fs: fix nobh error handling

[pv_ops_mirror.git] / drivers / md / md.c

/*
   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 <hpa@zytor.com>
   - boot support for linear and striped mode by Harald Hoyer <HarryH@Royal.Net>
   - kerneld support by Boris Tobotras <boris@xtalk.msk.su>
   - kmod support by: Cyrus Durgin
   - RAID0 bugfixes: Mark Anthony Lisher <markal@iname.com>
   - Devfs support by Richard Gooch <rgooch@atnf.csiro.au>

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

     Neil Brown <neilb@cse.unsw.edu.au>.

   - 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/module.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/linkage.h>
#include <linux/raid/md.h>
#include <linux/raid/bitmap.h>
#include <linux/sysctl.h>
#include <linux/buffer_head.h> /* for invalidate_bdev */
#include <linux/poll.h>
#include <linux/mutex.h>
#include <linux/ctype.h>
#include <linux/freezer.h>

#include <linux/init.h>

#include <linux/file.h>

#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif

#include <asm/unaligned.h>

#define MAJOR_NR MD_MAJOR
#define MD_DRIVER

/* 63 partitions with the alternate major number (mdp) */
#define MdpMinorShift 6

#define DEBUG 0
#define dprintk(x...) ((void)(DEBUG && printk(x)))


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

static LIST_HEAD(pers_list);
static DEFINE_SPINLOCK(pers_lock);

static void md_print_devices(void);

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

/*
 * 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(mddev_t *mddev)
{
        return mddev->sync_speed_min ?
                mddev->sync_speed_min : sysctl_speed_limit_min;
}

static inline int speed_max(mddev_t *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[] = {
        {
                .ctl_name       = DEV_RAID_SPEED_LIMIT_MIN,
                .procname       = "speed_limit_min",
                .data           = &sysctl_speed_limit_min,
                .maxlen         = sizeof(int),
                .mode           = S_IRUGO|S_IWUSR,
                .proc_handler   = &proc_dointvec,
        },
        {
                .ctl_name       = DEV_RAID_SPEED_LIMIT_MAX,
                .procname       = "speed_limit_max",
                .data           = &sysctl_speed_limit_max,
                .maxlen         = sizeof(int),
                .mode           = S_IRUGO|S_IWUSR,
                .proc_handler   = &proc_dointvec,
        },
        { .ctl_name = 0 }
};

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

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

static struct block_device_operations md_fops;

static int start_readonly;

/*
 * 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(mddev_t *mddev)
{
        atomic_inc(&md_event_count);
        wake_up(&md_event_waiters);
        sysfs_notify(&mddev->kobj, NULL, "sync_action");
}
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(mddev_t *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 ITERATE_MDDEV(mddev,tmp)                                        \
                                                                        \
        for (({ spin_lock(&all_mddevs_lock);                            \
                tmp = all_mddevs.next;                                  \
                mddev = NULL;});                                        \
             ({ if (tmp != &all_mddevs)                                 \
                        mddev_get(list_entry(tmp, mddev_t, all_mddevs));\
                spin_unlock(&all_mddevs_lock);                          \
                if (mddev) mddev_put(mddev);                            \
                mddev = list_entry(tmp, mddev_t, all_mddevs);           \
                tmp != &all_mddevs;});                                  \
             ({ spin_lock(&all_mddevs_lock);                            \
                tmp = tmp->next;})                                      \
                )


static int md_fail_request (struct request_queue *q, struct bio *bio)
{
        bio_io_error(bio);
        return 0;
}

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

static void mddev_put(mddev_t *mddev)
{
        if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
                return;
        if (!mddev->raid_disks && list_empty(&mddev->disks)) {
                list_del(&mddev->all_mddevs);
                spin_unlock(&all_mddevs_lock);
                blk_cleanup_queue(mddev->queue);
                kobject_unregister(&mddev->kobj);
        } else
                spin_unlock(&all_mddevs_lock);
}

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

 retry:
        spin_lock(&all_mddevs_lock);
        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);
                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;

        mutex_init(&new->reconfig_mutex);
        INIT_LIST_HEAD(&new->disks);
        INIT_LIST_HEAD(&new->all_mddevs);
        init_timer(&new->safemode_timer);
        atomic_set(&new->active, 1);
        spin_lock_init(&new->write_lock);
        init_waitqueue_head(&new->sb_wait);
        new->reshape_position = MaxSector;

        new->queue = blk_alloc_queue(GFP_KERNEL);
        if (!new->queue) {
                kfree(new);
                return NULL;
        }
        set_bit(QUEUE_FLAG_CLUSTER, &new->queue->queue_flags);

        blk_queue_make_request(new->queue, md_fail_request);

        goto retry;
}

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

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

static inline void mddev_unlock(mddev_t * mddev)
{
        mutex_unlock(&mddev->reconfig_mutex);

        md_wakeup_thread(mddev->thread);
}

static mdk_rdev_t * find_rdev_nr(mddev_t *mddev, int nr)
{
        mdk_rdev_t * rdev;
        struct list_head *tmp;

        ITERATE_RDEV(mddev,rdev,tmp) {
                if (rdev->desc_nr == nr)
                        return rdev;
        }
        return NULL;
}

static mdk_rdev_t * find_rdev(mddev_t * mddev, dev_t dev)
{
        struct list_head *tmp;
        mdk_rdev_t *rdev;

        ITERATE_RDEV(mddev,rdev,tmp) {
                if (rdev->bdev->bd_dev == dev)
                        return rdev;
        }
        return NULL;
}

static struct mdk_personality *find_pers(int level, char *clevel)
{
        struct mdk_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;
}

static inline sector_t calc_dev_sboffset(struct block_device *bdev)
{
        sector_t size = bdev->bd_inode->i_size >> BLOCK_SIZE_BITS;
        return MD_NEW_SIZE_BLOCKS(size);
}

static sector_t calc_dev_size(mdk_rdev_t *rdev, unsigned chunk_size)
{
        sector_t size;

        size = rdev->sb_offset;

        if (chunk_size)
                size &= ~((sector_t)chunk_size/1024 - 1);
        return size;
}

static int alloc_disk_sb(mdk_rdev_t * 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 -EINVAL;
        }

        return 0;
}

static void free_disk_sb(mdk_rdev_t * rdev)
{
        if (rdev->sb_page) {
                put_page(rdev->sb_page);
                rdev->sb_loaded = 0;
                rdev->sb_page = NULL;
                rdev->sb_offset = 0;
                rdev->size = 0;
        }
}


static void super_written(struct bio *bio, int error)
{
        mdk_rdev_t *rdev = bio->bi_private;
        mddev_t *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);
}

static void super_written_barrier(struct bio *bio, int error)
{
        struct bio *bio2 = bio->bi_private;
        mdk_rdev_t *rdev = bio2->bi_private;
        mddev_t *mddev = rdev->mddev;

        if (!test_bit(BIO_UPTODATE, &bio->bi_flags) &&
            error == -EOPNOTSUPP) {
                unsigned long flags;
                /* barriers don't appear to be supported :-( */
                set_bit(BarriersNotsupp, &rdev->flags);
                mddev->barriers_work = 0;
                spin_lock_irqsave(&mddev->write_lock, flags);
                bio2->bi_next = mddev->biolist;
                mddev->biolist = bio2;
                spin_unlock_irqrestore(&mddev->write_lock, flags);
                wake_up(&mddev->sb_wait);
                bio_put(bio);
        } else {
                bio_put(bio2);
                bio->bi_private = rdev;
                super_written(bio, error);
        }
}

void md_super_write(mddev_t *mddev, mdk_rdev_t *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
         *
         * As we might need to resubmit the request if BIO_RW_BARRIER
         * causes ENOTSUPP, we allocate a spare bio...
         */
        struct bio *bio = bio_alloc(GFP_NOIO, 1);
        int rw = (1<<BIO_RW) | (1<<BIO_RW_SYNC);

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

        atomic_inc(&mddev->pending_writes);
        if (!test_bit(BarriersNotsupp, &rdev->flags)) {
                struct bio *rbio;
                rw |= (1<<BIO_RW_BARRIER);
                rbio = bio_clone(bio, GFP_NOIO);
                rbio->bi_private = bio;
                rbio->bi_end_io = super_written_barrier;
                submit_bio(rw, rbio);
        } else
                submit_bio(rw, bio);
}

void md_super_wait(mddev_t *mddev)
{
        /* wait for all superblock writes that were scheduled to complete.
         * if any had to be retried (due to BARRIER problems), retry them
         */
        DEFINE_WAIT(wq);
        for(;;) {
                prepare_to_wait(&mddev->sb_wait, &wq, TASK_UNINTERRUPTIBLE);
                if (atomic_read(&mddev->pending_writes)==0)
                        break;
                while (mddev->biolist) {
                        struct bio *bio;
                        spin_lock_irq(&mddev->write_lock);
                        bio = mddev->biolist;
                        mddev->biolist = bio->bi_next ;
                        bio->bi_next = NULL;
                        spin_unlock_irq(&mddev->write_lock);
                        submit_bio(bio->bi_rw, bio);
                }
                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 block_device *bdev, sector_t sector, int size,
                   struct page *page, int rw)
{
        struct bio *bio = bio_alloc(GFP_NOIO, 1);
        struct completion event;
        int ret;

        rw |= (1 << BIO_RW_SYNC);

        bio->bi_bdev = bdev;
        bio->bi_sector = sector;
        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(mdk_rdev_t * 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->bdev, rdev->sb_offset<<1, size, rdev->sb_page, READ))
                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)
{
        if (    (sb1->set_uuid0 == sb2->set_uuid0) &&
                (sb1->set_uuid1 == sb2->set_uuid1) &&
                (sb1->set_uuid2 == sb2->set_uuid2) &&
                (sb1->set_uuid3 == sb2->set_uuid3))

                return 1;

        return 0;
}


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: sb1 is not equal to sb2!\n");
                goto abort;
        }

