md.h

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/*
   md.h : kernel internal structure of the Linux MD driver
          Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
      
   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.  
*/

#ifndef _MD_MD_H
#define _MD_MD_H

#include <linux/blkdev.h>
#include <linux/kobject.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/timer.h>
#include <linux/wait.h>
#include <linux/workqueue.h>

#define MaxSector (~(sector_t)0)

/* Bad block numbers are stored sorted in a single page.
 * 64bits is used for each block or extent.
 * 54 bits are sector number, 9 bits are extent size,
 * 1 bit is an 'acknowledged' flag.
 */
#define MD_MAX_BADBLOCKS    (PAGE_SIZE/8)

/*
 * MD's 'extended' device
 */
struct md_rdev {
    struct list_head same_set;  /* RAID devices within the same set */

    sector_t sectors;       /* Device size (in 512bytes sectors) */
    struct mddev *mddev;        /* RAID array if running */
    int last_events;        /* IO event timestamp */

    /*
     * If meta_bdev is non-NULL, it means that a separate device is
     * being used to store the metadata (superblock/bitmap) which
     * would otherwise be contained on the same device as the data (bdev).
     */
    struct block_device *meta_bdev;
    struct block_device *bdev;  /* block device handle */

    struct page *sb_page, *bb_page;
    int     sb_loaded;
    __u64       sb_events;
    sector_t    data_offset;    /* start of data in array */
    sector_t    new_data_offset;/* only relevant while reshaping */
    sector_t    sb_start;   /* offset of the super block (in 512byte sectors) */
    int     sb_size;    /* bytes in the superblock */
    int     preferred_minor;    /* autorun support */

    struct kobject  kobj;

    /* A device can be in one of three states based on two flags:
     * Not working:   faulty==1 in_sync==0
     * Fully working: faulty==0 in_sync==1
     * Working, but not
     * in sync with array
     *                faulty==0 in_sync==0
     *
     * It can never have faulty==1, in_sync==1
     * This reduces the burden of testing multiple flags in many cases
     */

    unsigned long   flags;  /* bit set of 'enum flag_bits' bits. */
    wait_queue_head_t blocked_wait;

    int desc_nr;            /* descriptor index in the superblock */
    int raid_disk;          /* role of device in array */
    int new_raid_disk;      /* role that the device will have in
                     * the array after a level-change completes.
                     */
    int saved_raid_disk;        /* role that device used to have in the
                     * array and could again if we did a partial
                     * resync from the bitmap
                     */
    sector_t    recovery_offset;/* If this device has been partially
                     * recovered, this is where we were
                     * up to.
                     */

    atomic_t    nr_pending; /* number of pending requests.
                     * only maintained for arrays that
                     * support hot removal
                     */
    atomic_t    read_errors;    /* number of consecutive read errors that
                     * we have tried to ignore.
                     */
    struct timespec last_read_error;    /* monotonic time since our
                         * last read error
                         */
    atomic_t    corrected_errors; /* number of corrected read errors,
                       * for reporting to userspace and storing
                       * in superblock.
                       */
    struct work_struct del_work;    /* used for delayed sysfs removal */

    struct sysfs_dirent *sysfs_state; /* handle for 'state'
                       * sysfs entry */

    struct badblocks {
        int count;      /* count of bad blocks */
        int unacked_exist;  /* there probably are unacknowledged
                     * bad blocks.  This is only cleared
                     * when a read discovers none
                     */
        int shift;      /* shift from sectors to block size
                     * a -ve shift means badblocks are
                     * disabled.*/
        u64 *page;      /* badblock list */
        int changed;
        seqlock_t lock;

