super.c

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/*
 * Copyright (C) 2005, 2006
 * Avishay Traeger ([email protected])
 * Copyright (C) 2008, 2009
 * Boaz Harrosh <[email protected]>
 *
 * Copyrights for code taken from ext2:
 *     Copyright (C) 1992, 1993, 1994, 1995
 *     Remy Card ([email protected])
 *     Laboratoire MASI - Institut Blaise Pascal
 *     Universite Pierre et Marie Curie (Paris VI)
 *     from
 *     linux/fs/minix/inode.c
 *     Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This file is part of exofs.
 *
 * exofs 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.  Since it is based on ext2, and the only
 * valid version of GPL for the Linux kernel is version 2, the only valid
 * version of GPL for exofs is version 2.
 *
 * exofs is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with exofs; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/string.h>
#include <linux/parser.h>
#include <linux/vfs.h>
#include <linux/random.h>
#include <linux/module.h>
#include <linux/exportfs.h>
#include <linux/slab.h>

#include "exofs.h"

#define EXOFS_DBGMSG2(M...) do {} while (0)

/******************************************************************************
 * MOUNT OPTIONS
 *****************************************************************************/

/*
 * struct to hold what we get from mount options
 */
struct exofs_mountopt {
    bool is_osdname;
    const char *dev_name;
    uint64_t pid;
    int timeout;
};

/*
 * exofs-specific mount-time options.
 */
enum { Opt_name, Opt_pid, Opt_to, Opt_err };

/*
 * Our mount-time options.  These should ideally be 64-bit unsigned, but the
 * kernel's parsing functions do not currently support that.  32-bit should be
 * sufficient for most applications now.
 */
static match_table_t tokens = {
    {Opt_name, "osdname=%s"},
    {Opt_pid, "pid=%u"},
    {Opt_to, "to=%u"},
    {Opt_err, NULL}
};

/*
 * The main option parsing method.  Also makes sure that all of the mandatory
 * mount options were set.
 */
static int parse_options(char *options, struct exofs_mountopt *opts)
{
    char *p;
    substring_t args[MAX_OPT_ARGS];
    int option;
    bool s_pid = false;

    EXOFS_DBGMSG("parse_options %s\n", options);
    /* defaults */
    memset(opts, 0, sizeof(*opts));
    opts->timeout = BLK_DEFAULT_SG_TIMEOUT;

    while ((p = strsep(&options, ",")) != NULL) {
        int token;
        char str[32];

        if (!*p)
            continue;

        token = match_token(p, tokens, args);
        switch (token) {
        case Opt_name:
            opts->dev_name = match_strdup(&args[0]);
            if (unlikely(!opts->dev_name)) {
                EXOFS_ERR("Error allocating dev_name");
                return -ENOMEM;
            }
            opts->is_osdname = true;
            break;
        case Opt_pid:
            if (0 == match_strlcpy(str, &args[0], sizeof(str)))
                return -EINVAL;
            opts->pid = simple_strtoull(str, NULL, 0);
            if (opts->pid < EXOFS_MIN_PID) {
                EXOFS_ERR("Partition ID must be >= %u",
                      EXOFS_MIN_PID);
                return -EINVAL;
            }
            s_pid = 1;
            break;
        case Opt_to:
            if (match_int(&args[0], &option))
                return -EINVAL;
            if (option <= 0) {
                EXOFS_ERR("Timout must be > 0");
                return -EINVAL;
            }
            opts->timeout = option * HZ;
            break;
        }
    }

    if (!s_pid) {
        EXOFS_ERR("Need to specify the following options:\n");
        EXOFS_ERR("    -o pid=pid_no_to_use\n");
        return -EINVAL;
    }

    return 0;
}

/******************************************************************************
 * INODE CACHE
 *****************************************************************************/

/*
 * Our inode cache.  Isn't it pretty?
 */
static struct kmem_cache *exofs_inode_cachep;

/*
 * Allocate an inode in the cache
 */
static struct inode *exofs_alloc_inode(struct super_block *sb)
{
    struct exofs_i_info *oi;

    oi = kmem_cache_alloc(exofs_inode_cachep, GFP_KERNEL);
    if (!oi)
        return NULL;

    oi->vfs_inode.i_version = 1;
    return &oi->vfs_inode;
}

static void exofs_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    kmem_cache_free(exofs_inode_cachep, exofs_i(inode));
}