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

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

        if (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4))
                ret = 0;
        else
                ret = 1;

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(mdk_rdev_t *dev, mdk_rdev_t *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(mddev_t *mddev, mdk_rdev_t *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(mddev_t *mddev, mdk_rdev_t *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)(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version);
        int             (*validate_super)(mddev_t *mddev, mdk_rdev_t *rdev);
        void            (*sync_super)(mddev_t *mddev, mdk_rdev_t *rdev);
};

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

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

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

        ret = -EINVAL;

        bdevname(rdev->bdev, b);
        sb = (mdp_super_t*)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->sb_size = MD_SB_BYTES;

        if (sb->state & (1<<MD_SB_BITMAP_PRESENT)) {
                if (sb->level != 1 && sb->level != 4
                    && sb->level != 5 && sb->level != 6
                    && sb->level != 10) {
                        /* FIXME use a better test */
                        printk(KERN_WARNING
                               "md: bitmaps not supported for this level.\n");
                        goto abort;
                }
        }

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

        if (refdev == 0)
                ret = 1;
        else {
                __u64 ev1, ev2;
                mdp_super_t *refsb = (mdp_super_t*)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->size = calc_dev_size(rdev, sb->chunk_size);

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

 abort:
        return ret;
}

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

        rdev->raid_disk = -1;
        rdev->flags = 0;
        if (mddev->raid_disks == 0) {
                mddev->major_version = 0;
                mddev->minor_version = sb->minor_version;
                mddev->patch_version = sb->patch_version;
                mddev->persistent = ! sb->not_persistent;
                mddev->chunk_size = sb->chunk_size;
                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->size = sb->size;
                mddev->events = ev1;
                mddev->bitmap_offset = 0;
                mddev->default_bitmap_offset = MD_SB_BYTES >> 9;

                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 = sb->new_chunk;
                } else {
                        mddev->reshape_position = MaxSector;
                        mddev->delta_disks = 0;
                        mddev->new_level = mddev->level;
                        mddev->new_layout = mddev->layout;
                        mddev->new_chunk = mddev->chunk_size;
                }

                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_file == NULL)
                        mddev->bitmap_offset = mddev->default_bitmap_offset;

        } else if (mddev->pers == NULL) {
                /* Insist on good event counter while assembling */
                ++ev1;
                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;
                }
                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(mddev_t *mddev, mdk_rdev_t *rdev)
{
        mdp_super_t *sb;
        struct list_head *tmp;
        mdk_rdev_t *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 = (mdp_super_t*)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->size;
        sb->raid_disks = mddev->raid_disks;
        sb->md_minor = mddev->md_minor;
        sb->not_persistent = !mddev->persistent;
        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;
        }
        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_size;

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

        sb->disks[0].state = (1<<MD_DISK_REMOVED);
        ITERATE_RDEV(mddev,rdev2,tmp) {
                mdp_disk_t *d;
                int desc_nr;
                if (rdev2->raid_disk >= 0 && test_bit(In_sync, &rdev2->flags)
                    && !test_bit(Faulty, &rdev2->flags))
                        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 (rdev2->raid_disk >= 0 && test_bit(In_sync, &rdev2->flags)
                    && !test_bit(Faulty, &rdev2->flags))
                        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 (test_bit(In_sync, &rdev2->flags)) {
                        d->state = (1<<MD_DISK_ACTIVE);
                        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);
}

/*
 * 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 super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
{
        struct mdp_superblock_1 *sb;
        int ret;
        sector_t sb_offset;
        char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
        int bmask;

        /*
         * Calculate the position of the superblock.
         * 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_offset = rdev->bdev->bd_inode->i_size >> 9;
                sb_offset -= 8*2;
                sb_offset &= ~(sector_t)(4*2-1);
                /* convert from sectors to K */
                sb_offset /= 2;
                break;
        case 1:
                sb_offset = 0;
                break;
        case 2:
                sb_offset = 4;
                break;
        default:
                return -EINVAL;
        }
        rdev->sb_offset = sb_offset;

        /* 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 = (struct mdp_superblock_1*)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_offset<<1) ||
            (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 ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BITMAP_OFFSET)) {
                if (sb->level != cpu_to_le32(1) &&
                    sb->level != cpu_to_le32(4) &&
                    sb->level != cpu_to_le32(5) &&
                    sb->level != cpu_to_le32(6) &&
                    sb->level != cpu_to_le32(10)) {
                        printk(KERN_WARNING
                               "md: bitmaps not supported for this level.\n");
                        return -EINVAL;
                }
        }

        rdev->preferred_minor = 0xffff;
        rdev->data_offset = le64_to_cpu(sb->data_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_hardsect_size(rdev->bdev->bd_disk->queue)-1;
        if (rdev->sb_size & bmask)
                rdev-> sb_size = (rdev->sb_size | bmask)+1;

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

        if (refdev == 0)
                ret = 1;
        else {
                __u64 ev1, ev2;
                struct mdp_superblock_1 *refsb = 
                        (struct mdp_superblock_1*)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) 
                rdev->size = ((rdev->bdev->bd_inode->i_size>>9) - le64_to_cpu(sb->data_offset)) / 2;
        else
                rdev->size = rdev->sb_offset;
        if (rdev->size < le64_to_cpu(sb->data_size)/2)
                return -EINVAL;
        rdev->size = le64_to_cpu(sb->data_size)/2;
        if (le32_to_cpu(sb->chunksize))
                rdev->size &= ~((sector_t)le32_to_cpu(sb->chunksize)/2 - 1);

        if (le64_to_cpu(sb->size) > rdev->size*2)
                return -EINVAL;
        return ret;
}

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

        rdev->raid_disk = -1;
        rdev->flags = 0;
        if (mddev->raid_disks == 0) {
                mddev->major_version = 1;
                mddev->patch_version = 0;
                mddev->persistent = 1;
                mddev->chunk_size = le32_to_cpu(sb->chunksize) << 9;
                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->size = le64_to_cpu(sb->size)/2;
                mddev->events = ev1;
                mddev->bitmap_offset = 0;
                mddev->default_bitmap_offset = 1024 >> 9;
                
                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_file == NULL )
                        mddev->bitmap_offset = (__s32)le32_to_cpu(sb->bitmap_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 = le32_to_cpu(sb->new_chunk)<<9;
                } else {
                        mddev->reshape_position = MaxSector;
                        mddev->delta_disks = 0;
                        mddev->new_level = mddev->level;
                        mddev->new_layout = mddev->layout;
                        mddev->new_chunk = mddev->chunk_size;
                }

        } else if (mddev->pers == NULL) {
                /* Insist of good event counter while assembling */
                ++ev1;
                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;
                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);
        } else /* MULTIPATH are always insync */
                set_bit(In_sync, &rdev->flags);

        return 0;
}

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

        sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);

        sb->feature_map = 0;
        sb->pad0 = 0;
        sb->recovery_offset = cpu_to_le64(0);
        memset(sb->pad1, 0, sizeof(sb->pad1));
        memset(sb->pad2, 0, sizeof(sb->pad2));
        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->size<<1);

        if (mddev->bitmap && mddev->bitmap_file == NULL) {
                sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_offset);
                sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
        }

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

        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>>9);
        }

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

        if (max_dev > le32_to_cpu(sb->max_dev))
                sb->max_dev = cpu_to_le32(max_dev);
        for (i=0; i<max_dev;i++)
                sb->dev_roles[i] = cpu_to_le16(0xfffe);
        
        ITERATE_RDEV(mddev,rdev2,tmp) {
                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 && rdev2->recovery_offset > 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 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,
        },
        [1] = {
                .name   = "md-1",
                .owner  = THIS_MODULE,
                .load_super     = super_1_load,
                .validate_super = super_1_validate,
                .sync_super     = super_1_sync,
        },
};

static int match_mddev_units(mddev_t *mddev1, mddev_t *mddev2)
{
        struct list_head *tmp, *tmp2;
        mdk_rdev_t *rdev, *rdev2;

        ITERATE_RDEV(mddev1,rdev,tmp)
                ITERATE_RDEV(mddev2, rdev2, tmp2)
                        if (rdev->bdev->bd_contains ==
                            rdev2->bdev->bd_contains)
                                return 1;

        return 0;
}

static LIST_HEAD(pending_raid_disks);

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

        if (rdev->mddev) {
                MD_BUG();
                return -EINVAL;
        }
        /* make sure rdev->size exceeds mddev->size */
        if (rdev->size && (mddev->size == 0 || rdev->size < mddev->size)) {
                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->size = rdev->size;
        }

        /* 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;
        }
        bdevname(rdev->bdev,b);
        if (kobject_set_name(&rdev->kobj, "dev-%s", b) < 0)
                return -ENOMEM;
        while ( (s=strchr(rdev->kobj.k_name, '/')) != NULL)
                *s = '!';
                        
        rdev->mddev = mddev;
        printk(KERN_INFO "md: bind<%s>\n", b);

        rdev->kobj.parent = &mddev->kobj;
        if ((err = kobject_add(&rdev->kobj)))
                goto fail;

        if (rdev->bdev->bd_part)
                ko = &rdev->bdev->bd_part->kobj;
        else
                ko = &rdev->bdev->bd_disk->kobj;
        if ((err = sysfs_create_link(&rdev->kobj, ko, "block"))) {
                kobject_del(&rdev->kobj);
                goto fail;
        }
        list_add(&rdev->same_set, &mddev->disks);
        bd_claim_by_disk(rdev->bdev, rdev, mddev->gendisk);
        return 0;

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

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

static void unbind_rdev_from_array(mdk_rdev_t * rdev)
{
        char b[BDEVNAME_SIZE];
        if (!rdev->mddev) {
                MD_BUG();
                return;
        }
        bd_release_from_disk(rdev->bdev, rdev->mddev->gendisk);
        list_del_init(&rdev->same_set);
        printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
        rdev->mddev = NULL;
        sysfs_remove_link(&rdev->kobj, "block");

