


static ssize_t
raid_disks_show(struct mddev *mddev, char *page)
{
    if (mddev->raid_disks == 0)
        return 0;
    if (mddev->reshape_position != MaxSector &&
        mddev->delta_disks != 0)
        return sprintf(page, "%d (%d)\n", mddev->raid_disks,
                   mddev->raid_disks - mddev->delta_disks);
    return sprintf(page, "%d\n", mddev->raid_disks);
}

static int update_raid_disks(struct mddev *mddev, int raid_disks);

static ssize_t
raid_disks_store(struct mddev *mddev, const char *buf, size_t len)
{
    char *e;
    int rv = 0;
    unsigned long n = simple_strtoul(buf, &e, 10);

    if (!*buf || (*e && *e != '\n'))
        return -EINVAL;

    if (mddev->pers)
        rv = update_raid_disks(mddev, n);
    else if (mddev->reshape_position != MaxSector) {
        struct md_rdev *rdev;
        int olddisks = mddev->raid_disks - mddev->delta_disks;

        rdev_for_each(rdev, mddev) {
            if (olddisks < n &&
                rdev->data_offset < rdev->new_data_offset)
                return -EINVAL;
            if (olddisks > n &&
                rdev->data_offset > rdev->new_data_offset)
                return -EINVAL;
        }
        mddev->delta_disks = n - olddisks;
        mddev->raid_disks = n;
        mddev->reshape_backwards = (mddev->delta_disks < 0);
    } else
        mddev->raid_disks = n;
    return rv ? rv : len;
}
static struct md_sysfs_entry md_raid_disks =
__ATTR(raid_disks, S_IRUGO|S_IWUSR, raid_disks_show, raid_disks_store);

static ssize_t
chunk_size_show(struct mddev *mddev, char *page)
{
    if (mddev->reshape_position != MaxSector &&
        mddev->chunk_sectors != mddev->new_chunk_sectors)
        return sprintf(page, "%d (%d)\n",
                   mddev->new_chunk_sectors << 9,
                   mddev->chunk_sectors << 9);
    return sprintf(page, "%d\n", mddev->chunk_sectors << 9);
}

static ssize_t
chunk_size_store(struct mddev *mddev, const char *buf, size_t len)
{
    char *e;
    unsigned long n = simple_strtoul(buf, &e, 10);

    if (!*buf || (*e && *e != '\n'))
        return -EINVAL;

    if (mddev->pers) {
        int err;
        if (mddev->pers->check_reshape == NULL)
            return -EBUSY;
        mddev->new_chunk_sectors = n >> 9;
        err = mddev->pers->check_reshape(mddev);
        if (err) {
            mddev->new_chunk_sectors = mddev->chunk_sectors;
            return err;
        }
    } else {
        mddev->new_chunk_sectors = n >> 9;
        if (mddev->reshape_position == MaxSector)
            mddev->chunk_sectors = n >> 9;
    }
    return len;
}
static struct md_sysfs_entry md_chunk_size =
__ATTR(chunk_size, S_IRUGO|S_IWUSR, chunk_size_show, chunk_size_store);

static ssize_t
resync_start_show(struct mddev *mddev, char *page)
{
    if (mddev->recovery_cp == MaxSector)
        return sprintf(page, "none\n");
    return sprintf(page, "%llu\n", (unsigned long long)mddev->recovery_cp);
}

static ssize_t
resync_start_store(struct mddev *mddev, const char *buf, size_t len)
{
    char *e;
    unsigned long long n = simple_strtoull(buf, &e, 10);

    if (mddev->pers && !test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
        return -EBUSY;
    if (cmd_match(buf, "none"))
        n = MaxSector;
    else if (!*buf || (*e && *e != '\n'))
        return -EINVAL;

    mddev->recovery_cp = n;
    if (mddev->pers)
        set_bit(MD_CHANGE_CLEAN, &mddev->flags);
    return len;
}
static struct md_sysfs_entry md_resync_start =
__ATTR(resync_start, S_IRUGO|S_IWUSR, resync_start_show, resync_start_store);

/*
 * The array state can be:
 *
 * clear
 *     No devices, no size, no level
 *     Equivalent to STOP_ARRAY ioctl
 * inactive
 *     May have some settings, but array is not active
 *        all IO results in error
 *     When written, doesn't tear down array, but just stops it
 * suspended (not supported yet)
 *     All IO requests will block. The array can be reconfigured.
 *     Writing this, if accepted, will block until array is quiescent
 * readonly
 *     no resync can happen.  no superblocks get written.
 *     write requests fail
 * read-auto
 *     like readonly, but behaves like 'clean' on a write request.
 *
 * clean - no pending writes, but otherwise active.
 *     When written to inactive array, starts without resync
 *     If a write request arrives then
 *       if metadata is known, mark 'dirty' and switch to 'active'.
 *       if not known, block and switch to write-pending
 *     If written to an active array that has pending writes, then fails.
 * active
 *     fully active: IO and resync can be happening.
 *     When written to inactive array, starts with resync
 *
 * write-pending
 *     clean, but writes are blocked waiting for 'active' to be written.
 *
 * active-idle
 *     like active, but no writes have been seen for a while (100msec).
 *
 */
enum array_state { clear, inactive, suspended, readonly, read_auto, clean, active,
           write_pending, active_idle, bad_word};
static char *array_states[] = {
    "clear", "inactive", "suspended", "readonly", "read-auto", "clean", "active",
    "write-pending", "active-idle", NULL };

static int match_word(const char *word, char **list)
{
    int n;
    for (n=0; list[n]; n++)
        if (cmd_match(word, list[n]))
            break;
    return n;
}

static ssize_t
array_state_show(struct mddev *mddev, char *page)
{
    enum array_state st = inactive;

    if (mddev->pers)
        switch(mddev->ro) {
        case 1:
            st = readonly;
            break;
        case 2:
            st = read_auto;
            break;
        case 0:
            if (mddev->in_sync)
                st = clean;
            else if (test_bit(MD_CHANGE_PENDING, &mddev->flags))
                st = write_pending;
            else if (mddev->safemode)
                st = active_idle;
            else
                st = active;
        }
    else {
        if (list_empty(&mddev->disks) &&
            mddev->raid_disks == 0 &&
            mddev->dev_sectors == 0)
            st = clear;
        else
            st = inactive;
    }
    return sprintf(page, "%s\n", array_states[st]);
}

static int do_md_stop(struct mddev * mddev, int ro, struct block_device *bdev);
static int md_set_readonly(struct mddev * mddev, struct block_device *bdev);
static int do_md_run(struct mddev * mddev);
static int restart_array(struct mddev *mddev);

static ssize_t
array_state_store(struct mddev *mddev, const char *buf, size_t len)
{
    int err = -EINVAL;
    enum array_state st = match_word(buf, array_states);
    switch(st) {
    case bad_word:
        break;
    case clear:
        /* stopping an active array */
        err = do_md_stop(mddev, 0, NULL);
        break;
    case inactive:
        /* stopping an active array */
        if (mddev->pers)
            err = do_md_stop(mddev, 2, NULL);
        else
            err = 0; /* already inactive */
        break;
    case suspended:
        break; /* not supported yet */
    case readonly:
        if (mddev->pers)
            err = md_set_readonly(mddev, NULL);
        else {
            mddev->ro = 1;
            set_disk_ro(mddev->gendisk, 1);
            err = do_md_run(mddev);
        }
        break;
    case read_auto:
        if (mddev->pers) {
            if (mddev->ro == 0)
                err = md_set_readonly(mddev, NULL);
            else if (mddev->ro == 1)
                err = restart_array(mddev);
            if (err == 0) {
                mddev->ro = 2;
                set_disk_ro(mddev->gendisk, 0);
            }
        } else {
            mddev->ro = 2;
            err = do_md_run(mddev);
        }
        break;
    case clean:
        if (mddev->pers) {
            restart_array(mddev);
            spin_lock_irq(&mddev->write_lock);
            if (atomic_read(&mddev->writes_pending) == 0) {
                if (mddev->in_sync == 0) {
                    mddev->in_sync = 1;
                    if (mddev->safemode == 1)
                        mddev->safemode = 0;
                    set_bit(MD_CHANGE_CLEAN, &mddev->flags);
                }
                err = 0;
            } else
                err = -EBUSY;
            spin_unlock_irq(&mddev->write_lock);
        } else
            err = -EINVAL;
        break;
    case active:
        if (mddev->pers) {
            restart_array(mddev);
            clear_bit(MD_CHANGE_PENDING, &mddev->flags);
            wake_up(&mddev->sb_wait);
            err = 0;
        } else {
            mddev->ro = 0;
            set_disk_ro(mddev->gendisk, 0);
            err = do_md_run(mddev);
        }
        break;
    case write_pending:
    case active_idle:
        /* these cannot be set */
        break;
    }
    if (err)
        return err;
    else {
        if (mddev->hold_active == UNTIL_IOCTL)
            mddev->hold_active = 0;
        sysfs_notify_dirent_safe(mddev->sysfs_state);
        return len;
    }
}
static struct md_sysfs_entry md_array_state =
__ATTR(array_state, S_IRUGO|S_IWUSR, array_state_show, array_state_store);

static ssize_t
max_corrected_read_errors_show(struct mddev *mddev, char *page) {
    return sprintf(page, "%d\n",
               atomic_read(&mddev->max_corr_read_errors));
}

static ssize_t
max_corrected_read_errors_store(struct mddev *mddev, const char *buf, size_t len)
{
    char *e;
    unsigned long n = simple_strtoul(buf, &e, 10);

    if (*buf && (*e == 0 || *e == '\n')) {
        atomic_set(&mddev->max_corr_read_errors, n);
        return len;
    }
    return -EINVAL;
}

static struct md_sysfs_entry max_corr_read_errors =
__ATTR(max_read_errors, S_IRUGO|S_IWUSR, max_corrected_read_errors_show,
    max_corrected_read_errors_store);

static ssize_t
null_show(struct mddev *mddev, char *page)
{
    return -EINVAL;
}

static ssize_t
new_dev_store(struct mddev *mddev, const char *buf, size_t len)
{
    /* buf must be %d:%d\n? giving major and minor numbers */
    /* The new device is added to the array.
     * If the array has a persistent superblock, we read the
     * superblock to initialise info and check validity.
     * Otherwise, only checking done is that in bind_rdev_to_array,
     * which mainly checks size.
     */
    char *e;
    int major = simple_strtoul(buf, &e, 10);
    int minor;
    dev_t dev;
    struct md_rdev *rdev;
    int err;

    if (!*buf || *e != ':' || !e[1] || e[1] == '\n')
        return -EINVAL;
    minor = simple_strtoul(e+1, &e, 10);
    if (*e && *e != '\n')
        return -EINVAL;
    dev = MKDEV(major, minor);
    if (major != MAJOR(dev) ||
        minor != MINOR(dev))
        return -EOVERFLOW;


    if (mddev->persistent) {
        rdev = md_import_device(dev, mddev->major_version,
                    mddev->minor_version);
        if (!IS_ERR(rdev) && !list_empty(&mddev->disks)) {
            struct md_rdev *rdev0
                = list_entry(mddev->disks.next,
                         struct md_rdev, same_set);
            err = super_types[mddev->major_version]
                .load_super(rdev, rdev0, mddev->minor_version);
            if (err < 0)
                goto out;
        }
    } else if (mddev->external)
        rdev = md_import_device(dev, -2, -1);
    else
        rdev = md_import_device(dev, -1, -1);

    if (IS_ERR(rdev))
        return PTR_ERR(rdev);
    err = bind_rdev_to_array(rdev, mddev);
 out:
    if (err)
        export_rdev(rdev);
    return err ? err : len;
}

static struct md_sysfs_entry md_new_device =
__ATTR(new_dev, S_IWUSR, null_show, new_dev_store);

static ssize_t
bitmap_store(struct mddev *mddev, const char *buf, size_t len)
{
    char *end;
    unsigned long chunk, end_chunk;

    if (!mddev->bitmap)
        goto out;
    /* buf should be <chunk> <chunk> ... or <chunk>-<chunk> ... (range) */
    while (*buf) {
        chunk = end_chunk = simple_strtoul(buf, &end, 0);
        if (buf == end) break;
        if (*end == '-') { /* range */
            buf = end + 1;
            end_chunk = simple_strtoul(buf, &end, 0);
            if (buf == end) break;
        }
        if (*end && !isspace(*end)) break;
        bitmap_dirty_bits(mddev->bitmap, chunk, end_chunk);
        buf = skip_spaces(end);
    }
    bitmap_unplug(mddev->bitmap); /* flush the bits to disk */
out:
    return len;
}

static struct md_sysfs_entry md_bitmap =
__ATTR(bitmap_set_bits, S_IWUSR, null_show, bitmap_store);

static ssize_t
size_show(struct mddev *mddev, char *page)
{
    return sprintf(page, "%llu\n",
        (unsigned long long)mddev->dev_sectors / 2);
}

static int update_size(struct mddev *mddev, sector_t num_sectors);

static ssize_t
size_store(struct mddev *mddev, const char *buf, size_t len)
{
    /* If array is inactive, we can reduce the component size, but
     * not increase it (except from 0).
     * If array is active, we can try an on-line resize
     */
    sector_t sectors;
    int err = strict_blocks_to_sectors(buf, &sectors);

    if (err < 0)
        return err;
    if (mddev->pers) {
        err = update_size(mddev, sectors);
        md_update_sb(mddev, 1);
    } else {
        if (mddev->dev_sectors == 0 ||
            mddev->dev_sectors > sectors)
            mddev->dev_sectors = sectors;
        else
            err = -ENOSPC;
    }
    return err ? err : len;
}

static struct md_sysfs_entry md_size =
__ATTR(component_size, S_IRUGO|S_IWUSR, size_show, size_store);


/* Metdata version.
 * This is one of
 *   'none' for arrays with no metadata (good luck...)
 *   'external' for arrays with externally managed metadata,
 * or N.M for internally known formats
 */
static ssize_t
metadata_show(struct mddev *mddev, char *page)
{
    if (mddev->persistent)
        return sprintf(page, "%d.%d\n",
                   mddev->major_version, mddev->minor_version);
    else if (mddev->external)
        return sprintf(page, "external:%s\n", mddev->metadata_type);
    else
        return sprintf(page, "none\n");
}

static ssize_t
metadata_store(struct mddev *mddev, const char *buf, size_t len)
{
    int major, minor;
    char *e;
    /* Changing the details of 'external' metadata is
     * always permitted.  Otherwise there must be
     * no devices attached to the array.
     */
    if (mddev->external && strncmp(buf, "external:", 9) == 0)
        ;
    else if (!list_empty(&mddev->disks))
        return -EBUSY;

    if (cmd_match(buf, "none")) {
        mddev->persistent = 0;
        mddev->external = 0;
        mddev->major_version = 0;
        mddev->minor_version = 90;
        return len;
    }
    if (strncmp(buf, "external:", 9) == 0) {
        size_t namelen = len-9;
        if (namelen >= sizeof(mddev->metadata_type))
            namelen = sizeof(mddev->metadata_type)-1;
        strncpy(mddev->metadata_type, buf+9, namelen);
        mddev->metadata_type[namelen] = 0;
        if (namelen && mddev->metadata_type[namelen-1] == '\n')
            mddev->metadata_type[--namelen] = 0;
        mddev->persistent = 0;
        mddev->external = 1;
        mddev->major_version = 0;
        mddev->minor_version = 90;
        return len;
    }
    major = simple_strtoul(buf, &e, 10);
    if (e==buf || *e != '.')
        return -EINVAL;
    buf = e+1;
    minor = simple_strtoul(buf, &e, 10);
    if (e==buf || (*e && *e != '\n') )
        return -EINVAL;
    if (major >= ARRAY_SIZE(super_types) || super_types[major].name == NULL)
        return -ENOENT;
    mddev->major_version = major;
    mddev->minor_version = minor;
    mddev->persistent = 1;
    mddev->external = 0;
    return len;
}

static struct md_sysfs_entry md_metadata =
__ATTR(metadata_version, S_IRUGO|S_IWUSR, metadata_show, metadata_store);

static ssize_t
action_show(struct mddev *mddev, char *page)
{
    char *type = "idle";
    if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
        type = "frozen";
    else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
        (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))) {
        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
            type = "reshape";
        else if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
            if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
                type = "resync";
            else if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
                type = "check";
            else
                type = "repair";
        } else if (test_bit(MD_RECOVERY_RECOVER, &mddev->recovery))
            type = "recover";
    }
    return sprintf(page, "%s\n", type);
}

static void reap_sync_thread(struct mddev *mddev);

static ssize_t
action_store(struct mddev *mddev, const char *page, size_t len)
{
    if (!mddev->pers || !mddev->pers->sync_request)
        return -EINVAL;

    if (cmd_match(page, "frozen"))
        set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
    else
        clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);

    if (cmd_match(page, "idle") || cmd_match(page, "frozen")) {
        if (mddev->sync_thread) {
            set_bit(MD_RECOVERY_INTR, &mddev->recovery);
            reap_sync_thread(mddev);
        }
    } else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
           test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
        return -EBUSY;
    else if (cmd_match(page, "resync"))
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
    else if (cmd_match(page, "recover")) {
        set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
    } else if (cmd_match(page, "reshape")) {
        int err;
        if (mddev->pers->start_reshape == NULL)
            return -EINVAL;
        err = mddev->pers->start_reshape(mddev);
        if (err)
            return err;
        sysfs_notify(&mddev->kobj, NULL, "degraded");
    } else {
        if (cmd_match(page, "check"))
            set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
        else if (!cmd_match(page, "repair"))
            return -EINVAL;
        set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
        set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
    }
    if (mddev->ro == 2) {
        /* A write to sync_action is enough to justify
         * canceling read-auto mode
         */
        mddev->ro = 0;
        md_wakeup_thread(mddev->sync_thread);
    }
    set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
    md_wakeup_thread(mddev->thread);
    sysfs_notify_dirent_safe(mddev->sysfs_action);
    return len;
}

static ssize_t
mismatch_cnt_show(struct mddev *mddev, char *page)
{
    return sprintf(page, "%llu\n",
               (unsigned long long)
               atomic64_read(&mddev->resync_mismatches));
}

static struct md_sysfs_entry md_scan_mode =
__ATTR(sync_action, S_IRUGO|S_IWUSR, action_show, action_store);


static struct md_sysfs_entry md_mismatches = __ATTR_RO(mismatch_cnt);

static ssize_t
sync_min_show(struct mddev *mddev, char *page)
{
    return sprintf(page, "%d (%s)\n", speed_min(mddev),
               mddev->sync_speed_min ? "local": "system");
}