/*
 * Remove an inode from the cache
 */
static void exofs_destroy_inode(struct inode *inode)
{
    call_rcu(&inode->i_rcu, exofs_i_callback);
}

/*
 * Initialize the inode
 */
static void exofs_init_once(void *foo)
{
    struct exofs_i_info *oi = foo;

    inode_init_once(&oi->vfs_inode);
}

/*
 * Create and initialize the inode cache
 */
static int init_inodecache(void)
{
    exofs_inode_cachep = kmem_cache_create("exofs_inode_cache",
                sizeof(struct exofs_i_info), 0,
                SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
                exofs_init_once);
    if (exofs_inode_cachep == NULL)
        return -ENOMEM;
    return 0;
}

/*
 * Destroy the inode cache
 */
static void destroy_inodecache(void)
{
    /*
     * Make sure all delayed rcu free inodes are flushed before we
     * destroy cache.
     */
    rcu_barrier();
    kmem_cache_destroy(exofs_inode_cachep);
}

/******************************************************************************
 * Some osd helpers
 *****************************************************************************/
void exofs_make_credential(u8 cred_a[OSD_CAP_LEN], const struct osd_obj_id *obj)
{
    osd_sec_init_nosec_doall_caps(cred_a, obj, false, true);
}

static int exofs_read_kern(struct osd_dev *od, u8 *cred, struct osd_obj_id *obj,
            u64 offset, void *p, unsigned length)
{
    struct osd_request *or = osd_start_request(od, GFP_KERNEL);
/*  struct osd_sense_info osi = {.key = 0};*/
    int ret;

    if (unlikely(!or)) {
        EXOFS_DBGMSG("%s: osd_start_request failed.\n", __func__);
        return -ENOMEM;
    }
    ret = osd_req_read_kern(or, obj, offset, p, length);
    if (unlikely(ret)) {
        EXOFS_DBGMSG("%s: osd_req_read_kern failed.\n", __func__);
        goto out;
    }

    ret = osd_finalize_request(or, 0, cred, NULL);
    if (unlikely(ret)) {
        EXOFS_DBGMSG("Failed to osd_finalize_request() => %d\n", ret);
        goto out;
    }

    ret = osd_execute_request(or);
    if (unlikely(ret))
        EXOFS_DBGMSG("osd_execute_request() => %d\n", ret);
    /* osd_req_decode_sense(or, ret); */

out:
    osd_end_request(or);
    EXOFS_DBGMSG2("read_kern(0x%llx) offset=0x%llx "
              "length=0x%llx dev=%p ret=>%d\n",
              _LLU(obj->id), _LLU(offset), _LLU(length), od, ret);
    return ret;
}

static const struct osd_attr g_attr_sb_stats = ATTR_DEF(
    EXOFS_APAGE_SB_DATA,
    EXOFS_ATTR_SB_STATS,
    sizeof(struct exofs_sb_stats));

static int __sbi_read_stats(struct exofs_sb_info *sbi)
{
    struct osd_attr attrs[] = {
        [0] = g_attr_sb_stats,
    };
    struct ore_io_state *ios;
    int ret;

    ret = ore_get_io_state(&sbi->layout, &sbi->oc, &ios);
    if (unlikely(ret)) {
        EXOFS_ERR("%s: ore_get_io_state failed.\n", __func__);
        return ret;
    }

    ios->in_attr = attrs;
    ios->in_attr_len = ARRAY_SIZE(attrs);

    ret = ore_read(ios);
    if (unlikely(ret)) {
        EXOFS_ERR("Error reading super_block stats => %d\n", ret);
        goto out;
    }

    ret = extract_attr_from_ios(ios, &attrs[0]);
    if (ret) {
        EXOFS_ERR("%s: extract_attr of sb_stats failed\n", __func__);
        goto out;
    }
    if (attrs[0].len) {
        struct exofs_sb_stats *ess;

        if (unlikely(attrs[0].len != sizeof(*ess))) {
            EXOFS_ERR("%s: Wrong version of exofs_sb_stats "
                  "size(%d) != expected(%zd)\n",
                  __func__, attrs[0].len, sizeof(*ess));
            goto out;
        }

        ess = attrs[0].val_ptr;
        sbi->s_nextid = le64_to_cpu(ess->s_nextid);
        sbi->s_numfiles = le32_to_cpu(ess->s_numfiles);
    }

out:
    ore_put_io_state(ios);
    return ret;
}

static void stats_done(struct ore_io_state *ios, void *p)
{
    ore_put_io_state(ios);
    /* Good thanks nothing to do anymore */
}