        /* We need to delay this, otherwise we can deadlock when
         * writing to 'remove' to "dev/state"
         */
        INIT_WORK(&rdev->del_work, delayed_delete);
        schedule_work(&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(mdk_rdev_t *rdev, dev_t dev)
{
        int err = 0;
        struct block_device *bdev;
        char b[BDEVNAME_SIZE];

        bdev = open_by_devnum(dev, FMODE_READ|FMODE_WRITE);
        if (IS_ERR(bdev)) {
                printk(KERN_ERR "md: could not open %s.\n",
                        __bdevname(dev, b));
                return PTR_ERR(bdev);
        }
        err = bd_claim(bdev, rdev);
        if (err) {
                printk(KERN_ERR "md: could not bd_claim %s.\n",
                        bdevname(bdev, b));
                blkdev_put(bdev);
                return err;
        }
        rdev->bdev = bdev;
        return err;
}

static void unlock_rdev(mdk_rdev_t *rdev)
{
        struct block_device *bdev = rdev->bdev;
        rdev->bdev = NULL;
        if (!bdev)
                MD_BUG();
        bd_release(bdev);
        blkdev_put(bdev);
}

void md_autodetect_dev(dev_t dev);

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

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

static void export_array(mddev_t *mddev)
{
        struct list_head *tmp;
        mdk_rdev_t *rdev;

        ITERATE_RDEV(mddev,rdev,tmp) {
                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(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_rdev(mdk_rdev_t *rdev)
{
        char b[BDEVNAME_SIZE];
        printk(KERN_INFO "md: rdev %s, SZ:%08llu F:%d S:%d DN:%u\n",
                bdevname(rdev->bdev,b), (unsigned long long)rdev->size,
                test_bit(Faulty, &rdev->flags), test_bit(In_sync, &rdev->flags),
                rdev->desc_nr);
        if (rdev->sb_loaded) {
                printk(KERN_INFO "md: rdev superblock:\n");
                print_sb((mdp_super_t*)page_address(rdev->sb_page));
        } else
                printk(KERN_INFO "md: no rdev superblock!\n");
}

static void md_print_devices(void)
{
        struct list_head *tmp, *tmp2;
        mdk_rdev_t *rdev;
        mddev_t *mddev;
        char b[BDEVNAME_SIZE];

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

                if (mddev->bitmap)
                        bitmap_print_sb(mddev->bitmap);
                else
                        printk("%s: ", mdname(mddev));
                ITERATE_RDEV(mddev,rdev,tmp2)
                        printk("<%s>", bdevname(rdev->bdev,b));
                printk("\n");

                ITERATE_RDEV(mddev,rdev,tmp2)
                        print_rdev(rdev);
        }
        printk("md:     **********************************\n");
        printk("\n");
}


static void sync_sbs(mddev_t * 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)
         */
        mdk_rdev_t *rdev;
        struct list_head *tmp;

        ITERATE_RDEV(mddev,rdev,tmp) {
                if (rdev->sb_events == mddev->events ||
                    (nospares &&
                     rdev->raid_disk < 0 &&
                     (rdev->sb_events&1)==0 &&
                     rdev->sb_events+1 == mddev->events)) {
                        /* Don't update this superblock */
                        rdev->sb_loaded = 2;
                } else {
                        super_types[mddev->major_version].
                                sync_super(mddev, rdev);
                        rdev->sb_loaded = 1;
                }
        }
}

static void md_update_sb(mddev_t * mddev, int force_change)
{
        struct list_head *tmp;
        mdk_rdev_t *rdev;
        int sync_req;
        int nospares = 0;

repeat:
        spin_lock_irq(&mddev->write_lock);

        set_bit(MD_CHANGE_PENDING, &mddev->flags);
        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;
        mddev->utime = get_seconds();

        /* 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->events & 1)
            && mddev->events != 1)
                mddev->events--;
        else {
                /* otherwise we have to go forward and ... */
                mddev->events ++;
                if (!mddev->in_sync || mddev->recovery_cp != MaxSector) { /* not clean */
                        /* .. if the array isn't clean, insist on an odd 'events' */
                        if ((mddev->events&1)==0) {
                                mddev->events++;
                                nospares = 0;
                        }
                } else {
                        /* otherwise insist on an even 'events' (for clean states) */
                        if ((mddev->events&1)) {
                                mddev->events++;
                                nospares = 0;
                        }
                }
        }

        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 --;
        }
        sync_sbs(mddev, nospares);

        /*
         * do not write anything to disk if using
         * nonpersistent superblocks
         */
        if (!mddev->persistent) {
                clear_bit(MD_CHANGE_PENDING, &mddev->flags);
                spin_unlock_irq(&mddev->write_lock);
                wake_up(&mddev->sb_wait);
                return;
        }
        spin_unlock_irq(&mddev->write_lock);

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

        bitmap_update_sb(mddev->bitmap);
        ITERATE_RDEV(mddev,rdev,tmp) {
                char b[BDEVNAME_SIZE];
                dprintk(KERN_INFO "md: ");
                if (rdev->sb_loaded != 1)
                        continue; /* no noise on spare devices */
                if (test_bit(Faulty, &rdev->flags))
                        dprintk("(skipping faulty ");

                dprintk("%s ", bdevname(rdev->bdev,b));
                if (!test_bit(Faulty, &rdev->flags)) {
                        md_super_write(mddev,rdev,
                                       rdev->sb_offset<<1, rdev->sb_size,
                                       rdev->sb_page);
                        dprintk(KERN_INFO "(write) %s's sb offset: %llu\n",
                                bdevname(rdev->bdev,b),
                                (unsigned long long)rdev->sb_offset);
                        rdev->sb_events = mddev->events;

                } else
                        dprintk(")\n");
                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);

}

/* words written to sysfs files may, or my 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)(mdk_rdev_t *, char *);
        ssize_t (*store)(mdk_rdev_t *, const char *, size_t);
};

static ssize_t
state_show(mdk_rdev_t *rdev, char *page)
{
        char *sep = "";
        int len=0;

        if (test_bit(Faulty, &rdev->flags)) {
                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(Faulty, &rdev->flags) &&
            !test_bit(In_sync, &rdev->flags)) {
                len += sprintf(page+len, "%sspare", sep);
                sep = ",";
        }
        return len+sprintf(page+len, "\n");
}

static ssize_t
state_store(mdk_rdev_t *rdev, const char *buf, size_t len)
{
        /* can write
         *  faulty  - simulates and error
         *  remove  - disconnects the device
         *  writemostly - sets write_mostly
         *  -writemostly - clears write_mostly
         */
        int err = -EINVAL;
        if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
                md_error(rdev->mddev, rdev);
                err = 0;
        } else if (cmd_match(buf, "remove")) {
                if (rdev->raid_disk >= 0)
                        err = -EBUSY;
                else {
                        mddev_t *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;
        }
        return err ? err : len;
}
static struct rdev_sysfs_entry rdev_state =
__ATTR(state, S_IRUGO|S_IWUSR, state_show, state_store);

static ssize_t
super_show(mdk_rdev_t *rdev, char *page)
{
        if (rdev->sb_loaded && rdev->sb_size) {
                memcpy(page, page_address(rdev->sb_page), rdev->sb_size);
                return rdev->sb_size;
        } else
                return 0;
}
static struct rdev_sysfs_entry rdev_super = __ATTR_RO(super);

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

static ssize_t
errors_store(mdk_rdev_t *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(mdk_rdev_t *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(mdk_rdev_t *rdev, const char *buf, size_t len)
{
        char *e;
        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)
                /* Cannot set slot in active array (yet) */
                return -EBUSY;
        if (slot >= rdev->mddev->raid_disks)
                return -ENOSPC;
        rdev->raid_disk = slot;
        /* assume it is working */
        rdev->flags = 0;
        set_bit(In_sync, &rdev->flags);
        return len;
}


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

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

static ssize_t
offset_store(mdk_rdev_t *rdev, const char *buf, size_t len)
{
        char *e;
        unsigned long long offset = simple_strtoull(buf, &e, 10);
        if (e==buf || (*e && *e != '\n'))
                return -EINVAL;
        if (rdev->mddev->pers)
                return -EBUSY;
        rdev->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
rdev_size_show(mdk_rdev_t *rdev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)rdev->size);
}

static ssize_t
rdev_size_store(mdk_rdev_t *rdev, const char *buf, size_t len)
{
        char *e;
        unsigned long long size = simple_strtoull(buf, &e, 10);
        if (e==buf || (*e && *e != '\n'))
                return -EINVAL;
        if (rdev->mddev->pers)
                return -EBUSY;
        rdev->size = size;
        if (size < rdev->mddev->size || rdev->mddev->size == 0)
                rdev->mddev->size = size;
        return len;
}

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

static struct attribute *rdev_default_attrs[] = {
        &rdev_state.attr,
        &rdev_super.attr,
        &rdev_errors.attr,
        &rdev_slot.attr,
        &rdev_offset.attr,
        &rdev_size.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);
        mdk_rdev_t *rdev = container_of(kobj, mdk_rdev_t, kobj);

        if (!entry->show)
                return -EIO;
        return entry->show(rdev, page);
}

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);
        mdk_rdev_t *rdev = container_of(kobj, mdk_rdev_t, kobj);

        if (!entry->store)
                return -EIO;
        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;
        return entry->store(rdev, page, length);
}

static void rdev_free(struct kobject *ko)
{
        mdk_rdev_t *rdev = container_of(ko, mdk_rdev_t, kobj);
        kfree(rdev);
}
static 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,
};

/*
 * 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 mdk_rdev_t *md_import_device(dev_t newdev, int super_format, int super_minor)
{
        char b[BDEVNAME_SIZE];
        int err;
        mdk_rdev_t *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);
        }

