Merge branch 'for-linus' of git://neil.brown.name/md

* 'for-linus' of git://neil.brown.name/md: (52 commits)
  md: Protect access to mddev->disks list using RCU
  md: only count actual openers as access which prevent a 'stop'
  md: linear: Make array_size sector-based and rename it to array_sectors.
  md: Make mddev->array_size sector-based.
  md: Make super_type->rdev_size_change() take sector-based sizes.
  md: Fix check for overlapping devices.
  md: Tidy up rdev_size_store a bit:
  md: Remove some unused macros.
  md: Turn rdev->sb_offset into a sector-based quantity.
  md: Make calc_dev_sboffset() return a sector count.
  md: Replace calc_dev_size() by calc_num_sectors().
  md: Make update_size() take the number of sectors.
  md: Better control of when do_md_stop is allowed to stop the array.
  md: get_disk_info(): Don't convert between signed and unsigned and back.
  md: Simplify restart_array().
  md: alloc_disk_sb(): Return proper error value.
  md: Simplify sb_equal().
  md: Simplify uuid_equal().
  md: sb_equal(): Fix misleading printk.
  md: Fix a typo in the comment to cmd_match().
  ...

16 files changed, 842 insertions, 790 deletions

diff --git a/Documentation/md.txt b/Documentation/md.txt
index a8b430627473..1da9d1b1793f 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -236,6 +236,11 @@ All md devices contain:
      writing the word for the desired state, however some states
      cannot be explicitly set, and some transitions are not allowed.
 
+     Select/poll works on this file.  All changes except between
+        active_idle and active (which can be frequent and are not
+        very interesting) are notified.  active->active_idle is
+        reported if the metadata is externally managed.
+
      clear
          No devices, no size, no level
          Writing is equivalent to STOP_ARRAY ioctl
@@ -292,6 +297,10 @@ Each directory contains:
               writemostly - device will only be subject to read
                          requests if there are no other options.
                          This applies only to raid1 arrays.
+              blocked  - device has failed, metadata is "external",
+                         and the failure hasn't been acknowledged yet.
+                         Writes that would write to this device if
+                         it were not faulty are blocked.
               spare    - device is working, but not a full member.
                          This includes spares that are in the process
                          of being recovered to
@@ -301,6 +310,12 @@ Each directory contains:
         Writing "remove" removes the device from the array.
         Writing "writemostly" sets the writemostly flag.
         Writing "-writemostly" clears the writemostly flag.
+        Writing "blocked" sets the "blocked" flag.
+        Writing "-blocked" clear the "blocked" flag and allows writes
+                to complete.
+
+        This file responds to select/poll. Any change to 'faulty'
+        or 'blocked' causes an event.
 
       errors
         An approximate count of read errors that have been detected on
@@ -332,7 +347,7 @@ Each directory contains:
         for storage of data.  This will normally be the same as the
         component_size.  This can be written while assembling an
         array.  If a value less than the current component_size is
-        written, component_size will be reduced to this value.
+        written, it will be rejected.
 
 
 An active md device will also contain and entry for each active device
@@ -381,6 +396,19 @@ also have
         'check' and 'repair' will start the appropriate process
            providing the current state is 'idle'.
 
+      This file responds to select/poll.  Any important change in the value
+      triggers a poll event.  Sometimes the value will briefly be
+      "recover" if a recovery seems to be needed, but cannot be
+      achieved. In that case, the transition to "recover" isn't
+      notified, but the transition away is.
+
+   degraded
+      This contains a count of the number of devices by which the
+      arrays is degraded.  So an optimal array with show '0'.  A
+      single failed/missing drive will show '1', etc.
+      This file responds to select/poll, any increase or decrease
+      in the count of missing devices will trigger an event.
+
    mismatch_count
       When performing 'check' and 'repair', and possibly when
       performing 'resync', md will count the number of errors that are
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index b26927ce889c..621a272a2c74 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -225,7 +225,7 @@ static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long inde
                     || test_bit(Faulty, &rdev->flags))
                         continue;
 
-                target = (rdev->sb_offset << 1) + offset + index * (PAGE_SIZE/512);
+                target = rdev->sb_start + offset + index * (PAGE_SIZE/512);
 
                 if (sync_page_io(rdev->bdev, target, PAGE_SIZE, page, READ)) {
                         page->index = index;
@@ -241,10 +241,10 @@ static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long inde
 static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
 {
         mdk_rdev_t *rdev;
-        struct list_head *tmp;
         mddev_t *mddev = bitmap->mddev;
 
-        rdev_for_each(rdev, tmp, mddev)
+        rcu_read_lock();
+        rdev_for_each_rcu(rdev, mddev)
                 if (test_bit(In_sync, &rdev->flags)
                     && !test_bit(Faulty, &rdev->flags)) {
                         int size = PAGE_SIZE;
@@ -260,32 +260,37 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
                                     + (long)(page->index * (PAGE_SIZE/512))
                                     + size/512 > 0)
                                         /* bitmap runs in to metadata */
-                                        return -EINVAL;
+                                        goto bad_alignment;
                                 if (rdev->data_offset + mddev->size*2
-                                    > rdev->sb_offset*2 + bitmap->offset)
+                                    > rdev->sb_start + bitmap->offset)
                                         /* data runs in to bitmap */
-                                        return -EINVAL;
-                        } else if (rdev->sb_offset*2 < rdev->data_offset) {
+                                        goto bad_alignment;
+                        } else if (rdev->sb_start < rdev->data_offset) {
                                 /* METADATA BITMAP DATA */
-                                if (rdev->sb_offset*2
+                                if (rdev->sb_start
                                     + bitmap->offset
                                     + page->index*(PAGE_SIZE/512) + size/512
                                     > rdev->data_offset)
                                         /* bitmap runs in to data */
-                                        return -EINVAL;
+                                        goto bad_alignment;
                         } else {
                                 /* DATA METADATA BITMAP - no problems */
                         }
                         md_super_write(mddev, rdev,
-                                       (rdev->sb_offset<<1) + bitmap->offset
+                                       rdev->sb_start + bitmap->offset
                                        + page->index * (PAGE_SIZE/512),
                                        size,
                                        page);
                 }
+        rcu_read_unlock();
 
         if (wait)
                 md_super_wait(mddev);
         return 0;
+
+ bad_alignment:
+        rcu_read_unlock();
+        return -EINVAL;
 }
 
 static void bitmap_file_kick(struct bitmap *bitmap);
@@ -454,8 +459,11 @@ void bitmap_update_sb(struct bitmap *bitmap)
         spin_unlock_irqrestore(&bitmap->lock, flags);
         sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
         sb->events = cpu_to_le64(bitmap->mddev->events);
-        if (!bitmap->mddev->degraded)
-                sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
+        if (bitmap->mddev->events < bitmap->events_cleared) {
+                /* rocking back to read-only */
+                bitmap->events_cleared = bitmap->mddev->events;
+                sb->events_cleared = cpu_to_le64(bitmap->events_cleared);
+        }
         kunmap_atomic(sb, KM_USER0);
         write_page(bitmap, bitmap->sb_page, 1);
 }
@@ -1085,9 +1093,19 @@ void bitmap_daemon_work(struct bitmap *bitmap)
                         } else
                                 spin_unlock_irqrestore(&bitmap->lock, flags);
                         lastpage = page;
-/*
-                        printk("bitmap clean at page %lu\n", j);
-*/
+
+                        /* We are possibly going to clear some bits, so make
+                         * sure that events_cleared is up-to-date.
+                         */
+                        if (bitmap->need_sync) {
+                                bitmap_super_t *sb;
+                                bitmap->need_sync = 0;
+                                sb = kmap_atomic(bitmap->sb_page, KM_USER0);
+                                sb->events_cleared =
+                                        cpu_to_le64(bitmap->events_cleared);
+                                kunmap_atomic(sb, KM_USER0);
+                                write_page(bitmap, bitmap->sb_page, 1);
+                        }
                         spin_lock_irqsave(&bitmap->lock, flags);
                         clear_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
                 }
@@ -1257,6 +1275,12 @@ void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long secto
                         return;
                 }
 
+                if (success &&
+                    bitmap->events_cleared < bitmap->mddev->events) {
+                        bitmap->events_cleared = bitmap->mddev->events;
+                        bitmap->need_sync = 1;
+                }
+
                 if (!success && ! (*bmc & NEEDED_MASK))
                         *bmc |= NEEDED_MASK;
 
diff --git a/drivers/md/faulty.c b/drivers/md/faulty.c
index d107ddceefcd..268547dbfbd3 100644
--- a/drivers/md/faulty.c
+++ b/drivers/md/faulty.c
@@ -297,7 +297,7 @@ static int run(mddev_t *mddev)
         rdev_for_each(rdev, tmp, mddev)
                 conf->rdev = rdev;
 
-        mddev->array_size = mddev->size;
+        mddev->array_sectors = mddev->size * 2;
         mddev->private = conf;
 
         reconfig(mddev, mddev->layout, -1);
diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 6a866d7c8ae5..b1eebf88c209 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -122,13 +122,13 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
                 return NULL;
 
         cnt = 0;
-        conf->array_size = 0;
+        conf->array_sectors = 0;
 
         rdev_for_each(rdev, tmp, mddev) {
                 int j = rdev->raid_disk;
                 dev_info_t *disk = conf->disks + j;
 
-                if (j < 0 || j > raid_disks || disk->rdev) {
+                if (j < 0 || j >= raid_disks || disk->rdev) {
                         printk("linear: disk numbering problem. Aborting!\n");
                         goto out;
                 }
@@ -146,7 +146,7 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
                         blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
 
                 disk->size = rdev->size;
-                conf->array_size += rdev->size;
+                conf->array_sectors += rdev->size * 2;
 
                 cnt++;
         }
@@ -155,7 +155,7 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
                 goto out;
         }
 
-        min_spacing = conf->array_size;
+        min_spacing = conf->array_sectors / 2;
         sector_div(min_spacing, PAGE_SIZE/sizeof(struct dev_info *));
 
         /* min_spacing is the minimum spacing that will fit the hash
@@ -164,7 +164,7 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
          * that is larger than min_spacing as use the size of that as
          * the actual spacing
          */
-        conf->hash_spacing = conf->array_size;
+        conf->hash_spacing = conf->array_sectors / 2;
         for (i=0; i < cnt-1 ; i++) {
                 sector_t sz = 0;
                 int j;
@@ -194,7 +194,7 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
                 unsigned round;
                 unsigned long base;
 
-                sz = conf->array_size >> conf->preshift;
+                sz = conf->array_sectors >> (conf->preshift + 1);
                 sz += 1; /* force round-up */
                 base = conf->hash_spacing >> conf->preshift;
                 round = sector_div(sz, base);
@@ -221,7 +221,7 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
         curr_offset = 0;
         i = 0;
         for (curr_offset = 0;
-             curr_offset < conf->array_size;
+             curr_offset < conf->array_sectors / 2;
              curr_offset += conf->hash_spacing) {
 
                 while (i < raid_disks-1 &&
@@ -258,7 +258,7 @@ static int linear_run (mddev_t *mddev)
         if (!conf)
                 return 1;
         mddev->private = conf;
-        mddev->array_size = conf->array_size;
+        mddev->array_sectors = conf->array_sectors;
 
         blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
         mddev->queue->unplug_fn = linear_unplug;
@@ -292,8 +292,8 @@ static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
         newconf->prev = mddev_to_conf(mddev);
         mddev->private = newconf;
         mddev->raid_disks++;
-        mddev->array_size = newconf->array_size;
-        set_capacity(mddev->gendisk, mddev->array_size << 1);
+        mddev->array_sectors = newconf->array_sectors;
+        set_capacity(mddev->gendisk, mddev->array_sectors);
         return 0;
 }
 