/* Asynchronously write the stats attribute */
int exofs_sbi_write_stats(struct exofs_sb_info *sbi)
{
    struct osd_attr attrs[] = {
        [0] = g_attr_sb_stats,
    };
    struct ore_io_state *ios;
    int ret;

    ret = ore_get_io_state(&sbi->layout, &sbi->oc, &ios);
    if (unlikely(ret)) {
        EXOFS_ERR("%s: ore_get_io_state failed.\n", __func__);
        return ret;
    }

    sbi->s_ess.s_nextid   = cpu_to_le64(sbi->s_nextid);
    sbi->s_ess.s_numfiles = cpu_to_le64(sbi->s_numfiles);
    attrs[0].val_ptr = &sbi->s_ess;


    ios->done = stats_done;
    ios->private = sbi;
    ios->out_attr = attrs;
    ios->out_attr_len = ARRAY_SIZE(attrs);

    ret = ore_write(ios);
    if (unlikely(ret)) {
        EXOFS_ERR("%s: ore_write failed.\n", __func__);
        ore_put_io_state(ios);
    }

    return ret;
}

/******************************************************************************
 * SUPERBLOCK FUNCTIONS
 *****************************************************************************/
static const struct super_operations exofs_sops;
static const struct export_operations exofs_export_ops;

/*
 * Write the superblock to the OSD
 */
static int exofs_sync_fs(struct super_block *sb, int wait)
{
    struct exofs_sb_info *sbi;
    struct exofs_fscb *fscb;
    struct ore_comp one_comp;
    struct ore_components oc;
    struct ore_io_state *ios;
    int ret = -ENOMEM;

    fscb = kmalloc(sizeof(*fscb), GFP_KERNEL);
    if (unlikely(!fscb))
        return -ENOMEM;

    sbi = sb->s_fs_info;

    /* NOTE: We no longer dirty the super_block anywhere in exofs. The
     * reason we write the fscb here on unmount is so we can stay backwards
     * compatible with fscb->s_version == 1. (What we are not compatible
     * with is if a new version FS crashed and then we try to mount an old
     * version). Otherwise the exofs_fscb is read-only from mkfs time. All
     * the writeable info is set in exofs_sbi_write_stats() above.
     */

    exofs_init_comps(&oc, &one_comp, sbi, EXOFS_SUPER_ID);

    ret = ore_get_io_state(&sbi->layout, &oc, &ios);
    if (unlikely(ret))
        goto out;

    ios->length = offsetof(struct exofs_fscb, s_dev_table_oid);
    memset(fscb, 0, ios->length);
    fscb->s_nextid = cpu_to_le64(sbi->s_nextid);
    fscb->s_numfiles = cpu_to_le64(sbi->s_numfiles);
    fscb->s_magic = cpu_to_le16(sb->s_magic);
    fscb->s_newfs = 0;
    fscb->s_version = EXOFS_FSCB_VER;

    ios->offset = 0;
    ios->kern_buff = fscb;

    ret = ore_write(ios);
    if (unlikely(ret))
        EXOFS_ERR("%s: ore_write failed.\n", __func__);

out:
    EXOFS_DBGMSG("s_nextid=0x%llx ret=%d\n", _LLU(sbi->s_nextid), ret);
    ore_put_io_state(ios);
    kfree(fscb);
    return ret;
}

static void _exofs_print_device(const char *msg, const char *dev_path,
                struct osd_dev *od, u64 pid)
{
    const struct osd_dev_info *odi = osduld_device_info(od);

    printk(KERN_NOTICE "exofs: %s %s osd_name-%s pid-0x%llx\n",
        msg, dev_path ?: "", odi->osdname, _LLU(pid));
}

static void exofs_free_sbi(struct exofs_sb_info *sbi)
{
    unsigned numdevs = sbi->oc.numdevs;

    while (numdevs) {
        unsigned i = --numdevs;
        struct osd_dev *od = ore_comp_dev(&sbi->oc, i);

        if (od) {
            ore_comp_set_dev(&sbi->oc, i, NULL);
            osduld_put_device(od);
        }
    }
    kfree(sbi->oc.ods);
    kfree(sbi);
}