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

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

        rdev->kobj.parent = NULL;
        rdev->kobj.ktype = &rdev_ktype;
        kobject_init(&rdev->kobj);

        rdev->desc_nr = -1;
        rdev->saved_raid_disk = -1;
        rdev->raid_disk = -1;
        rdev->flags = 0;
        rdev->data_offset = 0;
        rdev->sb_events = 0;
        atomic_set(&rdev->nr_pending, 0);
        atomic_set(&rdev->read_errors, 0);
        atomic_set(&rdev->corrected_errors, 0);

        size = rdev->bdev->bd_inode->i_size >> 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;
                }
        }
        INIT_LIST_HEAD(&rdev->same_set);

        return rdev;

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

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


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

        freshest = NULL;
        ITERATE_RDEV(mddev,rdev,tmp)
                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;
        ITERATE_RDEV(mddev,rdev,tmp) {
                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) {
                        rdev->raid_disk = -1;
                        clear_bit(In_sync, &rdev->flags);
                }
        }



        if (mddev->recovery_cp != MaxSector &&
            mddev->level >= 1)
                printk(KERN_ERR "md: %s: raid array is not clean"
                       " -- starting background reconstruction\n",
                       mdname(mddev));

}

static ssize_t
safe_delay_show(mddev_t *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(mddev_t *mddev, const char *cbuf, size_t len)
{
        int scale=1;
        int dot=0;
        int i;
        unsigned long msec;
        char buf[30];
        char *e;
        /* remove a period, and count digits after it */
        if (len >= sizeof(buf))
                return -EINVAL;
        strlcpy(buf, cbuf, len);
        buf[len] = 0;
        for (i=0; i<len; i++) {
                if (dot) {
                        if (isdigit(buf[i])) {
                                buf[i-1] = buf[i];
                                scale *= 10;
                        }
                        buf[i] = 0;
                } else if (buf[i] == '.') {
                        dot=1;
                        buf[i] = 0;
                }
        }
        msec = simple_strtoul(buf, &e, 10);
        if (e == buf || (*e && *e != '\n'))
                return -EINVAL;
        msec = (msec * 1000) / scale;
        if (msec == 0)
                mddev->safemode_delay = 0;
        else {
                mddev->safemode_delay = (msec*HZ)/1000;
                if (mddev->safemode_delay == 0)
                        mddev->safemode_delay = 1;
        }
        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(mddev_t *mddev, char *page)
{
        struct mdk_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(mddev_t *mddev, const char *buf, size_t len)
{
        int rv = len;
        if (mddev->pers)
                return -EBUSY;
        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;
}

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


static ssize_t
layout_show(mddev_t *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(mddev_t *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)
                return -EBUSY;
        if (mddev->reshape_position != MaxSector)
                mddev->new_layout = n;
        else
                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(mddev_t *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(mddev_t *mddev, int raid_disks);

static ssize_t
raid_disks_store(mddev_t *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) {
                int olddisks = mddev->raid_disks - mddev->delta_disks;
                mddev->delta_disks = n - olddisks;
                mddev->raid_disks = n;
        } 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(mddev_t *mddev, char *page)
{
        if (mddev->reshape_position != MaxSector &&
            mddev->chunk_size != mddev->new_chunk)
                return sprintf(page, "%d (%d)\n", mddev->new_chunk,
                               mddev->chunk_size);
        return sprintf(page, "%d\n", mddev->chunk_size);
}

static ssize_t
chunk_size_store(mddev_t *mddev, const char *buf, size_t len)
{
        /* can only set chunk_size if array is not yet active */
        char *e;
        unsigned long n = simple_strtoul(buf, &e, 10);

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

        if (mddev->pers)
                return -EBUSY;
        else if (mddev->reshape_position != MaxSector)
                mddev->new_chunk = n;
        else
                mddev->chunk_size = n;
        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(mddev_t *mddev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)mddev->recovery_cp);
}

static ssize_t
resync_start_store(mddev_t *mddev, const char *buf, size_t len)
{
        /* can only set chunk_size if array is not yet active */
        char *e;
        unsigned long long n = simple_strtoull(buf, &e, 10);

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

        mddev->recovery_cp = n;
        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 quiessent
 * 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(mddev_t *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 (mddev->safemode)
                                st = active_idle;
                        else
                                st = active;
                }
        else {
                if (list_empty(&mddev->disks) &&
                    mddev->raid_disks == 0 &&
                    mddev->size == 0)
                        st = clear;
                else
                        st = inactive;
        }
        return sprintf(page, "%s\n", array_states[st]);
}

static int do_md_stop(mddev_t * mddev, int ro);
static int do_md_run(mddev_t * mddev);
static int restart_array(mddev_t *mddev);

static ssize_t
array_state_store(mddev_t *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 */
                if (mddev->pers) {
                        if (atomic_read(&mddev->active) > 1)
                                return -EBUSY;
                        err = do_md_stop(mddev, 0);
                }
                break;
        case inactive:
                /* stopping an active array */
                if (mddev->pers) {
                        if (atomic_read(&mddev->active) > 1)
                                return -EBUSY;
                        err = do_md_stop(mddev, 2);
                }
                break;
        case suspended:
                break; /* not supported yet */
        case readonly:
                if (mddev->pers)
                        err = do_md_stop(mddev, 1);
                else {
                        mddev->ro = 1;
                        err = do_md_run(mddev);
                }
                break;
        case read_auto:
                /* stopping an active array */
                if (mddev->pers) {
                        err = do_md_stop(mddev, 1);
                        if (err == 0)
                                mddev->ro = 2; /* FIXME mark devices writable */
                } 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) {
                                mddev->in_sync = 1;
                                set_bit(MD_CHANGE_CLEAN, &mddev->flags);
                        }
                        spin_unlock_irq(&mddev->write_lock);
                } else {
                        mddev->ro = 0;
                        mddev->recovery_cp = MaxSector;
                        err = do_md_run(mddev);
                }
                break;
        case active:
                if (mddev->pers) {
                        restart_array(mddev);
                        clear_bit(MD_CHANGE_CLEAN, &mddev->flags);
                        wake_up(&mddev->sb_wait);
                        err = 0;
                } else {
                        mddev->ro = 0;
                        err = do_md_run(mddev);
                }
                break;
        case write_pending:
        case active_idle:
                /* these cannot be set */
                break;
        }
        if (err)
                return err;
        else
                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
null_show(mddev_t *mddev, char *page)
{
        return -EINVAL;
}

static ssize_t
new_dev_store(mddev_t *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;
        mdk_rdev_t *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)) {
                        mdk_rdev_t *rdev0 = list_entry(mddev->disks.next,
                                                       mdk_rdev_t, same_set);
                        err = super_types[mddev->major_version]
                                .load_super(rdev, rdev0, mddev->minor_version);
                        if (err < 0)
                                goto out;
                }
        } 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(mddev_t *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 = end;
                while (isspace(*buf)) buf++;
        }
        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(mddev_t *mddev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)mddev->size);
}

static int update_size(mddev_t *mddev, unsigned long size);

static ssize_t
size_store(mddev_t *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
         */
        char *e;
        int err = 0;
        unsigned long long size = simple_strtoull(buf, &e, 10);
        if (!*buf || *buf == '\n' ||
            (*e && *e != '\n'))
                return -EINVAL;

        if (mddev->pers) {
                err = update_size(mddev, size);
                md_update_sb(mddev, 1);
        } else {
                if (mddev->size == 0 ||
                    mddev->size > size)
                        mddev->size = size;
                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 either 'none' for arrays with externally managed metadata,
 * or N.M for internally known formats
 */
static ssize_t
metadata_show(mddev_t *mddev, char *page)
{
        if (mddev->persistent)
                return sprintf(page, "%d.%d\n",
                               mddev->major_version, mddev->minor_version);
        else
                return sprintf(page, "none\n");
}

static ssize_t
metadata_store(mddev_t *mddev, const char *buf, size_t len)
{
        int major, minor;
        char *e;
        if (!list_empty(&mddev->disks))
                return -EBUSY;

        if (cmd_match(buf, "none")) {
                mddev->persistent = 0;
                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;
        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(mddev_t *mddev, char *page)
{
        char *type = "idle";
        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
            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
                        type = "recover";
        }
        return sprintf(page, "%s\n", type);
}

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

        if (cmd_match(page, "idle")) {
                if (mddev->sync_thread) {
                        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                        md_unregister_thread(mddev->sync_thread);
                        mddev->sync_thread = NULL;
                        mddev->recovery = 0;
                }
        } else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
                   test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
                return -EBUSY;
        else if (cmd_match(page, "resync") || cmd_match(page, "recover"))
                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;
        } 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);
        }
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        return len;
}

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

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

static ssize_t
sync_max_store(mddev_t *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
sync_speed_show(mddev_t *mddev, char *page)
{
        unsigned long resync, dt, db;
        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, "%ld\n", db/dt/2); /* K/sec */
}

static struct md_sysfs_entry md_sync_speed = __ATTR_RO(sync_speed);

static ssize_t
sync_completed_show(mddev_t *mddev, char *page)
{
        unsigned long max_blocks, resync;

        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
                max_blocks = mddev->resync_max_sectors;
        else
                max_blocks = mddev->size << 1;

        resync = (mddev->curr_resync - atomic_read(&mddev->recovery_active));
        return sprintf(page, "%lu / %lu\n", resync, max_blocks);
}

static struct md_sysfs_entry md_sync_completed = __ATTR_RO(sync_completed);