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 2580ac1b9b0f..c2ff77ccec50 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -169,7 +169,6 @@ 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);
 
@@ -274,10 +273,12 @@ static mddev_t * mddev_find(dev_t unit)
         INIT_LIST_HEAD(&new->all_mddevs);
         init_timer(&new->safemode_timer);
         atomic_set(&new->active, 1);
+        atomic_set(&new->openers, 0);
         spin_lock_init(&new->write_lock);
         init_waitqueue_head(&new->sb_wait);
         init_waitqueue_head(&new->recovery_wait);
         new->reshape_position = MaxSector;
+        new->resync_min = 0;
         new->resync_max = MaxSector;
         new->level = LEVEL_NONE;
 
@@ -347,21 +348,20 @@ static struct mdk_personality *find_pers(int level, char *clevel)
         return NULL;
 }
 
+/* return the offset of the super block in 512byte sectors */
 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);
+        sector_t num_sectors = bdev->bd_inode->i_size / 512;
+        return MD_NEW_SIZE_SECTORS(num_sectors);
 }
 
-static sector_t calc_dev_size(mdk_rdev_t *rdev, unsigned chunk_size)
+static sector_t calc_num_sectors(mdk_rdev_t *rdev, unsigned chunk_size)
 {
-        sector_t size;
-
-        size = rdev->sb_offset;
+        sector_t num_sectors = rdev->sb_start;
 
         if (chunk_size)
-                size &= ~((sector_t)chunk_size/1024 - 1);
-        return size;
+                num_sectors &= ~((sector_t)chunk_size/512 - 1);
+        return num_sectors;
 }
 
 static int alloc_disk_sb(mdk_rdev_t * rdev)
@@ -372,7 +372,7 @@ static int alloc_disk_sb(mdk_rdev_t * rdev)
         rdev->sb_page = alloc_page(GFP_KERNEL);
         if (!rdev->sb_page) {
                 printk(KERN_ALERT "md: out of memory.\n");
-                return -EINVAL;
+                return -ENOMEM;
         }
 
         return 0;
@@ -384,7 +384,7 @@ static void free_disk_sb(mdk_rdev_t * rdev)
                 put_page(rdev->sb_page);
                 rdev->sb_loaded = 0;
                 rdev->sb_page = NULL;
-                rdev->sb_offset = 0;
+                rdev->sb_start = 0;
                 rdev->size = 0;
         }
 }
@@ -530,7 +530,7 @@ static int read_disk_sb(mdk_rdev_t * rdev, int size)
                 return 0;
 
 
-        if (!sync_page_io(rdev->bdev, rdev->sb_offset<<1, size, rdev->sb_page, READ))
+        if (!sync_page_io(rdev->bdev, rdev->sb_start, size, rdev->sb_page, READ))
                 goto fail;
         rdev->sb_loaded = 1;
         return 0;
@@ -543,17 +543,12 @@ fail:
 
 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;
+        return  sb1->set_uuid0 == sb2->set_uuid0 &&
+                sb1->set_uuid1 == sb2->set_uuid1 &&
+                sb1->set_uuid2 == sb2->set_uuid2 &&
+                sb1->set_uuid3 == sb2->set_uuid3;
 }
 
-
 static int sb_equal(mdp_super_t *sb1, mdp_super_t *sb2)
 {
         int ret;
@@ -564,7 +559,7 @@ static int sb_equal(mdp_super_t *sb1, mdp_super_t *sb2)
 
         if (!tmp1 || !tmp2) {
                 ret = 0;
-                printk(KERN_INFO "md.c: sb1 is not equal to sb2!\n");
+                printk(KERN_INFO "md.c sb_equal(): failed to allocate memory!\n");
                 goto abort;
         }
 
@@ -577,11 +572,7 @@ static int sb_equal(mdp_super_t *sb1, mdp_super_t *sb2)
         tmp1->nr_disks = 0;
         tmp2->nr_disks = 0;
 
-        if (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4))
-                ret = 0;
-        else
-                ret = 1;
-
+        ret = (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4) == 0);
 abort:
         kfree(tmp1);
         kfree(tmp2);
@@ -658,11 +649,14 @@ static unsigned int calc_sb_csum(mdp_super_t * sb)
  */
 
 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);
+        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);
+        unsigned long long  (*rdev_size_change)(mdk_rdev_t *rdev,
+                                                sector_t num_sectors);
 };
 
 /*
@@ -673,16 +667,14 @@ 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,
+         * Calculate the position of the superblock (512byte sectors),
          * it's at the end of the disk.
          *
          * It also happens to be a multiple of 4Kb.
          */
-        sb_offset = calc_dev_sboffset(rdev->bdev);
-        rdev->sb_offset = sb_offset;
+        rdev->sb_start = calc_dev_sboffset(rdev->bdev);
 
         ret = read_disk_sb(rdev, MD_SB_BYTES);
         if (ret) return ret;
@@ -759,7 +751,7 @@ static int super_90_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version
                 else 
                         ret = 0;
         }
-        rdev->size = calc_dev_size(rdev, sb->chunk_size);
+        rdev->size = calc_num_sectors(rdev, sb->chunk_size) / 2;
 
         if (rdev->size < sb->size && sb->level > 1)
                 /* "this cannot possibly happen" ... */
@@ -1004,6 +996,26 @@ static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
 }
 
 /*
+ * rdev_size_change for 0.90.0
+ */
+static unsigned long long
+super_90_rdev_size_change(mdk_rdev_t *rdev, sector_t num_sectors)
+{
+        if (num_sectors && num_sectors < rdev->mddev->size * 2)
+                return 0; /* component must fit device */
+        if (rdev->mddev->bitmap_offset)
+                return 0; /* can't move bitmap */
+        rdev->sb_start = calc_dev_sboffset(rdev->bdev);
+        if (!num_sectors || num_sectors > rdev->sb_start)
+                num_sectors = rdev->sb_start;
+        md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
+                       rdev->sb_page);
+        md_super_wait(rdev->mddev);
+        return num_sectors / 2; /* kB for sysfs */
+}
+
+
+/*
  * version 1 superblock
  */
 
@@ -1034,12 +1046,12 @@ 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;
+        sector_t sb_start;
         char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
         int bmask;
 
         /*
-         * Calculate the position of the superblock.
+         * Calculate the position of the superblock in 512byte sectors.
          * It is always aligned to a 4K boundary and
          * depeding on minor_version, it can be:
          * 0: At least 8K, but less than 12K, from end of device
@@ -1048,22 +1060,20 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
          */
         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;
+                sb_start = rdev->bdev->bd_inode->i_size >> 9;
+                sb_start -= 8*2;
+                sb_start &= ~(sector_t)(4*2-1);
                 break;
         case 1:
-                sb_offset = 0;
+                sb_start = 0;
                 break;
         case 2:
-                sb_offset = 4;
+                sb_start = 8;
                 break;
         default:
                 return -EINVAL;
         }
-        rdev->sb_offset = sb_offset;
+        rdev->sb_start = sb_start;
 
         /* superblock is rarely larger than 1K, but it can be larger,
          * and it is safe to read 4k, so we do that
@@ -1077,7 +1087,7 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
         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) ||
+            le64_to_cpu(sb->super_offset) != rdev->sb_start ||
             (le32_to_cpu(sb->feature_map) & ~MD_FEATURE_ALL) != 0)
                 return -EINVAL;
 
@@ -1113,7 +1123,7 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
                 rdev->sb_size = (rdev->sb_size | bmask) + 1;
 
         if (minor_version
-            && rdev->data_offset < sb_offset + (rdev->sb_size/512))
+            && rdev->data_offset < sb_start + (rdev->sb_size/512))
                 return -EINVAL;
 
         if (sb->level == cpu_to_le32(LEVEL_MULTIPATH))
@@ -1149,7 +1159,7 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
         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;
+                rdev->size = rdev->sb_start / 2;
         if (rdev->size < le64_to_cpu(sb->data_size)/2)
                 return -EINVAL;
         rdev->size = le64_to_cpu(sb->data_size)/2;
@@ -1328,35 +1338,74 @@ static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
         sb->sb_csum = calc_sb_1_csum(sb);
 }
 
+static unsigned long long
+super_1_rdev_size_change(mdk_rdev_t *rdev, sector_t num_sectors)
+{
+        struct mdp_superblock_1 *sb;
+        sector_t max_sectors;
+        if (num_sectors && num_sectors < rdev->mddev->size * 2)
+                return 0; /* component must fit device */
+        if (rdev->sb_start < rdev->data_offset) {
+                /* minor versions 1 and 2; superblock before data */
+                max_sectors = rdev->bdev->bd_inode->i_size >> 9;
+                max_sectors -= rdev->data_offset;
+                if (!num_sectors || num_sectors > max_sectors)
+                        num_sectors = max_sectors;
+        } else if (rdev->mddev->bitmap_offset) {
+                /* minor version 0 with bitmap we can't move */
+                return 0;
+        } else {
+                /* minor version 0; superblock after data */
+                sector_t sb_start;
+                sb_start = (rdev->bdev->bd_inode->i_size >> 9) - 8*2;
+                sb_start &= ~(sector_t)(4*2 - 1);
+                max_sectors = rdev->size * 2 + sb_start - rdev->sb_start;
+                if (!num_sectors || num_sectors > max_sectors)
+                        num_sectors = max_sectors;
+                rdev->sb_start = sb_start;
+        }
+        sb = (struct mdp_superblock_1 *) page_address(rdev->sb_page);
+        sb->data_size = cpu_to_le64(num_sectors);
+        sb->super_offset = rdev->sb_start;
+        sb->sb_csum = calc_sb_1_csum(sb);
+        md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
+                       rdev->sb_page);
+        md_super_wait(rdev->mddev);
+        return num_sectors / 2; /* kB for sysfs */
+}
 
 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,
+                .load_super         = super_90_load,
+                .validate_super     = super_90_validate,
+                .sync_super         = super_90_sync,
+                .rdev_size_change   = super_90_rdev_size_change,
         },
         [1] = {
                 .name   = "md-1",
                 .owner  = THIS_MODULE,
-                .load_super     = super_1_load,
-                .validate_super = super_1_validate,
-                .sync_super     = super_1_sync,
+                .load_super         = super_1_load,
+                .validate_super     = super_1_validate,
+                .sync_super         = super_1_sync,
+                .rdev_size_change   = super_1_rdev_size_change,
         },
 };
 
 static int match_mddev_units(mddev_t *mddev1, mddev_t *mddev2)
 {
-        struct list_head *tmp, *tmp2;
         mdk_rdev_t *rdev, *rdev2;
 