static ssize_t
sync_min_store(struct mddev *mddev, const char *buf, size_t len)
{
    int min;
    char *e;
    if (strncmp(buf, "system", 6)==0) {
        mddev->sync_speed_min = 0;
        return len;
    }
    min = simple_strtoul(buf, &e, 10);
    if (buf == e || (*e && *e != '\n') || min <= 0)
        return -EINVAL;
    mddev->sync_speed_min = min;
    return len;
}

static struct md_sysfs_entry md_sync_min =
__ATTR(sync_speed_min, S_IRUGO|S_IWUSR, sync_min_show, sync_min_store);

static ssize_t
sync_max_show(struct mddev *mddev, char *page)
{
    return sprintf(page, "%d (%s)\n", speed_max(mddev),
               mddev->sync_speed_max ? "local": "system");
}

static ssize_t
sync_max_store(struct mddev *mddev, const char *buf, size_t len)
{
    int max;
    char *e;
    if (strncmp(buf, "system", 6)==0) {
        mddev->sync_speed_max = 0;
        return len;
    }
    max = simple_strtoul(buf, &e, 10);
    if (buf == e || (*e && *e != '\n') || max <= 0)
        return -EINVAL;
    mddev->sync_speed_max = max;
    return len;
}

static struct md_sysfs_entry md_sync_max =
__ATTR(sync_speed_max, S_IRUGO|S_IWUSR, sync_max_show, sync_max_store);

static ssize_t
degraded_show(struct mddev *mddev, char *page)
{
    return sprintf(page, "%d\n", mddev->degraded);
}
static struct md_sysfs_entry md_degraded = __ATTR_RO(degraded);

static ssize_t
sync_force_parallel_show(struct mddev *mddev, char *page)
{
    return sprintf(page, "%d\n", mddev->parallel_resync);
}

static ssize_t
sync_force_parallel_store(struct mddev *mddev, const char *buf, size_t len)
{
    long n;

    if (strict_strtol(buf, 10, &n))
        return -EINVAL;

    if (n != 0 && n != 1)
        return -EINVAL;

    mddev->parallel_resync = n;

    if (mddev->sync_thread)
        wake_up(&resync_wait);

    return len;
}

/* force parallel resync, even with shared block devices */
static struct md_sysfs_entry md_sync_force_parallel =
__ATTR(sync_force_parallel, S_IRUGO|S_IWUSR,
       sync_force_parallel_show, sync_force_parallel_store);

static ssize_t
sync_speed_show(struct mddev *mddev, char *page)
{
    unsigned long resync, dt, db;
    if (mddev->curr_resync == 0)
        return sprintf(page, "none\n");
    resync = mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active);
    dt = (jiffies - mddev->resync_mark) / HZ;
    if (!dt) dt++;
    db = resync - mddev->resync_mark_cnt;
    return sprintf(page, "%lu\n", db/dt/2); /* K/sec */
}

static struct md_sysfs_entry md_sync_speed = __ATTR_RO(sync_speed);

static ssize_t
sync_completed_show(struct mddev *mddev, char *page)
{
    unsigned long long max_sectors, resync;

    if (!test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
        return sprintf(page, "none\n");

    if (mddev->curr_resync == 1 ||
        mddev->curr_resync == 2)
        return sprintf(page, "delayed\n");

    if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
        test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
        max_sectors = mddev->resync_max_sectors;
    else
        max_sectors = mddev->dev_sectors;

    resync = mddev->curr_resync_completed;
    return sprintf(page, "%llu / %llu\n", resync, max_sectors);
}

static struct md_sysfs_entry md_sync_completed = __ATTR_RO(sync_completed);

static ssize_t
min_sync_show(struct mddev *mddev, char *page)
{
    return sprintf(page, "%llu\n",
               (unsigned long long)mddev->resync_min);
}
static ssize_t
min_sync_store(struct mddev *mddev, const char *buf, size_t len)
{
    unsigned long long min;
    if (strict_strtoull(buf, 10, &min))
        return -EINVAL;
    if (min > mddev->resync_max)
        return -EINVAL;
    if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
        return -EBUSY;

    /* Must be a multiple of chunk_size */
    if (mddev->chunk_sectors) {
        sector_t temp = min;
        if (sector_div(temp, mddev->chunk_sectors))
            return -EINVAL;
    }
    mddev->resync_min = min;

    return len;
}

static struct md_sysfs_entry md_min_sync =
__ATTR(sync_min, S_IRUGO|S_IWUSR, min_sync_show, min_sync_store);

static ssize_t
max_sync_show(struct mddev *mddev, char *page)
{
    if (mddev->resync_max == MaxSector)
        return sprintf(page, "max\n");
    else
        return sprintf(page, "%llu\n",
                   (unsigned long long)mddev->resync_max);
}
static ssize_t
max_sync_store(struct mddev *mddev, const char *buf, size_t len)
{
    if (strncmp(buf, "max", 3) == 0)
        mddev->resync_max = MaxSector;
    else {
        unsigned long long max;
        if (strict_strtoull(buf, 10, &max))
            return -EINVAL;
        if (max < mddev->resync_min)
            return -EINVAL;
        if (max < mddev->resync_max &&
            mddev->ro == 0 &&
            test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
            return -EBUSY;

        /* Must be a multiple of chunk_size */
        if (mddev->chunk_sectors) {
            sector_t temp = max;
            if (sector_div(temp, mddev->chunk_sectors))
                return -EINVAL;
        }
        mddev->resync_max = max;
    }
    wake_up(&mddev->recovery_wait);
    return len;
}

static struct md_sysfs_entry md_max_sync =
__ATTR(sync_max, S_IRUGO|S_IWUSR, max_sync_show, max_sync_store);

static ssize_t
suspend_lo_show(struct mddev *mddev, char *page)
{
    return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_lo);
}

static ssize_t
suspend_lo_store(struct mddev *mddev, const char *buf, size_t len)
{
    char *e;
    unsigned long long new = simple_strtoull(buf, &e, 10);
    unsigned long long old = mddev->suspend_lo;

    if (mddev->pers == NULL || 
        mddev->pers->quiesce == NULL)
        return -EINVAL;
    if (buf == e || (*e && *e != '\n'))
        return -EINVAL;

    mddev->suspend_lo = new;
    if (new >= old)
        /* Shrinking suspended region */
        mddev->pers->quiesce(mddev, 2);
    else {
        /* Expanding suspended region - need to wait */
        mddev->pers->quiesce(mddev, 1);
        mddev->pers->quiesce(mddev, 0);
    }
    return len;
}
static struct md_sysfs_entry md_suspend_lo =
__ATTR(suspend_lo, S_IRUGO|S_IWUSR, suspend_lo_show, suspend_lo_store);


static ssize_t
suspend_hi_show(struct mddev *mddev, char *page)
{
    return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_hi);
}

static ssize_t
suspend_hi_store(struct mddev *mddev, const char *buf, size_t len)
{
    char *e;
    unsigned long long new = simple_strtoull(buf, &e, 10);
    unsigned long long old = mddev->suspend_hi;

    if (mddev->pers == NULL ||
        mddev->pers->quiesce == NULL)
        return -EINVAL;
    if (buf == e || (*e && *e != '\n'))
        return -EINVAL;

    mddev->suspend_hi = new;
    if (new <= old)
        /* Shrinking suspended region */
        mddev->pers->quiesce(mddev, 2);
    else {
        /* Expanding suspended region - need to wait */
        mddev->pers->quiesce(mddev, 1);
        mddev->pers->quiesce(mddev, 0);
    }
    return len;
}
static struct md_sysfs_entry md_suspend_hi =
__ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);

static ssize_t
reshape_position_show(struct mddev *mddev, char *page)
{
    if (mddev->reshape_position != MaxSector)
        return sprintf(page, "%llu\n",
                   (unsigned long long)mddev->reshape_position);
    strcpy(page, "none\n");
    return 5;
}

static ssize_t
reshape_position_store(struct mddev *mddev, const char *buf, size_t len)
{
    struct md_rdev *rdev;
    char *e;
    unsigned long long new = simple_strtoull(buf, &e, 10);
    if (mddev->pers)
        return -EBUSY;
    if (buf == e || (*e && *e != '\n'))
        return -EINVAL;
    mddev->reshape_position = new;
    mddev->delta_disks = 0;
    mddev->reshape_backwards = 0;
    mddev->new_level = mddev->level;
    mddev->new_layout = mddev->layout;
    mddev->new_chunk_sectors = mddev->chunk_sectors;
    rdev_for_each(rdev, mddev)
        rdev->new_data_offset = rdev->data_offset;
    return len;
}

static struct md_sysfs_entry md_reshape_position =
__ATTR(reshape_position, S_IRUGO|S_IWUSR, reshape_position_show,
       reshape_position_store);

static ssize_t
reshape_direction_show(struct mddev *mddev, char *page)
{
    return sprintf(page, "%s\n",
               mddev->reshape_backwards ? "backwards" : "forwards");
}

static ssize_t
reshape_direction_store(struct mddev *mddev, const char *buf, size_t len)
{
    int backwards = 0;
    if (cmd_match(buf, "forwards"))
        backwards = 0;
    else if (cmd_match(buf, "backwards"))
        backwards = 1;
    else
        return -EINVAL;
    if (mddev->reshape_backwards == backwards)
        return len;

    /* check if we are allowed to change */
    if (mddev->delta_disks)
        return -EBUSY;

    if (mddev->persistent &&
        mddev->major_version == 0)
        return -EINVAL;

    mddev->reshape_backwards = backwards;
    return len;
}

static struct md_sysfs_entry md_reshape_direction =
__ATTR(reshape_direction, S_IRUGO|S_IWUSR, reshape_direction_show,
       reshape_direction_store);

static ssize_t
array_size_show(struct mddev *mddev, char *page)
{
    if (mddev->external_size)
        return sprintf(page, "%llu\n",
                   (unsigned long long)mddev->array_sectors/2);
    else
        return sprintf(page, "default\n");
}

static ssize_t
array_size_store(struct mddev *mddev, const char *buf, size_t len)
{
    sector_t sectors;

    if (strncmp(buf, "default", 7) == 0) {
        if (mddev->pers)
            sectors = mddev->pers->size(mddev, 0, 0);
        else
            sectors = mddev->array_sectors;

        mddev->external_size = 0;
    } else {
        if (strict_blocks_to_sectors(buf, &sectors) < 0)
            return -EINVAL;
        if (mddev->pers && mddev->pers->size(mddev, 0, 0) < sectors)
            return -E2BIG;

        mddev->external_size = 1;
    }

    mddev->array_sectors = sectors;
    if (mddev->pers) {
        set_capacity(mddev->gendisk, mddev->array_sectors);
        revalidate_disk(mddev->gendisk);
    }
    return len;
}

static struct md_sysfs_entry md_array_size =
__ATTR(array_size, S_IRUGO|S_IWUSR, array_size_show,
       array_size_store);

static struct attribute *md_default_attrs[] = {
    &md_level.attr,
    &md_layout.attr,
    &md_raid_disks.attr,
    &md_chunk_size.attr,
    &md_size.attr,
    &md_resync_start.attr,
    &md_metadata.attr,
    &md_new_device.attr,
    &md_safe_delay.attr,
    &md_array_state.attr,
    &md_reshape_position.attr,
    &md_reshape_direction.attr,
    &md_array_size.attr,
    &max_corr_read_errors.attr,
    NULL,
};

static struct attribute *md_redundancy_attrs[] = {
    &md_scan_mode.attr,
    &md_mismatches.attr,
    &md_sync_min.attr,
    &md_sync_max.attr,
    &md_sync_speed.attr,
    &md_sync_force_parallel.attr,
    &md_sync_completed.attr,
    &md_min_sync.attr,
    &md_max_sync.attr,
    &md_suspend_lo.attr,
    &md_suspend_hi.attr,
    &md_bitmap.attr,
    &md_degraded.attr,
    NULL,
};
static struct attribute_group md_redundancy_group = {
    .name = NULL,
    .attrs = md_redundancy_attrs,
};


static ssize_t
md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
    struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
    struct mddev *mddev = container_of(kobj, struct mddev, kobj);
    ssize_t rv;

    if (!entry->show)
        return -EIO;
    spin_lock(&all_mddevs_lock);
    if (list_empty(&mddev->all_mddevs)) {
        spin_unlock(&all_mddevs_lock);
        return -EBUSY;
    }
    mddev_get(mddev);
    spin_unlock(&all_mddevs_lock);

    rv = mddev_lock(mddev);
    if (!rv) {
        rv = entry->show(mddev, page);
        mddev_unlock(mddev);
    }
    mddev_put(mddev);
    return rv;
}

static ssize_t
md_attr_store(struct kobject *kobj, struct attribute *attr,
          const char *page, size_t length)
{
    struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
    struct mddev *mddev = container_of(kobj, struct mddev, kobj);
    ssize_t rv;

    if (!entry->store)
        return -EIO;
    if (!capable(CAP_SYS_ADMIN))
        return -EACCES;
    spin_lock(&all_mddevs_lock);
    if (list_empty(&mddev->all_mddevs)) {
        spin_unlock(&all_mddevs_lock);
        return -EBUSY;
    }
    mddev_get(mddev);
    spin_unlock(&all_mddevs_lock);
    rv = mddev_lock(mddev);
    if (!rv) {
        rv = entry->store(mddev, page, length);
        mddev_unlock(mddev);
    }
    mddev_put(mddev);
    return rv;
}

static void md_free(struct kobject *ko)
{
    struct mddev *mddev = container_of(ko, struct mddev, kobj);

    if (mddev->sysfs_state)
        sysfs_put(mddev->sysfs_state);

    if (mddev->gendisk) {
        del_gendisk(mddev->gendisk);
        put_disk(mddev->gendisk);
    }
    if (mddev->queue)
        blk_cleanup_queue(mddev->queue);

    kfree(mddev);
}

static const struct sysfs_ops md_sysfs_ops = {
    .show   = md_attr_show,
    .store  = md_attr_store,
};
static struct kobj_type md_ktype = {
    .release    = md_free,
    .sysfs_ops  = &md_sysfs_ops,
    .default_attrs  = md_default_attrs,
};

int mdp_major = 0;

static void mddev_delayed_delete(struct work_struct *ws)
{
    struct mddev *mddev = container_of(ws, struct mddev, del_work);

    sysfs_remove_group(&mddev->kobj, &md_bitmap_group);
    kobject_del(&mddev->kobj);
    kobject_put(&mddev->kobj);
}

static int md_alloc(dev_t dev, char *name)
{
    static DEFINE_MUTEX(disks_mutex);
    struct mddev *mddev = mddev_find(dev);
    struct gendisk *disk;
    int partitioned;
    int shift;
    int unit;
    int error;

    if (!mddev)
        return -ENODEV;

    partitioned = (MAJOR(mddev->unit) != MD_MAJOR);
    shift = partitioned ? MdpMinorShift : 0;
    unit = MINOR(mddev->unit) >> shift;

    /* wait for any previous instance of this device to be
     * completely removed (mddev_delayed_delete).
     */
    flush_workqueue(md_misc_wq);

    mutex_lock(&disks_mutex);
    error = -EEXIST;
    if (mddev->gendisk)
        goto abort;

    if (name) {
        /* Need to ensure that 'name' is not a duplicate.
         */
        struct mddev *mddev2;
        spin_lock(&all_mddevs_lock);

        list_for_each_entry(mddev2, &all_mddevs, all_mddevs)
            if (mddev2->gendisk &&
                strcmp(mddev2->gendisk->disk_name, name) == 0) {
                spin_unlock(&all_mddevs_lock);
                goto abort;
            }
        spin_unlock(&all_mddevs_lock);
    }

    error = -ENOMEM;
    mddev->queue = blk_alloc_queue(GFP_KERNEL);
    if (!mddev->queue)
        goto abort;
    mddev->queue->queuedata = mddev;

    blk_queue_make_request(mddev->queue, md_make_request);
    blk_set_stacking_limits(&mddev->queue->limits);

    disk = alloc_disk(1 << shift);
    if (!disk) {
        blk_cleanup_queue(mddev->queue);
        mddev->queue = NULL;
        goto abort;
    }
    disk->major = MAJOR(mddev->unit);
    disk->first_minor = unit << shift;
    if (name)
        strcpy(disk->disk_name, name);
    else if (partitioned)
        sprintf(disk->disk_name, "md_d%d", unit);
    else
        sprintf(disk->disk_name, "md%d", unit);
    disk->fops = &md_fops;
    disk->private_data = mddev;
    disk->queue = mddev->queue;
    blk_queue_flush(mddev->queue, REQ_FLUSH | REQ_FUA);
    /* Allow extended partitions.  This makes the
     * 'mdp' device redundant, but we can't really
     * remove it now.
     */
    disk->flags |= GENHD_FL_EXT_DEVT;
    mddev->gendisk = disk;
    /* As soon as we call add_disk(), another thread could get
     * through to md_open, so make sure it doesn't get too far
     */
    mutex_lock(&mddev->open_mutex);
    add_disk(disk);

    error = kobject_init_and_add(&mddev->kobj, &md_ktype,
                     &disk_to_dev(disk)->kobj, "%s", "md");
    if (error) {
        /* This isn't possible, but as kobject_init_and_add is marked
         * __must_check, we must do something with the result
         */
        printk(KERN_WARNING "md: cannot register %s/md - name in use\n",
               disk->disk_name);
        error = 0;
    }
    if (mddev->kobj.sd &&
        sysfs_create_group(&mddev->kobj, &md_bitmap_group))
        printk(KERN_DEBUG "pointless warning\n");
    mutex_unlock(&mddev->open_mutex);
 abort:
    mutex_unlock(&disks_mutex);
    if (!error && mddev->kobj.sd) {
        kobject_uevent(&mddev->kobj, KOBJ_ADD);
        mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
    }
    mddev_put(mddev);
    return error;
}

static struct kobject *md_probe(dev_t dev, int *part, void *data)
{
    md_alloc(dev, NULL);
    return NULL;
}

static int add_named_array(const char *val, struct kernel_param *kp)
{
    /* val must be "md_*" where * is not all digits.
     * We allocate an array with a large free minor number, and
     * set the name to val.  val must not already be an active name.
     */
    int len = strlen(val);
    char buf[DISK_NAME_LEN];

    while (len && val[len-1] == '\n')
        len--;
    if (len >= DISK_NAME_LEN)
        return -E2BIG;
    strlcpy(buf, val, len+1);
    if (strncmp(buf, "md_", 3) != 0)
        return -EINVAL;
    return md_alloc(0, buf);
}

static void md_safemode_timeout(unsigned long data)
{
    struct mddev *mddev = (struct mddev *) data;

    if (!atomic_read(&mddev->writes_pending)) {
        mddev->safemode = 1;
        if (mddev->external)
            sysfs_notify_dirent_safe(mddev->sysfs_state);
    }
    md_wakeup_thread(mddev->thread);
}

static int start_dirty_degraded;

int md_run(struct mddev *mddev)
{
    int err;
    struct md_rdev *rdev;
    struct md_personality *pers;

    if (list_empty(&mddev->disks))
        /* cannot run an array with no devices.. */
        return -EINVAL;

    if (mddev->pers)
        return -EBUSY;
    /* Cannot run until previous stop completes properly */
    if (mddev->sysfs_active)
        return -EBUSY;