        sector_t sector;
        sector_t size;      /* in sectors */
    } badblocks;
};
enum flag_bits {
    Faulty,         /* device is known to have a fault */
    In_sync,        /* device is in_sync with rest of array */
    Unmerged,       /* device is being added to array and should
                 * be considerred for bvec_merge_fn but not
                 * yet for actual IO
                 */
    WriteMostly,        /* Avoid reading if at all possible */
    AutoDetected,       /* added by auto-detect */
    Blocked,        /* An error occurred but has not yet
                 * been acknowledged by the metadata
                 * handler, so don't allow writes
                 * until it is cleared */
    WriteErrorSeen,     /* A write error has been seen on this
                 * device
                 */
    FaultRecorded,      /* Intermediate state for clearing
                 * Blocked.  The Fault is/will-be
                 * recorded in the metadata, but that
                 * metadata hasn't been stored safely
                 * on disk yet.
                 */
    BlockedBadBlocks,   /* A writer is blocked because they
                 * found an unacknowledged bad-block.
                 * This can safely be cleared at any
                 * time, and the writer will re-check.
                 * It may be set at any time, and at
                 * worst the writer will timeout and
                 * re-check.  So setting it as
                 * accurately as possible is good, but
                 * not absolutely critical.
                 */
    WantReplacement,    /* This device is a candidate to be
                 * hot-replaced, either because it has
                 * reported some faults, or because
                 * of explicit request.
                 */
    Replacement,        /* This device is a replacement for
                 * a want_replacement device with same
                 * raid_disk number.
                 */
};

#define BB_LEN_MASK (0x00000000000001FFULL)
#define BB_OFFSET_MASK  (0x7FFFFFFFFFFFFE00ULL)
#define BB_ACK_MASK (0x8000000000000000ULL)
#define BB_MAX_LEN  512
#define BB_OFFSET(x)    (((x) & BB_OFFSET_MASK) >> 9)
#define BB_LEN(x)   (((x) & BB_LEN_MASK) + 1)
#define BB_ACK(x)   (!!((x) & BB_ACK_MASK))
#define BB_MAKE(a, l, ack) (((a)<<9) | ((l)-1) | ((u64)(!!(ack)) << 63))

extern int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
              sector_t *first_bad, int *bad_sectors);
static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
                  sector_t *first_bad, int *bad_sectors)
{
    if (unlikely(rdev->badblocks.count)) {
        int rv = md_is_badblock(&rdev->badblocks, rdev->data_offset + s,
                    sectors,
                    first_bad, bad_sectors);
        if (rv)
            *first_bad -= rdev->data_offset;
        return rv;
    }
    return 0;
}
extern int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
                  int is_new);
extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
                int is_new);
extern void md_ack_all_badblocks(struct badblocks *bb);

struct mddev {
    void                *private;
    struct md_personality       *pers;
    dev_t               unit;
    int             md_minor;
    struct list_head        disks;
    unsigned long           flags;
#define MD_CHANGE_DEVS  0   /* Some device status has changed */
#define MD_CHANGE_CLEAN 1   /* transition to or from 'clean' */
#define MD_CHANGE_PENDING 2 /* switch from 'clean' to 'active' in progress */
#define MD_ARRAY_FIRST_USE 3    /* First use of array, needs initialization */

    int             suspended;
    atomic_t            active_io;
    int             ro;
    int             sysfs_active; /* set when sysfs deletes
                               * are happening, so run/
                               * takeover/stop are not safe
                               */
    int             ready; /* See when safe to pass 
                        * IO requests down */
    struct gendisk          *gendisk;

    struct kobject          kobj;
    int             hold_active;
#define UNTIL_IOCTL 1
#define UNTIL_STOP  2

    /* Superblock information */
    int             major_version,
                    minor_version,
                    patch_version;
    int             persistent;
    int                 external;   /* metadata is
                             * managed externally */
    char                metadata_type[17]; /* externally set*/
    int             chunk_sectors;
    time_t              ctime, utime;
    int             level, layout;
    char                clevel[16];
    int             raid_disks;
    int             max_disks;
    sector_t            dev_sectors;    /* used size of
                             * component devices */
    sector_t            array_sectors; /* exported array size */
    int             external_size; /* size managed
                            * externally */
    __u64               events;
    /* If the last 'event' was simply a clean->dirty transition, and
     * we didn't write it to the spares, then it is safe and simple
     * to just decrement the event count on a dirty->clean transition.
     * So we record that possibility here.
     */
    int             can_decrease_events;

    char                uuid[16];