/*
 * This function is called when the vfs is freeing the superblock.  We just
 * need to free our own part.
 */
static void exofs_put_super(struct super_block *sb)
{
    int num_pend;
    struct exofs_sb_info *sbi = sb->s_fs_info;

    /* make sure there are no pending commands */
    for (num_pend = atomic_read(&sbi->s_curr_pending); num_pend > 0;
         num_pend = atomic_read(&sbi->s_curr_pending)) {
        wait_queue_head_t wq;

        printk(KERN_NOTICE "%s: !!Pending operations in flight. "
               "This is a BUG. please report to [email protected]\n",
               __func__);
        init_waitqueue_head(&wq);
        wait_event_timeout(wq,
                  (atomic_read(&sbi->s_curr_pending) == 0),
                  msecs_to_jiffies(100));
    }

    _exofs_print_device("Unmounting", NULL, ore_comp_dev(&sbi->oc, 0),
                sbi->one_comp.obj.partition);

    exofs_sysfs_sb_del(sbi);
    bdi_destroy(&sbi->bdi);
    exofs_free_sbi(sbi);
    sb->s_fs_info = NULL;
}

static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
                    struct exofs_device_table *dt)
{
    int ret;

    sbi->layout.stripe_unit =
                le64_to_cpu(dt->dt_data_map.cb_stripe_unit);
    sbi->layout.group_width =
                le32_to_cpu(dt->dt_data_map.cb_group_width);
    sbi->layout.group_depth =
                le32_to_cpu(dt->dt_data_map.cb_group_depth);
    sbi->layout.mirrors_p1  =
                le32_to_cpu(dt->dt_data_map.cb_mirror_cnt) + 1;
    sbi->layout.raid_algorithm  =
                le32_to_cpu(dt->dt_data_map.cb_raid_algorithm);

    ret = ore_verify_layout(numdevs, &sbi->layout);

    EXOFS_DBGMSG("exofs: layout: "
        "num_comps=%u stripe_unit=0x%x group_width=%u "
        "group_depth=0x%llx mirrors_p1=%u raid_algorithm=%u\n",
        numdevs,
        sbi->layout.stripe_unit,
        sbi->layout.group_width,
        _LLU(sbi->layout.group_depth),
        sbi->layout.mirrors_p1,
        sbi->layout.raid_algorithm);
    return ret;
}

static unsigned __ra_pages(struct ore_layout *layout)
{
    const unsigned _MIN_RA = 32; /* min 128K read-ahead */
    unsigned ra_pages = layout->group_width * layout->stripe_unit /
                PAGE_SIZE;
    unsigned max_io_pages = exofs_max_io_pages(layout, ~0);

    ra_pages *= 2; /* two stripes */
    if (ra_pages < _MIN_RA)
        ra_pages = roundup(_MIN_RA, ra_pages / 2);

    if (ra_pages > max_io_pages)
        ra_pages = max_io_pages;

    return ra_pages;
}

/* @odi is valid only as long as @fscb_dev is valid */
static int exofs_devs_2_odi(struct exofs_dt_device_info *dt_dev,
                 struct osd_dev_info *odi)
{
    odi->systemid_len = le32_to_cpu(dt_dev->systemid_len);
    if (likely(odi->systemid_len))
        memcpy(odi->systemid, dt_dev->systemid, OSD_SYSTEMID_LEN);

    odi->osdname_len = le32_to_cpu(dt_dev->osdname_len);
    odi->osdname = dt_dev->osdname;

    /* FIXME support long names. Will need a _put function */
    if (dt_dev->long_name_offset)
        return -EINVAL;

    /* Make sure osdname is printable!
     * mkexofs should give us space for a null-terminator else the
     * device-table is invalid.
     */
    if (unlikely(odi->osdname_len >= sizeof(dt_dev->osdname)))
        odi->osdname_len = sizeof(dt_dev->osdname) - 1;
    dt_dev->osdname[odi->osdname_len] = 0;