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

static ssize_t
suspend_lo_store(mddev_t *mddev, const char *buf, size_t len)
{
        char *e;
        unsigned long long new = simple_strtoull(buf, &e, 10);

        if (mddev->pers->quiesce == NULL)
                return -EINVAL;
        if (buf == e || (*e && *e != '\n'))
                return -EINVAL;
        if (new >= mddev->suspend_hi ||
            (new > mddev->suspend_lo && new < mddev->suspend_hi)) {
                mddev->suspend_lo = new;
                mddev->pers->quiesce(mddev, 2);
                return len;
        } else
                return -EINVAL;
}
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(mddev_t *mddev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_hi);
}

static ssize_t
suspend_hi_store(mddev_t *mddev, const char *buf, size_t len)
{
        char *e;
        unsigned long long new = simple_strtoull(buf, &e, 10);

        if (mddev->pers->quiesce == NULL)
                return -EINVAL;
        if (buf == e || (*e && *e != '\n'))
                return -EINVAL;
        if ((new <= mddev->suspend_lo && mddev->suspend_lo >= mddev->suspend_hi) ||
            (new > mddev->suspend_lo && new > mddev->suspend_hi)) {
                mddev->suspend_hi = new;
                mddev->pers->quiesce(mddev, 1);
                mddev->pers->quiesce(mddev, 0);
                return len;
        } else
                return -EINVAL;
}
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(mddev_t *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(mddev_t *mddev, const char *buf, size_t len)
{
        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->new_level = mddev->level;
        mddev->new_layout = mddev->layout;
        mddev->new_chunk = mddev->chunk_size;
        return len;
}

static struct md_sysfs_entry md_reshape_position =
__ATTR(reshape_position, S_IRUGO|S_IWUSR, reshape_position_show,
       reshape_position_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,
        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_completed.attr,
        &md_suspend_lo.attr,
        &md_suspend_hi.attr,
        &md_bitmap.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);
        mddev_t *mddev = container_of(kobj, struct mddev_s, kobj);
        ssize_t rv;

        if (!entry->show)
                return -EIO;
        rv = mddev_lock(mddev);
        if (!rv) {
                rv = entry->show(mddev, page);
                mddev_unlock(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);
        mddev_t *mddev = container_of(kobj, struct mddev_s, kobj);
        ssize_t rv;

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

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

static 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 struct kobject *md_probe(dev_t dev, int *part, void *data)
{
        static DEFINE_MUTEX(disks_mutex);
        mddev_t *mddev = mddev_find(dev);
        struct gendisk *disk;
        int partitioned = (MAJOR(dev) != MD_MAJOR);
        int shift = partitioned ? MdpMinorShift : 0;
        int unit = MINOR(dev) >> shift;

        if (!mddev)
                return NULL;

        mutex_lock(&disks_mutex);
        if (mddev->gendisk) {
                mutex_unlock(&disks_mutex);
                mddev_put(mddev);
                return NULL;
        }
        disk = alloc_disk(1 << shift);
        if (!disk) {
                mutex_unlock(&disks_mutex);
                mddev_put(mddev);
                return NULL;
        }
        disk->major = MAJOR(dev);
        disk->first_minor = unit << shift;
        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;
        add_disk(disk);
        mddev->gendisk = disk;
        mutex_unlock(&disks_mutex);
        mddev->kobj.parent = &disk->kobj;
        kobject_set_name(&mddev->kobj, "%s", "md");
        mddev->kobj.ktype = &md_ktype;
        if (kobject_register(&mddev->kobj))
                printk(KERN_WARNING "md: cannot register %s/md - name in use\n",
                       disk->disk_name);
        return NULL;
}

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

        mddev->safemode = 1;
        md_wakeup_thread(mddev->thread);
}

static int start_dirty_degraded;

static int do_md_run(mddev_t * mddev)
{
        int err;
        int chunk_size;
        struct list_head *tmp;
        mdk_rdev_t *rdev;
        struct gendisk *disk;
        struct mdk_personality *pers;
        char b[BDEVNAME_SIZE];

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

        if (mddev->pers)
                return -EBUSY;

        /*
         * Analyze all RAID superblock(s)
         */
        if (!mddev->raid_disks)
                analyze_sbs(mddev);

        chunk_size = mddev->chunk_size;

        if (chunk_size) {
                if (chunk_size > MAX_CHUNK_SIZE) {
                        printk(KERN_ERR "too big chunk_size: %d > %d\n",
                                chunk_size, MAX_CHUNK_SIZE);
                        return -EINVAL;
                }
                /*
                 * chunk-size has to be a power of 2 and multiples of PAGE_SIZE
                 */
                if ( (1 << ffz(~chunk_size)) != chunk_size) {
                        printk(KERN_ERR "chunk_size of %d not valid\n", chunk_size);
                        return -EINVAL;
                }
                if (chunk_size < PAGE_SIZE) {
                        printk(KERN_ERR "too small chunk_size: %d < %ld\n",
                                chunk_size, PAGE_SIZE);
                        return -EINVAL;
                }

                /* devices must have minimum size of one chunk */
                ITERATE_RDEV(mddev,rdev,tmp) {
                        if (test_bit(Faulty, &rdev->flags))
                                continue;
                        if (rdev->size < chunk_size / 1024) {
                                printk(KERN_WARNING
                                        "md: Dev %s smaller than chunk_size:"
                                        " %lluk < %dk\n",
                                        bdevname(rdev->bdev,b),
                                        (unsigned long long)rdev->size,
                                        chunk_size / 1024);
                                return -EINVAL;
                        }
                }
        }

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

        /*
         * Drop all container device buffers, from now on
         * the only valid external interface is through the md
         * device.
         */
        ITERATE_RDEV(mddev,rdev,tmp) {
                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 has handled elsewhere.
                 */
                if (rdev->data_offset < rdev->sb_offset) {
                        if (mddev->size &&
                            rdev->data_offset + mddev->size*2
                            > rdev->sb_offset*2) {
                                printk("md: %s: data overlaps metadata\n",
                                       mdname(mddev));
                                return -EINVAL;
                        }
                } else {
                        if (rdev->sb_offset*2 + rdev->sb_size/512
                            > rdev->data_offset) {
                                printk("md: %s: metadata overlaps data\n",
                                       mdname(mddev));
                                return -EINVAL;
                        }
                }
        }

        md_probe(mddev->unit, NULL, NULL);
        disk = mddev->gendisk;
        if (!disk)
                return -ENOMEM;

        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);
        mddev->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];
                mdk_rdev_t *rdev2;
                struct list_head *tmp2;
                int warned = 0;
                ITERATE_RDEV(mddev, rdev, tmp) {
                        ITERATE_RDEV(mddev, rdev2, tmp2) {
                                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;
        mddev->resync_max_sectors = mddev->size << 1; /* may be over-ridden by personality */
        mddev->barriers_work = 1;
        mddev->ok_start_degraded = start_dirty_degraded;

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

        err = mddev->pers->run(mddev);
        if (!err && mddev->pers->sync_request) {
                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) {
                printk(KERN_ERR "md: pers->run() failed ...\n");
                module_put(mddev->pers->owner);
                mddev->pers = NULL;
                bitmap_destroy(mddev);
                return err;
        }
        if (mddev->pers->sync_request) {
                if (sysfs_create_group(&mddev->kobj, &md_redundancy_group))
                        printk(KERN_WARNING
                               "md: cannot register extra attributes for %s\n",
                               mdname(mddev));
        } else if (mddev->ro == 2) /* auto-readonly not meaningful */
                mddev->ro = 0;

        atomic_set(&mddev->writes_pending,0);
        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;

        ITERATE_RDEV(mddev,rdev,tmp)
                if (rdev->raid_disk >= 0) {
                        char nm[20];
                        sprintf(nm, "rd%d", rdev->raid_disk);
                        if (sysfs_create_link(&mddev->kobj, &rdev->kobj, nm))
                                printk("md: cannot register %s for %s\n",
                                       nm, mdname(mddev));
                }
        
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        
        if (mddev->flags)
                md_update_sb(mddev, 0);

        set_capacity(disk, mddev->array_size<<1);

        /* If we call blk_queue_make_request here, it will
         * re-initialise max_sectors etc which may have been
         * refined inside -> run.  So just set the bits we need to set.
         * Most initialisation happended when we called
         * blk_queue_make_request(..., md_fail_request)
         * earlier.
         */
        mddev->queue->queuedata = mddev;
        mddev->queue->make_request_fn = mddev->pers->make_request;

        /* If there is a partially-recovered drive we need to
         * start recovery here.  If we leave it to md_check_recovery,
         * it will remove the drives and not do the right thing
         */
        if (mddev->degraded && !mddev->sync_thread) {
                struct list_head *rtmp;
                int spares = 0;
                ITERATE_RDEV(mddev,rdev,rtmp)
                        if (rdev->raid_disk >= 0 &&
                            !test_bit(In_sync, &rdev->flags) &&
                            !test_bit(Faulty, &rdev->flags))
                                /* complete an interrupted recovery */
                                spares++;
                if (spares && mddev->pers->sync_request) {
                        mddev->recovery = 0;
                        set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
                        mddev->sync_thread = md_register_thread(md_do_sync,
                                                                mddev,
                                                                "%s_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 */
                                mddev->recovery = 0;
                        }
                }
        }
        md_wakeup_thread(mddev->thread);
        md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */

        mddev->changed = 1;
        md_new_event(mddev);
        kobject_uevent(&mddev->gendisk->kobj, KOBJ_CHANGE);
        return 0;
}

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

        /*
         * Complain if it has no devices
         */
        err = -ENXIO;
        if (list_empty(&mddev->disks))
                goto out;

        if (mddev->pers) {
                err = -EBUSY;
                if (!mddev->ro)
                        goto out;