-        rdev_for_each(rdev, tmp, mddev1)
-                rdev_for_each(rdev2, tmp2, mddev2)
+        rcu_read_lock();
+        rdev_for_each_rcu(rdev, mddev1)
+                rdev_for_each_rcu(rdev2, mddev2)
                         if (rdev->bdev->bd_contains ==
-                            rdev2->bdev->bd_contains)
+                            rdev2->bdev->bd_contains) {
+                                rcu_read_unlock();
                                 return 1;
-
+                        }
+        rcu_read_unlock();
         return 0;
 }
 
@@ -1423,7 +1472,7 @@ static int bind_rdev_to_array(mdk_rdev_t * rdev, mddev_t * mddev)
                 kobject_del(&rdev->kobj);
                 goto fail;
         }
-        list_add(&rdev->same_set, &mddev->disks);
+        list_add_rcu(&rdev->same_set, &mddev->disks);
         bd_claim_by_disk(rdev->bdev, rdev->bdev->bd_holder, mddev->gendisk);
         return 0;
 
@@ -1448,14 +1497,16 @@ static void unbind_rdev_from_array(mdk_rdev_t * rdev)
                 return;
         }
         bd_release_from_disk(rdev->bdev, rdev->mddev->gendisk);
-        list_del_init(&rdev->same_set);
+        list_del_rcu(&rdev->same_set);
         printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
         rdev->mddev = NULL;
         sysfs_remove_link(&rdev->kobj, "block");
 
         /* We need to delay this, otherwise we can deadlock when
-         * writing to 'remove' to "dev/state"
+         * writing to 'remove' to "dev/state".  We also need
+         * to delay it due to rcu usage.
          */
+        synchronize_rcu();
         INIT_WORK(&rdev->del_work, md_delayed_delete);
         kobject_get(&rdev->kobj);
         schedule_work(&rdev->del_work);
@@ -1511,7 +1562,6 @@ static void export_rdev(mdk_rdev_t * rdev)
         if (rdev->mddev)
                 MD_BUG();
         free_disk_sb(rdev);
-        list_del_init(&rdev->same_set);
 #ifndef MODULE
         if (test_bit(AutoDetected, &rdev->flags))
                 md_autodetect_dev(rdev->bdev->bd_dev);
@@ -1758,11 +1808,11 @@ repeat:
                 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_start, 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);
+                                (unsigned long long)rdev->sb_start);
                         rdev->sb_events = mddev->events;
 
                 } else
@@ -1787,7 +1837,7 @@ repeat:
 
 }
 
-/* words written to sysfs files may, or my not, be \n terminated.
+/* words written to sysfs files may, or may not, be \n terminated.
  * We want to accept with case. For this we use cmd_match.
  */
 static int cmd_match(const char *cmd, const char *str)
@@ -1886,6 +1936,8 @@ state_store(mdk_rdev_t *rdev, const char *buf, size_t len)
 
                 err = 0;
         }
+        if (!err)
+                sysfs_notify(&rdev->kobj, NULL, "state");
         return err ? err : len;
 }
 static struct rdev_sysfs_entry rdev_state =
@@ -1931,7 +1983,7 @@ slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                 slot = -1;
         else if (e==buf || (*e && *e!= '\n'))
                 return -EINVAL;
-        if (rdev->mddev->pers) {
+        if (rdev->mddev->pers && slot == -1) {
                 /* Setting 'slot' on an active array requires also
                  * updating the 'rd%d' link, and communicating
                  * with the personality with ->hot_*_disk.
@@ -1939,8 +1991,6 @@ slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                  * failed/spare devices.  This normally happens automatically,
                  * but not when the metadata is externally managed.
                  */
-                if (slot != -1)
-                        return -EBUSY;
                 if (rdev->raid_disk == -1)
                         return -EEXIST;
                 /* personality does all needed checks */
@@ -1954,6 +2004,43 @@ slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                 sysfs_remove_link(&rdev->mddev->kobj, nm);
                 set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
                 md_wakeup_thread(rdev->mddev->thread);
+        } else if (rdev->mddev->pers) {
+                mdk_rdev_t *rdev2;
+                struct list_head *tmp;
+                /* Activating a spare .. or possibly reactivating
+                 * if we every get bitmaps working here.
+                 */
+
+                if (rdev->raid_disk != -1)
+                        return -EBUSY;
+
+                if (rdev->mddev->pers->hot_add_disk == NULL)
+                        return -EINVAL;
+
+                rdev_for_each(rdev2, tmp, rdev->mddev)
+                        if (rdev2->raid_disk == slot)
+                                return -EEXIST;
+
+                rdev->raid_disk = slot;
+                if (test_bit(In_sync, &rdev->flags))
+                        rdev->saved_raid_disk = slot;
+                else
+                        rdev->saved_raid_disk = -1;
+                err = rdev->mddev->pers->
+                        hot_add_disk(rdev->mddev, rdev);
+                if (err) {
+                        rdev->raid_disk = -1;
+                        return err;
+                } else
+                        sysfs_notify(&rdev->kobj, NULL, "state");
+                sprintf(nm, "rd%d", rdev->raid_disk);
+                if (sysfs_create_link(&rdev->mddev->kobj, &rdev->kobj, nm))
+                        printk(KERN_WARNING
+                               "md: cannot register "
+                               "%s for %s\n",
+                               nm, mdname(rdev->mddev));
+
+                /* don't wakeup anyone, leave that to userspace. */
         } else {
                 if (slot >= rdev->mddev->raid_disks)
                         return -ENOSPC;
@@ -1962,6 +2049,7 @@ slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                 clear_bit(Faulty, &rdev->flags);
                 clear_bit(WriteMostly, &rdev->flags);
                 set_bit(In_sync, &rdev->flags);
+                sysfs_notify(&rdev->kobj, NULL, "state");
         }
         return len;
 }
@@ -1983,7 +2071,7 @@ offset_store(mdk_rdev_t *rdev, const char *buf, size_t len)
         unsigned long long offset = simple_strtoull(buf, &e, 10);
         if (e==buf || (*e && *e != '\n'))
                 return -EINVAL;
-        if (rdev->mddev->pers)
+        if (rdev->mddev->pers && rdev->raid_disk >= 0)
                 return -EBUSY;
         if (rdev->size && rdev->mddev->external)
                 /* Must set offset before size, so overlap checks
@@ -2015,17 +2103,30 @@ static int overlaps(sector_t s1, sector_t l1, sector_t s2, sector_t l2)
 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);
+        unsigned long long size;
         unsigned long long oldsize = rdev->size;
         mddev_t *my_mddev = rdev->mddev;
 
-        if (e==buf || (*e && *e != '\n'))
+        if (strict_strtoull(buf, 10, &size) < 0)
                 return -EINVAL;
-        if (my_mddev->pers)
-                return -EBUSY;
+        if (size < my_mddev->size)
+                return -EINVAL;
+        if (my_mddev->pers && rdev->raid_disk >= 0) {
+                if (my_mddev->persistent) {
+                        size = super_types[my_mddev->major_version].
+                                rdev_size_change(rdev, size * 2);
+                        if (!size)
+                                return -EBUSY;
+                } else if (!size) {
+                        size = (rdev->bdev->bd_inode->i_size >> 10);
+                        size -= rdev->data_offset/2;
+                }
+                if (size < my_mddev->size)
+                        return -EINVAL; /* component must fit device */
+        }
+
         rdev->size = size;
-        if (size > oldsize && rdev->mddev->external) {
+        if (size > oldsize && my_mddev->external) {
                 /* need to check that all other rdevs with the same ->bdev
                  * do not overlap.  We need to unlock the mddev to avoid
                  * a deadlock.  We have already changed rdev->size, and if
@@ -2044,8 +2145,9 @@ rdev_size_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                                 if (test_bit(AllReserved, &rdev2->flags) ||
                                     (rdev->bdev == rdev2->bdev &&
                                      rdev != rdev2 &&
-                                     overlaps(rdev->data_offset, rdev->size,
-                                            rdev2->data_offset, rdev2->size))) {
+                                     overlaps(rdev->data_offset, rdev->size * 2,
+                                              rdev2->data_offset,
+                                              rdev2->size * 2))) {
                                         overlap = 1;
                                         break;
                                 }
@@ -2067,8 +2169,6 @@ rdev_size_store(mdk_rdev_t *rdev, const char *buf, size_t len)
                         return -EBUSY;
                 }
         }
-        if (size < my_mddev->size || my_mddev->size == 0)
-                my_mddev->size = size;
         return len;
 }
 
@@ -2512,7 +2612,7 @@ __ATTR(resync_start, S_IRUGO|S_IWUSR, resync_start_show, resync_start_store);
  *     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
+ *     Writing this, if accepted, will block until array is quiescent
  * readonly
  *     no resync can happen.  no superblocks get written.
  *     write requests fail
@@ -2585,7 +2685,7 @@ array_state_show(mddev_t *mddev, char *page)
         return sprintf(page, "%s\n", array_states[st]);
 }
 
-static int do_md_stop(mddev_t * mddev, int ro);
+static int do_md_stop(mddev_t * mddev, int ro, int is_open);
 static int do_md_run(mddev_t * mddev);
 static int restart_array(mddev_t *mddev);
 
@@ -2599,16 +2699,16 @@ array_state_store(mddev_t *mddev, const char *buf, size_t len)
                 break;
         case clear:
                 /* stopping an active array */
-                if (atomic_read(&mddev->active) > 1)
+                if (atomic_read(&mddev->openers) > 0)
                         return -EBUSY;
-                err = do_md_stop(mddev, 0);
+                err = do_md_stop(mddev, 0, 0);
                 break;
         case inactive:
                 /* stopping an active array */
                 if (mddev->pers) {
-                        if (atomic_read(&mddev->active) > 1)
+                        if (atomic_read(&mddev->openers) > 0)
                                 return -EBUSY;
-                        err = do_md_stop(mddev, 2);
+                        err = do_md_stop(mddev, 2, 0);
                 } else
                         err = 0; /* already inactive */
                 break;
@@ -2616,7 +2716,7 @@ array_state_store(mddev_t *mddev, const char *buf, size_t len)
                 break; /* not supported yet */
         case readonly:
                 if (mddev->pers)
-                        err = do_md_stop(mddev, 1);
+                        err = do_md_stop(mddev, 1, 0);
                 else {
                         mddev->ro = 1;
                         set_disk_ro(mddev->gendisk, 1);
@@ -2626,7 +2726,7 @@ array_state_store(mddev_t *mddev, const char *buf, size_t len)
         case read_auto:
                 if (mddev->pers) {
                         if (mddev->ro != 1)
-                                err = do_md_stop(mddev, 1);
+                                err = do_md_stop(mddev, 1, 0);
                         else
                                 err = restart_array(mddev);
                         if (err == 0) {
@@ -2681,8 +2781,10 @@ array_state_store(mddev_t *mddev, const char *buf, size_t len)
         }
         if (err)
                 return err;
-        else
+        else {
+                sysfs_notify(&mddev->kobj, NULL, "array_state");
                 return len;
+        }
 }
 static struct md_sysfs_entry md_array_state =
 __ATTR(array_state, S_IRUGO|S_IWUSR, array_state_show, array_state_store);
@@ -2785,7 +2887,7 @@ 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 int update_size(mddev_t *mddev, sector_t num_sectors);
 