    /* If the array is being reshaped, we need to record the
     * new shape and an indication of where we are up to.
     * This is written to the superblock.
     * If reshape_position is MaxSector, then no reshape is happening (yet).
     */
    sector_t            reshape_position;
    int             delta_disks, new_level, new_layout;
    int             new_chunk_sectors;
    int             reshape_backwards;

    struct md_thread        *thread;    /* management thread */
    struct md_thread        *sync_thread;   /* doing resync or reconstruct */
    sector_t            curr_resync;    /* last block scheduled */
    /* As resync requests can complete out of order, we cannot easily track
     * how much resync has been completed.  So we occasionally pause until
     * everything completes, then set curr_resync_completed to curr_resync.
     * As such it may be well behind the real resync mark, but it is a value
     * we are certain of.
     */
    sector_t            curr_resync_completed;
    unsigned long           resync_mark;    /* a recent timestamp */
    sector_t            resync_mark_cnt;/* blocks written at resync_mark */
    sector_t            curr_mark_cnt; /* blocks scheduled now */

    sector_t            resync_max_sectors; /* may be set by personality */

    atomic64_t          resync_mismatches; /* count of sectors where
                                * parity/replica mismatch found
                                */

    /* allow user-space to request suspension of IO to regions of the array */
    sector_t            suspend_lo;
    sector_t            suspend_hi;
    /* if zero, use the system-wide default */
    int             sync_speed_min;
    int             sync_speed_max;

    /* resync even though the same disks are shared among md-devices */
    int             parallel_resync;

    int             ok_start_degraded;
    /* recovery/resync flags 
     * NEEDED:   we might need to start a resync/recover
     * RUNNING:  a thread is running, or about to be started
     * SYNC:     actually doing a resync, not a recovery
     * RECOVER:  doing recovery, or need to try it.
     * INTR:     resync needs to be aborted for some reason
     * DONE:     thread is done and is waiting to be reaped
     * REQUEST:  user-space has requested a sync (used with SYNC)
     * CHECK:    user-space request for check-only, no repair
     * RESHAPE:  A reshape is happening
     *
     * If neither SYNC or RESHAPE are set, then it is a recovery.
     */
#define MD_RECOVERY_RUNNING 0
#define MD_RECOVERY_SYNC    1
#define MD_RECOVERY_RECOVER 2
#define MD_RECOVERY_INTR    3
#define MD_RECOVERY_DONE    4
#define MD_RECOVERY_NEEDED  5
#define MD_RECOVERY_REQUESTED   6
#define MD_RECOVERY_CHECK   7
#define MD_RECOVERY_RESHAPE 8
#define MD_RECOVERY_FROZEN  9

    unsigned long           recovery;
    /* If a RAID personality determines that recovery (of a particular
     * device) will fail due to a read error on the source device, it
     * takes a copy of this number and does not attempt recovery again
     * until this number changes.
     */
    int             recovery_disabled;

    int             in_sync;    /* know to not need resync */
    /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
     * that we are never stopping an array while it is open.
     * 'reconfig_mutex' protects all other reconfiguration.
     * These locks are separate due to conflicting interactions
     * with bdev->bd_mutex.
     * Lock ordering is:
     *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
     *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
     */
    struct mutex            open_mutex;
    struct mutex            reconfig_mutex;
    atomic_t            active;     /* general refcount */
    atomic_t            openers;    /* number of active opens */

    int             changed;    /* True if we might need to
                             * reread partition info */
    int             degraded;   /* whether md should consider
                             * adding a spare
                             */
    int             merge_check_needed; /* at least one
                                 * member device
                                 * has a
                                 * merge_bvec_fn */

    atomic_t            recovery_active; /* blocks scheduled, but not written */
    wait_queue_head_t       recovery_wait;
    sector_t            recovery_cp;
    sector_t            resync_min; /* user requested sync
                             * starts here */
    sector_t            resync_max; /* resync should pause
                             * when it gets here */

    struct sysfs_dirent     *sysfs_state;   /* handle for 'array_state'
                             * file in sysfs.
                             */
    struct sysfs_dirent     *sysfs_action;  /* handle for 'sync_action' */

    struct work_struct del_work;    /* used for delayed sysfs removal */

    spinlock_t          write_lock;
    wait_queue_head_t       sb_wait;    /* for waiting on superblock updates */
    atomic_t            pending_writes; /* number of active superblock writes */

    unsigned int            safemode;   /* if set, update "clean" superblock
                             * when no writes pending.
                             */ 
    unsigned int            safemode_delay;
    struct timer_list       safemode_timer;
    atomic_t            writes_pending; 
    struct request_queue        *queue; /* for plugging ... */