                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);
                err = 0;
        } else
                err = -EINVAL;

out:
        return err;
}

/* 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;
}

static 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);
}

/* mode:
 *   0 - completely stop and dis-assemble array
 *   1 - switch to readonly
 *   2 - stop but do not disassemble array
 */
static int do_md_stop(mddev_t * mddev, int mode)
{
        int err = 0;
        struct gendisk *disk = mddev->gendisk;

        if (mddev->pers) {
                if (atomic_read(&mddev->active)>2) {
                        printk("md: %s still in use.\n",mdname(mddev));
                        return -EBUSY;
                }

                if (mddev->sync_thread) {
                        set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                        md_unregister_thread(mddev->sync_thread);
                        mddev->sync_thread = NULL;
                }

                del_timer_sync(&mddev->safemode_timer);

                invalidate_partition(disk, 0);

                switch(mode) {
                case 1: /* readonly */
                        err  = -ENXIO;
                        if (mddev->ro==1)
                                goto out;
                        mddev->ro = 1;
                        break;
                case 0: /* disassemble */
                case 2: /* stop */
                        bitmap_flush(mddev);
                        md_super_wait(mddev);
                        if (mddev->ro)
                                set_disk_ro(disk, 0);
                        blk_queue_make_request(mddev->queue, md_fail_request);
                        mddev->pers->stop(mddev);
                        mddev->queue->merge_bvec_fn = NULL;
                        mddev->queue->unplug_fn = NULL;
                        mddev->queue->issue_flush_fn = NULL;
                        mddev->queue->backing_dev_info.congested_fn = NULL;
                        if (mddev->pers->sync_request)
                                sysfs_remove_group(&mddev->kobj, &md_redundancy_group);

                        module_put(mddev->pers->owner);
                        mddev->pers = NULL;

                        set_capacity(disk, 0);
                        mddev->changed = 1;

                        if (mddev->ro)
                                mddev->ro = 0;
                }
                if (!mddev->in_sync || mddev->flags) {
                        /* mark array as shutdown cleanly */
                        mddev->in_sync = 1;
                        md_update_sb(mddev, 1);
                }
                if (mode == 1)
                        set_disk_ro(disk, 1);
                clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
        }

        /*
         * Free resources if final stop
         */
        if (mode == 0) {
                mdk_rdev_t *rdev;
                struct list_head *tmp;

                printk(KERN_INFO "md: %s stopped.\n", mdname(mddev));

                bitmap_destroy(mddev);
                if (mddev->bitmap_file) {
                        restore_bitmap_write_access(mddev->bitmap_file);
                        fput(mddev->bitmap_file);
                        mddev->bitmap_file = NULL;
                }
                mddev->bitmap_offset = 0;

                ITERATE_RDEV(mddev,rdev,tmp)
                        if (rdev->raid_disk >= 0) {
                                char nm[20];
                                sprintf(nm, "rd%d", rdev->raid_disk);
                                sysfs_remove_link(&mddev->kobj, nm);
                        }

                /* make sure all delayed_delete calls have finished */
                flush_scheduled_work();

                export_array(mddev);

                mddev->array_size = 0;
                mddev->size = 0;
                mddev->raid_disks = 0;
                mddev->recovery_cp = 0;
                mddev->reshape_position = MaxSector;

        } else if (mddev->pers)
                printk(KERN_INFO "md: %s switched to read-only mode.\n",
                        mdname(mddev));
        err = 0;
        md_new_event(mddev);
out:
        return err;
}

#ifndef MODULE
static void autorun_array(mddev_t *mddev)
{
        mdk_rdev_t *rdev;
        struct list_head *tmp;
        int err;

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

        printk(KERN_INFO "md: running: ");

        ITERATE_RDEV(mddev,rdev,tmp) {
                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);
        }
}

/*
 * 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 list_head *tmp;
        mdk_rdev_t *rdev0, *rdev;
        mddev_t *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,
                                         mdk_rdev_t, same_set);

                printk(KERN_INFO "md: considering %s ...\n",
                        bdevname(rdev0->bdev,b));
                INIT_LIST_HEAD(&candidates);
                ITERATE_RDEV_PENDING(rdev,tmp)
                        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) {
                        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));
                        ITERATE_RDEV_GENERIC(candidates,rdev,tmp) {
                                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...
                 */
                ITERATE_RDEV_GENERIC(candidates,rdev,tmp)
                        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(mddev_t * mddev, void __user * arg)
{
        mdu_array_info_t info;
        int nr,working,active,failed,spare;
        mdk_rdev_t *rdev;
        struct list_head *tmp;

        nr=working=active=failed=spare=0;
        ITERATE_RDEV(mddev,rdev,tmp) {
                nr++;
                if (test_bit(Faulty, &rdev->flags))
                        failed++;
                else {
                        working++;
                        if (test_bit(In_sync, &rdev->flags))
                                active++;       
                        else
                                spare++;
                }
        }

        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->size;
        if (info.size != mddev->size) /* 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_offset)
                info.state = (1<<MD_SB_BITMAP_PRESENT);
        info.active_disks  = active;
        info.working_disks = working;
        info.failed_disks  = failed;
        info.spare_disks   = spare;

        info.layout        = mddev->layout;
        info.chunk_size    = mddev->chunk_size;

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

        return 0;
}

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

        md_allow_write(mddev);

        file = kmalloc(sizeof(*file), GFP_KERNEL);
        if (!file)
                goto out;

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

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

        ptr = file_path(mddev->bitmap->file, buf, sizeof(file->pathname));
        if (!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(mddev_t * mddev, void __user * arg)
{
        mdu_disk_info_t info;
        unsigned int nr;
        mdk_rdev_t *rdev;

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

        nr = info.number;

        rdev = find_rdev_nr(mddev, nr);
        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);
        }

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

        return 0;
}

static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
{
        char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
        mdk_rdev_t *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)) {
                        mdk_rdev_t *rdev0 = list_entry(mddev->disks.next,
                                                        mdk_rdev_t, same_set);
                        int 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 save_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;
                        else
                                rdev->raid_disk = -1;
                } else
                        super_types[mddev->major_version].
                                validate_super(mddev, rdev);
                rdev->saved_raid_disk = rdev->raid_disk;

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

                md_update_sb(mddev, 1);
                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                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;

                rdev->flags = 0;

                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_offset = rdev->bdev->bd_inode->i_size >> BLOCK_SIZE_BITS;
                } else 
                        rdev->sb_offset = calc_dev_sboffset(rdev->bdev);
                rdev->size = calc_dev_size(rdev, mddev->chunk_size);

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

        return 0;
}

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

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

        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(mddev_t * mddev, dev_t dev)
{
        char b[BDEVNAME_SIZE];
        int err;
        unsigned int size;
        mdk_rdev_t *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_offset = calc_dev_sboffset(rdev->bdev);
        else
                rdev->sb_offset =
                        rdev->bdev->bd_inode->i_size >> BLOCK_SIZE_BITS;

        size = calc_dev_size(rdev, mddev->chunk_size);
        rdev->size = size;

        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 ...
         */

        if (rdev->desc_nr == mddev->max_disks) {
                printk(KERN_WARNING "%s: can not hot-add to full array!\n",
                        mdname(mddev));
                err = -EBUSY;
                goto abort_unbind_export;
        }

        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_unbind_export:
        unbind_rdev_from_array(rdev);

abort_export:
        export_rdev(rdev);
        return err;
}

static int set_bitmap_file(mddev_t *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_file = fget(fd);

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

                err = deny_bitmap_write_access(mddev->bitmap_file);
                if (err) {
                        printk(KERN_ERR "%s: error: bitmap file is already in use\n",
                               mdname(mddev));
                        fput(mddev->bitmap_file);
                        mddev->bitmap_file = NULL;
                        return err;
                }
                mddev->bitmap_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 (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_file) {
                        restore_bitmap_write_access(mddev->bitmap_file);
                        fput(mddev->bitmap_file);
                }
                mddev->bitmap_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(mddev_t * 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;
                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->size          = 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->layout        = info->layout;
        mddev->chunk_size    = info->chunk_size;

        mddev->max_disks     = MD_SB_DISKS;

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

        mddev->default_bitmap_offset = MD_SB_BYTES >> 9;
        mddev->bitmap_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 = mddev->chunk_size;
        mddev->new_layout = mddev->layout;
        mddev->delta_disks = 0;

        return 0;
}

static int update_size(mddev_t *mddev, unsigned long size)
{
        mdk_rdev_t * rdev;
        int rv;
        struct list_head *tmp;
        int fit = (size == 0);

        if (mddev->pers->resize == NULL)
                return -EINVAL;
        /* The "size" is the amount 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 the size if no resync
         * or reconstruction is happening, and if the new size
         * is acceptable. It must fit before the sb_offset or,
         * if that is <data_offset, it must fit before the
         * size of each device.
         * If size is zero, we find the largest size that fits.
         */
        if (mddev->sync_thread)
                return -EBUSY;
        ITERATE_RDEV(mddev,rdev,tmp) {
                sector_t avail;
                avail = rdev->size * 2;

                if (fit && (size == 0 || size > avail/2))
                        size = avail/2;
                if (avail < ((sector_t)size << 1))
                        return -ENOSPC;
        }
        rv = mddev->pers->resize(mddev, (sector_t)size *2);
        if (!rv) {
                struct block_device *bdev;

                bdev = bdget_disk(mddev->gendisk, 0);
                if (bdev) {
                        mutex_lock(&bdev->bd_inode->i_mutex);
                        i_size_write(bdev->bd_inode, (loff_t)mddev->array_size << 10);
                        mutex_unlock(&bdev->bd_inode->i_mutex);
                        bdput(bdev);
                }
        }
        return rv;
}

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

        rv = mddev->pers->check_reshape(mddev);
        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(mddev_t *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_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_size    != info->chunk_size    ||
            /* 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->size != 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->reconfig == NULL)
                        return -EINVAL;
                else
                        return mddev->pers->reconfig(mddev, info->layout, -1);
        }
        if (info->size >= 0 && mddev->size != info->size)
                rv = update_size(mddev, info->size);