    /*
     * Analyze all RAID superblock(s)
     */
    if (!mddev->raid_disks) {
        if (!mddev->persistent)
            return -EINVAL;
        analyze_sbs(mddev);
    }

    if (mddev->level != LEVEL_NONE)
        request_module("md-level-%d", mddev->level);
    else if (mddev->clevel[0])
        request_module("md-%s", mddev->clevel);

    /*
     * Drop all container device buffers, from now on
     * the only valid external interface is through the md
     * device.
     */
    rdev_for_each(rdev, mddev) {
        if (test_bit(Faulty, &rdev->flags))
            continue;
        sync_blockdev(rdev->bdev);
        invalidate_bdev(rdev->bdev);

        /* perform some consistency tests on the device.
         * We don't want the data to overlap the metadata,
         * Internal Bitmap issues have been handled elsewhere.
         */
        if (rdev->meta_bdev) {
            /* Nothing to check */;
        } else if (rdev->data_offset < rdev->sb_start) {
            if (mddev->dev_sectors &&
                rdev->data_offset + mddev->dev_sectors
                > rdev->sb_start) {
                printk("md: %s: data overlaps metadata\n",
                       mdname(mddev));
                return -EINVAL;
            }
        } else {
            if (rdev->sb_start + rdev->sb_size/512
                > rdev->data_offset) {
                printk("md: %s: metadata overlaps data\n",
                       mdname(mddev));
                return -EINVAL;
            }
        }
        sysfs_notify_dirent_safe(rdev->sysfs_state);
    }

    if (mddev->bio_set == NULL)
        mddev->bio_set = bioset_create(BIO_POOL_SIZE, 0);

    spin_lock(&pers_lock);
    pers = find_pers(mddev->level, mddev->clevel);
    if (!pers || !try_module_get(pers->owner)) {
        spin_unlock(&pers_lock);
        if (mddev->level != LEVEL_NONE)
            printk(KERN_WARNING "md: personality for level %d is not loaded!\n",
                   mddev->level);
        else
            printk(KERN_WARNING "md: personality for level %s is not loaded!\n",
                   mddev->clevel);
        return -EINVAL;
    }
    mddev->pers = pers;
    spin_unlock(&pers_lock);
    if (mddev->level != pers->level) {
        mddev->level = pers->level;
        mddev->new_level = pers->level;
    }
    strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));

    if (mddev->reshape_position != MaxSector &&
        pers->start_reshape == NULL) {
        /* This personality cannot handle reshaping... */
        mddev->pers = NULL;
        module_put(pers->owner);
        return -EINVAL;
    }

    if (pers->sync_request) {
        /* Warn if this is a potentially silly
         * configuration.
         */
        char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
        struct md_rdev *rdev2;
        int warned = 0;

        rdev_for_each(rdev, mddev)
            rdev_for_each(rdev2, mddev) {
                if (rdev < rdev2 &&
                    rdev->bdev->bd_contains ==
                    rdev2->bdev->bd_contains) {
                    printk(KERN_WARNING
                           "%s: WARNING: %s appears to be"
                           " on the same physical disk as"
                           " %s.\n",
                           mdname(mddev),
                           bdevname(rdev->bdev,b),
                           bdevname(rdev2->bdev,b2));
                    warned = 1;
                }
            }

        if (warned)
            printk(KERN_WARNING
                   "True protection against single-disk"
                   " failure might be compromised.\n");
    }

    mddev->recovery = 0;
    /* may be over-ridden by personality */
    mddev->resync_max_sectors = mddev->dev_sectors;

    mddev->ok_start_degraded = start_dirty_degraded;

    if (start_readonly && mddev->ro == 0)
        mddev->ro = 2; /* read-only, but switch on first write */

    err = mddev->pers->run(mddev);
    if (err)
        printk(KERN_ERR "md: pers->run() failed ...\n");
    else if (mddev->pers->size(mddev, 0, 0) < mddev->array_sectors) {
        WARN_ONCE(!mddev->external_size, "%s: default size too small,"
              " but 'external_size' not in effect?\n", __func__);
        printk(KERN_ERR
               "md: invalid array_size %llu > default size %llu\n",
               (unsigned long long)mddev->array_sectors / 2,
               (unsigned long long)mddev->pers->size(mddev, 0, 0) / 2);
        err = -EINVAL;
        mddev->pers->stop(mddev);
    }
    if (err == 0 && mddev->pers->sync_request &&
        (mddev->bitmap_info.file || mddev->bitmap_info.offset)) {
        err = bitmap_create(mddev);
        if (err) {
            printk(KERN_ERR "%s: failed to create bitmap (%d)\n",
                   mdname(mddev), err);
            mddev->pers->stop(mddev);
        }
    }
    if (err) {
        module_put(mddev->pers->owner);
        mddev->pers = NULL;
        bitmap_destroy(mddev);
        return err;
    }
    if (mddev->pers->sync_request) {
        if (mddev->kobj.sd &&
            sysfs_create_group(&mddev->kobj, &md_redundancy_group))
            printk(KERN_WARNING
                   "md: cannot register extra attributes for %s\n",
                   mdname(mddev));
        mddev->sysfs_action = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_action");
    } else if (mddev->ro == 2) /* auto-readonly not meaningful */
        mddev->ro = 0;

    atomic_set(&mddev->writes_pending,0);
    atomic_set(&mddev->max_corr_read_errors,
           MD_DEFAULT_MAX_CORRECTED_READ_ERRORS);
    mddev->safemode = 0;
    mddev->safemode_timer.function = md_safemode_timeout;
    mddev->safemode_timer.data = (unsigned long) mddev;
    mddev->safemode_delay = (200 * HZ)/1000 +1; /* 200 msec delay */
    mddev->in_sync = 1;
    smp_wmb();
    mddev->ready = 1;
    rdev_for_each(rdev, mddev)
        if (rdev->raid_disk >= 0)
            if (sysfs_link_rdev(mddev, rdev))
                /* failure here is OK */;
    
    set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
    
    if (mddev->flags)
        md_update_sb(mddev, 0);

    md_new_event(mddev);
    sysfs_notify_dirent_safe(mddev->sysfs_state);
    sysfs_notify_dirent_safe(mddev->sysfs_action);
    sysfs_notify(&mddev->kobj, NULL, "degraded");
    return 0;
}
EXPORT_SYMBOL_GPL(md_run);

static int do_md_run(struct mddev *mddev)
{
    int err;

    err = md_run(mddev);
    if (err)
        goto out;
    err = bitmap_load(mddev);
    if (err) {
        bitmap_destroy(mddev);
        goto out;
    }

    md_wakeup_thread(mddev->thread);
    md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */

    set_capacity(mddev->gendisk, mddev->array_sectors);
    revalidate_disk(mddev->gendisk);
    mddev->changed = 1;
    kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
out:
    return err;
}

static int restart_array(struct mddev *mddev)
{
    struct gendisk *disk = mddev->gendisk;

    /* Complain if it has no devices */
    if (list_empty(&mddev->disks))
        return -ENXIO;
    if (!mddev->pers)
        return -EINVAL;
    if (!mddev->ro)
        return -EBUSY;
    mddev->safemode = 0;
    mddev->ro = 0;
    set_disk_ro(disk, 0);
    printk(KERN_INFO "md: %s switched to read-write mode.\n",
        mdname(mddev));
    /* Kick recovery or resync if necessary */
    set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
    md_wakeup_thread(mddev->thread);
    md_wakeup_thread(mddev->sync_thread);
    sysfs_notify_dirent_safe(mddev->sysfs_state);
    return 0;
}

/* similar to deny_write_access, but accounts for our holding a reference
 * to the file ourselves */
static int deny_bitmap_write_access(struct file * file)
{
    struct inode *inode = file->f_mapping->host;

    spin_lock(&inode->i_lock);
    if (atomic_read(&inode->i_writecount) > 1) {
        spin_unlock(&inode->i_lock);
        return -ETXTBSY;
    }
    atomic_set(&inode->i_writecount, -1);
    spin_unlock(&inode->i_lock);

    return 0;
}

void restore_bitmap_write_access(struct file *file)
{
    struct inode *inode = file->f_mapping->host;

    spin_lock(&inode->i_lock);
    atomic_set(&inode->i_writecount, 1);
    spin_unlock(&inode->i_lock);
}

static void md_clean(struct mddev *mddev)
{
    mddev->array_sectors = 0;
    mddev->external_size = 0;
    mddev->dev_sectors = 0;
    mddev->raid_disks = 0;
    mddev->recovery_cp = 0;
    mddev->resync_min = 0;
    mddev->resync_max = MaxSector;
    mddev->reshape_position = MaxSector;
    mddev->external = 0;
    mddev->persistent = 0;
    mddev->level = LEVEL_NONE;
    mddev->clevel[0] = 0;
    mddev->flags = 0;
    mddev->ro = 0;
    mddev->metadata_type[0] = 0;
    mddev->chunk_sectors = 0;
    mddev->ctime = mddev->utime = 0;
    mddev->layout = 0;
    mddev->max_disks = 0;
    mddev->events = 0;
    mddev->can_decrease_events = 0;
    mddev->delta_disks = 0;
    mddev->reshape_backwards = 0;
    mddev->new_level = LEVEL_NONE;
    mddev->new_layout = 0;
    mddev->new_chunk_sectors = 0;
    mddev->curr_resync = 0;
    atomic64_set(&mddev->resync_mismatches, 0);
    mddev->suspend_lo = mddev->suspend_hi = 0;
    mddev->sync_speed_min = mddev->sync_speed_max = 0;
    mddev->recovery = 0;
    mddev->in_sync = 0;
    mddev->changed = 0;
    mddev->degraded = 0;
    mddev->safemode = 0;
    mddev->merge_check_needed = 0;
    mddev->bitmap_info.offset = 0;
    mddev->bitmap_info.default_offset = 0;
    mddev->bitmap_info.default_space = 0;
    mddev->bitmap_info.chunksize = 0;
    mddev->bitmap_info.daemon_sleep = 0;
    mddev->bitmap_info.max_write_behind = 0;
}

static void __md_stop_writes(struct mddev *mddev)
{
    if (mddev->sync_thread) {
        set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
        reap_sync_thread(mddev);
    }

    del_timer_sync(&mddev->safemode_timer);

    bitmap_flush(mddev);
    md_super_wait(mddev);

    if (!mddev->in_sync || mddev->flags) {
        /* mark array as shutdown cleanly */
        mddev->in_sync = 1;
        md_update_sb(mddev, 1);
    }
}

void md_stop_writes(struct mddev *mddev)
{
    mddev_lock(mddev);
    __md_stop_writes(mddev);
    mddev_unlock(mddev);
}
EXPORT_SYMBOL_GPL(md_stop_writes);

static void __md_stop(struct mddev *mddev)
{
    mddev->ready = 0;
    mddev->pers->stop(mddev);
    if (mddev->pers->sync_request && mddev->to_remove == NULL)
        mddev->to_remove = &md_redundancy_group;
    module_put(mddev->pers->owner);
    mddev->pers = NULL;
    clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
}

void md_stop(struct mddev *mddev)
{
    /* stop the array and free an attached data structures.
     * This is called from dm-raid
     */
    __md_stop(mddev);
    bitmap_destroy(mddev);
    if (mddev->bio_set)
        bioset_free(mddev->bio_set);
}

EXPORT_SYMBOL_GPL(md_stop);

static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
{
    int err = 0;
    mutex_lock(&mddev->open_mutex);
    if (atomic_read(&mddev->openers) > !!bdev) {
        printk("md: %s still in use.\n",mdname(mddev));
        err = -EBUSY;
        goto out;
    }
    if (bdev)
        sync_blockdev(bdev);
    if (mddev->pers) {
        __md_stop_writes(mddev);

        err  = -ENXIO;
        if (mddev->ro==1)
            goto out;
        mddev->ro = 1;
        set_disk_ro(mddev->gendisk, 1);
        clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
        sysfs_notify_dirent_safe(mddev->sysfs_state);
        err = 0;    
    }
out:
    mutex_unlock(&mddev->open_mutex);
    return err;
}

/* mode:
 *   0 - completely stop and dis-assemble array
 *   2 - stop but do not disassemble array
 */
static int do_md_stop(struct mddev * mddev, int mode,
              struct block_device *bdev)
{
    struct gendisk *disk = mddev->gendisk;
    struct md_rdev *rdev;

    mutex_lock(&mddev->open_mutex);
    if (atomic_read(&mddev->openers) > !!bdev ||
        mddev->sysfs_active) {
        printk("md: %s still in use.\n",mdname(mddev));
        mutex_unlock(&mddev->open_mutex);
        return -EBUSY;
    }
    if (bdev)
        /* It is possible IO was issued on some other
         * open file which was closed before we took ->open_mutex.
         * As that was not the last close __blkdev_put will not
         * have called sync_blockdev, so we must.
         */
        sync_blockdev(bdev);

    if (mddev->pers) {
        if (mddev->ro)
            set_disk_ro(disk, 0);

        __md_stop_writes(mddev);
        __md_stop(mddev);
        mddev->queue->merge_bvec_fn = NULL;
        mddev->queue->backing_dev_info.congested_fn = NULL;

        /* tell userspace to handle 'inactive' */
        sysfs_notify_dirent_safe(mddev->sysfs_state);

        rdev_for_each(rdev, mddev)
            if (rdev->raid_disk >= 0)
                sysfs_unlink_rdev(mddev, rdev);

        set_capacity(disk, 0);
        mutex_unlock(&mddev->open_mutex);
        mddev->changed = 1;
        revalidate_disk(disk);

        if (mddev->ro)
            mddev->ro = 0;
    } else
        mutex_unlock(&mddev->open_mutex);
    /*
     * Free resources if final stop
     */
    if (mode == 0) {
        printk(KERN_INFO "md: %s stopped.\n", mdname(mddev));

        bitmap_destroy(mddev);
        if (mddev->bitmap_info.file) {
            restore_bitmap_write_access(mddev->bitmap_info.file);
            fput(mddev->bitmap_info.file);
            mddev->bitmap_info.file = NULL;
        }
        mddev->bitmap_info.offset = 0;

        export_array(mddev);

        md_clean(mddev);
        kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
        if (mddev->hold_active == UNTIL_STOP)
            mddev->hold_active = 0;
    }
    blk_integrity_unregister(disk);
    md_new_event(mddev);
    sysfs_notify_dirent_safe(mddev->sysfs_state);
    return 0;
}

#ifndef MODULE
static void autorun_array(struct mddev *mddev)
{
    struct md_rdev *rdev;
    int err;

    if (list_empty(&mddev->disks))
        return;

    printk(KERN_INFO "md: running: ");

    rdev_for_each(rdev, mddev) {
        char b[BDEVNAME_SIZE];
        printk("<%s>", bdevname(rdev->bdev,b));
    }
    printk("\n");

    err = do_md_run(mddev);
    if (err) {
        printk(KERN_WARNING "md: do_md_run() returned %d\n", err);
        do_md_stop(mddev, 0, NULL);
    }
}