 static ssize_t
 size_store(mddev_t *mddev, const char *buf, size_t len)
@@ -2802,7 +2904,7 @@ size_store(mddev_t *mddev, const char *buf, size_t len)
                 return -EINVAL;
 
         if (mddev->pers) {
-                err = update_size(mddev, size);
+                err = update_size(mddev, size * 2);
                 md_update_sb(mddev, 1);
         } else {
                 if (mddev->size == 0 ||
@@ -2899,7 +3001,7 @@ action_show(mddev_t *mddev, char *page)
                                 type = "check";
                         else
                                 type = "repair";
-                } else
+                } else if (test_bit(MD_RECOVERY_RECOVER, &mddev->recovery))
                         type = "recover";
         }
         return sprintf(page, "%s\n", type);
@@ -2921,15 +3023,19 @@ action_store(mddev_t *mddev, const char *page, size_t len)
         } 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"))
+        else if (cmd_match(page, "resync"))
+                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+        else if (cmd_match(page, "recover")) {
+                set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-        else if (cmd_match(page, "reshape")) {
+        } else if (cmd_match(page, "reshape")) {
                 int err;
                 if (mddev->pers->start_reshape == NULL)
                         return -EINVAL;
                 err = mddev->pers->start_reshape(mddev);
                 if (err)
                         return err;
+                sysfs_notify(&mddev->kobj, NULL, "degraded");
         } else {
                 if (cmd_match(page, "check"))
                         set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
@@ -2940,6 +3046,7 @@ action_store(mddev_t *mddev, const char *page, size_t len)
         }
         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
+        sysfs_notify(&mddev->kobj, NULL, "sync_action");
         return len;
 }
 
@@ -3049,11 +3156,11 @@ 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);
+        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 */
+        db = resync - mddev->resync_mark_cnt;
+        return sprintf(page, "%lu\n", db/dt/2); /* K/sec */
 }
 
 static struct md_sysfs_entry md_sync_speed = __ATTR_RO(sync_speed);
@@ -3075,6 +3182,36 @@ sync_completed_show(mddev_t *mddev, char *page)
 static struct md_sysfs_entry md_sync_completed = __ATTR_RO(sync_completed);
 
 static ssize_t
+min_sync_show(mddev_t *mddev, char *page)
+{
+        return sprintf(page, "%llu\n",
+                       (unsigned long long)mddev->resync_min);
+}
+static ssize_t
+min_sync_store(mddev_t *mddev, const char *buf, size_t len)
+{
+        unsigned long long min;
+        if (strict_strtoull(buf, 10, &min))
+                return -EINVAL;
+        if (min > mddev->resync_max)
+                return -EINVAL;
+        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+                return -EBUSY;
+
+        /* Must be a multiple of chunk_size */
+        if (mddev->chunk_size) {
+                if (min & (sector_t)((mddev->chunk_size>>9)-1))
+                        return -EINVAL;
+        }
+        mddev->resync_min = min;
+
+        return len;
+}
+
+static struct md_sysfs_entry md_min_sync =
+__ATTR(sync_min, S_IRUGO|S_IWUSR, min_sync_show, min_sync_store);
+
+static ssize_t
 max_sync_show(mddev_t *mddev, char *page)
 {
         if (mddev->resync_max == MaxSector)
@@ -3089,9 +3226,10 @@ max_sync_store(mddev_t *mddev, const char *buf, size_t len)
         if (strncmp(buf, "max", 3) == 0)
                 mddev->resync_max = MaxSector;
         else {
-                char *ep;
-                unsigned long long max = simple_strtoull(buf, &ep, 10);
-                if (ep == buf || (*ep != 0 && *ep != '\n'))
+                unsigned long long max;
+                if (strict_strtoull(buf, 10, &max))
+                        return -EINVAL;
+                if (max < mddev->resync_min)
                         return -EINVAL;
                 if (max < mddev->resync_max &&
                     test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
@@ -3222,6 +3360,7 @@ static struct attribute *md_redundancy_attrs[] = {
         &md_sync_speed.attr,
         &md_sync_force_parallel.attr,
         &md_sync_completed.attr,
+        &md_min_sync.attr,
         &md_max_sync.attr,
         &md_suspend_lo.attr,
         &md_suspend_hi.attr,
@@ -3326,9 +3465,9 @@ static struct kobject *md_probe(dev_t dev, int *part, void *data)
         disk->queue = mddev->queue;
         add_disk(disk);
         mddev->gendisk = disk;
-        mutex_unlock(&disks_mutex);
         error = kobject_init_and_add(&mddev->kobj, &md_ktype, &disk->dev.kobj,
                                      "%s", "md");
+        mutex_unlock(&disks_mutex);
         if (error)
                 printk(KERN_WARNING "md: cannot register %s/md - name in use\n",
                        disk->disk_name);
@@ -3341,7 +3480,11 @@ static void md_safemode_timeout(unsigned long data)
 {
         mddev_t *mddev = (mddev_t *) data;
 
-        mddev->safemode = 1;
+        if (!atomic_read(&mddev->writes_pending)) {
+                mddev->safemode = 1;
+                if (mddev->external)
+                        sysfs_notify(&mddev->kobj, NULL, "array_state");
+        }
         md_wakeup_thread(mddev->thread);
 }
 
@@ -3432,22 +3575,23 @@ static int do_md_run(mddev_t * mddev)
                  * We don't want the data to overlap the metadata,
                  * Internal Bitmap issues has handled elsewhere.
                  */
-                if (rdev->data_offset < rdev->sb_offset) {
+                if (rdev->data_offset < rdev->sb_start) {
                         if (mddev->size &&
                             rdev->data_offset + mddev->size*2
-                            > rdev->sb_offset*2) {
+                            > rdev->sb_start) {
                                 printk("md: %s: data overlaps metadata\n",
                                        mdname(mddev));
                                 return -EINVAL;
                         }
                 } else {
-                        if (rdev->sb_offset*2 + rdev->sb_size/512
+                        if (rdev->sb_start + rdev->sb_size/512
                             > rdev->data_offset) {
                                 printk("md: %s: metadata overlaps data\n",
                                        mdname(mddev));
                                 return -EINVAL;
                         }
                 }
+                sysfs_notify(&rdev->kobj, NULL, "state");
         }
 
         md_probe(mddev->unit, NULL, NULL);
@@ -3519,7 +3663,9 @@ static int do_md_run(mddev_t * mddev)
                 mddev->ro = 2; /* read-only, but switch on first write */
 
         err = mddev->pers->run(mddev);
-        if (!err && mddev->pers->sync_request) {
+        if (err)
+                printk(KERN_ERR "md: pers->run() failed ...\n");
+        else if (mddev->pers->sync_request) {
                 err = bitmap_create(mddev);
                 if (err) {
                         printk(KERN_ERR "%s: failed to create bitmap (%d)\n",
@@ -3528,7 +3674,6 @@ static int do_md_run(mddev_t * mddev)
                 }
         }
         if (err) {
-                printk(KERN_ERR "md: pers->run() failed ...\n");
                 module_put(mddev->pers->owner);
                 mddev->pers = NULL;
                 bitmap_destroy(mddev);
@@ -3563,7 +3708,7 @@ static int do_md_run(mddev_t * mddev)
         if (mddev->flags)
                 md_update_sb(mddev, 0);
 
-        set_capacity(disk, mddev->array_size<<1);
+        set_capacity(disk, mddev->array_sectors);
 
         /* If we call blk_queue_make_request here, it will
          * re-initialise max_sectors etc which may have been
@@ -3608,6 +3753,9 @@ static int do_md_run(mddev_t * mddev)
 
         mddev->changed = 1;
         md_new_event(mddev);
+        sysfs_notify(&mddev->kobj, NULL, "array_state");
+        sysfs_notify(&mddev->kobj, NULL, "sync_action");
+        sysfs_notify(&mddev->kobj, NULL, "degraded");
         kobject_uevent(&mddev->gendisk->dev.kobj, KOBJ_CHANGE);
         return 0;
 }
@@ -3615,38 +3763,25 @@ static int do_md_run(mddev_t * mddev)
 static int restart_array(mddev_t *mddev)
 {
         struct gendisk *disk = mddev->gendisk;
-        int err;
 
-        /*
-         * Complain if it has no devices
-         */
-        err = -ENXIO;
+        /* Complain if it has no devices */
         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;
+                return -ENXIO;
+        if (!mddev->pers)
+                return -EINVAL;
+        if (!mddev->ro)
+                return -EBUSY;
+        mddev->safemode = 0;
+        mddev->ro = 0;
+        set_disk_ro(disk, 0);
+        printk(KERN_INFO "md: %s switched to read-write mode.\n",
+                mdname(mddev));
+        /* Kick recovery or resync if necessary */
+        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+        md_wakeup_thread(mddev->thread);
+        md_wakeup_thread(mddev->sync_thread);
+        sysfs_notify(&mddev->kobj, NULL, "array_state");
+        return 0;
 }
 
 /* similar to deny_write_access, but accounts for our holding a reference
@@ -3680,16 +3815,17 @@ static void restore_bitmap_write_access(struct file *file)
  *   1 - switch to readonly
  *   2 - stop but do not disassemble array
  */
-static int do_md_stop(mddev_t * mddev, int mode)
+static int do_md_stop(mddev_t * mddev, int mode, int is_open)
 {
         int err = 0;
         struct gendisk *disk = mddev->gendisk;
 
+        if (atomic_read(&mddev->openers) > is_open) {
+                printk("md: %s still in use.\n",mdname(mddev));
+                return -EBUSY;
+        }
+
         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);
@@ -3773,10 +3909,11 @@ static int do_md_stop(mddev_t * mddev, int mode)
 
                 export_array(mddev);
 
-                mddev->array_size = 0;
+                mddev->array_sectors = 0;
                 mddev->size = 0;
                 mddev->raid_disks = 0;
                 mddev->recovery_cp = 0;
+                mddev->resync_min = 0;
                 mddev->resync_max = MaxSector;
                 mddev->reshape_position = MaxSector;
                 mddev->external = 0;
@@ -3811,6 +3948,7 @@ static int do_md_stop(mddev_t * mddev, int mode)
                         mdname(mddev));
         err = 0;
         md_new_event(mddev);
+        sysfs_notify(&mddev->kobj, NULL, "array_state");
 out:
         return err;
 }
@@ -3836,7 +3974,7 @@ static void autorun_array(mddev_t *mddev)
         err = do_md_run (mddev);
         if (err) {
                 printk(KERN_WARNING "md: do_md_run() returned %d\n", err);
-                do_md_stop (mddev, 0);
+                do_md_stop (mddev, 0, 0);
         }
 }
 