        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->default_bitmap_offset == 0)
                                return -EINVAL;
                        mddev->bitmap_offset = mddev->default_bitmap_offset;
                        mddev->pers->quiesce(mddev, 1);
                        rv = bitmap_create(mddev);
                        if (rv)
                                bitmap_destroy(mddev);
                        mddev->pers->quiesce(mddev, 0);
                } else {
                        /* remove the bitmap */
                        if (!mddev->bitmap)
                                return -ENOENT;
                        if (mddev->bitmap->file)
                                return -EINVAL;
                        mddev->pers->quiesce(mddev, 1);
                        bitmap_destroy(mddev);
                        mddev->pers->quiesce(mddev, 0);
                        mddev->bitmap_offset = 0;
                }
        }
        md_update_sb(mddev, 1);
        return rv;
}

static int set_disk_faulty(mddev_t *mddev, dev_t dev)
{
        mdk_rdev_t *rdev;

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

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

        md_error(mddev, rdev);
        return 0;
}

static int md_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
        mddev_t *mddev = bdev->bd_disk->private_data;

        geo->heads = 2;
        geo->sectors = 4;
        geo->cylinders = get_capacity(mddev->gendisk) / 8;
        return 0;
}

static int md_ioctl(struct inode *inode, struct file *file,
                        unsigned int cmd, unsigned long arg)
{
        int err = 0;
        void __user *argp = (void __user *)arg;
        mddev_t *mddev = NULL;

        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 = inode->i_bdev->bd_disk->private_data;

        if (!mddev) {
                BUG();
                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 && 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_ARRAY_INFO:
                        err = get_array_info(mddev, argp);
                        goto done_unlock;

                case GET_BITMAP_FILE:
                        err = get_bitmap_file(mddev, argp);
                        goto done_unlock;

                case GET_DISK_INFO:
                        err = get_disk_info(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);
                        goto done_unlock;

                case STOP_ARRAY_RO:
                        err = do_md_stop (mddev, 1);
                        goto done_unlock;

        /*
         * 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... ;-)
         */
        }

        /*
         * 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;
                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 SET_DISK_FAULTY:
                        err = set_disk_faulty(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:
        mddev_unlock(mddev);

        return err;
done:
        if (err)
                MD_BUG();
abort:
        return err;
}

static int md_open(struct inode *inode, struct file *file)
{
        /*
         * Succeed if we can lock the mddev, which confirms that
         * it isn't being stopped right now.
         */
        mddev_t *mddev = inode->i_bdev->bd_disk->private_data;
        int err;

        if ((err = mutex_lock_interruptible_nested(&mddev->reconfig_mutex, 1)))
                goto out;

        err = 0;
        mddev_get(mddev);
        mddev_unlock(mddev);

        check_disk_change(inode->i_bdev);
 out:
        return err;
}

static int md_release(struct inode *inode, struct file * file)
{
        mddev_t *mddev = inode->i_bdev->bd_disk->private_data;

        BUG_ON(!mddev);
        mddev_put(mddev);

        return 0;
}

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

        return mddev->changed;
}

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

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

static int md_thread(void * arg)
{
        mdk_thread_t *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);

                thread->run(thread->mddev);
        }

        return 0;
}

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

mdk_thread_t *md_register_thread(void (*run) (mddev_t *), mddev_t *mddev,
                                 const char *name)
{
        mdk_thread_t *thread;

        thread = kzalloc(sizeof(mdk_thread_t), 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, name, mdname(thread->mddev));
        if (IS_ERR(thread->tsk)) {
                kfree(thread);
                return NULL;
        }
        return thread;
}

void md_unregister_thread(mdk_thread_t *thread)
{
        dprintk("interrupting MD-thread pid %d\n", thread->tsk->pid);

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

void md_error(mddev_t *mddev, mdk_rdev_t *rdev)
{
        if (!mddev) {
                MD_BUG();
                return;
        }

        if (!rdev || test_bit(Faulty, &rdev->flags))
                return;
/*
        dprintk("md_error dev:%s, rdev:(%d:%d), (caller: %p,%p,%p,%p).\n",
                mdname(mddev),
                MAJOR(rdev->bdev->bd_dev), MINOR(rdev->bdev->bd_dev),
                __builtin_return_address(0),__builtin_return_address(1),
                __builtin_return_address(2),__builtin_return_address(3));
*/
        if (!mddev->pers)
                return;
        if (!mddev->pers->error_handler)
                return;
        mddev->pers->error_handler(mddev,rdev);
        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        md_new_event_inintr(mddev);
}

/* seq_file implementation /proc/mdstat */

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

        seq_printf(seq, "unused devices: ");

        ITERATE_RDEV_PENDING(rdev,tmp) {
                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, mddev_t * mddev)
{
        sector_t max_blocks, resync, res;
        unsigned long dt, db, rt;
        int scale;
        unsigned int per_milli;

        resync = (mddev->curr_resync - atomic_read(&mddev->recovery_active))/2;

        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
                max_blocks = mddev->resync_max_sectors >> 1;
        else
                max_blocks = mddev->size;

        /*
         * Should not happen.
         */
        if (!max_blocks) {
                MD_BUG();
                return;
        }
        /* Pick 'scale' such that (resync>>scale)*1000 will fit
         * in a sector_t, and (max_blocks>>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_blocks/2 > (1ULL<<(scale+32)))
                        scale++;
        }
        res = (resync>>scale)*1000;
        sector_div(res, (u32)((max_blocks>>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,
                   (unsigned long long) max_blocks);

        /*
         * We do not want to overflow, so the order of operands and
         * the * 100 / 100 trick are important. We do a +1 to be
         * safe against division by zero. We only estimate anyway.
         *
         * dt: time from mark until now
         * db: blocks written from mark until now
         * rt: remaining time
         */
        dt = ((jiffies - mddev->resync_mark) / HZ);
        if (!dt) dt++;
        db = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active))
                - mddev->resync_mark_cnt;
        rt = (dt * ((unsigned long)(max_blocks-resync) / (db/2/100+1)))/100;

        seq_printf(seq, " finish=%lu.%lumin", rt / 60, (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;
        mddev_t *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, mddev_t, 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;
        mddev_t *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,mddev_t,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)
{
        mddev_t *mddev = v;

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

struct mdstat_info {
        int event;
};

static int md_seq_show(struct seq_file *seq, void *v)
{
        mddev_t *mddev = v;
        sector_t size;
        struct list_head *tmp2;
        mdk_rdev_t *rdev;
        struct mdstat_info *mi = seq->private;
        struct bitmap *bitmap;

        if (v == (void*)1) {
                struct mdk_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");
                mi->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);
                }

                size = 0;
                ITERATE_RDEV(mddev,rdev,tmp2) {
                        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;
                        } else if (rdev->raid_disk < 0)
                                seq_printf(seq, "(S)"); /* spare */
                        size += rdev->size;
                }

                if (!list_empty(&mddev->disks)) {
                        if (mddev->pers)
                                seq_printf(seq, "\n      %llu blocks",
                                        (unsigned long long)mddev->array_size);
                        else
                                seq_printf(seq, "\n      %llu blocks",
                                        (unsigned long long)size);
                }
                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
                        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 || mddev->curr_resync == 2)
                                        seq_printf(seq, "\tresync=DELAYED\n      ");
                                else if (mddev->recovery_cp < MaxSector)
                                        seq_printf(seq, "\tresync=PENDING\n      ");
                        }
                } else
                        seq_printf(seq, "\n       ");

                if ((bitmap = mddev->bitmap)) {
                        unsigned long chunk_kb;
                        unsigned long flags;
                        spin_lock_irqsave(&bitmap->lock, flags);
                        chunk_kb = bitmap->chunksize >> 10;
                        seq_printf(seq, "bitmap: %lu/%lu pages [%luKB], "
                                "%lu%s chunk",
                                bitmap->pages - bitmap->missing_pages,
                                bitmap->pages,
                                (bitmap->pages - bitmap->missing_pages)
                                        << (PAGE_SHIFT - 10),
                                chunk_kb ? chunk_kb : bitmap->chunksize,
                                chunk_kb ? "KB" : "B");
                        if (bitmap->file) {
                                seq_printf(seq, ", file: ");
                                seq_path(seq, bitmap->file->f_path.mnt,
                                         bitmap->file->f_path.dentry," \t\n");
                        }

                        seq_printf(seq, "\n");
                        spin_unlock_irqrestore(&bitmap->lock, flags);
                }

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

static 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)
{
        int error;
        struct mdstat_info *mi = kmalloc(sizeof(*mi), GFP_KERNEL);
        if (mi == NULL)
                return -ENOMEM;

        error = seq_open(file, &md_seq_ops);
        if (error)
                kfree(mi);
        else {
                struct seq_file *p = file->private_data;
                p->private = mi;
                mi->event = atomic_read(&md_event_count);
        }
        return error;
}

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

        poll_wait(filp, &md_event_waiters, wait);

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

        if (mi->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 mdk_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 mdk_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(mddev_t *mddev)
{
        mdk_rdev_t * rdev;
        struct list_head *tmp;
        int idle;
        long curr_events;

        idle = 1;
        ITERATE_RDEV(mddev,rdev,tmp) {
                struct gendisk *disk = rdev->bdev->bd_contains->bd_disk;
                curr_events = disk_stat_read(disk, sectors[0]) + 
                                disk_stat_read(disk, 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 (curr_events - rdev->last_events > 4096) {
                        rdev->last_events = curr_events;
                        idle = 0;
                }
        }
        return idle;
}

void md_done_sync(mddev_t *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_ERR, &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(mddev_t *mddev, struct bio *bi)
{
        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);
        }
        atomic_inc(&mddev->writes_pending);
        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);
                        md_wakeup_thread(mddev->thread);
                }
                spin_unlock_irq(&mddev->write_lock);
        }
        wait_event(mddev->sb_wait, mddev->flags==0);
}

void md_write_end(mddev_t *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.
 */
void md_allow_write(mddev_t *mddev)
{
        if (!mddev->pers)
                return;
        if (mddev->ro)
                return;

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

static DECLARE_WAIT_QUEUE_HEAD(resync_wait);