/*
 * lets try to run arrays based on all disks that have arrived
 * until now. (those are in pending_raid_disks)
 *
 * the method: pick the first pending disk, collect all disks with
 * the same UUID, remove all from the pending list and put them into
 * the 'same_array' list. Then order this list based on superblock
 * update time (freshest comes first), kick out 'old' disks and
 * compare superblocks. If everything's fine then run it.
 *
 * If "unit" is allocated, then bump its reference count
 */
static void autorun_devices(int part)
{
    struct md_rdev *rdev0, *rdev, *tmp;
    struct mddev *mddev;
    char b[BDEVNAME_SIZE];

    printk(KERN_INFO "md: autorun ...\n");
    while (!list_empty(&pending_raid_disks)) {
        int unit;
        dev_t dev;
        LIST_HEAD(candidates);
        rdev0 = list_entry(pending_raid_disks.next,
                     struct md_rdev, same_set);

        printk(KERN_INFO "md: considering %s ...\n",
            bdevname(rdev0->bdev,b));
        INIT_LIST_HEAD(&candidates);
        rdev_for_each_list(rdev, tmp, &pending_raid_disks)
            if (super_90_load(rdev, rdev0, 0) >= 0) {
                printk(KERN_INFO "md:  adding %s ...\n",
                    bdevname(rdev->bdev,b));
                list_move(&rdev->same_set, &candidates);
            }
        /*
         * now we have a set of devices, with all of them having
         * mostly sane superblocks. It's time to allocate the
         * mddev.
         */
        if (part) {
            dev = MKDEV(mdp_major,
                    rdev0->preferred_minor << MdpMinorShift);
            unit = MINOR(dev) >> MdpMinorShift;
        } else {
            dev = MKDEV(MD_MAJOR, rdev0->preferred_minor);
            unit = MINOR(dev);
        }
        if (rdev0->preferred_minor != unit) {
            printk(KERN_INFO "md: unit number in %s is bad: %d\n",
                   bdevname(rdev0->bdev, b), rdev0->preferred_minor);
            break;
        }

        md_probe(dev, NULL, NULL);
        mddev = mddev_find(dev);
        if (!mddev || !mddev->gendisk) {
            if (mddev)
                mddev_put(mddev);
            printk(KERN_ERR
                "md: cannot allocate memory for md drive.\n");
            break;
        }
        if (mddev_lock(mddev)) 
            printk(KERN_WARNING "md: %s locked, cannot run\n",
                   mdname(mddev));
        else if (mddev->raid_disks || mddev->major_version
             || !list_empty(&mddev->disks)) {
            printk(KERN_WARNING 
                "md: %s already running, cannot run %s\n",
                mdname(mddev), bdevname(rdev0->bdev,b));
            mddev_unlock(mddev);
        } else {
            printk(KERN_INFO "md: created %s\n", mdname(mddev));
            mddev->persistent = 1;
            rdev_for_each_list(rdev, tmp, &candidates) {
                list_del_init(&rdev->same_set);
                if (bind_rdev_to_array(rdev, mddev))
                    export_rdev(rdev);
            }
            autorun_array(mddev);
            mddev_unlock(mddev);
        }
        /* on success, candidates will be empty, on error
         * it won't...
         */
        rdev_for_each_list(rdev, tmp, &candidates) {
            list_del_init(&rdev->same_set);
            export_rdev(rdev);
        }
        mddev_put(mddev);
    }
    printk(KERN_INFO "md: ... autorun DONE.\n");
}
#endif /* !MODULE */

static int get_version(void __user * arg)
{
    mdu_version_t ver;

    ver.major = MD_MAJOR_VERSION;
    ver.minor = MD_MINOR_VERSION;
    ver.patchlevel = MD_PATCHLEVEL_VERSION;

    if (copy_to_user(arg, &ver, sizeof(ver)))
        return -EFAULT;

    return 0;
}

static int get_array_info(struct mddev * mddev, void __user * arg)
{
    mdu_array_info_t info;
    int nr,working,insync,failed,spare;
    struct md_rdev *rdev;

    nr = working = insync = failed = spare = 0;
    rcu_read_lock();
    rdev_for_each_rcu(rdev, mddev) {
        nr++;
        if (test_bit(Faulty, &rdev->flags))
            failed++;
        else {
            working++;
            if (test_bit(In_sync, &rdev->flags))
                insync++;   
            else
                spare++;
        }
    }
    rcu_read_unlock();

    info.major_version = mddev->major_version;
    info.minor_version = mddev->minor_version;
    info.patch_version = MD_PATCHLEVEL_VERSION;
    info.ctime         = mddev->ctime;
    info.level         = mddev->level;
    info.size          = mddev->dev_sectors / 2;
    if (info.size != mddev->dev_sectors / 2) /* overflow */
        info.size = -1;
    info.nr_disks      = nr;
    info.raid_disks    = mddev->raid_disks;
    info.md_minor      = mddev->md_minor;
    info.not_persistent= !mddev->persistent;

    info.utime         = mddev->utime;
    info.state         = 0;
    if (mddev->in_sync)
        info.state = (1<<MD_SB_CLEAN);
    if (mddev->bitmap && mddev->bitmap_info.offset)
        info.state = (1<<MD_SB_BITMAP_PRESENT);
    info.active_disks  = insync;
    info.working_disks = working;
    info.failed_disks  = failed;
    info.spare_disks   = spare;

    info.layout        = mddev->layout;
    info.chunk_size    = mddev->chunk_sectors << 9;

    if (copy_to_user(arg, &info, sizeof(info)))
        return -EFAULT;

    return 0;
}

static int get_bitmap_file(struct mddev * mddev, void __user * arg)
{
    mdu_bitmap_file_t *file = NULL; /* too big for stack allocation */
    char *ptr, *buf = NULL;
    int err = -ENOMEM;

    if (md_allow_write(mddev))
        file = kmalloc(sizeof(*file), GFP_NOIO);
    else
        file = kmalloc(sizeof(*file), GFP_KERNEL);

    if (!file)
        goto out;

    /* bitmap disabled, zero the first byte and copy out */
    if (!mddev->bitmap || !mddev->bitmap->storage.file) {
        file->pathname[0] = '\0';
        goto copy_out;
    }

    buf = kmalloc(sizeof(file->pathname), GFP_KERNEL);
    if (!buf)
        goto out;

    ptr = d_path(&mddev->bitmap->storage.file->f_path,
             buf, sizeof(file->pathname));
    if (IS_ERR(ptr))
        goto out;

    strcpy(file->pathname, ptr);

copy_out:
    err = 0;
    if (copy_to_user(arg, file, sizeof(*file)))
        err = -EFAULT;
out:
    kfree(buf);
    kfree(file);
    return err;
}

static int get_disk_info(struct mddev * mddev, void __user * arg)
{
    mdu_disk_info_t info;
    struct md_rdev *rdev;

    if (copy_from_user(&info, arg, sizeof(info)))
        return -EFAULT;

    rcu_read_lock();
    rdev = find_rdev_nr_rcu(mddev, info.number);
    if (rdev) {
        info.major = MAJOR(rdev->bdev->bd_dev);
        info.minor = MINOR(rdev->bdev->bd_dev);
        info.raid_disk = rdev->raid_disk;
        info.state = 0;
        if (test_bit(Faulty, &rdev->flags))
            info.state |= (1<<MD_DISK_FAULTY);
        else if (test_bit(In_sync, &rdev->flags)) {
            info.state |= (1<<MD_DISK_ACTIVE);
            info.state |= (1<<MD_DISK_SYNC);
        }
        if (test_bit(WriteMostly, &rdev->flags))
            info.state |= (1<<MD_DISK_WRITEMOSTLY);
    } else {
        info.major = info.minor = 0;
        info.raid_disk = -1;
        info.state = (1<<MD_DISK_REMOVED);
    }
    rcu_read_unlock();

    if (copy_to_user(arg, &info, sizeof(info)))
        return -EFAULT;

    return 0;
}

static int add_new_disk(struct mddev * mddev, mdu_disk_info_t *info)
{
    char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
    struct md_rdev *rdev;
    dev_t dev = MKDEV(info->major,info->minor);

    if (info->major != MAJOR(dev) || info->minor != MINOR(dev))
        return -EOVERFLOW;

    if (!mddev->raid_disks) {
        int err;
        /* expecting a device which has a superblock */
        rdev = md_import_device(dev, mddev->major_version, mddev->minor_version);
        if (IS_ERR(rdev)) {
            printk(KERN_WARNING 
                "md: md_import_device returned %ld\n",
                PTR_ERR(rdev));
            return PTR_ERR(rdev);
        }
        if (!list_empty(&mddev->disks)) {
            struct md_rdev *rdev0
                = list_entry(mddev->disks.next,
                         struct md_rdev, same_set);
            err = super_types[mddev->major_version]
                .load_super(rdev, rdev0, mddev->minor_version);
            if (err < 0) {
                printk(KERN_WARNING 
                    "md: %s has different UUID to %s\n",
                    bdevname(rdev->bdev,b), 
                    bdevname(rdev0->bdev,b2));
                export_rdev(rdev);
                return -EINVAL;
            }
        }
        err = bind_rdev_to_array(rdev, mddev);
        if (err)
            export_rdev(rdev);
        return err;
    }

    /*
     * add_new_disk can be used once the array is assembled
     * to add "hot spares".  They must already have a superblock
     * written
     */
    if (mddev->pers) {
        int err;
        if (!mddev->pers->hot_add_disk) {
            printk(KERN_WARNING 
                "%s: personality does not support diskops!\n",
                   mdname(mddev));
            return -EINVAL;
        }
        if (mddev->persistent)
            rdev = md_import_device(dev, mddev->major_version,
                        mddev->minor_version);
        else
            rdev = md_import_device(dev, -1, -1);
        if (IS_ERR(rdev)) {
            printk(KERN_WARNING 
                "md: md_import_device returned %ld\n",
                PTR_ERR(rdev));
            return PTR_ERR(rdev);
        }
        /* set saved_raid_disk if appropriate */
        if (!mddev->persistent) {
            if (info->state & (1<<MD_DISK_SYNC)  &&
                info->raid_disk < mddev->raid_disks) {
                rdev->raid_disk = info->raid_disk;
                set_bit(In_sync, &rdev->flags);
            } else
                rdev->raid_disk = -1;
        } else
            super_types[mddev->major_version].
                validate_super(mddev, rdev);
        if ((info->state & (1<<MD_DISK_SYNC)) &&
             rdev->raid_disk != info->raid_disk) {
            /* This was a hot-add request, but events doesn't
             * match, so reject it.
             */
            export_rdev(rdev);
            return -EINVAL;
        }

        if (test_bit(In_sync, &rdev->flags))
            rdev->saved_raid_disk = rdev->raid_disk;
        else
            rdev->saved_raid_disk = -1;

        clear_bit(In_sync, &rdev->flags); /* just to be sure */
        if (info->state & (1<<MD_DISK_WRITEMOSTLY))
            set_bit(WriteMostly, &rdev->flags);
        else
            clear_bit(WriteMostly, &rdev->flags);

        rdev->raid_disk = -1;
        err = bind_rdev_to_array(rdev, mddev);
        if (!err && !mddev->pers->hot_remove_disk) {
            /* If there is hot_add_disk but no hot_remove_disk
             * then added disks for geometry changes,
             * and should be added immediately.
             */
            super_types[mddev->major_version].
                validate_super(mddev, rdev);
            err = mddev->pers->hot_add_disk(mddev, rdev);
            if (err)
                unbind_rdev_from_array(rdev);
        }
        if (err)
            export_rdev(rdev);
        else
            sysfs_notify_dirent_safe(rdev->sysfs_state);

        md_update_sb(mddev, 1);
        if (mddev->degraded)
            set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        if (!err)
            md_new_event(mddev);
        md_wakeup_thread(mddev->thread);
        return err;
    }

    /* otherwise, add_new_disk is only allowed
     * for major_version==0 superblocks
     */
    if (mddev->major_version != 0) {
        printk(KERN_WARNING "%s: ADD_NEW_DISK not supported\n",
               mdname(mddev));
        return -EINVAL;
    }

    if (!(info->state & (1<<MD_DISK_FAULTY))) {
        int err;
        rdev = md_import_device(dev, -1, 0);
        if (IS_ERR(rdev)) {
            printk(KERN_WARNING 
                "md: error, md_import_device() returned %ld\n",
                PTR_ERR(rdev));
            return PTR_ERR(rdev);
        }
        rdev->desc_nr = info->number;
        if (info->raid_disk < mddev->raid_disks)
            rdev->raid_disk = info->raid_disk;
        else
            rdev->raid_disk = -1;

        if (rdev->raid_disk < mddev->raid_disks)
            if (info->state & (1<<MD_DISK_SYNC))
                set_bit(In_sync, &rdev->flags);

        if (info->state & (1<<MD_DISK_WRITEMOSTLY))
            set_bit(WriteMostly, &rdev->flags);

        if (!mddev->persistent) {
            printk(KERN_INFO "md: nonpersistent superblock ...\n");
            rdev->sb_start = i_size_read(rdev->bdev->bd_inode) / 512;
        } else
            rdev->sb_start = calc_dev_sboffset(rdev);
        rdev->sectors = rdev->sb_start;

        err = bind_rdev_to_array(rdev, mddev);
        if (err) {
            export_rdev(rdev);
            return err;
        }
    }

    return 0;
}

static int hot_remove_disk(struct mddev * mddev, dev_t dev)
{
    char b[BDEVNAME_SIZE];
    struct md_rdev *rdev;

    rdev = find_rdev(mddev, dev);
    if (!rdev)
        return -ENXIO;

    if (rdev->raid_disk >= 0)
        goto busy;

    kick_rdev_from_array(rdev);
    md_update_sb(mddev, 1);
    md_new_event(mddev);

    return 0;
busy:
    printk(KERN_WARNING "md: cannot remove active disk %s from %s ...\n",
        bdevname(rdev->bdev,b), mdname(mddev));
    return -EBUSY;
}

static int hot_add_disk(struct mddev * mddev, dev_t dev)
{
    char b[BDEVNAME_SIZE];
    int err;
    struct md_rdev *rdev;

    if (!mddev->pers)
        return -ENODEV;

    if (mddev->major_version != 0) {
        printk(KERN_WARNING "%s: HOT_ADD may only be used with"
            " version-0 superblocks.\n",
            mdname(mddev));
        return -EINVAL;
    }
    if (!mddev->pers->hot_add_disk) {
        printk(KERN_WARNING 
            "%s: personality does not support diskops!\n",
            mdname(mddev));
        return -EINVAL;
    }

    rdev = md_import_device(dev, -1, 0);
    if (IS_ERR(rdev)) {
        printk(KERN_WARNING 
            "md: error, md_import_device() returned %ld\n",
            PTR_ERR(rdev));
        return -EINVAL;
    }

    if (mddev->persistent)
        rdev->sb_start = calc_dev_sboffset(rdev);
    else
        rdev->sb_start = i_size_read(rdev->bdev->bd_inode) / 512;

    rdev->sectors = rdev->sb_start;

    if (test_bit(Faulty, &rdev->flags)) {
        printk(KERN_WARNING 
            "md: can not hot-add faulty %s disk to %s!\n",
            bdevname(rdev->bdev,b), mdname(mddev));
        err = -EINVAL;
        goto abort_export;
    }
    clear_bit(In_sync, &rdev->flags);
    rdev->desc_nr = -1;
    rdev->saved_raid_disk = -1;
    err = bind_rdev_to_array(rdev, mddev);
    if (err)
        goto abort_export;

    /*
     * The rest should better be atomic, we can have disk failures
     * noticed in interrupt contexts ...
     */

    rdev->raid_disk = -1;

    md_update_sb(mddev, 1);

    /*
     * Kick recovery, maybe this spare has to be added to the
     * array immediately.
     */
    set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
    md_wakeup_thread(mddev->thread);
    md_new_event(mddev);
    return 0;

abort_export:
    export_rdev(rdev);
    return err;
}

static int set_bitmap_file(struct mddev *mddev, int fd)
{
    int err;

    if (mddev->pers) {
        if (!mddev->pers->quiesce)
            return -EBUSY;
        if (mddev->recovery || mddev->sync_thread)
            return -EBUSY;
        /* we should be able to change the bitmap.. */
    }


    if (fd >= 0) {
        if (mddev->bitmap)
            return -EEXIST; /* cannot add when bitmap is present */
        mddev->bitmap_info.file = fget(fd);

        if (mddev->bitmap_info.file == NULL) {
            printk(KERN_ERR "%s: error: failed to get bitmap file\n",
                   mdname(mddev));
            return -EBADF;
        }

        err = deny_bitmap_write_access(mddev->bitmap_info.file);
        if (err) {
            printk(KERN_ERR "%s: error: bitmap file is already in use\n",
                   mdname(mddev));
            fput(mddev->bitmap_info.file);
            mddev->bitmap_info.file = NULL;
            return err;
        }
        mddev->bitmap_info.offset = 0; /* file overrides offset */
    } else if (mddev->bitmap == NULL)
        return -ENOENT; /* cannot remove what isn't there */
    err = 0;
    if (mddev->pers) {
        mddev->pers->quiesce(mddev, 1);
        if (fd >= 0) {
            err = bitmap_create(mddev);
            if (!err)
                err = bitmap_load(mddev);
        }
        if (fd < 0 || err) {
            bitmap_destroy(mddev);
            fd = -1; /* make sure to put the file */
        }
        mddev->pers->quiesce(mddev, 0);
    }
    if (fd < 0) {
        if (mddev->bitmap_info.file) {
            restore_bitmap_write_access(mddev->bitmap_info.file);
            fput(mddev->bitmap_info.file);
        }
        mddev->bitmap_info.file = NULL;
    }

    return err;
}

/*
 * set_array_info is used two different ways
 * The original usage is when creating a new array.
 * In this usage, raid_disks is > 0 and it together with
 *  level, size, not_persistent,layout,chunksize determine the
 *  shape of the array.
 *  This will always create an array with a type-0.90.0 superblock.
 * The newer usage is when assembling an array.
 *  In this case raid_disks will be 0, and the major_version field is
 *  use to determine which style super-blocks are to be found on the devices.
 *  The minor and patch _version numbers are also kept incase the
 *  super_block handler wishes to interpret them.
 */
static int set_array_info(struct mddev * mddev, mdu_array_info_t *info)
{

    if (info->raid_disks == 0) {
        /* just setting version number for superblock loading */
        if (info->major_version < 0 ||
            info->major_version >= ARRAY_SIZE(super_types) ||
            super_types[info->major_version].name == NULL) {
            /* maybe try to auto-load a module? */
            printk(KERN_INFO 
                "md: superblock version %d not known\n",
                info->major_version);
            return -EINVAL;
        }
        mddev->major_version = info->major_version;
        mddev->minor_version = info->minor_version;
        mddev->patch_version = info->patch_version;
        mddev->persistent = !info->not_persistent;
        /* ensure mddev_put doesn't delete this now that there
         * is some minimal configuration.
         */
        mddev->ctime         = get_seconds();
        return 0;
    }
    mddev->major_version = MD_MAJOR_VERSION;
    mddev->minor_version = MD_MINOR_VERSION;
    mddev->patch_version = MD_PATCHLEVEL_VERSION;
    mddev->ctime         = get_seconds();

    mddev->level         = info->level;
    mddev->clevel[0]     = 0;
    mddev->dev_sectors   = 2 * (sector_t)info->size;
    mddev->raid_disks    = info->raid_disks;
    /* don't set md_minor, it is determined by which /dev/md* was
     * openned
     */
    if (info->state & (1<<MD_SB_CLEAN))
        mddev->recovery_cp = MaxSector;
    else
        mddev->recovery_cp = 0;
    mddev->persistent    = ! info->not_persistent;
    mddev->external      = 0;

    mddev->layout        = info->layout;
    mddev->chunk_sectors = info->chunk_size >> 9;

    mddev->max_disks     = MD_SB_DISKS;

    if (mddev->persistent)
        mddev->flags         = 0;
    set_bit(MD_CHANGE_DEVS, &mddev->flags);

    mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
    mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
    mddev->bitmap_info.offset = 0;

    mddev->reshape_position = MaxSector;