    struct bitmap                   *bitmap; /* the bitmap for the device */
    struct {
        struct file     *file; /* the bitmap file */
        loff_t          offset; /* offset from superblock of
                         * start of bitmap. May be
                         * negative, but not '0'
                         * For external metadata, offset
                         * from start of device. 
                         */
        unsigned long       space; /* space available at this offset */
        loff_t          default_offset; /* this is the offset to use when
                             * hot-adding a bitmap.  It should
                             * eventually be settable by sysfs.
                             */
        unsigned long       default_space; /* space available at
                            * default offset */
        struct mutex        mutex;
        unsigned long       chunksize;
        unsigned long       daemon_sleep; /* how many jiffies between updates? */
        unsigned long       max_write_behind; /* write-behind mode */
        int         external;
    } bitmap_info;

    atomic_t            max_corr_read_errors; /* max read retries */
    struct list_head        all_mddevs;

    struct attribute_group      *to_remove;

    struct bio_set          *bio_set;

    /* Generic flush handling.
     * The last to finish preflush schedules a worker to submit
     * the rest of the request (without the REQ_FLUSH flag).
     */
    struct bio *flush_bio;
    atomic_t flush_pending;
    struct work_struct flush_work;
    struct work_struct event_work;  /* used by dm to report failure event */
    void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
};


static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
{
    int faulty = test_bit(Faulty, &rdev->flags);
    if (atomic_dec_and_test(&rdev->nr_pending) && faulty)
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
}

static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
{
        atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
}

struct md_personality
{
    char *name;
    int level;
    struct list_head list;
    struct module *owner;
    void (*make_request)(struct mddev *mddev, struct bio *bio);
    int (*run)(struct mddev *mddev);
    int (*stop)(struct mddev *mddev);
    void (*status)(struct seq_file *seq, struct mddev *mddev);
    /* error_handler must set ->faulty and clear ->in_sync
     * if appropriate, and should abort recovery if needed 
     */
    void (*error_handler)(struct mddev *mddev, struct md_rdev *rdev);
    int (*hot_add_disk) (struct mddev *mddev, struct md_rdev *rdev);
    int (*hot_remove_disk) (struct mddev *mddev, struct md_rdev *rdev);
    int (*spare_active) (struct mddev *mddev);
    sector_t (*sync_request)(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster);
    int (*resize) (struct mddev *mddev, sector_t sectors);
    sector_t (*size) (struct mddev *mddev, sector_t sectors, int raid_disks);
    int (*check_reshape) (struct mddev *mddev);
    int (*start_reshape) (struct mddev *mddev);
    void (*finish_reshape) (struct mddev *mddev);
    /* quiesce moves between quiescence states
     * 0 - fully active
     * 1 - no new requests allowed
     * others - reserved
     */
    void (*quiesce) (struct mddev *mddev, int state);
    /* takeover is used to transition an array from one
     * personality to another.  The new personality must be able
     * to handle the data in the current layout.
     * e.g. 2drive raid1 -> 2drive raid5
     *      ndrive raid5 -> degraded n+1drive raid6 with special layout
     * If the takeover succeeds, a new 'private' structure is returned.
     * This needs to be installed and then ->run used to activate the
     * array.
     */
    void *(*takeover) (struct mddev *mddev);
};


struct md_sysfs_entry {
    struct attribute attr;
    ssize_t (*show)(struct mddev *, char *);
    ssize_t (*store)(struct mddev *, const char *, size_t);
};
extern struct attribute_group md_bitmap_group;

static inline struct sysfs_dirent *sysfs_get_dirent_safe(struct sysfs_dirent *sd, char *name)
{
    if (sd)
        return sysfs_get_dirent(sd, NULL, name);
    return sd;
}
static inline void sysfs_notify_dirent_safe(struct sysfs_dirent *sd)
{
    if (sd)
        sysfs_notify_dirent(sd);
}

static inline char * mdname (struct mddev * mddev)
{
    return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
}

static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
{
    char nm[20];
    if (!test_bit(Replacement, &rdev->flags)) {
        sprintf(nm, "rd%d", rdev->raid_disk);
        return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
    } else
        return 0;
}

static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
{
    char nm[20];
    if (!test_bit(Replacement, &rdev->flags)) {
        sprintf(nm, "rd%d", rdev->raid_disk);
        sysfs_remove_link(&mddev->kobj, nm);
    }
}