    /* If it's all zeros something is bad we read past end-of-obj */
    return !(odi->systemid_len || odi->osdname_len);
}

int __alloc_dev_table(struct exofs_sb_info *sbi, unsigned numdevs,
              struct exofs_dev **peds)
{
    struct __alloc_ore_devs_and_exofs_devs {
        /* Twice bigger table: See exofs_init_comps() and comment at
         * exofs_read_lookup_dev_table()
         */
        struct ore_dev *oreds[numdevs * 2 - 1];
        struct exofs_dev eds[numdevs];
    } *aoded;
    struct exofs_dev *eds;
    unsigned i;

    aoded = kzalloc(sizeof(*aoded), GFP_KERNEL);
    if (unlikely(!aoded)) {
        EXOFS_ERR("ERROR: failed allocating Device array[%d]\n",
              numdevs);
        return -ENOMEM;
    }

    sbi->oc.ods = aoded->oreds;
    *peds = eds = aoded->eds;
    for (i = 0; i < numdevs; ++i)
        aoded->oreds[i] = &eds[i].ored;
    return 0;
}

static int exofs_read_lookup_dev_table(struct exofs_sb_info *sbi,
                       struct osd_dev *fscb_od,
                       unsigned table_count)
{
    struct ore_comp comp;
    struct exofs_device_table *dt;
    struct exofs_dev *eds;
    unsigned table_bytes = table_count * sizeof(dt->dt_dev_table[0]) +
                         sizeof(*dt);
    unsigned numdevs, i;
    int ret;

    dt = kmalloc(table_bytes, GFP_KERNEL);
    if (unlikely(!dt)) {
        EXOFS_ERR("ERROR: allocating %x bytes for device table\n",
              table_bytes);
        return -ENOMEM;
    }

    sbi->oc.numdevs = 0;

    comp.obj.partition = sbi->one_comp.obj.partition;
    comp.obj.id = EXOFS_DEVTABLE_ID;
    exofs_make_credential(comp.cred, &comp.obj);

    ret = exofs_read_kern(fscb_od, comp.cred, &comp.obj, 0, dt,
                  table_bytes);
    if (unlikely(ret)) {
        EXOFS_ERR("ERROR: reading device table\n");
        goto out;
    }

    numdevs = le64_to_cpu(dt->dt_num_devices);
    if (unlikely(!numdevs)) {
        ret = -EINVAL;
        goto out;
    }
    WARN_ON(table_count != numdevs);

    ret = _read_and_match_data_map(sbi, numdevs, dt);
    if (unlikely(ret))
        goto out;

    ret = __alloc_dev_table(sbi, numdevs, &eds);
    if (unlikely(ret))
        goto out;
    /* exofs round-robins the device table view according to inode
     * number. We hold a: twice bigger table hence inodes can point
     * to any device and have a sequential view of the table
     * starting at this device. See exofs_init_comps()
     */
    memcpy(&sbi->oc.ods[numdevs], &sbi->oc.ods[0],
        (numdevs - 1) * sizeof(sbi->oc.ods[0]));

    /* create sysfs subdir under which we put the device table
     * And cluster layout. A Superblock is identified by the string:
     *  "dev[0].osdname"_"pid"
     */
    exofs_sysfs_sb_add(sbi, &dt->dt_dev_table[0]);

    for (i = 0; i < numdevs; i++) {
        struct exofs_fscb fscb;
        struct osd_dev_info odi;
        struct osd_dev *od;

        if (exofs_devs_2_odi(&dt->dt_dev_table[i], &odi)) {
            EXOFS_ERR("ERROR: Read all-zeros device entry\n");
            ret = -EINVAL;
            goto out;
        }

        printk(KERN_NOTICE "Add device[%d]: osd_name-%s\n",
               i, odi.osdname);

        /* the exofs id is currently the table index */
        eds[i].did = i;

        /* On all devices the device table is identical. The user can
         * specify any one of the participating devices on the command
         * line. We always keep them in device-table order.
         */
        if (fscb_od && osduld_device_same(fscb_od, &odi)) {
            eds[i].ored.od = fscb_od;
            ++sbi->oc.numdevs;
            fscb_od = NULL;
            exofs_sysfs_odev_add(&eds[i], sbi);
            continue;
        }

        od = osduld_info_lookup(&odi);
        if (IS_ERR(od)) {
            ret = PTR_ERR(od);
            EXOFS_ERR("ERROR: device requested is not found "
                  "osd_name-%s =>%d\n", odi.osdname, ret);
            goto out;
        }

        eds[i].ored.od = od;
        ++sbi->oc.numdevs;