    /*
     * Generate a 128 bit UUID
     */
    get_random_bytes(mddev->uuid, 16);

    mddev->new_level = mddev->level;
    mddev->new_chunk_sectors = mddev->chunk_sectors;
    mddev->new_layout = mddev->layout;
    mddev->delta_disks = 0;
    mddev->reshape_backwards = 0;

    return 0;
}

void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors)
{
    WARN(!mddev_is_locked(mddev), "%s: unlocked mddev!\n", __func__);

    if (mddev->external_size)
        return;

    mddev->array_sectors = array_sectors;
}
EXPORT_SYMBOL(md_set_array_sectors);

static int update_size(struct mddev *mddev, sector_t num_sectors)
{
    struct md_rdev *rdev;
    int rv;
    int fit = (num_sectors == 0);

    if (mddev->pers->resize == NULL)
        return -EINVAL;
    /* The "num_sectors" is the number of sectors of each device that
     * is used.  This can only make sense for arrays with redundancy.
     * linear and raid0 always use whatever space is available. We can only
     * consider changing this number if no resync or reconstruction is
     * happening, and if the new size is acceptable. It must fit before the
     * sb_start or, if that is <data_offset, it must fit before the size
     * of each device.  If num_sectors is zero, we find the largest size
     * that fits.
     */
    if (mddev->sync_thread)
        return -EBUSY;

    rdev_for_each(rdev, mddev) {
        sector_t avail = rdev->sectors;

        if (fit && (num_sectors == 0 || num_sectors > avail))
            num_sectors = avail;
        if (avail < num_sectors)
            return -ENOSPC;
    }
    rv = mddev->pers->resize(mddev, num_sectors);
    if (!rv)
        revalidate_disk(mddev->gendisk);
    return rv;
}

static int update_raid_disks(struct mddev *mddev, int raid_disks)
{
    int rv;
    struct md_rdev *rdev;
    /* change the number of raid disks */
    if (mddev->pers->check_reshape == NULL)
        return -EINVAL;
    if (raid_disks <= 0 ||
        (mddev->max_disks && raid_disks >= mddev->max_disks))
        return -EINVAL;
    if (mddev->sync_thread || mddev->reshape_position != MaxSector)
        return -EBUSY;

    rdev_for_each(rdev, mddev) {
        if (mddev->raid_disks < raid_disks &&
            rdev->data_offset < rdev->new_data_offset)
            return -EINVAL;
        if (mddev->raid_disks > raid_disks &&
            rdev->data_offset > rdev->new_data_offset)
            return -EINVAL;
    }

    mddev->delta_disks = raid_disks - mddev->raid_disks;
    if (mddev->delta_disks < 0)
        mddev->reshape_backwards = 1;
    else if (mddev->delta_disks > 0)
        mddev->reshape_backwards = 0;

    rv = mddev->pers->check_reshape(mddev);
    if (rv < 0) {
        mddev->delta_disks = 0;
        mddev->reshape_backwards = 0;
    }
    return rv;
}


/*
 * update_array_info is used to change the configuration of an
 * on-line array.
 * The version, ctime,level,size,raid_disks,not_persistent, layout,chunk_size
 * fields in the info are checked against the array.
 * Any differences that cannot be handled will cause an error.
 * Normally, only one change can be managed at a time.
 */
static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
{
    int rv = 0;
    int cnt = 0;
    int state = 0;

    /* calculate expected state,ignoring low bits */
    if (mddev->bitmap && mddev->bitmap_info.offset)
        state |= (1 << MD_SB_BITMAP_PRESENT);

    if (mddev->major_version != info->major_version ||
        mddev->minor_version != info->minor_version ||
/*      mddev->patch_version != info->patch_version || */
        mddev->ctime         != info->ctime         ||
        mddev->level         != info->level         ||
/*      mddev->layout        != info->layout        || */
        !mddev->persistent   != info->not_persistent||
        mddev->chunk_sectors != info->chunk_size >> 9 ||
        /* ignore bottom 8 bits of state, and allow SB_BITMAP_PRESENT to change */
        ((state^info->state) & 0xfffffe00)
        )
        return -EINVAL;
    /* Check there is only one change */
    if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
        cnt++;
    if (mddev->raid_disks != info->raid_disks)
        cnt++;
    if (mddev->layout != info->layout)
        cnt++;
    if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT))
        cnt++;
    if (cnt == 0)
        return 0;
    if (cnt > 1)
        return -EINVAL;

    if (mddev->layout != info->layout) {
        /* Change layout
         * we don't need to do anything at the md level, the
         * personality will take care of it all.
         */
        if (mddev->pers->check_reshape == NULL)
            return -EINVAL;
        else {
            mddev->new_layout = info->layout;
            rv = mddev->pers->check_reshape(mddev);
            if (rv)
                mddev->new_layout = mddev->layout;
            return rv;
        }
    }
    if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
        rv = update_size(mddev, (sector_t)info->size * 2);

    if (mddev->raid_disks    != info->raid_disks)
        rv = update_raid_disks(mddev, info->raid_disks);

    if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT)) {
        if (mddev->pers->quiesce == NULL)
            return -EINVAL;
        if (mddev->recovery || mddev->sync_thread)
            return -EBUSY;
        if (info->state & (1<<MD_SB_BITMAP_PRESENT)) {
            /* add the bitmap */
            if (mddev->bitmap)
                return -EEXIST;
            if (mddev->bitmap_info.default_offset == 0)
                return -EINVAL;
            mddev->bitmap_info.offset =
                mddev->bitmap_info.default_offset;
            mddev->bitmap_info.space =
                mddev->bitmap_info.default_space;
            mddev->pers->quiesce(mddev, 1);
            rv = bitmap_create(mddev);
            if (!rv)
                rv = bitmap_load(mddev);
            if (rv)
                bitmap_destroy(mddev);
            mddev->pers->quiesce(mddev, 0);
        } else {
            /* remove the bitmap */
            if (!mddev->bitmap)
                return -ENOENT;
            if (mddev->bitmap->storage.file)
                return -EINVAL;
            mddev->pers->quiesce(mddev, 1);
            bitmap_destroy(mddev);
            mddev->pers->quiesce(mddev, 0);
            mddev->bitmap_info.offset = 0;
        }
    }
    md_update_sb(mddev, 1);
    return rv;
}

static int set_disk_faulty(struct mddev *mddev, dev_t dev)
{
    struct md_rdev *rdev;
    int err = 0;

    if (mddev->pers == NULL)
        return -ENODEV;

    rcu_read_lock();
    rdev = find_rdev_rcu(mddev, dev);
    if (!rdev)
        err =  -ENODEV;
    else {
        md_error(mddev, rdev);
        if (!test_bit(Faulty, &rdev->flags))
            err = -EBUSY;
    }
    rcu_read_unlock();
    return err;
}

/*
 * We have a problem here : there is no easy way to give a CHS
 * virtual geometry. We currently pretend that we have a 2 heads
 * 4 sectors (with a BIG number of cylinders...). This drives
 * dosfs just mad... ;-)
 */
static int md_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
    struct mddev *mddev = bdev->bd_disk->private_data;

    geo->heads = 2;
    geo->sectors = 4;
    geo->cylinders = mddev->array_sectors / 8;
    return 0;
}

static int md_ioctl(struct block_device *bdev, fmode_t mode,
            unsigned int cmd, unsigned long arg)
{
    int err = 0;
    void __user *argp = (void __user *)arg;
    struct mddev *mddev = NULL;
    int ro;

    switch (cmd) {
    case RAID_VERSION:
    case GET_ARRAY_INFO:
    case GET_DISK_INFO:
        break;
    default:
        if (!capable(CAP_SYS_ADMIN))
            return -EACCES;
    }

    /*
     * Commands dealing with the RAID driver but not any
     * particular array:
     */
    switch (cmd)
    {
        case RAID_VERSION:
            err = get_version(argp);
            goto done;

        case PRINT_RAID_DEBUG:
            err = 0;
            md_print_devices();
            goto done;

#ifndef MODULE
        case RAID_AUTORUN:
            err = 0;
            autostart_arrays(arg);
            goto done;
#endif
        default:;
    }

    /*
     * Commands creating/starting a new array:
     */

    mddev = bdev->bd_disk->private_data;

    if (!mddev) {
        BUG();
        goto abort;
    }

    /* Some actions do not requires the mutex */
    switch (cmd) {
    case GET_ARRAY_INFO:
        if (!mddev->raid_disks && !mddev->external)
            err = -ENODEV;
        else
            err = get_array_info(mddev, argp);
        goto abort;

    case GET_DISK_INFO:
        if (!mddev->raid_disks && !mddev->external)
            err = -ENODEV;
        else
            err = get_disk_info(mddev, argp);
        goto abort;

    case SET_DISK_FAULTY:
        err = set_disk_faulty(mddev, new_decode_dev(arg));
        goto abort;
    }

    err = mddev_lock(mddev);
    if (err) {
        printk(KERN_INFO 
            "md: ioctl lock interrupted, reason %d, cmd %d\n",
            err, cmd);
        goto abort;
    }

    switch (cmd)
    {
        case SET_ARRAY_INFO:
            {
                mdu_array_info_t info;
                if (!arg)
                    memset(&info, 0, sizeof(info));
                else if (copy_from_user(&info, argp, sizeof(info))) {
                    err = -EFAULT;
                    goto abort_unlock;
                }
                if (mddev->pers) {
                    err = update_array_info(mddev, &info);
                    if (err) {
                        printk(KERN_WARNING "md: couldn't update"
                               " array info. %d\n", err);
                        goto abort_unlock;
                    }
                    goto done_unlock;
                }
                if (!list_empty(&mddev->disks)) {
                    printk(KERN_WARNING
                           "md: array %s already has disks!\n",
                           mdname(mddev));
                    err = -EBUSY;
                    goto abort_unlock;
                }
                if (mddev->raid_disks) {
                    printk(KERN_WARNING
                           "md: array %s already initialised!\n",
                           mdname(mddev));
                    err = -EBUSY;
                    goto abort_unlock;
                }
                err = set_array_info(mddev, &info);
                if (err) {
                    printk(KERN_WARNING "md: couldn't set"
                           " array info. %d\n", err);
                    goto abort_unlock;
                }
            }
            goto done_unlock;

        default:;
    }

    /*
     * Commands querying/configuring an existing array:
     */
    /* if we are not initialised yet, only ADD_NEW_DISK, STOP_ARRAY,
     * RUN_ARRAY, and GET_ and SET_BITMAP_FILE are allowed */
    if ((!mddev->raid_disks && !mddev->external)
        && cmd != ADD_NEW_DISK && cmd != STOP_ARRAY
        && cmd != RUN_ARRAY && cmd != SET_BITMAP_FILE
        && cmd != GET_BITMAP_FILE) {
        err = -ENODEV;
        goto abort_unlock;
    }

    /*
     * Commands even a read-only array can execute:
     */
    switch (cmd)
    {
        case GET_BITMAP_FILE:
            err = get_bitmap_file(mddev, argp);
            goto done_unlock;

        case RESTART_ARRAY_RW:
            err = restart_array(mddev);
            goto done_unlock;

        case STOP_ARRAY:
            err = do_md_stop(mddev, 0, bdev);
            goto done_unlock;

        case STOP_ARRAY_RO:
            err = md_set_readonly(mddev, bdev);
            goto done_unlock;

        case BLKROSET:
            if (get_user(ro, (int __user *)(arg))) {
                err = -EFAULT;
                goto done_unlock;
            }
            err = -EINVAL;

            /* if the bdev is going readonly the value of mddev->ro
             * does not matter, no writes are coming
             */
            if (ro)
                goto done_unlock;

            /* are we are already prepared for writes? */
            if (mddev->ro != 1)
                goto done_unlock;

            /* transitioning to readauto need only happen for
             * arrays that call md_write_start
             */
            if (mddev->pers) {
                err = restart_array(mddev);
                if (err == 0) {
                    mddev->ro = 2;
                    set_disk_ro(mddev->gendisk, 0);
                }
            }
            goto done_unlock;
    }

    /*
     * The remaining ioctls are changing the state of the
     * superblock, so we do not allow them on read-only arrays.
     * However non-MD ioctls (e.g. get-size) will still come through
     * here and hit the 'default' below, so only disallow
     * 'md' ioctls, and switch to rw mode if started auto-readonly.
     */
    if (_IOC_TYPE(cmd) == MD_MAJOR && mddev->ro && mddev->pers) {
        if (mddev->ro == 2) {
            mddev->ro = 0;
            sysfs_notify_dirent_safe(mddev->sysfs_state);
            set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
            md_wakeup_thread(mddev->thread);
        } else {
            err = -EROFS;
            goto abort_unlock;
        }
    }

    switch (cmd)
    {
        case ADD_NEW_DISK:
        {
            mdu_disk_info_t info;
            if (copy_from_user(&info, argp, sizeof(info)))
                err = -EFAULT;
            else
                err = add_new_disk(mddev, &info);
            goto done_unlock;
        }

        case HOT_REMOVE_DISK:
            err = hot_remove_disk(mddev, new_decode_dev(arg));
            goto done_unlock;

        case HOT_ADD_DISK:
            err = hot_add_disk(mddev, new_decode_dev(arg));
            goto done_unlock;

        case RUN_ARRAY:
            err = do_md_run(mddev);
            goto done_unlock;

        case SET_BITMAP_FILE:
            err = set_bitmap_file(mddev, (int)arg);
            goto done_unlock;

        default:
            err = -EINVAL;
            goto abort_unlock;
    }

done_unlock:
abort_unlock:
    if (mddev->hold_active == UNTIL_IOCTL &&
        err != -EINVAL)
        mddev->hold_active = 0;
    mddev_unlock(mddev);

    return err;
done:
    if (err)
        MD_BUG();
abort:
    return err;
}
#ifdef CONFIG_COMPAT
static int md_compat_ioctl(struct block_device *bdev, fmode_t mode,
            unsigned int cmd, unsigned long arg)
{
    switch (cmd) {
    case HOT_REMOVE_DISK:
    case HOT_ADD_DISK:
    case SET_DISK_FAULTY:
    case SET_BITMAP_FILE:
        /* These take in integer arg, do not convert */
        break;
    default:
        arg = (unsigned long)compat_ptr(arg);
        break;
    }

    return md_ioctl(bdev, mode, cmd, arg);
}
#endif /* CONFIG_COMPAT */

static int md_open(struct block_device *bdev, fmode_t mode)
{
    /*
     * Succeed if we can lock the mddev, which confirms that
     * it isn't being stopped right now.
     */
    struct mddev *mddev = mddev_find(bdev->bd_dev);
    int err;

    if (!mddev)
        return -ENODEV;

    if (mddev->gendisk != bdev->bd_disk) {
        /* we are racing with mddev_put which is discarding this
         * bd_disk.
         */
        mddev_put(mddev);
        /* Wait until bdev->bd_disk is definitely gone */
        flush_workqueue(md_misc_wq);
        /* Then retry the open from the top */
        return -ERESTARTSYS;
    }
    BUG_ON(mddev != bdev->bd_disk->private_data);

    if ((err = mutex_lock_interruptible(&mddev->open_mutex)))
        goto out;

    err = 0;
    atomic_inc(&mddev->openers);
    mutex_unlock(&mddev->open_mutex);

    check_disk_change(bdev);
 out:
    return err;
}

static int md_release(struct gendisk *disk, fmode_t mode)
{
    struct mddev *mddev = disk->private_data;

    BUG_ON(!mddev);
    atomic_dec(&mddev->openers);
    mddev_put(mddev);

    return 0;
}

static int md_media_changed(struct gendisk *disk)
{
    struct mddev *mddev = disk->private_data;

    return mddev->changed;
}

static int md_revalidate(struct gendisk *disk)
{
    struct mddev *mddev = disk->private_data;

    mddev->changed = 0;
    return 0;
}
static const struct block_device_operations md_fops =
{
    .owner      = THIS_MODULE,
    .open       = md_open,
    .release    = md_release,
    .ioctl      = md_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl   = md_compat_ioctl,
#endif
    .getgeo     = md_getgeo,
    .media_changed  = md_media_changed,
    .revalidate_disk= md_revalidate,
};

static int md_thread(void * arg)
{
    struct md_thread *thread = arg;

    /*
     * md_thread is a 'system-thread', it's priority should be very
     * high. We avoid resource deadlocks individually in each
     * raid personality. (RAID5 does preallocation) We also use RR and
     * the very same RT priority as kswapd, thus we will never get
     * into a priority inversion deadlock.
     *
     * we definitely have to have equal or higher priority than
     * bdflush, otherwise bdflush will deadlock if there are too
     * many dirty RAID5 blocks.
     */

    allow_signal(SIGKILL);
    while (!kthread_should_stop()) {

        /* We need to wait INTERRUPTIBLE so that
         * we don't add to the load-average.
         * That means we need to be sure no signals are
         * pending
         */
        if (signal_pending(current))
            flush_signals(current);

        wait_event_interruptible_timeout
            (thread->wqueue,
             test_bit(THREAD_WAKEUP, &thread->flags)
             || kthread_should_stop(),
             thread->timeout);

        clear_bit(THREAD_WAKEUP, &thread->flags);
        if (!kthread_should_stop())
            thread->run(thread);
    }

    return 0;
}

void md_wakeup_thread(struct md_thread *thread)
{
    if (thread) {
        pr_debug("md: waking up MD thread %s.\n", thread->tsk->comm);
        set_bit(THREAD_WAKEUP, &thread->flags);
        wake_up(&thread->wqueue);
    }
}

struct md_thread *md_register_thread(void (*run) (struct md_thread *),
        struct mddev *mddev, const char *name)
{
    struct md_thread *thread;

    thread = kzalloc(sizeof(struct md_thread), GFP_KERNEL);
    if (!thread)
        return NULL;

    init_waitqueue_head(&thread->wqueue);

    thread->run = run;
    thread->mddev = mddev;
    thread->timeout = MAX_SCHEDULE_TIMEOUT;
    thread->tsk = kthread_run(md_thread, thread,
                  "%s_%s",
                  mdname(thread->mddev),
                  name);
    if (IS_ERR(thread->tsk)) {
        kfree(thread);
        return NULL;
    }
    return thread;
}

void md_unregister_thread(struct md_thread **threadp)
{
    struct md_thread *thread = *threadp;
    if (!thread)
        return;
    pr_debug("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk));
    /* Locking ensures that mddev_unlock does not wake_up a
     * non-existent thread
     */
    spin_lock(&pers_lock);
    *threadp = NULL;
    spin_unlock(&pers_lock);

    kthread_stop(thread->tsk);
    kfree(thread);
}

void md_error(struct mddev *mddev, struct md_rdev *rdev)
{
    if (!mddev) {
        MD_BUG();
        return;
    }

    if (!rdev || test_bit(Faulty, &rdev->flags))
        return;

    if (!mddev->pers || !mddev->pers->error_handler)
        return;
    mddev->pers->error_handler(mddev,rdev);
    if (mddev->degraded)
        set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
    sysfs_notify_dirent_safe(rdev->sysfs_state);
    set_bit(MD_RECOVERY_INTR, &mddev->recovery);
    set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
    md_wakeup_thread(mddev->thread);
    if (mddev->event_work.func)
        queue_work(md_misc_wq, &mddev->event_work);
    md_new_event_inintr(mddev);
}