@@ -3927,8 +4065,10 @@ static void autorun_devices(int part)
                 /* on success, candidates will be empty, on error
                  * it won't...
                  */
-                rdev_for_each_list(rdev, tmp, candidates)
+                rdev_for_each_list(rdev, tmp, candidates) {
+                        list_del_init(&rdev->same_set);
                         export_rdev(rdev);
+                }
                 mddev_put(mddev);
         }
         printk(KERN_INFO "md: ... autorun DONE.\n");
@@ -4009,9 +4149,11 @@ static int get_bitmap_file(mddev_t * mddev, void __user * arg)
         char *ptr, *buf = NULL;
         int err = -ENOMEM;
 
-        md_allow_write(mddev);
+        if (md_allow_write(mddev))
+                file = kmalloc(sizeof(*file), GFP_NOIO);
+        else
+                file = kmalloc(sizeof(*file), GFP_KERNEL);
 
-        file = kmalloc(sizeof(*file), GFP_KERNEL);
         if (!file)
                 goto out;
 
@@ -4044,15 +4186,12 @@ out:
 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);
+        rdev = find_rdev_nr(mddev, info.number);
         if (rdev) {
                 info.major = MAJOR(rdev->bdev->bd_dev);
                 info.minor = MINOR(rdev->bdev->bd_dev);
@@ -4172,8 +4311,12 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
                 }
                 if (err)
                         export_rdev(rdev);
+                else
+                        sysfs_notify(&rdev->kobj, NULL, "state");
 
                 md_update_sb(mddev, 1);
+                if (mddev->degraded)
+                        set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                 md_wakeup_thread(mddev->thread);
                 return err;
@@ -4212,10 +4355,10 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
 
                 if (!mddev->persistent) {
                         printk(KERN_INFO "md: nonpersistent superblock ...\n");
-                        rdev->sb_offset = rdev->bdev->bd_inode->i_size >> BLOCK_SIZE_BITS;
+                        rdev->sb_start = rdev->bdev->bd_inode->i_size / 512;
                 } else 
-                        rdev->sb_offset = calc_dev_sboffset(rdev->bdev);
-                rdev->size = calc_dev_size(rdev, mddev->chunk_size);
+                        rdev->sb_start = calc_dev_sboffset(rdev->bdev);
+                rdev->size = calc_num_sectors(rdev, mddev->chunk_size) / 2;
 
                 err = bind_rdev_to_array(rdev, mddev);
                 if (err) {
@@ -4232,9 +4375,6 @@ 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;
@@ -4257,7 +4397,6 @@ 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)
@@ -4285,13 +4424,11 @@ static int hot_add_disk(mddev_t * mddev, dev_t dev)
         }
 
         if (mddev->persistent)
-                rdev->sb_offset = calc_dev_sboffset(rdev->bdev);
+                rdev->sb_start = calc_dev_sboffset(rdev->bdev);
         else
-                rdev->sb_offset =
-                        rdev->bdev->bd_inode->i_size >> BLOCK_SIZE_BITS;
+                rdev->sb_start = rdev->bdev->bd_inode->i_size / 512;
 
-        size = calc_dev_size(rdev, mddev->chunk_size);
-        rdev->size = size;
+        rdev->size = calc_num_sectors(rdev, mddev->chunk_size) / 2;
 
         if (test_bit(Faulty, &rdev->flags)) {
                 printk(KERN_WARNING 
@@ -4476,24 +4613,24 @@ static int set_array_info(mddev_t * mddev, mdu_array_info_t *info)
         return 0;
 }
 
-static int update_size(mddev_t *mddev, unsigned long size)
+static int update_size(mddev_t *mddev, sector_t num_sectors)
 {
         mdk_rdev_t * rdev;
         int rv;
         struct list_head *tmp;
-        int fit = (size == 0);
+        int fit = (num_sectors == 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.
+        /* The "num_sectors" is the number of sectors of each device that
+         * is used.  This can only make sense for arrays with redundancy.
+         * linear and raid0 always use whatever space is available. We can only
+         * consider changing this number if no resync or reconstruction is
+         * happening, and if the new size is acceptable. It must fit before the
+         * sb_start or, if that is <data_offset, it must fit before the size
+         * of each device.  If num_sectors is zero, we find the largest size
+         * that fits.
+
          */
         if (mddev->sync_thread)
                 return -EBUSY;
@@ -4501,19 +4638,20 @@ static int update_size(mddev_t *mddev, unsigned long size)
                 sector_t avail;
                 avail = rdev->size * 2;
 
-                if (fit && (size == 0 || size > avail/2))
-                        size = avail/2;
-                if (avail < ((sector_t)size << 1))
+                if (fit && (num_sectors == 0 || num_sectors > avail))
+                        num_sectors = avail;
+                if (avail < num_sectors)
                         return -ENOSPC;
         }
-        rv = mddev->pers->resize(mddev, (sector_t)size *2);
+        rv = mddev->pers->resize(mddev, num_sectors);
         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);
+                        i_size_write(bdev->bd_inode,
+                                     (loff_t)mddev->array_sectors << 9);
                         mutex_unlock(&bdev->bd_inode->i_mutex);
                         bdput(bdev);
                 }
@@ -4588,7 +4726,7 @@ static int update_array_info(mddev_t *mddev, mdu_array_info_t *info)
                         return mddev->pers->reconfig(mddev, info->layout, -1);
         }
         if (info->size >= 0 && mddev->size != info->size)
-                rv = update_size(mddev, info->size);
+                rv = update_size(mddev, (sector_t)info->size * 2);
 
         if (mddev->raid_disks    != info->raid_disks)
                 rv = update_raid_disks(mddev, info->raid_disks);
@@ -4641,6 +4779,12 @@ static int set_disk_faulty(mddev_t *mddev, dev_t dev)
         return 0;
 }
 
+/*
+ * We have a problem here : there is no easy way to give a CHS
+ * virtual geometry. We currently pretend that we have a 2 heads
+ * 4 sectors (with a BIG number of cylinders...). This drives
+ * dosfs just mad... ;-)
+ */
 static int md_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {
         mddev_t *mddev = bdev->bd_disk->private_data;
@@ -4785,19 +4929,13 @@ static int md_ioctl(struct inode *inode, struct file *file,
                         goto done_unlock;
 
                 case STOP_ARRAY:
-                        err = do_md_stop (mddev, 0);
+                        err = do_md_stop (mddev, 0, 1);
                         goto done_unlock;
 
                 case STOP_ARRAY_RO:
-                        err = do_md_stop (mddev, 1);
+                        err = do_md_stop (mddev, 1, 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... ;-)
-         */
         }
 
         /*
@@ -4807,13 +4945,12 @@ static int md_ioctl(struct inode *inode, struct file *file,
          * 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 (_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);
-
+                        sysfs_notify(&mddev->kobj, NULL, "array_state");
+                        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+                        md_wakeup_thread(mddev->thread);
                 } else {
                         err = -EROFS;
                         goto abort_unlock;
@@ -4883,6 +5020,7 @@ static int md_open(struct inode *inode, struct file *file)
 
         err = 0;
         mddev_get(mddev);
+        atomic_inc(&mddev->openers);
         mddev_unlock(mddev);
 
         check_disk_change(inode->i_bdev);
@@ -4895,6 +5033,7 @@ static int md_release(struct inode *inode, struct file * file)
         mddev_t *mddev = inode->i_bdev->bd_disk->private_data;
 
         BUG_ON(!mddev);
+        atomic_dec(&mddev->openers);
         mddev_put(mddev);
 
         return 0;
@@ -5029,6 +5168,9 @@ void md_error(mddev_t *mddev, mdk_rdev_t *rdev)
         if (!mddev->pers->error_handler)
                 return;
         mddev->pers->error_handler(mddev,rdev);
+        if (mddev->degraded)
+                set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+        set_bit(StateChanged, &rdev->flags);
         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
@@ -5258,10 +5400,11 @@ static int md_seq_show(struct seq_file *seq, void *v)
                 if (!list_empty(&mddev->disks)) {
                         if (mddev->pers)
                                 seq_printf(seq, "\n      %llu blocks",
-                                        (unsigned long long)mddev->array_size);
+                                           (unsigned long long)
+                                           mddev->array_sectors / 2);
                         else
                                 seq_printf(seq, "\n      %llu blocks",
-                                        (unsigned long long)size);
+                                           (unsigned long long)size);
                 }
                 if (mddev->persistent) {
                         if (mddev->major_version != 0 ||
@@ -5391,12 +5534,12 @@ int unregister_md_personality(struct mdk_personality *p)
 static int is_mddev_idle(mddev_t *mddev)
 {
         mdk_rdev_t * rdev;
-        struct list_head *tmp;
         int idle;
         long curr_events;
 
         idle = 1;
-        rdev_for_each(rdev, tmp, mddev) {
+        rcu_read_lock();
+        rdev_for_each_rcu(rdev, mddev) {
                 struct gendisk *disk = rdev->bdev->bd_contains->bd_disk;
                 curr_events = disk_stat_read(disk, sectors[0]) + 
                                 disk_stat_read(disk, sectors[1]) - 
@@ -5428,6 +5571,7 @@ static int is_mddev_idle(mddev_t *mddev)
                         idle = 0;
                 }
         }
+        rcu_read_unlock();
         return idle;
 }
 
@@ -5451,6 +5595,7 @@ void md_done_sync(mddev_t *mddev, int blocks, int ok)
  */
 void md_write_start(mddev_t *mddev, struct bio *bi)
 {
+        int did_change = 0;
         if (bio_data_dir(bi) != WRITE)
                 return;
 
@@ -5461,6 +5606,7 @@ void md_write_start(mddev_t *mddev, struct bio *bi)
                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                 md_wakeup_thread(mddev->thread);
                 md_wakeup_thread(mddev->sync_thread);
+                did_change = 1;
         }
         atomic_inc(&mddev->writes_pending);
         if (mddev->safemode == 1)
@@ -5471,10 +5617,12 @@ void md_write_start(mddev_t *mddev, struct bio *bi)
                         mddev->in_sync = 0;
                         set_bit(MD_CHANGE_CLEAN, &mddev->flags);
                         md_wakeup_thread(mddev->thread);
+                        did_change = 1;
                 }
                 spin_unlock_irq(&mddev->write_lock);
-                sysfs_notify(&mddev->kobj, NULL, "array_state");
         }
+        if (did_change)
+                sysfs_notify(&mddev->kobj, NULL, "array_state");
         wait_event(mddev->sb_wait,
                    !test_bit(MD_CHANGE_CLEAN, &mddev->flags) &&
                    !test_bit(MD_CHANGE_PENDING, &mddev->flags));
@@ -5495,13 +5643,18 @@ void md_write_end(mddev_t *mddev)
  * may proceed without blocking.  It is important to call this before
  * attempting a GFP_KERNEL allocation while holding the mddev lock.
  * Must be called with mddev_lock held.
+ *
+ * In the ->external case MD_CHANGE_CLEAN can not be cleared until mddev->lock
+ * is dropped, so return -EAGAIN after notifying userspace.
  */
-void md_allow_write(mddev_t *mddev)
+int md_allow_write(mddev_t *mddev)
 {
         if (!mddev->pers)
-                return;
+                return 0;
         if (mddev->ro)
-                return;
+                return 0;
+        if (!mddev->pers->sync_request)
+                return 0;
 
         spin_lock_irq(&mddev->write_lock);
         if (mddev->in_sync) {
@@ -5512,14 +5665,14 @@ void md_allow_write(mddev_t *mddev)
                         mddev->safemode = 1;
                 spin_unlock_irq(&mddev->write_lock);
                 md_update_sb(mddev, 0);
-
                 sysfs_notify(&mddev->kobj, NULL, "array_state");
-                /* wait for the dirty state to be recorded in the metadata */
-                wait_event(mddev->sb_wait,
-                           !test_bit(MD_CHANGE_CLEAN, &mddev->flags) &&
-                           !test_bit(MD_CHANGE_PENDING, &mddev->flags));
         } else
                 spin_unlock_irq(&mddev->write_lock);
+
+        if (test_bit(MD_CHANGE_CLEAN, &mddev->flags))
+                return -EAGAIN;
+        else
+                return 0;
 }
 EXPORT_SYMBOL_GPL(md_allow_write);
 