#define SYNC_MARKS      10
#define SYNC_MARK_STEP  (3*HZ)
void md_do_sync(mddev_t *mddev)
{
        mddev_t *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 list_head *rtmp;
        mdk_rdev_t *rdev;
        char *desc;

        /* 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);
                        goto skip;
                }
                ITERATE_MDDEV(mddev2,tmp) {
                        if (mddev2 == mddev)
                                continue;
                        if (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;
                                prepare_to_wait(&resync_wait, &wq, TASK_UNINTERRUPTIBLE);
                                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);
                                        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;
                mddev->resync_mismatches = 0;
                /* we don't use the checkpoint if there's a bitmap */
                if (!mddev->bitmap &&
                    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
                        j = mddev->recovery_cp;
        } else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
                max_sectors = mddev->size << 1;
        else {
                /* recovery follows the physical size of devices */
                max_sectors = mddev->size << 1;
                j = MaxSector;
                ITERATE_RDEV(mddev,rdev,rtmp)
                        if (rdev->raid_disk >= 0 &&
                            !test_bit(Faulty, &rdev->flags) &&
                            !test_bit(In_sync, &rdev->flags) &&
                            rdev->recovery_offset < j)
                                j = rdev->recovery_offset;
        }

        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); /* this also 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 %llu blocks.\n",
                window/2,(unsigned long long) max_sectors/2);

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

        if (j>2) {
                printk(KERN_INFO 
                       "md: resuming %s of %s from checkpoint.\n",
                       desc, mdname(mddev));
                mddev->curr_resync = j;
        }

        while (j < max_sectors) {
                sector_t sectors;

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

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

                j += sectors;
                if (j>1) mddev->curr_resync = j;
                mddev->curr_mark_cnt = io_sectors;
                if (last_check == 0)
                        /* this is the earliers that rebuilt will be
                         * visible in /proc/mdstat
                         */
                        md_new_event(mddev);

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

                last_check = io_sectors;

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

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

                /*
                 * 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)
                 */
                mddev->queue->unplug_fn(mddev->queue);
                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)) {
                                msleep(500);
                                goto repeat;
                        }
                }
        }
        printk(KERN_INFO "md: %s: %s done.\n",mdname(mddev), desc);
        /*
         * this also signals 'finished resyncing' to md_stop
         */
 out:
        mddev->queue->unplug_fn(mddev->queue);

        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_ERR, &mddev->recovery) &&
            !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;
                                }
                        } else
                                mddev->recovery_cp = MaxSector;
                } else {
                        if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
                                mddev->curr_resync = MaxSector;
                        ITERATE_RDEV(mddev,rdev,rtmp)
                                if (rdev->raid_disk >= 0 &&
                                    !test_bit(Faulty, &rdev->flags) &&
                                    !test_bit(In_sync, &rdev->flags) &&
                                    rdev->recovery_offset < mddev->curr_resync)
                                        rdev->recovery_offset = mddev->curr_resync;
                }
        }
        set_bit(MD_CHANGE_DEVS, &mddev->flags);

 skip:
        mddev->curr_resync = 0;
        wake_up(&resync_wait);
        set_bit(MD_RECOVERY_DONE, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
}
EXPORT_SYMBOL_GPL(md_do_sync);


static int remove_and_add_spares(mddev_t *mddev)
{
        mdk_rdev_t *rdev;
        struct list_head *rtmp;
        int spares = 0;

        ITERATE_RDEV(mddev,rdev,rtmp)
                if (rdev->raid_disk >= 0 &&
                    (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->raid_disk)==0) {
                                char nm[20];
                                sprintf(nm,"rd%d", rdev->raid_disk);
                                sysfs_remove_link(&mddev->kobj, nm);
                                rdev->raid_disk = -1;
                        }
                }

        if (mddev->degraded) {
                ITERATE_RDEV(mddev,rdev,rtmp)
                        if (rdev->raid_disk < 0
                            && !test_bit(Faulty, &rdev->flags)) {
                                rdev->recovery_offset = 0;
                                if (mddev->pers->hot_add_disk(mddev,rdev)) {
                                        char nm[20];
                                        sprintf(nm, "rd%d", rdev->raid_disk);
                                        if (sysfs_create_link(&mddev->kobj,
                                                              &rdev->kobj, nm))
                                                printk(KERN_WARNING
                                                       "md: cannot register "
                                                       "%s for %s\n",
                                                       nm, mdname(mddev));
                                        spares++;
                                        md_new_event(mddev);
                                } else
                                        break;
                        }
        }
        return spares;
}
/*
 * 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 might set MD_RECOVERY_ERR)
 * 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(mddev_t *mddev)
{
        mdk_rdev_t *rdev;
        struct list_head *rtmp;


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

        if (mddev->ro)
                return;

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

        if ( ! (
                mddev->flags ||
                test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
                test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
                (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;

                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;
                        set_bit(MD_CHANGE_CLEAN, &mddev->flags);
                }
                if (mddev->safemode == 1)
                        mddev->safemode = 0;
                spin_unlock_irq(&mddev->write_lock);

                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) {
                        /* resync has finished, collect result */
                        md_unregister_thread(mddev->sync_thread);
                        mddev->sync_thread = NULL;
                        if (!test_bit(MD_RECOVERY_ERR, &mddev->recovery) &&
                            !test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
                                /* success...*/
                                /* activate any spares */
                                mddev->pers->spare_active(mddev);
                        }
                        md_update_sb(mddev, 1);

                        /* if array is no-longer degraded, then any saved_raid_disk
                         * information must be scrapped
                         */
                        if (!mddev->degraded)
                                ITERATE_RDEV(mddev,rdev,rtmp)
                                        rdev->saved_raid_disk = -1;

                        mddev->recovery = 0;
                        /* flag recovery needed just to double check */
                        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                        md_new_event(mddev);
                        goto unlock;
                }
                /* Clear some bits that don't mean anything, but
                 * might be left set
                 */
                clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                clear_bit(MD_RECOVERY_ERR, &mddev->recovery);
                clear_bit(MD_RECOVERY_INTR, &mddev->recovery);
                clear_bit(MD_RECOVERY_DONE, &mddev->recovery);

                if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
                        goto unlock;
                /* no recovery is running.
                 * remove any failed drives, then
                 * add spares if possible.
                 * Spare 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(mddev) != 0)
                                /* Cannot proceed */
                                goto unlock;
                        set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
                } else if ((spares = remove_and_add_spares(mddev))) {
                        clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
                        clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
                } else if (mddev->recovery_cp < MaxSector) {
                        set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
                } else if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
                        /* nothing to be done ... */
                        goto unlock;

                if (mddev->pers->sync_request) {
                        set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
                        if (spares && mddev->bitmap && ! mddev->bitmap->file) {
                                /* 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,
                                                                "%s_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 */
                                mddev->recovery = 0;
                        } else
                                md_wakeup_thread(mddev->sync_thread);
                        md_new_event(mddev);
                }
        unlock:
                mddev_unlock(mddev);
        }
}

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

        if ((code == SYS_DOWN) || (code == SYS_HALT) || (code == SYS_POWER_OFF)) {

                printk(KERN_INFO "md: stopping all md devices.\n");

                ITERATE_MDDEV(mddev,tmp)
                        if (mddev_trylock(mddev)) {
                                do_md_stop (mddev, 1);
                                mddev_unlock(mddev);
                        }
                /*
                 * 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 ...
                 */
                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)
{
        struct proc_dir_entry *p;

        dprintk("md: sizeof(mdp_super_t) = %d\n", (int)sizeof(mdp_super_t));

        p = create_proc_entry("mdstat", S_IRUGO, NULL);
        if (p)
                p->proc_fops = &md_seq_fops;
}

static int __init md_init(void)
{
        if (register_blkdev(MAJOR_NR, "md"))
                return -1;
        if ((mdp_major=register_blkdev(0, "mdp"))<=0) {
                unregister_blkdev(MAJOR_NR, "md");
                return -1;
        }
        blk_register_region(MKDEV(MAJOR_NR, 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);
}


#ifndef MODULE

/*
 * Searches all registered partitions for autorun RAID arrays
 * at boot time.
 */
static dev_t detected_devices[128];
static int dev_cnt;

void md_autodetect_dev(dev_t dev)
{
        if (dev_cnt >= 0 && dev_cnt < 127)
                detected_devices[dev_cnt++] = dev;
}


static void autostart_arrays(int part)
{
        mdk_rdev_t *rdev;
        int i;

        printk(KERN_INFO "md: Autodetecting RAID arrays.\n");

        for (i = 0; i < dev_cnt; i++) {
                dev_t dev = detected_devices[i];

                rdev = md_import_device(dev,0, 90);
                if (IS_ERR(rdev))
                        continue;

                if (test_bit(Faulty, &rdev->flags)) {
                        MD_BUG();
                        continue;
                }
                list_add(&rdev->same_set, &pending_raid_disks);
        }
        dev_cnt = 0;

        autorun_devices(part);
}

#endif /* !MODULE */

static __exit void md_exit(void)
{
        mddev_t *mddev;
        struct list_head *tmp;

        blk_unregister_region(MKDEV(MAJOR_NR,0), 1U << MINORBITS);
        blk_unregister_region(MKDEV(mdp_major,0), 1U << MINORBITS);

        unregister_blkdev(MAJOR_NR,"md");
        unregister_blkdev(mdp_major, "mdp");
        unregister_reboot_notifier(&md_notifier);
        unregister_sysctl_table(raid_table_header);
        remove_proc_entry("mdstat", NULL);
        ITERATE_MDDEV(mddev,tmp) {
                struct gendisk *disk = mddev->gendisk;
                if (!disk)
                        continue;
                export_array(mddev);
                del_gendisk(disk);
                put_disk(disk);
                mddev->gendisk = NULL;
                mddev_put(mddev);
        }
}

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);


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_ALIAS("md");
MODULE_ALIAS_BLOCKDEV_MAJOR(MD_MAJOR);