        /* Read the fscb of the other devices to make sure the FS
         * partition is there.
         */
        ret = exofs_read_kern(od, comp.cred, &comp.obj, 0, &fscb,
                      sizeof(fscb));
        if (unlikely(ret)) {
            EXOFS_ERR("ERROR: Malformed participating device "
                  "error reading fscb osd_name-%s\n",
                  odi.osdname);
            goto out;
        }
        exofs_sysfs_odev_add(&eds[i], sbi);

        /* TODO: verify other information is correct and FS-uuid
         *   matches. Benny what did you say about device table
         *   generation and old devices?
         */
    }

out:
    kfree(dt);
    if (unlikely(fscb_od && !ret)) {
            EXOFS_ERR("ERROR: Bad device-table container device not present\n");
            osduld_put_device(fscb_od);
            return -EINVAL;
    }
    return ret;
}

/*
 * Read the superblock from the OSD and fill in the fields
 */
static int exofs_fill_super(struct super_block *sb, void *data, int silent)
{
    struct inode *root;
    struct exofs_mountopt *opts = data;
    struct exofs_sb_info *sbi;  /*extended info                  */
    struct osd_dev *od;     /* Master device                 */
    struct exofs_fscb fscb;     /*on-disk superblock info        */
    struct ore_comp comp;
    unsigned table_count;
    int ret;

    sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
    if (!sbi)
        return -ENOMEM;

    /* use mount options to fill superblock */
    if (opts->is_osdname) {
        struct osd_dev_info odi = {.systemid_len = 0};

        odi.osdname_len = strlen(opts->dev_name);
        odi.osdname = (u8 *)opts->dev_name;
        od = osduld_info_lookup(&odi);
        kfree(opts->dev_name);
        opts->dev_name = NULL;
    } else {
        od = osduld_path_lookup(opts->dev_name);
    }
    if (IS_ERR(od)) {
        ret = -EINVAL;
        goto free_sbi;
    }

    /* Default layout in case we do not have a device-table */
    sbi->layout.stripe_unit = PAGE_SIZE;
    sbi->layout.mirrors_p1 = 1;
    sbi->layout.group_width = 1;
    sbi->layout.group_depth = -1;
    sbi->layout.group_count = 1;
    sbi->s_timeout = opts->timeout;

    sbi->one_comp.obj.partition = opts->pid;
    sbi->one_comp.obj.id = 0;
    exofs_make_credential(sbi->one_comp.cred, &sbi->one_comp.obj);
    sbi->oc.single_comp = EC_SINGLE_COMP;
    sbi->oc.comps = &sbi->one_comp;

    /* fill in some other data by hand */
    memset(sb->s_id, 0, sizeof(sb->s_id));
    strcpy(sb->s_id, "exofs");
    sb->s_blocksize = EXOFS_BLKSIZE;
    sb->s_blocksize_bits = EXOFS_BLKSHIFT;
    sb->s_maxbytes = MAX_LFS_FILESIZE;
    sb->s_max_links = EXOFS_LINK_MAX;
    atomic_set(&sbi->s_curr_pending, 0);
    sb->s_bdev = NULL;
    sb->s_dev = 0;

    comp.obj.partition = sbi->one_comp.obj.partition;
    comp.obj.id = EXOFS_SUPER_ID;
    exofs_make_credential(comp.cred, &comp.obj);

    ret = exofs_read_kern(od, comp.cred, &comp.obj, 0, &fscb, sizeof(fscb));
    if (unlikely(ret))
        goto free_sbi;

    sb->s_magic = le16_to_cpu(fscb.s_magic);
    /* NOTE: we read below to be backward compatible with old versions */
    sbi->s_nextid = le64_to_cpu(fscb.s_nextid);
    sbi->s_numfiles = le32_to_cpu(fscb.s_numfiles);

    /* make sure what we read from the object store is correct */
    if (sb->s_magic != EXOFS_SUPER_MAGIC) {
        if (!silent)
            EXOFS_ERR("ERROR: Bad magic value\n");
        ret = -EINVAL;
        goto free_sbi;
    }
    if (le32_to_cpu(fscb.s_version) > EXOFS_FSCB_VER) {
        EXOFS_ERR("ERROR: Bad FSCB version expected-%d got-%d\n",
              EXOFS_FSCB_VER, le32_to_cpu(fscb.s_version));
        ret = -EINVAL;
        goto free_sbi;
    }