/* seq_file implementation /proc/mdstat */

static void status_unused(struct seq_file *seq)
{
    int i = 0;
    struct md_rdev *rdev;

    seq_printf(seq, "unused devices: ");

    list_for_each_entry(rdev, &pending_raid_disks, same_set) {
        char b[BDEVNAME_SIZE];
        i++;
        seq_printf(seq, "%s ",
                  bdevname(rdev->bdev,b));
    }
    if (!i)
        seq_printf(seq, "<none>");

    seq_printf(seq, "\n");
}


static void status_resync(struct seq_file *seq, struct mddev * mddev)
{
    sector_t max_sectors, resync, res;
    unsigned long dt, db;
    sector_t rt;
    int scale;
    unsigned int per_milli;

    if (mddev->curr_resync <= 3)
        resync = 0;
    else
        resync = mddev->curr_resync
            - atomic_read(&mddev->recovery_active);

    if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
        test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
        max_sectors = mddev->resync_max_sectors;
    else
        max_sectors = mddev->dev_sectors;

    /*
     * Should not happen.
     */
    if (!max_sectors) {
        MD_BUG();
        return;
    }
    /* Pick 'scale' such that (resync>>scale)*1000 will fit
     * in a sector_t, and (max_sectors>>scale) will fit in a
     * u32, as those are the requirements for sector_div.
     * Thus 'scale' must be at least 10
     */
    scale = 10;
    if (sizeof(sector_t) > sizeof(unsigned long)) {
        while ( max_sectors/2 > (1ULL<<(scale+32)))
            scale++;
    }
    res = (resync>>scale)*1000;
    sector_div(res, (u32)((max_sectors>>scale)+1));

    per_milli = res;
    {
        int i, x = per_milli/50, y = 20-x;
        seq_printf(seq, "[");
        for (i = 0; i < x; i++)
            seq_printf(seq, "=");
        seq_printf(seq, ">");
        for (i = 0; i < y; i++)
            seq_printf(seq, ".");
        seq_printf(seq, "] ");
    }
    seq_printf(seq, " %s =%3u.%u%% (%llu/%llu)",
           (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)?
            "reshape" :
            (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)?
             "check" :
             (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ?
              "resync" : "recovery"))),
           per_milli/10, per_milli % 10,
           (unsigned long long) resync/2,
           (unsigned long long) max_sectors/2);

    /*
     * dt: time from mark until now
     * db: blocks written from mark until now
     * rt: remaining time
     *
     * rt is a sector_t, so could be 32bit or 64bit.
     * So we divide before multiply in case it is 32bit and close
     * to the limit.
     * We scale the divisor (db) by 32 to avoid losing precision
     * near the end of resync when the number of remaining sectors
     * is close to 'db'.
     * We then divide rt by 32 after multiplying by db to compensate.
     * The '+1' avoids division by zero if db is very small.
     */
    dt = ((jiffies - mddev->resync_mark) / HZ);
    if (!dt) dt++;
    db = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active))
        - mddev->resync_mark_cnt;

    rt = max_sectors - resync;    /* number of remaining sectors */
    sector_div(rt, db/32+1);
    rt *= dt;
    rt >>= 5;

    seq_printf(seq, " finish=%lu.%lumin", (unsigned long)rt / 60,
           ((unsigned long)rt % 60)/6);

    seq_printf(seq, " speed=%ldK/sec", db/2/dt);
}

static void *md_seq_start(struct seq_file *seq, loff_t *pos)
{
    struct list_head *tmp;
    loff_t l = *pos;
    struct mddev *mddev;

    if (l >= 0x10000)
        return NULL;
    if (!l--)
        /* header */
        return (void*)1;

    spin_lock(&all_mddevs_lock);
    list_for_each(tmp,&all_mddevs)
        if (!l--) {
            mddev = list_entry(tmp, struct mddev, all_mddevs);
            mddev_get(mddev);
            spin_unlock(&all_mddevs_lock);
            return mddev;
        }
    spin_unlock(&all_mddevs_lock);
    if (!l--)
        return (void*)2;/* tail */
    return NULL;
}

static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    struct list_head *tmp;
    struct mddev *next_mddev, *mddev = v;
    
    ++*pos;
    if (v == (void*)2)
        return NULL;

    spin_lock(&all_mddevs_lock);
    if (v == (void*)1)
        tmp = all_mddevs.next;
    else
        tmp = mddev->all_mddevs.next;
    if (tmp != &all_mddevs)
        next_mddev = mddev_get(list_entry(tmp,struct mddev,all_mddevs));
    else {
        next_mddev = (void*)2;
        *pos = 0x10000;
    }       
    spin_unlock(&all_mddevs_lock);

    if (v != (void*)1)
        mddev_put(mddev);
    return next_mddev;

}

static void md_seq_stop(struct seq_file *seq, void *v)
{
    struct mddev *mddev = v;

    if (mddev && v != (void*)1 && v != (void*)2)
        mddev_put(mddev);
}

static int md_seq_show(struct seq_file *seq, void *v)
{
    struct mddev *mddev = v;
    sector_t sectors;
    struct md_rdev *rdev;

    if (v == (void*)1) {
        struct md_personality *pers;
        seq_printf(seq, "Personalities : ");
        spin_lock(&pers_lock);
        list_for_each_entry(pers, &pers_list, list)
            seq_printf(seq, "[%s] ", pers->name);

        spin_unlock(&pers_lock);
        seq_printf(seq, "\n");
        seq->poll_event = atomic_read(&md_event_count);
        return 0;
    }
    if (v == (void*)2) {
        status_unused(seq);
        return 0;
    }

    if (mddev_lock(mddev) < 0)
        return -EINTR;

    if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {
        seq_printf(seq, "%s : %sactive", mdname(mddev),
                        mddev->pers ? "" : "in");
        if (mddev->pers) {
            if (mddev->ro==1)
                seq_printf(seq, " (read-only)");
            if (mddev->ro==2)
                seq_printf(seq, " (auto-read-only)");
            seq_printf(seq, " %s", mddev->pers->name);
        }

        sectors = 0;
        rdev_for_each(rdev, mddev) {
            char b[BDEVNAME_SIZE];
            seq_printf(seq, " %s[%d]",
                bdevname(rdev->bdev,b), rdev->desc_nr);
            if (test_bit(WriteMostly, &rdev->flags))
                seq_printf(seq, "(W)");
            if (test_bit(Faulty, &rdev->flags)) {
                seq_printf(seq, "(F)");
                continue;
            }
            if (rdev->raid_disk < 0)
                seq_printf(seq, "(S)"); /* spare */
            if (test_bit(Replacement, &rdev->flags))
                seq_printf(seq, "(R)");
            sectors += rdev->sectors;
        }

        if (!list_empty(&mddev->disks)) {
            if (mddev->pers)
                seq_printf(seq, "\n      %llu blocks",
                       (unsigned long long)
                       mddev->array_sectors / 2);
            else
                seq_printf(seq, "\n      %llu blocks",
                       (unsigned long long)sectors / 2);
        }
        if (mddev->persistent) {
            if (mddev->major_version != 0 ||
                mddev->minor_version != 90) {
                seq_printf(seq," super %d.%d",
                       mddev->major_version,
                       mddev->minor_version);
            }
        } else if (mddev->external)
            seq_printf(seq, " super external:%s",
                   mddev->metadata_type);
        else
            seq_printf(seq, " super non-persistent");

        if (mddev->pers) {
            mddev->pers->status(seq, mddev);
            seq_printf(seq, "\n      ");
            if (mddev->pers->sync_request) {
                if (mddev->curr_resync > 2) {
                    status_resync(seq, mddev);
                    seq_printf(seq, "\n      ");
                } else if (mddev->curr_resync >= 1)
                    seq_printf(seq, "\tresync=DELAYED\n      ");
                else if (mddev->recovery_cp < MaxSector)
                    seq_printf(seq, "\tresync=PENDING\n      ");
            }
        } else
            seq_printf(seq, "\n       ");

        bitmap_status(seq, mddev->bitmap);

        seq_printf(seq, "\n");
    }
    mddev_unlock(mddev);
    
    return 0;
}

static const struct seq_operations md_seq_ops = {
    .start  = md_seq_start,
    .next   = md_seq_next,
    .stop   = md_seq_stop,
    .show   = md_seq_show,
};

static int md_seq_open(struct inode *inode, struct file *file)
{
    struct seq_file *seq;
    int error;

    error = seq_open(file, &md_seq_ops);
    if (error)
        return error;

    seq = file->private_data;
    seq->poll_event = atomic_read(&md_event_count);
    return error;
}

static unsigned int mdstat_poll(struct file *filp, poll_table *wait)
{
    struct seq_file *seq = filp->private_data;
    int mask;

    poll_wait(filp, &md_event_waiters, wait);

    /* always allow read */
    mask = POLLIN | POLLRDNORM;

    if (seq->poll_event != atomic_read(&md_event_count))
        mask |= POLLERR | POLLPRI;
    return mask;
}

static const struct file_operations md_seq_fops = {
    .owner      = THIS_MODULE,
    .open           = md_seq_open,
    .read           = seq_read,
    .llseek         = seq_lseek,
    .release    = seq_release_private,
    .poll       = mdstat_poll,
};

int register_md_personality(struct md_personality *p)
{
    spin_lock(&pers_lock);
    list_add_tail(&p->list, &pers_list);
    printk(KERN_INFO "md: %s personality registered for level %d\n", p->name, p->level);
    spin_unlock(&pers_lock);
    return 0;
}

int unregister_md_personality(struct md_personality *p)
{
    printk(KERN_INFO "md: %s personality unregistered\n", p->name);
    spin_lock(&pers_lock);
    list_del_init(&p->list);
    spin_unlock(&pers_lock);
    return 0;
}

static int is_mddev_idle(struct mddev *mddev, int init)
{
    struct md_rdev * rdev;
    int idle;
    int curr_events;

    idle = 1;
    rcu_read_lock();
    rdev_for_each_rcu(rdev, mddev) {
        struct gendisk *disk = rdev->bdev->bd_contains->bd_disk;
        curr_events = (int)part_stat_read(&disk->part0, sectors[0]) +
                  (int)part_stat_read(&disk->part0, sectors[1]) -
                  atomic_read(&disk->sync_io);
        /* sync IO will cause sync_io to increase before the disk_stats
         * as sync_io is counted when a request starts, and
         * disk_stats is counted when it completes.
         * So resync activity will cause curr_events to be smaller than
         * when there was no such activity.
         * non-sync IO will cause disk_stat to increase without
         * increasing sync_io so curr_events will (eventually)
         * be larger than it was before.  Once it becomes
         * substantially larger, the test below will cause
         * the array to appear non-idle, and resync will slow
         * down.
         * If there is a lot of outstanding resync activity when
         * we set last_event to curr_events, then all that activity
         * completing might cause the array to appear non-idle
         * and resync will be slowed down even though there might
         * not have been non-resync activity.  This will only
         * happen once though.  'last_events' will soon reflect
         * the state where there is little or no outstanding
         * resync requests, and further resync activity will
         * always make curr_events less than last_events.
         *
         */
        if (init || curr_events - rdev->last_events > 64) {
            rdev->last_events = curr_events;
            idle = 0;
        }
    }
    rcu_read_unlock();
    return idle;
}

void md_done_sync(struct mddev *mddev, int blocks, int ok)
{
    /* another "blocks" (512byte) blocks have been synced */
    atomic_sub(blocks, &mddev->recovery_active);
    wake_up(&mddev->recovery_wait);
    if (!ok) {
        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        // stop recovery, signal do_sync ....
    }
}


/* md_write_start(mddev, bi)
 * If we need to update some array metadata (e.g. 'active' flag
 * in superblock) before writing, schedule a superblock update
 * and wait for it to complete.
 */
void md_write_start(struct mddev *mddev, struct bio *bi)
{
    int did_change = 0;
    if (bio_data_dir(bi) != WRITE)
        return;

    BUG_ON(mddev->ro == 1);
    if (mddev->ro == 2) {
        /* need to switch to read/write */
        mddev->ro = 0;
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        md_wakeup_thread(mddev->sync_thread);
        did_change = 1;
    }
    atomic_inc(&mddev->writes_pending);
    if (mddev->safemode == 1)
        mddev->safemode = 0;
    if (mddev->in_sync) {
        spin_lock_irq(&mddev->write_lock);
        if (mddev->in_sync) {
            mddev->in_sync = 0;
            set_bit(MD_CHANGE_CLEAN, &mddev->flags);
            set_bit(MD_CHANGE_PENDING, &mddev->flags);
            md_wakeup_thread(mddev->thread);
            did_change = 1;
        }
        spin_unlock_irq(&mddev->write_lock);
    }
    if (did_change)
        sysfs_notify_dirent_safe(mddev->sysfs_state);
    wait_event(mddev->sb_wait,
           !test_bit(MD_CHANGE_PENDING, &mddev->flags));
}

void md_write_end(struct mddev *mddev)
{
    if (atomic_dec_and_test(&mddev->writes_pending)) {
        if (mddev->safemode == 2)
            md_wakeup_thread(mddev->thread);
        else if (mddev->safemode_delay)
            mod_timer(&mddev->safemode_timer, jiffies + mddev->safemode_delay);
    }
}

/* md_allow_write(mddev)
 * Calling this ensures that the array is marked 'active' so that writes
 * may proceed without blocking.  It is important to call this before
 * attempting a GFP_KERNEL allocation while holding the mddev lock.
 * Must be called with mddev_lock held.
 *
 * In the ->external case MD_CHANGE_CLEAN can not be cleared until mddev->lock
 * is dropped, so return -EAGAIN after notifying userspace.
 */
int md_allow_write(struct mddev *mddev)
{
    if (!mddev->pers)
        return 0;
    if (mddev->ro)
        return 0;
    if (!mddev->pers->sync_request)
        return 0;

    spin_lock_irq(&mddev->write_lock);
    if (mddev->in_sync) {
        mddev->in_sync = 0;
        set_bit(MD_CHANGE_CLEAN, &mddev->flags);
        set_bit(MD_CHANGE_PENDING, &mddev->flags);
        if (mddev->safemode_delay &&
            mddev->safemode == 0)
            mddev->safemode = 1;
        spin_unlock_irq(&mddev->write_lock);
        md_update_sb(mddev, 0);
        sysfs_notify_dirent_safe(mddev->sysfs_state);
    } else
        spin_unlock_irq(&mddev->write_lock);

    if (test_bit(MD_CHANGE_PENDING, &mddev->flags))
        return -EAGAIN;
    else
        return 0;
}
EXPORT_SYMBOL_GPL(md_allow_write);

#define SYNC_MARKS  10
#define SYNC_MARK_STEP  (3*HZ)
void md_do_sync(struct md_thread *thread)
{
    struct mddev *mddev = thread->mddev;
    struct mddev *mddev2;
    unsigned int currspeed = 0,
         window;
    sector_t max_sectors,j, io_sectors;
    unsigned long mark[SYNC_MARKS];
    sector_t mark_cnt[SYNC_MARKS];
    int last_mark,m;
    struct list_head *tmp;
    sector_t last_check;
    int skipped = 0;
    struct md_rdev *rdev;
    char *desc;
    struct blk_plug plug;

    /* just incase thread restarts... */
    if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
        return;
    if (mddev->ro) /* never try to sync a read-only array */
        return;

    if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
        if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
            desc = "data-check";
        else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
            desc = "requested-resync";
        else
            desc = "resync";
    } else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
        desc = "reshape";
    else
        desc = "recovery";

    /* we overload curr_resync somewhat here.
     * 0 == not engaged in resync at all
     * 2 == checking that there is no conflict with another sync
     * 1 == like 2, but have yielded to allow conflicting resync to
     *      commense
     * other == active in resync - this many blocks
     *
     * Before starting a resync we must have set curr_resync to
     * 2, and then checked that every "conflicting" array has curr_resync
     * less than ours.  When we find one that is the same or higher
     * we wait on resync_wait.  To avoid deadlock, we reduce curr_resync
     * to 1 if we choose to yield (based arbitrarily on address of mddev structure).
     * This will mean we have to start checking from the beginning again.
     *
     */

    do {
        mddev->curr_resync = 2;

    try_again:
        if (kthread_should_stop())
            set_bit(MD_RECOVERY_INTR, &mddev->recovery);

        if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
            goto skip;
        for_each_mddev(mddev2, tmp) {
            if (mddev2 == mddev)
                continue;
            if (!mddev->parallel_resync
            &&  mddev2->curr_resync
            &&  match_mddev_units(mddev, mddev2)) {
                DEFINE_WAIT(wq);
                if (mddev < mddev2 && mddev->curr_resync == 2) {
                    /* arbitrarily yield */
                    mddev->curr_resync = 1;
                    wake_up(&resync_wait);
                }
                if (mddev > mddev2 && mddev->curr_resync == 1)
                    /* no need to wait here, we can wait the next
                     * time 'round when curr_resync == 2
                     */
                    continue;
                /* We need to wait 'interruptible' so as not to
                 * contribute to the load average, and not to
                 * be caught by 'softlockup'
                 */
                prepare_to_wait(&resync_wait, &wq, TASK_INTERRUPTIBLE);
                if (!kthread_should_stop() &&
                    mddev2->curr_resync >= mddev->curr_resync) {
                    printk(KERN_INFO "md: delaying %s of %s"
                           " until %s has finished (they"
                           " share one or more physical units)\n",
                           desc, mdname(mddev), mdname(mddev2));
                    mddev_put(mddev2);
                    if (signal_pending(current))
                        flush_signals(current);
                    schedule();
                    finish_wait(&resync_wait, &wq);
                    goto try_again;
                }
                finish_wait(&resync_wait, &wq);
            }
        }
    } while (mddev->curr_resync < 2);

    j = 0;
    if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
        /* resync follows the size requested by the personality,
         * which defaults to physical size, but can be virtual size
         */
        max_sectors = mddev->resync_max_sectors;
        atomic64_set(&mddev->resync_mismatches, 0);
        /* we don't use the checkpoint if there's a bitmap */
        if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
            j = mddev->resync_min;
        else if (!mddev->bitmap)
            j = mddev->recovery_cp;

    } else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
        max_sectors = mddev->resync_max_sectors;
    else {
        /* recovery follows the physical size of devices */
        max_sectors = mddev->dev_sectors;
        j = MaxSector;
        rcu_read_lock();
        rdev_for_each_rcu(rdev, mddev)
            if (rdev->raid_disk >= 0 &&
                !test_bit(Faulty, &rdev->flags) &&
                !test_bit(In_sync, &rdev->flags) &&
                rdev->recovery_offset < j)
                j = rdev->recovery_offset;
        rcu_read_unlock();
    }

    printk(KERN_INFO "md: %s of RAID array %s\n", desc, mdname(mddev));
    printk(KERN_INFO "md: minimum _guaranteed_  speed:"
        " %d KB/sec/disk.\n", speed_min(mddev));
    printk(KERN_INFO "md: using maximum available idle IO bandwidth "
           "(but not more than %d KB/sec) for %s.\n",
           speed_max(mddev), desc);

    is_mddev_idle(mddev, 1); /* this initializes IO event counters */

    io_sectors = 0;
    for (m = 0; m < SYNC_MARKS; m++) {
        mark[m] = jiffies;
        mark_cnt[m] = io_sectors;
    }
    last_mark = 0;
    mddev->resync_mark = mark[last_mark];
    mddev->resync_mark_cnt = mark_cnt[last_mark];

