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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) ||
          (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))) {
            if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
                  type = "reshape";
            else if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
                  if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
                        type = "resync";
                  else if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
                        type = "check";
                  else
                        type = "repair";
            } else
                  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
degraded_show(mddev_t *mddev, char *page)
{
      return sprintf(page, "%d\n", mddev->degraded);
}
static struct md_sysfs_entry md_degraded = __ATTR_RO(degraded);

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,
      &md_degraded.attr,
      NULL,
};
static struct attribute_group md_redundancy_group = {
      .name = NULL,
      .attrs = md_redundancy_attrs,
};


static ssize_t
md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
      struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
      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->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", task_pid_nr(thread->tsk));

      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)
             */
            blk_unplug(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:
      blk_unplug(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 LIST_HEAD(all_detected_devices);
struct detected_devices_node {
      struct list_head list;
      dev_t dev;
};

void md_autodetect_dev(dev_t dev)
{
      struct detected_devices_node *node_detected_dev;

      node_detected_dev = kzalloc(sizeof(*node_detected_dev), GFP_KERNEL);
      if (node_detected_dev) {
            node_detected_dev->dev = dev;
            list_add_tail(&node_detected_dev->list, &all_detected_devices);
      } else {
            printk(KERN_CRIT "md: md_autodetect_dev: kzalloc failed"
                  ", skipping dev(%d,%d)\n", MAJOR(dev), MINOR(dev));
      }
}


static void autostart_arrays(int part)
{
      mdk_rdev_t *rdev;
      struct detected_devices_node *node_detected_dev;
      dev_t dev;
      int i_scanned, i_passed;

      i_scanned = 0;
      i_passed = 0;

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

      while (!list_empty(&all_detected_devices) && i_scanned < INT_MAX) {
            i_scanned++;
            node_detected_dev = list_entry(all_detected_devices.next,
                              struct detected_devices_node, list);
            list_del(&node_detected_dev->list);
            dev = node_detected_dev->dev;
            kfree(node_detected_dev);
            rdev = md_import_device(dev,0, 90);
            if (IS_ERR(rdev))
                  continue;

            if (test_bit(Faulty, &rdev->flags)) {
                  MD_BUG();
                  continue;
            }
            list_add(&rdev->same_set, &pending_raid_disks);
            i_passed++;
      }

      printk(KERN_INFO "md: Scanned %d and added %d devices.\n",
                                    i_scanned, i_passed);

      autorun_devices(part);
}

#endif /* !MODULE */

static __exit void md_exit(void)
{
      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);

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