    /* start generation numbers from a random point */
    get_random_bytes(&sbi->s_next_generation, sizeof(u32));
    spin_lock_init(&sbi->s_next_gen_lock);

    table_count = le64_to_cpu(fscb.s_dev_table_count);
    if (table_count) {
        ret = exofs_read_lookup_dev_table(sbi, od, table_count);
        if (unlikely(ret))
            goto free_sbi;
    } else {
        struct exofs_dev *eds;

        ret = __alloc_dev_table(sbi, 1, &eds);
        if (unlikely(ret))
            goto free_sbi;

        ore_comp_set_dev(&sbi->oc, 0, od);
        sbi->oc.numdevs = 1;
    }

    __sbi_read_stats(sbi);

    /* set up operation vectors */
    sbi->bdi.ra_pages = __ra_pages(&sbi->layout);
    sb->s_bdi = &sbi->bdi;
    sb->s_fs_info = sbi;
    sb->s_op = &exofs_sops;
    sb->s_export_op = &exofs_export_ops;
    root = exofs_iget(sb, EXOFS_ROOT_ID - EXOFS_OBJ_OFF);
    if (IS_ERR(root)) {
        EXOFS_ERR("ERROR: exofs_iget failed\n");
        ret = PTR_ERR(root);
        goto free_sbi;
    }
    sb->s_root = d_make_root(root);
    if (!sb->s_root) {
        EXOFS_ERR("ERROR: get root inode failed\n");
        ret = -ENOMEM;
        goto free_sbi;
    }

    if (!S_ISDIR(root->i_mode)) {
        dput(sb->s_root);
        sb->s_root = NULL;
        EXOFS_ERR("ERROR: corrupt root inode (mode = %hd)\n",
               root->i_mode);
        ret = -EINVAL;
        goto free_sbi;
    }

    ret = bdi_setup_and_register(&sbi->bdi, "exofs", BDI_CAP_MAP_COPY);
    if (ret) {
        EXOFS_DBGMSG("Failed to bdi_setup_and_register\n");
        dput(sb->s_root);
        sb->s_root = NULL;
        goto free_sbi;
    }

    exofs_sysfs_dbg_print();
    _exofs_print_device("Mounting", opts->dev_name,
                ore_comp_dev(&sbi->oc, 0),
                sbi->one_comp.obj.partition);
    return 0;

free_sbi:
    EXOFS_ERR("Unable to mount exofs on %s pid=0x%llx err=%d\n",
          opts->dev_name, sbi->one_comp.obj.partition, ret);
    exofs_free_sbi(sbi);
    return ret;
}

/*
 * Set up the superblock (calls exofs_fill_super eventually)
 */
static struct dentry *exofs_mount(struct file_system_type *type,
              int flags, const char *dev_name,
              void *data)
{
    struct exofs_mountopt opts;
    int ret;

    ret = parse_options(data, &opts);
    if (ret)
        return ERR_PTR(ret);

    if (!opts.dev_name)
        opts.dev_name = dev_name;
    return mount_nodev(type, flags, &opts, exofs_fill_super);
}

/*
 * Return information about the file system state in the buffer.  This is used
 * by the 'df' command, for example.
 */
static int exofs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
    struct super_block *sb = dentry->d_sb;
    struct exofs_sb_info *sbi = sb->s_fs_info;
    struct ore_io_state *ios;
    struct osd_attr attrs[] = {
        ATTR_DEF(OSD_APAGE_PARTITION_QUOTAS,
            OSD_ATTR_PQ_CAPACITY_QUOTA, sizeof(__be64)),
        ATTR_DEF(OSD_APAGE_PARTITION_INFORMATION,
            OSD_ATTR_PI_USED_CAPACITY, sizeof(__be64)),
    };
    uint64_t capacity = ULLONG_MAX;
    uint64_t used = ULLONG_MAX;
    int ret;

    ret = ore_get_io_state(&sbi->layout, &sbi->oc, &ios);
    if (ret) {
        EXOFS_DBGMSG("ore_get_io_state failed.\n");
        return ret;
    }