    /*
     * Tune reconstruction:
     */
    window = 32*(PAGE_SIZE/512);
    printk(KERN_INFO "md: using %dk window, over a total of %lluk.\n",
        window/2, (unsigned long long)max_sectors/2);

    atomic_set(&mddev->recovery_active, 0);
    last_check = 0;

    if (j>2) {
        printk(KERN_INFO 
               "md: resuming %s of %s from checkpoint.\n",
               desc, mdname(mddev));
        mddev->curr_resync = j;
    } else
        mddev->curr_resync = 3; /* no longer delayed */
    mddev->curr_resync_completed = j;
    sysfs_notify(&mddev->kobj, NULL, "sync_completed");
    md_new_event(mddev);

    blk_start_plug(&plug);
    while (j < max_sectors) {
        sector_t sectors;

        skipped = 0;

        if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
            ((mddev->curr_resync > mddev->curr_resync_completed &&
              (mddev->curr_resync - mddev->curr_resync_completed)
              > (max_sectors >> 4)) ||
             (j - mddev->curr_resync_completed)*2
             >= mddev->resync_max - mddev->curr_resync_completed
                )) {
            /* time to update curr_resync_completed */
            wait_event(mddev->recovery_wait,
                   atomic_read(&mddev->recovery_active) == 0);
            mddev->curr_resync_completed = j;
            set_bit(MD_CHANGE_CLEAN, &mddev->flags);
            sysfs_notify(&mddev->kobj, NULL, "sync_completed");
        }

        while (j >= mddev->resync_max && !kthread_should_stop()) {
            /* As this condition is controlled by user-space,
             * we can block indefinitely, so use '_interruptible'
             * to avoid triggering warnings.
             */
            flush_signals(current); /* just in case */
            wait_event_interruptible(mddev->recovery_wait,
                         mddev->resync_max > j
                         || kthread_should_stop());
        }

        if (kthread_should_stop())
            goto interrupted;

        sectors = mddev->pers->sync_request(mddev, j, &skipped,
                          currspeed < speed_min(mddev));
        if (sectors == 0) {
            set_bit(MD_RECOVERY_INTR, &mddev->recovery);
            goto out;
        }

        if (!skipped) { /* actual IO requested */
            io_sectors += sectors;
            atomic_add(sectors, &mddev->recovery_active);
        }

        if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
            break;

        j += sectors;
        if (j > 2)
            mddev->curr_resync = j;
        mddev->curr_mark_cnt = io_sectors;
        if (last_check == 0)
            /* this is the earliest that rebuild will be
             * visible in /proc/mdstat
             */
            md_new_event(mddev);

        if (last_check + window > io_sectors || j == max_sectors)
            continue;

        last_check = io_sectors;
    repeat:
        if (time_after_eq(jiffies, mark[last_mark] + SYNC_MARK_STEP )) {
            /* step marks */
            int next = (last_mark+1) % SYNC_MARKS;

            mddev->resync_mark = mark[next];
            mddev->resync_mark_cnt = mark_cnt[next];
            mark[next] = jiffies;
            mark_cnt[next] = io_sectors - atomic_read(&mddev->recovery_active);
            last_mark = next;
        }


        if (kthread_should_stop())
            goto interrupted;


        /*
         * this loop exits only if either when we are slower than
         * the 'hard' speed limit, or the system was IO-idle for
         * a jiffy.
         * the system might be non-idle CPU-wise, but we only care
         * about not overloading the IO subsystem. (things like an
         * e2fsck being done on the RAID array should execute fast)
         */
        cond_resched();

        currspeed = ((unsigned long)(io_sectors-mddev->resync_mark_cnt))/2
            /((jiffies-mddev->resync_mark)/HZ +1) +1;

        if (currspeed > speed_min(mddev)) {
            if ((currspeed > speed_max(mddev)) ||
                    !is_mddev_idle(mddev, 0)) {
                msleep(500);
                goto repeat;
            }
        }
    }
    printk(KERN_INFO "md: %s: %s done.\n",mdname(mddev), desc);
    /*
     * this also signals 'finished resyncing' to md_stop
     */
 out:
    blk_finish_plug(&plug);
    wait_event(mddev->recovery_wait, !atomic_read(&mddev->recovery_active));

    /* tell personality that we are finished */
    mddev->pers->sync_request(mddev, max_sectors, &skipped, 1);

    if (!test_bit(MD_RECOVERY_CHECK, &mddev->recovery) &&
        mddev->curr_resync > 2) {
        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
            if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
                if (mddev->curr_resync >= mddev->recovery_cp) {
                    printk(KERN_INFO
                           "md: checkpointing %s of %s.\n",
                           desc, mdname(mddev));
                    mddev->recovery_cp =
                        mddev->curr_resync_completed;
                }
            } else
                mddev->recovery_cp = MaxSector;
        } else {
            if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
                mddev->curr_resync = MaxSector;
            rcu_read_lock();
            rdev_for_each_rcu(rdev, mddev)
                if (rdev->raid_disk >= 0 &&
                    mddev->delta_disks >= 0 &&
                    !test_bit(Faulty, &rdev->flags) &&
                    !test_bit(In_sync, &rdev->flags) &&
                    rdev->recovery_offset < mddev->curr_resync)
                    rdev->recovery_offset = mddev->curr_resync;
            rcu_read_unlock();
        }
    }
 skip:
    set_bit(MD_CHANGE_DEVS, &mddev->flags);

    if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
        /* We completed so min/max setting can be forgotten if used. */
        if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
            mddev->resync_min = 0;
        mddev->resync_max = MaxSector;
    } else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
        mddev->resync_min = mddev->curr_resync_completed;
    mddev->curr_resync = 0;
    wake_up(&resync_wait);
    set_bit(MD_RECOVERY_DONE, &mddev->recovery);
    md_wakeup_thread(mddev->thread);
    return;

 interrupted:
    /*
     * got a signal, exit.
     */
    printk(KERN_INFO
           "md: md_do_sync() got signal ... exiting\n");
    set_bit(MD_RECOVERY_INTR, &mddev->recovery);
    goto out;

}
EXPORT_SYMBOL_GPL(md_do_sync);

static int remove_and_add_spares(struct mddev *mddev)
{
    struct md_rdev *rdev;
    int spares = 0;
    int removed = 0;

    rdev_for_each(rdev, mddev)
        if (rdev->raid_disk >= 0 &&
            !test_bit(Blocked, &rdev->flags) &&
            (test_bit(Faulty, &rdev->flags) ||
             ! test_bit(In_sync, &rdev->flags)) &&
            atomic_read(&rdev->nr_pending)==0) {
            if (mddev->pers->hot_remove_disk(
                    mddev, rdev) == 0) {
                sysfs_unlink_rdev(mddev, rdev);
                rdev->raid_disk = -1;
                removed++;
            }
        }
    if (removed)
        sysfs_notify(&mddev->kobj, NULL,
                 "degraded");


    rdev_for_each(rdev, mddev) {
        if (rdev->raid_disk >= 0 &&
            !test_bit(In_sync, &rdev->flags) &&
            !test_bit(Faulty, &rdev->flags))
            spares++;
        if (rdev->raid_disk < 0
            && !test_bit(Faulty, &rdev->flags)) {
            rdev->recovery_offset = 0;
            if (mddev->pers->
                hot_add_disk(mddev, rdev) == 0) {
                if (sysfs_link_rdev(mddev, rdev))
                    /* failure here is OK */;
                spares++;
                md_new_event(mddev);
                set_bit(MD_CHANGE_DEVS, &mddev->flags);
            }
        }
    }
    if (removed)
        set_bit(MD_CHANGE_DEVS, &mddev->flags);
    return spares;
}

static void reap_sync_thread(struct mddev *mddev)
{
    struct md_rdev *rdev;

    /* resync has finished, collect result */
    md_unregister_thread(&mddev->sync_thread);
    if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
        !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
        /* success...*/
        /* activate any spares */
        if (mddev->pers->spare_active(mddev)) {
            sysfs_notify(&mddev->kobj, NULL,
                     "degraded");
            set_bit(MD_CHANGE_DEVS, &mddev->flags);
        }
    }
    if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
        mddev->pers->finish_reshape)
        mddev->pers->finish_reshape(mddev);

    /* If array is no-longer degraded, then any saved_raid_disk
     * information must be scrapped.  Also if any device is now
     * In_sync we must scrape the saved_raid_disk for that device
     * do the superblock for an incrementally recovered device
     * written out.
     */
    rdev_for_each(rdev, mddev)
        if (!mddev->degraded ||
            test_bit(In_sync, &rdev->flags))
            rdev->saved_raid_disk = -1;

    md_update_sb(mddev, 1);
    clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
    clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
    clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
    clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
    clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
    /* flag recovery needed just to double check */
    set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
    sysfs_notify_dirent_safe(mddev->sysfs_action);
    md_new_event(mddev);
    if (mddev->event_work.func)
        queue_work(md_misc_wq, &mddev->event_work);
}

/*
 * This routine is regularly called by all per-raid-array threads to
 * deal with generic issues like resync and super-block update.
 * Raid personalities that don't have a thread (linear/raid0) do not
 * need this as they never do any recovery or update the superblock.
 *
 * It does not do any resync itself, but rather "forks" off other threads
 * to do that as needed.
 * When it is determined that resync is needed, we set MD_RECOVERY_RUNNING in
 * "->recovery" and create a thread at ->sync_thread.
 * When the thread finishes it sets MD_RECOVERY_DONE
 * and wakeups up this thread which will reap the thread and finish up.
 * This thread also removes any faulty devices (with nr_pending == 0).
 *
 * The overall approach is:
 *  1/ if the superblock needs updating, update it.
 *  2/ If a recovery thread is running, don't do anything else.
 *  3/ If recovery has finished, clean up, possibly marking spares active.
 *  4/ If there are any faulty devices, remove them.
 *  5/ If array is degraded, try to add spares devices
 *  6/ If array has spares or is not in-sync, start a resync thread.
 */
void md_check_recovery(struct mddev *mddev)
{
    if (mddev->suspended)
        return;

    if (mddev->bitmap)
        bitmap_daemon_work(mddev);

    if (signal_pending(current)) {
        if (mddev->pers->sync_request && !mddev->external) {
            printk(KERN_INFO "md: %s in immediate safe mode\n",
                   mdname(mddev));
            mddev->safemode = 2;
        }
        flush_signals(current);
    }

    if (mddev->ro && !test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
        return;
    if ( ! (
        (mddev->flags & ~ (1<<MD_CHANGE_PENDING)) ||
        test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
        test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
        (mddev->external == 0 && mddev->safemode == 1) ||
        (mddev->safemode == 2 && ! atomic_read(&mddev->writes_pending)
         && !mddev->in_sync && mddev->recovery_cp == MaxSector)
        ))
        return;

    if (mddev_trylock(mddev)) {
        int spares = 0;

        if (mddev->ro) {
            /* Only thing we do on a ro array is remove
             * failed devices.
             */
            struct md_rdev *rdev;
            rdev_for_each(rdev, mddev)
                if (rdev->raid_disk >= 0 &&
                    !test_bit(Blocked, &rdev->flags) &&
                    test_bit(Faulty, &rdev->flags) &&
                    atomic_read(&rdev->nr_pending)==0) {
                    if (mddev->pers->hot_remove_disk(
                            mddev, rdev) == 0) {
                        sysfs_unlink_rdev(mddev, rdev);
                        rdev->raid_disk = -1;
                    }
                }
            clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
            goto unlock;
        }

        if (!mddev->external) {
            int did_change = 0;
            spin_lock_irq(&mddev->write_lock);
            if (mddev->safemode &&
                !atomic_read(&mddev->writes_pending) &&
                !mddev->in_sync &&
                mddev->recovery_cp == MaxSector) {
                mddev->in_sync = 1;
                did_change = 1;
                set_bit(MD_CHANGE_CLEAN, &mddev->flags);
            }
            if (mddev->safemode == 1)
                mddev->safemode = 0;
            spin_unlock_irq(&mddev->write_lock);
            if (did_change)
                sysfs_notify_dirent_safe(mddev->sysfs_state);
        }

        if (mddev->flags)
            md_update_sb(mddev, 0);

        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
            !test_bit(MD_RECOVERY_DONE, &mddev->recovery)) {
            /* resync/recovery still happening */
            clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
            goto unlock;
        }
        if (mddev->sync_thread) {
            reap_sync_thread(mddev);
            goto unlock;
        }
        /* Set RUNNING before clearing NEEDED to avoid
         * any transients in the value of "sync_action".
         */
        mddev->curr_resync_completed = 0;
        set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
        /* Clear some bits that don't mean anything, but
         * might be left set
         */
        clear_bit(MD_RECOVERY_INTR, &mddev->recovery);
        clear_bit(MD_RECOVERY_DONE, &mddev->recovery);

        if (!test_and_clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
            test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
            goto unlock;
        /* no recovery is running.
         * remove any failed drives, then
         * add spares if possible.
         * Spares are also removed and re-added, to allow
         * the personality to fail the re-add.
         */

        if (mddev->reshape_position != MaxSector) {
            if (mddev->pers->check_reshape == NULL ||
                mddev->pers->check_reshape(mddev) != 0)
                /* Cannot proceed */
                goto unlock;
            set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
            clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
        } else if ((spares = remove_and_add_spares(mddev))) {
            clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
            clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
            clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
            set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
        } else if (mddev->recovery_cp < MaxSector) {
            set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
            clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
        } else if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
            /* nothing to be done ... */
            goto unlock;

        if (mddev->pers->sync_request) {
            if (spares) {
                /* We are adding a device or devices to an array
                 * which has the bitmap stored on all devices.
                 * So make sure all bitmap pages get written
                 */
                bitmap_write_all(mddev->bitmap);
            }
            mddev->sync_thread = md_register_thread(md_do_sync,
                                mddev,
                                "resync");
            if (!mddev->sync_thread) {
                printk(KERN_ERR "%s: could not start resync"
                    " thread...\n", 
                    mdname(mddev));
                /* leave the spares where they are, it shouldn't hurt */
                clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
                clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
                clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
                clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
                clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
            } else
                md_wakeup_thread(mddev->sync_thread);
            sysfs_notify_dirent_safe(mddev->sysfs_action);
            md_new_event(mddev);
        }
    unlock:
        if (!mddev->sync_thread) {
            clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
            if (test_and_clear_bit(MD_RECOVERY_RECOVER,
                           &mddev->recovery))
                if (mddev->sysfs_action)
                    sysfs_notify_dirent_safe(mddev->sysfs_action);
        }
        mddev_unlock(mddev);
    }
}

void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev)
{
    sysfs_notify_dirent_safe(rdev->sysfs_state);
    wait_event_timeout(rdev->blocked_wait,
               !test_bit(Blocked, &rdev->flags) &&
               !test_bit(BlockedBadBlocks, &rdev->flags),
               msecs_to_jiffies(5000));
    rdev_dec_pending(rdev, mddev);
}
EXPORT_SYMBOL(md_wait_for_blocked_rdev);

void md_finish_reshape(struct mddev *mddev)
{
    /* called be personality module when reshape completes. */
    struct md_rdev *rdev;

    rdev_for_each(rdev, mddev) {
        if (rdev->data_offset > rdev->new_data_offset)
            rdev->sectors += rdev->data_offset - rdev->new_data_offset;
        else
            rdev->sectors -= rdev->new_data_offset - rdev->data_offset;
        rdev->data_offset = rdev->new_data_offset;
    }
}
EXPORT_SYMBOL(md_finish_reshape);

/* Bad block management.
 * We can record which blocks on each device are 'bad' and so just
 * fail those blocks, or that stripe, rather than the whole device.
 * Entries in the bad-block table are 64bits wide.  This comprises:
 * Length of bad-range, in sectors: 0-511 for lengths 1-512
 * Start of bad-range, sector offset, 54 bits (allows 8 exbibytes)
 *  A 'shift' can be set so that larger blocks are tracked and
 *  consequently larger devices can be covered.
 * 'Acknowledged' flag - 1 bit. - the most significant bit.
 *
 * Locking of the bad-block table uses a seqlock so md_is_badblock
 * might need to retry if it is very unlucky.
 * We will sometimes want to check for bad blocks in a bi_end_io function,
 * so we use the write_seqlock_irq variant.
 *
 * When looking for a bad block we specify a range and want to
 * know if any block in the range is bad.  So we binary-search
 * to the last range that starts at-or-before the given endpoint,
 * (or "before the sector after the target range")
 * then see if it ends after the given start.
 * We return
 *  0 if there are no known bad blocks in the range
 *  1 if there are known bad block which are all acknowledged
 * -1 if there are bad blocks which have not yet been acknowledged in metadata.
 * plus the start/length of the first bad section we overlap.
 */
int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
           sector_t *first_bad, int *bad_sectors)
{
    int hi;
    int lo;
    u64 *p = bb->page;
    int rv;
    sector_t target = s + sectors;
    unsigned seq;

    if (bb->shift > 0) {
        /* round the start down, and the end up */
        s >>= bb->shift;
        target += (1<<bb->shift) - 1;
        target >>= bb->shift;
        sectors = target - s;
    }
    /* 'target' is now the first block after the bad range */

retry:
    seq = read_seqbegin(&bb->lock);
    lo = 0;
    rv = 0;
    hi = bb->count;