@@ -5625,9 +5778,11 @@ void md_do_sync(mddev_t *mddev)
                 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))
+                if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+                        j = mddev->resync_min;
+                else if (!mddev->bitmap)
                         j = mddev->recovery_cp;
+
         } else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
                 max_sectors = mddev->size << 1;
         else {
@@ -5796,6 +5951,7 @@ void md_do_sync(mddev_t *mddev)
 
  skip:
         mddev->curr_resync = 0;
+        mddev->resync_min = 0;
         mddev->resync_max = MaxSector;
         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
         wake_up(&resync_wait);
@@ -5845,7 +6001,8 @@ static int remove_and_add_spares(mddev_t *mddev)
                         if (rdev->raid_disk < 0
                             && !test_bit(Faulty, &rdev->flags)) {
                                 rdev->recovery_offset = 0;
-                                if (mddev->pers->hot_add_disk(mddev,rdev)) {
+                                if (mddev->pers->
+                                    hot_add_disk(mddev, rdev) == 0) {
                                         char nm[20];
                                         sprintf(nm, "rd%d", rdev->raid_disk);
                                         if (sysfs_create_link(&mddev->kobj,
@@ -5920,23 +6077,31 @@ void md_check_recovery(mddev_t *mddev)
                 int spares = 0;
 
                 if (!mddev->external) {
+                        int did_change = 0;
                         spin_lock_irq(&mddev->write_lock);
                         if (mddev->safemode &&
                             !atomic_read(&mddev->writes_pending) &&
                             !mddev->in_sync &&
                             mddev->recovery_cp == MaxSector) {
                                 mddev->in_sync = 1;
+                                did_change = 1;
                                 if (mddev->persistent)
                                         set_bit(MD_CHANGE_CLEAN, &mddev->flags);
                         }
                         if (mddev->safemode == 1)
                                 mddev->safemode = 0;
                         spin_unlock_irq(&mddev->write_lock);
+                        if (did_change)
+                                sysfs_notify(&mddev->kobj, NULL, "array_state");
                 }
 
                 if (mddev->flags)
                         md_update_sb(mddev, 0);
 
+                rdev_for_each(rdev, rtmp, mddev)
+                        if (test_and_clear_bit(StateChanged, &rdev->flags))
+                                sysfs_notify(&rdev->kobj, NULL, "state");
+
 
                 if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
                     !test_bit(MD_RECOVERY_DONE, &mddev->recovery)) {
@@ -5951,7 +6116,9 @@ void md_check_recovery(mddev_t *mddev)
                         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
                                 /* success...*/
                                 /* activate any spares */
-                                mddev->pers->spare_active(mddev);
+                                if (mddev->pers->spare_active(mddev))
+                                        sysfs_notify(&mddev->kobj, NULL,
+                                                     "degraded");
                         }
                         md_update_sb(mddev, 1);
 
@@ -5965,13 +6132,18 @@ void md_check_recovery(mddev_t *mddev)
                         mddev->recovery = 0;
                         /* flag recovery needed just to double check */
                         set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+                        sysfs_notify(&mddev->kobj, NULL, "sync_action");
                         md_new_event(mddev);
                         goto unlock;
                 }
+                /* Set RUNNING before clearing NEEDED to avoid
+                 * any transients in the value of "sync_action".
+                 */
+                set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+                clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                 /* Clear some bits that don't mean anything, but
                  * might be left set
                  */
-                clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                 clear_bit(MD_RECOVERY_INTR, &mddev->recovery);
                 clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
 
@@ -5989,17 +6161,19 @@ void md_check_recovery(mddev_t *mddev)
                                 /* Cannot proceed */
                                 goto unlock;
                         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
+                        clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
                 } else if ((spares = remove_and_add_spares(mddev))) {
                         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
                         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+                        set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
                 } else if (mddev->recovery_cp < MaxSector) {
                         set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+                        clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
                 } else if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
                         /* nothing to be done ... */
                         goto unlock;
 
                 if (mddev->pers->sync_request) {
-                        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.
@@ -6018,9 +6192,16 @@ void md_check_recovery(mddev_t *mddev)
                                 mddev->recovery = 0;
                         } else
                                 md_wakeup_thread(mddev->sync_thread);
+                        sysfs_notify(&mddev->kobj, NULL, "sync_action");
                         md_new_event(mddev);
                 }
         unlock:
+                if (!mddev->sync_thread) {
+                        clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+                        if (test_and_clear_bit(MD_RECOVERY_RECOVER,
+                                               &mddev->recovery))
+                                sysfs_notify(&mddev->kobj, NULL, "sync_action");
+                }
                 mddev_unlock(mddev);
         }
 }
@@ -6047,7 +6228,7 @@ static int md_notify_reboot(struct notifier_block *this,
 
                 for_each_mddev(mddev, tmp)
                         if (mddev_trylock(mddev)) {
-                                do_md_stop (mddev, 1);
+                                do_md_stop (mddev, 1, 0);
                                 mddev_unlock(mddev);
                         }
                 /*
diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index e968116e0de9..c4779ccba1c3 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -281,13 +281,18 @@ static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
 {
         multipath_conf_t *conf = mddev->private;
         struct request_queue *q;
-        int found = 0;
+        int err = -EEXIST;
         int path;
         struct multipath_info *p;
+        int first = 0;
+        int last = mddev->raid_disks - 1;
+
+        if (rdev->raid_disk >= 0)
+                first = last = rdev->raid_disk;
 
         print_multipath_conf(conf);
 
-        for (path=0; path<mddev->raid_disks; path++) 
+        for (path = first; path <= last; path++)
                 if ((p=conf->multipaths+path)->rdev == NULL) {
                         q = rdev->bdev->bd_disk->queue;
                         blk_queue_stack_limits(mddev->queue, q);
@@ -307,11 +312,13 @@ static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
                         rdev->raid_disk = path;
                         set_bit(In_sync, &rdev->flags);
                         rcu_assign_pointer(p->rdev, rdev);
-                        found = 1;
+                        err = 0;
+                        break;
                 }
 
         print_multipath_conf(conf);
-        return found;
+
+        return err;
 }
 
 static int multipath_remove_disk(mddev_t *mddev, int number)
@@ -497,7 +504,7 @@ static int multipath_run (mddev_t *mddev)
         /*
          * Ok, everything is just fine now
          */
-        mddev->array_size = mddev->size;
+        mddev->array_sectors = mddev->size * 2;
 
         mddev->queue->unplug_fn = multipath_unplug;
         mddev->queue->backing_dev_info.congested_fn = multipath_congested;
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index bcbb82594a19..183610635661 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -295,16 +295,16 @@ static int raid0_run (mddev_t *mddev)
                 goto out_free_conf;
 
         /* calculate array device size */
-        mddev->array_size = 0;
+        mddev->array_sectors = 0;
         rdev_for_each(rdev, tmp, mddev)
-                mddev->array_size += rdev->size;
+                mddev->array_sectors += rdev->size * 2;
 
         printk("raid0 : md_size is %llu blocks.\n", 
-                (unsigned long long)mddev->array_size);
+                (unsigned long long)mddev->array_sectors / 2);
         printk("raid0 : conf->hash_spacing is %llu blocks.\n",
                 (unsigned long long)conf->hash_spacing);
         {
-                sector_t s = mddev->array_size;
+                sector_t s = mddev->array_sectors / 2;
                 sector_t space = conf->hash_spacing;
                 int round;
                 conf->preshift = 0;
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index c610b947218a..03a5ab705c20 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1100,11 +1100,16 @@ static int raid1_spare_active(mddev_t *mddev)
 static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
 {
         conf_t *conf = mddev->private;
-        int found = 0;
+        int err = -EEXIST;
         int mirror = 0;
         mirror_info_t *p;
+        int first = 0;
+        int last = mddev->raid_disks - 1;
 
-        for (mirror=0; mirror < mddev->raid_disks; mirror++)
+        if (rdev->raid_disk >= 0)
+                first = last = rdev->raid_disk;
+
+        for (mirror = first; mirror <= last; mirror++)
                 if ( !(p=conf->mirrors+mirror)->rdev) {
 
                         blk_queue_stack_limits(mddev->queue,
@@ -1119,7 +1124,7 @@ static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
 
                         p->head_position = 0;
                         rdev->raid_disk = mirror;
-                        found = 1;
+                        err = 0;
                         /* As all devices are equivalent, we don't need a full recovery
                          * if this was recently any drive of the array
                          */
@@ -1130,7 +1135,7 @@ static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
                 }
 
         print_conf(conf);
-        return found;
+        return err;
 }
 
 static int raid1_remove_disk(mddev_t *mddev, int number)
@@ -2038,7 +2043,7 @@ static int run(mddev_t *mddev)
         /*
          * Ok, everything is just fine now
          */
-        mddev->array_size = mddev->size;
+        mddev->array_sectors = mddev->size * 2;
 
         mddev->queue->unplug_fn = raid1_unplug;
         mddev->queue->backing_dev_info.congested_fn = raid1_congested;
@@ -2100,14 +2105,15 @@ static int raid1_resize(mddev_t *mddev, sector_t sectors)
          * any io in the removed space completes, but it hardly seems
          * worth it.
          */
-        mddev->array_size = sectors>>1;
-        set_capacity(mddev->gendisk, mddev->array_size << 1);
+        mddev->array_sectors = sectors;
+        set_capacity(mddev->gendisk, mddev->array_sectors);
         mddev->changed = 1;
-        if (mddev->array_size > mddev->size && mddev->recovery_cp == MaxSector) {
+        if (mddev->array_sectors / 2 > mddev->size &&
+            mddev->recovery_cp == MaxSector) {
                 mddev->recovery_cp = mddev->size << 1;
                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
         }
-        mddev->size = mddev->array_size;
+        mddev->size = mddev->array_sectors / 2;
         mddev->resync_max_sectors = sectors;
         return 0;
 }
@@ -2131,7 +2137,7 @@ static int raid1_reshape(mddev_t *mddev)
         conf_t *conf = mddev_to_conf(mddev);
         int cnt, raid_disks;
         unsigned long flags;
-        int d, d2;
+        int d, d2, err;
 