    ios->in_attr = attrs;
    ios->in_attr_len = ARRAY_SIZE(attrs);

    ret = ore_read(ios);
    if (unlikely(ret))
        goto out;

    ret = extract_attr_from_ios(ios, &attrs[0]);
    if (likely(!ret)) {
        capacity = get_unaligned_be64(attrs[0].val_ptr);
        if (unlikely(!capacity))
            capacity = ULLONG_MAX;
    } else
        EXOFS_DBGMSG("exofs_statfs: get capacity failed.\n");

    ret = extract_attr_from_ios(ios, &attrs[1]);
    if (likely(!ret))
        used = get_unaligned_be64(attrs[1].val_ptr);
    else
        EXOFS_DBGMSG("exofs_statfs: get used-space failed.\n");

    /* fill in the stats buffer */
    buf->f_type = EXOFS_SUPER_MAGIC;
    buf->f_bsize = EXOFS_BLKSIZE;
    buf->f_blocks = capacity >> 9;
    buf->f_bfree = (capacity - used) >> 9;
    buf->f_bavail = buf->f_bfree;
    buf->f_files = sbi->s_numfiles;
    buf->f_ffree = EXOFS_MAX_ID - sbi->s_numfiles;
    buf->f_namelen = EXOFS_NAME_LEN;

out:
    ore_put_io_state(ios);
    return ret;
}

static const struct super_operations exofs_sops = {
    .alloc_inode    = exofs_alloc_inode,
    .destroy_inode  = exofs_destroy_inode,
    .write_inode    = exofs_write_inode,
    .evict_inode    = exofs_evict_inode,
    .put_super      = exofs_put_super,
    .sync_fs    = exofs_sync_fs,
    .statfs         = exofs_statfs,
};

/******************************************************************************
 * EXPORT OPERATIONS
 *****************************************************************************/

static struct dentry *exofs_get_parent(struct dentry *child)
{
    unsigned long ino = exofs_parent_ino(child);

    if (!ino)
        return ERR_PTR(-ESTALE);

    return d_obtain_alias(exofs_iget(child->d_inode->i_sb, ino));
}

static struct inode *exofs_nfs_get_inode(struct super_block *sb,
        u64 ino, u32 generation)
{
    struct inode *inode;

    inode = exofs_iget(sb, ino);
    if (IS_ERR(inode))
        return ERR_CAST(inode);
    if (generation && inode->i_generation != generation) {
        /* we didn't find the right inode.. */
        iput(inode);
        return ERR_PTR(-ESTALE);
    }
    return inode;
}

static struct dentry *exofs_fh_to_dentry(struct super_block *sb,
                struct fid *fid, int fh_len, int fh_type)
{
    return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
                    exofs_nfs_get_inode);
}

static struct dentry *exofs_fh_to_parent(struct super_block *sb,
                struct fid *fid, int fh_len, int fh_type)
{
    return generic_fh_to_parent(sb, fid, fh_len, fh_type,
                    exofs_nfs_get_inode);
}

static const struct export_operations exofs_export_ops = {
    .fh_to_dentry = exofs_fh_to_dentry,
    .fh_to_parent = exofs_fh_to_parent,
    .get_parent = exofs_get_parent,
};

/******************************************************************************
 * INSMOD/RMMOD
 *****************************************************************************/

/*
 * struct that describes this file system
 */
static struct file_system_type exofs_type = {
    .owner          = THIS_MODULE,
    .name           = "exofs",
    .mount          = exofs_mount,
    .kill_sb        = generic_shutdown_super,
};

static int __init init_exofs(void)
{
    int err;

    err = init_inodecache();
    if (err)
        goto out;

    err = register_filesystem(&exofs_type);
    if (err)
        goto out_d;

    /* We don't fail if sysfs creation failed */
    exofs_sysfs_init();

    return 0;
out_d:
    destroy_inodecache();
out:
    return err;
}

static void __exit exit_exofs(void)
{
    exofs_sysfs_uninit();
    unregister_filesystem(&exofs_type);
    destroy_inodecache();
}

MODULE_AUTHOR("Avishay Traeger <[email protected]>");
MODULE_DESCRIPTION("exofs");
MODULE_LICENSE("GPL");

module_init(init_exofs)
module_exit(exit_exofs)