    /* Binary search between lo and hi for 'target'
     * i.e. for the last range that starts before 'target'
     */
    /* INVARIANT: ranges before 'lo' and at-or-after 'hi'
     * are known not to be the last range before target.
     * VARIANT: hi-lo is the number of possible
     * ranges, and decreases until it reaches 1
     */
    while (hi - lo > 1) {
        int mid = (lo + hi) / 2;
        sector_t a = BB_OFFSET(p[mid]);
        if (a < target)
            /* This could still be the one, earlier ranges
             * could not. */
            lo = mid;
        else
            /* This and later ranges are definitely out. */
            hi = mid;
    }
    /* 'lo' might be the last that started before target, but 'hi' isn't */
    if (hi > lo) {
        /* need to check all range that end after 's' to see if
         * any are unacknowledged.
         */
        while (lo >= 0 &&
               BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) {
            if (BB_OFFSET(p[lo]) < target) {
                /* starts before the end, and finishes after
                 * the start, so they must overlap
                 */
                if (rv != -1 && BB_ACK(p[lo]))
                    rv = 1;
                else
                    rv = -1;
                *first_bad = BB_OFFSET(p[lo]);
                *bad_sectors = BB_LEN(p[lo]);
            }
            lo--;
        }
    }

    if (read_seqretry(&bb->lock, seq))
        goto retry;

    return rv;
}
EXPORT_SYMBOL_GPL(md_is_badblock);

/*
 * Add a range of bad blocks to the table.
 * This might extend the table, or might contract it
 * if two adjacent ranges can be merged.
 * We binary-search to find the 'insertion' point, then
 * decide how best to handle it.
 */
static int md_set_badblocks(struct badblocks *bb, sector_t s, int sectors,
                int acknowledged)
{
    u64 *p;
    int lo, hi;
    int rv = 1;

    if (bb->shift < 0)
        /* badblocks are disabled */
        return 0;

    if (bb->shift) {
        /* round the start down, and the end up */
        sector_t next = s + sectors;
        s >>= bb->shift;
        next += (1<<bb->shift) - 1;
        next >>= bb->shift;
        sectors = next - s;
    }

    write_seqlock_irq(&bb->lock);

    p = bb->page;
    lo = 0;
    hi = bb->count;
    /* Find the last range that starts at-or-before 's' */
    while (hi - lo > 1) {
        int mid = (lo + hi) / 2;
        sector_t a = BB_OFFSET(p[mid]);
        if (a <= s)
            lo = mid;
        else
            hi = mid;
    }
    if (hi > lo && BB_OFFSET(p[lo]) > s)
        hi = lo;

    if (hi > lo) {
        /* we found a range that might merge with the start
         * of our new range
         */
        sector_t a = BB_OFFSET(p[lo]);
        sector_t e = a + BB_LEN(p[lo]);
        int ack = BB_ACK(p[lo]);
        if (e >= s) {
            /* Yes, we can merge with a previous range */
            if (s == a && s + sectors >= e)
                /* new range covers old */
                ack = acknowledged;
            else
                ack = ack && acknowledged;

            if (e < s + sectors)
                e = s + sectors;
            if (e - a <= BB_MAX_LEN) {
                p[lo] = BB_MAKE(a, e-a, ack);
                s = e;
            } else {
                /* does not all fit in one range,
                 * make p[lo] maximal
                 */
                if (BB_LEN(p[lo]) != BB_MAX_LEN)
                    p[lo] = BB_MAKE(a, BB_MAX_LEN, ack);
                s = a + BB_MAX_LEN;
            }
            sectors = e - s;
        }
    }
    if (sectors && hi < bb->count) {
        /* 'hi' points to the first range that starts after 's'.
         * Maybe we can merge with the start of that range */
        sector_t a = BB_OFFSET(p[hi]);
        sector_t e = a + BB_LEN(p[hi]);
        int ack = BB_ACK(p[hi]);
        if (a <= s + sectors) {
            /* merging is possible */
            if (e <= s + sectors) {
                /* full overlap */
                e = s + sectors;
                ack = acknowledged;
            } else
                ack = ack && acknowledged;

            a = s;
            if (e - a <= BB_MAX_LEN) {
                p[hi] = BB_MAKE(a, e-a, ack);
                s = e;
            } else {
                p[hi] = BB_MAKE(a, BB_MAX_LEN, ack);
                s = a + BB_MAX_LEN;
            }
            sectors = e - s;
            lo = hi;
            hi++;
        }
    }
    if (sectors == 0 && hi < bb->count) {
        /* we might be able to combine lo and hi */
        /* Note: 's' is at the end of 'lo' */
        sector_t a = BB_OFFSET(p[hi]);
        int lolen = BB_LEN(p[lo]);
        int hilen = BB_LEN(p[hi]);
        int newlen = lolen + hilen - (s - a);
        if (s >= a && newlen < BB_MAX_LEN) {
            /* yes, we can combine them */
            int ack = BB_ACK(p[lo]) && BB_ACK(p[hi]);
            p[lo] = BB_MAKE(BB_OFFSET(p[lo]), newlen, ack);
            memmove(p + hi, p + hi + 1,
                (bb->count - hi - 1) * 8);
            bb->count--;
        }
    }
    while (sectors) {
        /* didn't merge (it all).
         * Need to add a range just before 'hi' */
        if (bb->count >= MD_MAX_BADBLOCKS) {
            /* No room for more */
            rv = 0;
            break;
        } else {
            int this_sectors = sectors;
            memmove(p + hi + 1, p + hi,
                (bb->count - hi) * 8);
            bb->count++;

            if (this_sectors > BB_MAX_LEN)
                this_sectors = BB_MAX_LEN;
            p[hi] = BB_MAKE(s, this_sectors, acknowledged);
            sectors -= this_sectors;
            s += this_sectors;
        }
    }

    bb->changed = 1;
    if (!acknowledged)
        bb->unacked_exist = 1;
    write_sequnlock_irq(&bb->lock);

    return rv;
}

int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
               int is_new)
{
    int rv;
    if (is_new)
        s += rdev->new_data_offset;
    else
        s += rdev->data_offset;
    rv = md_set_badblocks(&rdev->badblocks,
                  s, sectors, 0);
    if (rv) {
        /* Make sure they get written out promptly */
        sysfs_notify_dirent_safe(rdev->sysfs_state);
        set_bit(MD_CHANGE_CLEAN, &rdev->mddev->flags);
        md_wakeup_thread(rdev->mddev->thread);
    }
    return rv;
}
EXPORT_SYMBOL_GPL(rdev_set_badblocks);

/*
 * Remove a range of bad blocks from the table.
 * This may involve extending the table if we spilt a region,
 * but it must not fail.  So if the table becomes full, we just
 * drop the remove request.
 */
static int md_clear_badblocks(struct badblocks *bb, sector_t s, int sectors)
{
    u64 *p;
    int lo, hi;
    sector_t target = s + sectors;
    int rv = 0;

    if (bb->shift > 0) {
        /* When clearing we round the start up and the end down.
         * This should not matter as the shift should align with
         * the block size and no rounding should ever be needed.
         * However it is better the think a block is bad when it
         * isn't than to think a block is not bad when it is.
         */
        s += (1<<bb->shift) - 1;
        s >>= bb->shift;
        target >>= bb->shift;
        sectors = target - s;
    }

    write_seqlock_irq(&bb->lock);

    p = bb->page;
    lo = 0;
    hi = bb->count;
    /* Find the last range that starts before 'target' */
    while (hi - lo > 1) {
        int mid = (lo + hi) / 2;
        sector_t a = BB_OFFSET(p[mid]);
        if (a < target)
            lo = mid;
        else
            hi = mid;
    }
    if (hi > lo) {
        /* p[lo] is the last range that could overlap the
         * current range.  Earlier ranges could also overlap,
         * but only this one can overlap the end of the range.
         */
        if (BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > target) {
            /* Partial overlap, leave the tail of this range */
            int ack = BB_ACK(p[lo]);
            sector_t a = BB_OFFSET(p[lo]);
            sector_t end = a + BB_LEN(p[lo]);

            if (a < s) {
                /* we need to split this range */
                if (bb->count >= MD_MAX_BADBLOCKS) {
                    rv = 0;
                    goto out;
                }
                memmove(p+lo+1, p+lo, (bb->count - lo) * 8);
                bb->count++;
                p[lo] = BB_MAKE(a, s-a, ack);
                lo++;
            }
            p[lo] = BB_MAKE(target, end - target, ack);
            /* there is no longer an overlap */
            hi = lo;
            lo--;
        }
        while (lo >= 0 &&
               BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) {
            /* This range does overlap */
            if (BB_OFFSET(p[lo]) < s) {
                /* Keep the early parts of this range. */
                int ack = BB_ACK(p[lo]);
                sector_t start = BB_OFFSET(p[lo]);
                p[lo] = BB_MAKE(start, s - start, ack);
                /* now low doesn't overlap, so.. */
                break;
            }
            lo--;
        }
        /* 'lo' is strictly before, 'hi' is strictly after,
         * anything between needs to be discarded
         */
        if (hi - lo > 1) {
            memmove(p+lo+1, p+hi, (bb->count - hi) * 8);
            bb->count -= (hi - lo - 1);
        }
    }

    bb->changed = 1;
out:
    write_sequnlock_irq(&bb->lock);
    return rv;
}

int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
             int is_new)
{
    if (is_new)
        s += rdev->new_data_offset;
    else
        s += rdev->data_offset;
    return md_clear_badblocks(&rdev->badblocks,
                  s, sectors);
}
EXPORT_SYMBOL_GPL(rdev_clear_badblocks);

/*
 * Acknowledge all bad blocks in a list.
 * This only succeeds if ->changed is clear.  It is used by
 * in-kernel metadata updates
 */
void md_ack_all_badblocks(struct badblocks *bb)
{
    if (bb->page == NULL || bb->changed)
        /* no point even trying */
        return;
    write_seqlock_irq(&bb->lock);

    if (bb->changed == 0 && bb->unacked_exist) {
        u64 *p = bb->page;
        int i;
        for (i = 0; i < bb->count ; i++) {
            if (!BB_ACK(p[i])) {
                sector_t start = BB_OFFSET(p[i]);
                int len = BB_LEN(p[i]);
                p[i] = BB_MAKE(start, len, 1);
            }
        }
        bb->unacked_exist = 0;
    }
    write_sequnlock_irq(&bb->lock);
}
EXPORT_SYMBOL_GPL(md_ack_all_badblocks);

/* sysfs access to bad-blocks list.
 * We present two files.
 * 'bad-blocks' lists sector numbers and lengths of ranges that
 *    are recorded as bad.  The list is truncated to fit within
 *    the one-page limit of sysfs.
 *    Writing "sector length" to this file adds an acknowledged
 *    bad block list.
 * 'unacknowledged-bad-blocks' lists bad blocks that have not yet
 *    been acknowledged.  Writing to this file adds bad blocks
 *    without acknowledging them.  This is largely for testing.
 */

static ssize_t
badblocks_show(struct badblocks *bb, char *page, int unack)
{
    size_t len;
    int i;
    u64 *p = bb->page;
    unsigned seq;

    if (bb->shift < 0)
        return 0;

retry:
    seq = read_seqbegin(&bb->lock);

    len = 0;
    i = 0;

    while (len < PAGE_SIZE && i < bb->count) {
        sector_t s = BB_OFFSET(p[i]);
        unsigned int length = BB_LEN(p[i]);
        int ack = BB_ACK(p[i]);
        i++;

        if (unack && ack)
            continue;

        len += snprintf(page+len, PAGE_SIZE-len, "%llu %u\n",
                (unsigned long long)s << bb->shift,
                length << bb->shift);
    }
    if (unack && len == 0)
        bb->unacked_exist = 0;

    if (read_seqretry(&bb->lock, seq))
        goto retry;

    return len;
}

#define DO_DEBUG 1

static ssize_t
badblocks_store(struct badblocks *bb, const char *page, size_t len, int unack)
{
    unsigned long long sector;
    int length;
    char newline;
#ifdef DO_DEBUG
    /* Allow clearing via sysfs *only* for testing/debugging.
     * Normally only a successful write may clear a badblock
     */
    int clear = 0;
    if (page[0] == '-') {
        clear = 1;
        page++;
    }
#endif /* DO_DEBUG */

    switch (sscanf(page, "%llu %d%c", &sector, &length, &newline)) {
    case 3:
        if (newline != '\n')
            return -EINVAL;
    case 2:
        if (length <= 0)
            return -EINVAL;
        break;
    default:
        return -EINVAL;
    }

#ifdef DO_DEBUG
    if (clear) {
        md_clear_badblocks(bb, sector, length);
        return len;
    }
#endif /* DO_DEBUG */
    if (md_set_badblocks(bb, sector, length, !unack))
        return len;
    else
        return -ENOSPC;
}

static int md_notify_reboot(struct notifier_block *this,
                unsigned long code, void *x)
{
    struct list_head *tmp;
    struct mddev *mddev;
    int need_delay = 0;

    for_each_mddev(mddev, tmp) {
        if (mddev_trylock(mddev)) {
            if (mddev->pers)
                __md_stop_writes(mddev);
            mddev->safemode = 2;
            mddev_unlock(mddev);
        }
        need_delay = 1;
    }
    /*
     * certain more exotic SCSI devices are known to be
     * volatile wrt too early system reboots. While the
     * right place to handle this issue is the given
     * driver, we do want to have a safe RAID driver ...
     */
    if (need_delay)
        mdelay(1000*1);

    return NOTIFY_DONE;
}

static struct notifier_block md_notifier = {
    .notifier_call  = md_notify_reboot,
    .next       = NULL,
    .priority   = INT_MAX, /* before any real devices */
};

static void md_geninit(void)
{
    pr_debug("md: sizeof(mdp_super_t) = %d\n", (int)sizeof(mdp_super_t));

    proc_create("mdstat", S_IRUGO, NULL, &md_seq_fops);
}

static int __init md_init(void)
{
    int ret = -ENOMEM;

    md_wq = alloc_workqueue("md", WQ_MEM_RECLAIM, 0);
    if (!md_wq)
        goto err_wq;

    md_misc_wq = alloc_workqueue("md_misc", 0, 0);
    if (!md_misc_wq)
        goto err_misc_wq;

    if ((ret = register_blkdev(MD_MAJOR, "md")) < 0)
        goto err_md;

    if ((ret = register_blkdev(0, "mdp")) < 0)
        goto err_mdp;
    mdp_major = ret;

    blk_register_region(MKDEV(MD_MAJOR, 0), 1UL<<MINORBITS, THIS_MODULE,
                md_probe, NULL, NULL);
    blk_register_region(MKDEV(mdp_major, 0), 1UL<<MINORBITS, THIS_MODULE,
                md_probe, NULL, NULL);

    register_reboot_notifier(&md_notifier);
    raid_table_header = register_sysctl_table(raid_root_table);

    md_geninit();
    return 0;

err_mdp:
    unregister_blkdev(MD_MAJOR, "md");
err_md:
    destroy_workqueue(md_misc_wq);
err_misc_wq:
    destroy_workqueue(md_wq);
err_wq:
    return ret;
}

#ifndef MODULE

/*
 * Searches all registered partitions for autorun RAID arrays
 * at boot time.
 */

static LIST_HEAD(all_detected_devices);
struct detected_devices_node {
    struct list_head list;
    dev_t dev;
};

void md_autodetect_dev(dev_t dev)
{
    struct detected_devices_node *node_detected_dev;

    node_detected_dev = kzalloc(sizeof(*node_detected_dev), GFP_KERNEL);
    if (node_detected_dev) {
        node_detected_dev->dev = dev;
        list_add_tail(&node_detected_dev->list, &all_detected_devices);
    } else {
        printk(KERN_CRIT "md: md_autodetect_dev: kzalloc failed"
            ", skipping dev(%d,%d)\n", MAJOR(dev), MINOR(dev));
    }
}


static void autostart_arrays(int part)
{
    struct md_rdev *rdev;
    struct detected_devices_node *node_detected_dev;
    dev_t dev;
    int i_scanned, i_passed;

    i_scanned = 0;
    i_passed = 0;

    printk(KERN_INFO "md: Autodetecting RAID arrays.\n");

    while (!list_empty(&all_detected_devices) && i_scanned < INT_MAX) {
        i_scanned++;
        node_detected_dev = list_entry(all_detected_devices.next,
                    struct detected_devices_node, list);
        list_del(&node_detected_dev->list);
        dev = node_detected_dev->dev;
        kfree(node_detected_dev);
        rdev = md_import_device(dev,0, 90);
        if (IS_ERR(rdev))
            continue;

        if (test_bit(Faulty, &rdev->flags)) {
            MD_BUG();
            continue;
        }
        set_bit(AutoDetected, &rdev->flags);
        list_add(&rdev->same_set, &pending_raid_disks);
        i_passed++;
    }

    printk(KERN_INFO "md: Scanned %d and added %d devices.\n",
                        i_scanned, i_passed);

    autorun_devices(part);
}

#endif /* !MODULE */

static __exit void md_exit(void)
{
    struct mddev *mddev;
    struct list_head *tmp;

    blk_unregister_region(MKDEV(MD_MAJOR,0), 1U << MINORBITS);
    blk_unregister_region(MKDEV(mdp_major,0), 1U << MINORBITS);

    unregister_blkdev(MD_MAJOR,"md");
    unregister_blkdev(mdp_major, "mdp");
    unregister_reboot_notifier(&md_notifier);
    unregister_sysctl_table(raid_table_header);
    remove_proc_entry("mdstat", NULL);
    for_each_mddev(mddev, tmp) {
        export_array(mddev);
        mddev->hold_active = 0;
    }
    destroy_workqueue(md_misc_wq);
    destroy_workqueue(md_wq);
}

subsys_initcall(md_init);
module_exit(md_exit)

static int get_ro(char *buffer, struct kernel_param *kp)
{
    return sprintf(buffer, "%d", start_readonly);
}
static int set_ro(const char *val, struct kernel_param *kp)
{
    char *e;
    int num = simple_strtoul(val, &e, 10);
    if (*val && (*e == '\0' || *e == '\n')) {
        start_readonly = num;
        return 0;
    }
    return -EINVAL;
}

module_param_call(start_ro, set_ro, get_ro, NULL, S_IRUSR|S_IWUSR);
module_param(start_dirty_degraded, int, S_IRUGO|S_IWUSR);

module_param_call(new_array, add_named_array, NULL, NULL, S_IWUSR);

EXPORT_SYMBOL(register_md_personality);
EXPORT_SYMBOL(unregister_md_personality);
EXPORT_SYMBOL(md_error);
EXPORT_SYMBOL(md_done_sync);
EXPORT_SYMBOL(md_write_start);
EXPORT_SYMBOL(md_write_end);
EXPORT_SYMBOL(md_register_thread);
EXPORT_SYMBOL(md_unregister_thread);
EXPORT_SYMBOL(md_wakeup_thread);
EXPORT_SYMBOL(md_check_recovery);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("MD RAID framework");
MODULE_ALIAS("md");
MODULE_ALIAS_BLOCKDEV_MAJOR(MD_MAJOR);