/*
 * iterates through some rdev ringlist. It's safe to remove the
 * current 'rdev'. Dont touch 'tmp' though.
 */
#define rdev_for_each_list(rdev, tmp, head)             \
    list_for_each_entry_safe(rdev, tmp, head, same_set)

/*
 * iterates through the 'same array disks' ringlist
 */
#define rdev_for_each(rdev, mddev)              \
    list_for_each_entry(rdev, &((mddev)->disks), same_set)

#define rdev_for_each_safe(rdev, tmp, mddev)                \
    list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)

#define rdev_for_each_rcu(rdev, mddev)              \
    list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)

struct md_thread {
    void            (*run) (struct md_thread *thread);
    struct mddev        *mddev;
    wait_queue_head_t   wqueue;
    unsigned long           flags;
    struct task_struct  *tsk;
    unsigned long       timeout;
    void            *private;
};

#define THREAD_WAKEUP  0

#define __wait_event_lock_irq(wq, condition, lock, cmd)         \
do {                                    \
    wait_queue_t __wait;                        \
    init_waitqueue_entry(&__wait, current);             \
                                    \
    add_wait_queue(&wq, &__wait);                   \
    for (;;) {                          \
        set_current_state(TASK_UNINTERRUPTIBLE);        \
        if (condition)                      \
            break;                      \
        spin_unlock_irq(&lock);                 \
        cmd;                            \
        schedule();                     \
        spin_lock_irq(&lock);                   \
    }                               \
    current->state = TASK_RUNNING;                  \
    remove_wait_queue(&wq, &__wait);                \
} while (0)

#define wait_event_lock_irq(wq, condition, lock, cmd)           \
do {                                    \
    if (condition)                          \
        break;                          \
    __wait_event_lock_irq(wq, condition, lock, cmd);        \
} while (0)

static inline void safe_put_page(struct page *p)
{
    if (p) put_page(p);
}

extern int register_md_personality(struct md_personality *p);
extern int unregister_md_personality(struct md_personality *p);
extern struct md_thread *md_register_thread(
    void (*run)(struct md_thread *thread),
    struct mddev *mddev,
    const char *name);
extern void md_unregister_thread(struct md_thread **threadp);
extern void md_wakeup_thread(struct md_thread *thread);
extern void md_check_recovery(struct mddev *mddev);
extern void md_write_start(struct mddev *mddev, struct bio *bi);
extern void md_write_end(struct mddev *mddev);
extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
extern void md_finish_reshape(struct mddev *mddev);

extern int mddev_congested(struct mddev *mddev, int bits);
extern void md_flush_request(struct mddev *mddev, struct bio *bio);
extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
               sector_t sector, int size, struct page *page);
extern void md_super_wait(struct mddev *mddev);
extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size, 
            struct page *page, int rw, bool metadata_op);
extern void md_do_sync(struct md_thread *thread);
extern void md_new_event(struct mddev *mddev);
extern int md_allow_write(struct mddev *mddev);
extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
extern int md_check_no_bitmap(struct mddev *mddev);
extern int md_integrity_register(struct mddev *mddev);
extern void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
extern void restore_bitmap_write_access(struct file *file);

extern void mddev_init(struct mddev *mddev);
extern int md_run(struct mddev *mddev);
extern void md_stop(struct mddev *mddev);
extern void md_stop_writes(struct mddev *mddev);
extern int md_rdev_init(struct md_rdev *rdev);
extern void md_rdev_clear(struct md_rdev *rdev);

extern void mddev_suspend(struct mddev *mddev);
extern void mddev_resume(struct mddev *mddev);
extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
                   struct mddev *mddev);
extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
                   struct mddev *mddev);
extern void md_trim_bio(struct bio *bio, int offset, int size);

extern void md_unplug(struct blk_plug_cb *cb, bool from_schedule);
static inline int mddev_check_plugged(struct mddev *mddev)
{
    return !!blk_check_plugged(md_unplug, mddev,
                   sizeof(struct blk_plug_cb));
}
#endif /* _MD_MD_H */