         /* Cannot change chunk_size, layout, or level */
         if (mddev->chunk_size != mddev->new_chunk ||
@@ -2143,7 +2149,9 @@ static int raid1_reshape(mddev_t *mddev)
                 return -EINVAL;
         }
 
-        md_allow_write(mddev);
+        err = md_allow_write(mddev);
+        if (err)
+                return err;
 
         raid_disks = mddev->raid_disks + mddev->delta_disks;
 
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 22bb2b1b886d..159535d73567 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1114,24 +1114,30 @@ static int raid10_spare_active(mddev_t *mddev)
 static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
 {
         conf_t *conf = mddev->private;
-        int found = 0;
+        int err = -EEXIST;
         int mirror;
         mirror_info_t *p;
+        int first = 0;
+        int last = mddev->raid_disks - 1;
 
         if (mddev->recovery_cp < MaxSector)
                 /* only hot-add to in-sync arrays, as recovery is
                  * very different from resync
                  */
-                return 0;
+                return -EBUSY;
         if (!enough(conf))
-                return 0;
+                return -EINVAL;
+
+        if (rdev->raid_disk)
+                first = last = rdev->raid_disk;
 
         if (rdev->saved_raid_disk >= 0 &&
+            rdev->saved_raid_disk >= first &&
             conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
                 mirror = rdev->saved_raid_disk;
         else
-                mirror = 0;
-        for ( ; mirror < mddev->raid_disks; mirror++)
+                mirror = first;
+        for ( ; mirror <= last ; mirror++)
                 if ( !(p=conf->mirrors+mirror)->rdev) {
 
                         blk_queue_stack_limits(mddev->queue,
@@ -1146,7 +1152,7 @@ static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
 
                         p->head_position = 0;
                         rdev->raid_disk = mirror;
-                        found = 1;
+                        err = 0;
                         if (rdev->saved_raid_disk != mirror)
                                 conf->fullsync = 1;
                         rcu_assign_pointer(p->rdev, rdev);
@@ -1154,7 +1160,7 @@ static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
                 }
 
         print_conf(conf);
-        return found;
+        return err;
 }
 
 static int raid10_remove_disk(mddev_t *mddev, int number)
@@ -2159,7 +2165,7 @@ static int run(mddev_t *mddev)
         /*
          * Ok, everything is just fine now
          */
-        mddev->array_size = size << (conf->chunk_shift-1);
+        mddev->array_sectors = size << conf->chunk_shift;
         mddev->resync_max_sectors = size << conf->chunk_shift;
 
         mddev->queue->unplug_fn = raid10_unplug;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 9ce7154845c6..55e7c56045a0 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -115,15 +115,20 @@ static void return_io(struct bio *return_bi)
                 return_bi = bi->bi_next;
                 bi->bi_next = NULL;
                 bi->bi_size = 0;
-                bi->bi_end_io(bi,
-                              test_bit(BIO_UPTODATE, &bi->bi_flags)
-                                ? 0 : -EIO);
+                bio_endio(bi, 0);
                 bi = return_bi;
         }
 }
 
 static void print_raid5_conf (raid5_conf_t *conf);
 
+static int stripe_operations_active(struct stripe_head *sh)
+{
+        return sh->check_state || sh->reconstruct_state ||
+               test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
+               test_bit(STRIPE_COMPUTE_RUN, &sh->state);
+}
+
 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
 {
         if (atomic_dec_and_test(&sh->count)) {
@@ -143,7 +148,7 @@ static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
                         }
                         md_wakeup_thread(conf->mddev->thread);
                 } else {
-                        BUG_ON(sh->ops.pending);
+                        BUG_ON(stripe_operations_active(sh));
                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
                                 atomic_dec(&conf->preread_active_stripes);
                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
@@ -245,7 +250,7 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int
 
         BUG_ON(atomic_read(&sh->count) != 0);
         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
-        BUG_ON(sh->ops.pending || sh->ops.ack || sh->ops.complete);
+        BUG_ON(stripe_operations_active(sh));
 
         CHECK_DEVLOCK();
         pr_debug("init_stripe called, stripe %llu\n",
@@ -346,62 +351,18 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
         return sh;
 }
 
-/* test_and_ack_op() ensures that we only dequeue an operation once */
-#define test_and_ack_op(op, pend) \
-do {                                                    \
-        if (test_bit(op, &sh->ops.pending) &&           \
-                !test_bit(op, &sh->ops.complete)) {     \
-                if (test_and_set_bit(op, &sh->ops.ack)) \
-                        clear_bit(op, &pend);           \
-                else                                    \
-                        ack++;                          \
-        } else                                          \
-                clear_bit(op, &pend);                   \
-} while (0)
-
-/* find new work to run, do not resubmit work that is already
- * in flight
- */
-static unsigned long get_stripe_work(struct stripe_head *sh)
-{
-        unsigned long pending;
-        int ack = 0;
-
-        pending = sh->ops.pending;
-
-        test_and_ack_op(STRIPE_OP_BIOFILL, pending);
-        test_and_ack_op(STRIPE_OP_COMPUTE_BLK, pending);
-        test_and_ack_op(STRIPE_OP_PREXOR, pending);
-        test_and_ack_op(STRIPE_OP_BIODRAIN, pending);
-        test_and_ack_op(STRIPE_OP_POSTXOR, pending);
-        test_and_ack_op(STRIPE_OP_CHECK, pending);
-        if (test_and_clear_bit(STRIPE_OP_IO, &sh->ops.pending))
-                ack++;
-
-        sh->ops.count -= ack;
-        if (unlikely(sh->ops.count < 0)) {
-                printk(KERN_ERR "pending: %#lx ops.pending: %#lx ops.ack: %#lx "
-                        "ops.complete: %#lx\n", pending, sh->ops.pending,
-                        sh->ops.ack, sh->ops.complete);
-                BUG();
-        }
-
-        return pending;
-}
-
 static void
 raid5_end_read_request(struct bio *bi, int error);
 static void
 raid5_end_write_request(struct bio *bi, int error);
 
-static void ops_run_io(struct stripe_head *sh)
+static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 {
         raid5_conf_t *conf = sh->raid_conf;
         int i, disks = sh->disks;
 
         might_sleep();
 
-        set_bit(STRIPE_IO_STARTED, &sh->state);
         for (i = disks; i--; ) {
                 int rw;
                 struct bio *bi;
@@ -430,11 +391,11 @@ static void ops_run_io(struct stripe_head *sh)
                 rcu_read_unlock();
 
                 if (rdev) {
-                        if (test_bit(STRIPE_SYNCING, &sh->state) ||
-                                test_bit(STRIPE_EXPAND_SOURCE, &sh->state) ||
-                                test_bit(STRIPE_EXPAND_READY, &sh->state))
+                        if (s->syncing || s->expanding || s->expanded)
                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
 
+                        set_bit(STRIPE_IO_STARTED, &sh->state);
+
                         bi->bi_bdev = rdev->bdev;
                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
                                 __func__, (unsigned long long)sh->sector,
@@ -528,38 +489,34 @@ static void ops_complete_biofill(void *stripe_head_ref)
                 (unsigned long long)sh->sector);
 
         /* clear completed biofills */
+        spin_lock_irq(&conf->device_lock);
         for (i = sh->disks; i--; ) {
                 struct r5dev *dev = &sh->dev[i];
 
                 /* acknowledge completion of a biofill operation */
                 /* and check if we need to reply to a read request,
                  * new R5_Wantfill requests are held off until
-                 * !test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending)
+                 * !STRIPE_BIOFILL_RUN
                  */
                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
                         struct bio *rbi, *rbi2;
 
-                        /* The access to dev->read is outside of the
-                         * spin_lock_irq(&conf->device_lock), but is protected
-                         * by the STRIPE_OP_BIOFILL pending bit
-                         */
                         BUG_ON(!dev->read);
                         rbi = dev->read;
                         dev->read = NULL;
                         while (rbi && rbi->bi_sector <
                                 dev->sector + STRIPE_SECTORS) {
                                 rbi2 = r5_next_bio(rbi, dev->sector);
-                                spin_lock_irq(&conf->device_lock);
                                 if (--rbi->bi_phys_segments == 0) {
                                         rbi->bi_next = return_bi;
                                         return_bi = rbi;
                                 }
-                                spin_unlock_irq(&conf->device_lock);
                                 rbi = rbi2;
                         }
                 }
         }
-        set_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
+        spin_unlock_irq(&conf->device_lock);
+        clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
 
         return_io(return_bi);
 
@@ -610,13 +567,14 @@ static void ops_complete_compute5(void *stripe_head_ref)
         set_bit(R5_UPTODATE, &tgt->flags);
         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
         clear_bit(R5_Wantcompute, &tgt->flags);
-        set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
+        clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
+        if (sh->check_state == check_state_compute_run)
+                sh->check_state = check_state_compute_result;
         set_bit(STRIPE_HANDLE, &sh->state);
         release_stripe(sh);
 }
 
-static struct dma_async_tx_descriptor *
-ops_run_compute5(struct stripe_head *sh, unsigned long pending)
+static struct dma_async_tx_descriptor *ops_run_compute5(struct stripe_head *sh)
 {
         /* kernel stack size limits the total number of disks */
         int disks = sh->disks;
@@ -646,10 +604,6 @@ ops_run_compute5(struct stripe_head *sh, unsigned long pending)
                         ASYNC_TX_XOR_ZERO_DST, NULL,
                         ops_complete_compute5, sh);
 
-        /* ack now if postxor is not set to be run */
-        if (tx && !test_bit(STRIPE_OP_POSTXOR, &pending))
-                async_tx_ack(tx);
-
         return tx;
 }
 
@@ -659,8 +613,6 @@ static void ops_complete_prexor(void *stripe_head_ref)
 
         pr_debug("%s: stripe %llu\n", __func__,
                 (unsigned long long)sh->sector);
-
-        set_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
 }
 
 static struct dma_async_tx_descriptor *
@@ -680,7 +632,7 @@ ops_run_prexor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
         for (i = disks; i--; ) {
                 struct r5dev *dev = &sh->dev[i];
                 /* Only process blocks that are known to be uptodate */
-                if (dev->towrite && test_bit(R5_Wantprexor, &dev->flags))
+                if (test_bit(R5_Wantdrain, &dev->flags))
                         xor_srcs[count++] = dev->page;
         }
 
@@ -692,16 +644,10 @@ ops_run_prexor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
 }
 
 static struct dma_async_tx_descriptor *
-ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
-                 unsigned long pending)
+ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
 {
         int disks = sh->disks;
-        int pd_idx = sh->pd_idx, i;
-
-        /* check if prexor is active which means only process blocks
-         * that are part of a read-modify-write (Wantprexor)
-         */
-        int prexor = test_bit(STRIPE_OP_PREXOR, &pending);
+        int i;
 
         pr_debug("%s: stripe %llu\n", __func__,
                 (unsigned long long)sh->sector);
@@ -709,20 +655,8 @@ ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
         for (i = disks; i--; ) {
                 struct r5dev *dev = &sh->dev[i];
                 struct bio *chosen;
-                int towrite;
-
-                towrite = 0;
-                if (prexor) { /* rmw */
-                        if (dev->towrite &&
-                            test_bit(R5_Wantprexor, &dev->flags))
-                                towrite = 1;
-                } else { /* rcw */
-                        if (i != pd_idx && dev->towrite &&
-                                test_bit(R5_LOCKED, &dev->flags))
-                                towrite = 1;
-                }
 
-                if (towrite) {
+                if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
                         struct bio *wbi;
 
                         spin_lock(&sh->lock);
@@ -747,18 +681,6 @@ ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
 static void ops_complete_postxor(void *stripe_head_ref)
 {
         struct stripe_head *sh = stripe_head_ref;
-
-        pr_debug("%s: stripe %llu\n", __func__,
-                (unsigned long long)sh->sector);
-
-        set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
-        set_bit(STRIPE_HANDLE, &sh->state);
-        release_stripe(sh);
-}
-
-static void ops_complete_write(void *stripe_head_ref)
-{
-        struct stripe_head *sh = stripe_head_ref;
         int disks = sh->disks, i, pd_idx = sh->pd_idx;
 
         pr_debug("%s: stripe %llu\n", __func__,
@@ -770,16 +692,21 @@ static void ops_complete_write(void *stripe_head_ref)
                         set_bit(R5_UPTODATE, &dev->flags);
         }
 
-        set_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
-        set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
+        if (sh->reconstruct_state == reconstruct_state_drain_run)
+                sh->reconstruct_state = reconstruct_state_drain_result;
+        else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
+                sh->reconstruct_state = reconstruct_state_prexor_drain_result;
+        else {
+                BUG_ON(sh->reconstruct_state != reconstruct_state_run);
+                sh->reconstruct_state = reconstruct_state_result;
+        }
 
         set_bit(STRIPE_HANDLE, &sh->state);
         release_stripe(sh);
 }
 
 static void
-ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
-                unsigned long pending)
+ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
 {
         /* kernel stack size limits the total number of disks */
         int disks = sh->disks;
@@ -787,9 +714,8 @@ ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
 
         int count = 0, pd_idx = sh->pd_idx, i;
         struct page *xor_dest;
-        int prexor = test_bit(STRIPE_OP_PREXOR, &pending);
+        int prexor = 0;
         unsigned long flags;
-        dma_async_tx_callback callback;
 
         pr_debug("%s: stripe %llu\n", __func__,
                 (unsigned long long)sh->sector);
@@ -797,7 +723,8 @@ ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
         /* check if prexor is active which means only process blocks
          * that are part of a read-modify-write (written)
          */
-        if (prexor) {
+        if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
+                prexor = 1;
                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
                 for (i = disks; i--; ) {
                         struct r5dev *dev = &sh->dev[i];
@@ -813,10 +740,6 @@ ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
                 }
         }
 
-        /* check whether this postxor is part of a write */
-        callback = test_bit(STRIPE_OP_BIODRAIN, &pending) ?
-                ops_complete_write : ops_complete_postxor;
-
         /* 1/ if we prexor'd then the dest is reused as a source
          * 2/ if we did not prexor then we are redoing the parity
          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
@@ -830,25 +753,20 @@ ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
         if (unlikely(count == 1)) {
                 flags &= ~(ASYNC_TX_XOR_DROP_DST | ASYNC_TX_XOR_ZERO_DST);
                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE,
-                        flags, tx, callback, sh);
+                        flags, tx, ops_complete_postxor, sh);
         } else
                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
-                        flags, tx, callback, sh);
+                        flags, tx, ops_complete_postxor, sh);
 }
 
 static void ops_complete_check(void *stripe_head_ref)
 {
         struct stripe_head *sh = stripe_head_ref;
-        int pd_idx = sh->pd_idx;
 
         pr_debug("%s: stripe %llu\n", __func__,
                 (unsigned long long)sh->sector);
 
-        if (test_and_clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending) &&
-                sh->ops.zero_sum_result == 0)
-                set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
-
-        set_bit(STRIPE_OP_CHECK, &sh->ops.complete);
+        sh->check_state = check_state_check_result;
         set_bit(STRIPE_HANDLE, &sh->state);
         release_stripe(sh);
 }
@@ -875,46 +793,42 @@ static void ops_run_check(struct stripe_head *sh)
         tx = async_xor_zero_sum(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
                 &sh->ops.zero_sum_result, 0, NULL, NULL, NULL);
 
-        if (tx)
-                set_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
-        else
-                clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
-
         atomic_inc(&sh->count);
         tx = async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
                 ops_complete_check, sh);
 }
 
-static void raid5_run_ops(struct stripe_head *sh, unsigned long pending)
+static void raid5_run_ops(struct stripe_head *sh, unsigned long ops_request)
 {
         int overlap_clear = 0, i, disks = sh->disks;
         struct dma_async_tx_descriptor *tx = NULL;
 
-        if (test_bit(STRIPE_OP_BIOFILL, &pending)) {
+        if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
                 ops_run_biofill(sh);
                 overlap_clear++;
         }
 
-        if (test_bit(STRIPE_OP_COMPUTE_BLK, &pending))
-                tx = ops_run_compute5(sh, pending);
+        if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
+                tx = ops_run_compute5(sh);
+                /* terminate the chain if postxor is not set to be run */
+                if (tx && !test_bit(STRIPE_OP_POSTXOR, &ops_request))
+                        async_tx_ack(tx);
+        }
 
-        if (test_bit(STRIPE_OP_PREXOR, &pending))
+        if (test_bit(STRIPE_OP_PREXOR, &ops_request))
                 tx = ops_run_prexor(sh, tx);
 
-        if (test_bit(STRIPE_OP_BIODRAIN, &pending)) {
-                tx = ops_run_biodrain(sh, tx, pending);
+        if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
+                tx = ops_run_biodrain(sh, tx);
                 overlap_clear++;
         }
 
-        if (test_bit(STRIPE_OP_POSTXOR, &pending))
-                ops_run_postxor(sh, tx, pending);
+        if (test_bit(STRIPE_OP_POSTXOR, &ops_request))
+                ops_run_postxor(sh, tx);
 
-        if (test_bit(STRIPE_OP_CHECK, &pending))
+        if (test_bit(STRIPE_OP_CHECK, &ops_request))
                 ops_run_check(sh);
 
-        if (test_bit(STRIPE_OP_IO, &pending))
-                ops_run_io(sh);
-
         if (overlap_clear)
                 for (i = disks; i--; ) {
                         struct r5dev *dev = &sh->dev[i];
@@ -997,14 +911,16 @@ static int resize_stripes(raid5_conf_t *conf, int newsize)
         struct stripe_head *osh, *nsh;
         LIST_HEAD(newstripes);
         struct disk_info *ndisks;
-        int err = 0;
+        int err;
         struct kmem_cache *sc;
         int i;
 
         if (newsize <= conf->pool_size)
                 return 0; /* never bother to shrink */
 
-        md_allow_write(conf->mddev);
+        err = md_allow_write(conf->mddev);
+        if (err)
+                return err;
 
         /* Step 1 */
         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
@@ -1703,11 +1619,11 @@ static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
         }
 }
 
-static int
-handle_write_operations5(struct stripe_head *sh, int rcw, int expand)
+static void
+schedule_reconstruction5(struct stripe_head *sh, struct stripe_head_state *s,
+                         int rcw, int expand)
 {
         int i, pd_idx = sh->pd_idx, disks = sh->disks;
-        int locked = 0;
 
         if (rcw) {
                 /* if we are not expanding this is a proper write request, and
@@ -1715,53 +1631,48 @@ handle_write_operations5(struct stripe_head *sh, int rcw, int expand)
                  * stripe cache
                  */
                 if (!expand) {
-                        set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
-                        sh->ops.count++;
-                }
+                        sh->reconstruct_state = reconstruct_state_drain_run;
+                        set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
+                } else
+                        sh->reconstruct_state = reconstruct_state_run;
 
-                set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
-                sh->ops.count++;
+                set_bit(STRIPE_OP_POSTXOR, &s->ops_request);
 
                 for (i = disks; i--; ) {
                         struct r5dev *dev = &sh->dev[i];
 
                         if (dev->towrite) {
                                 set_bit(R5_LOCKED, &dev->flags);
+                                set_bit(R5_Wantdrain, &dev->flags);
                                 if (!expand)
                                         clear_bit(R5_UPTODATE, &dev->flags);
-                                locked++;
+                                s->locked++;
                         }
                 }
-                if (locked + 1 == disks)
+                if (s->locked + 1 == disks)
                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
                                 atomic_inc(&sh->raid_conf->pending_full_writes);
         } else {
                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
 
-                set_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
-                set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
-                set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
-
-                sh->ops.count += 3;
+                sh->reconstruct_state = reconstruct_state_prexor_drain_run;
+                set_bit(STRIPE_OP_PREXOR, &s->ops_request);
+                set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
+                set_bit(STRIPE_OP_POSTXOR, &s->ops_request);
 
                 for (i = disks; i--; ) {
                         struct r5dev *dev = &sh->dev[i];
                         if (i == pd_idx)
                                 continue;
 
-                        /* For a read-modify write there may be blocks that are
-                         * locked for reading while others are ready to be
-                         * written so we distinguish these blocks by the
-                         * R5_Wantprexor bit
-                         */
                         if (dev->towrite &&
                             (test_bit(R5_UPTODATE, &dev->flags) ||
-                            test_bit(R5_Wantcompute, &dev->flags))) {
-                                set_bit(R5_Wantprexor, &dev->flags);
+                             test_bit(R5_Wantcompute, &dev->flags))) {
+                                set_bit(R5_Wantdrain, &dev->flags);
                                 set_bit(R5_LOCKED, &dev->flags);
                                 clear_bit(R5_UPTODATE, &dev->flags);
-                                locked++;
+                                s->locked++;
                         }
                 }
         }
@@ -1771,13 +1682,11 @@ handle_write_operations5(struct stripe_head *sh, int rcw, int expand)
          */
         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
-        locked++;
+        s->locked++;
 
-        pr_debug("%s: stripe %llu locked: %d pending: %lx\n",
+        pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
                 __func__, (unsigned long long)sh->sector,
-                locked, sh->ops.pending);
-
-        return locked;
+                s->locked, s->ops_request);
 }
 
 /*
@@ -1876,7 +1785,7 @@ static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
 }
 
 static void
-handle_requests_to_failed_array(raid5_conf_t *conf, struct stripe_head *sh,
+handle_failed_stripe(raid5_conf_t *conf, struct stripe_head *sh,
                                 struct stripe_head_state *s, int disks,
                                 struct bio **return_bi)
 {
@@ -1967,48 +1876,38 @@ handle_requests_to_failed_array(raid5_conf_t *conf, struct stripe_head *sh,
                         md_wakeup_thread(conf->mddev->thread);
 }
 
-/* __handle_issuing_new_read_requests5 - returns 0 if there are no more disks
- * to process
+/* fetch_block5 - checks the given member device to see if its data needs
+ * to be read or computed to satisfy a request.
+ *
+ * Returns 1 when no more member devices need to be checked, otherwise returns
+ * 0 to tell the loop in handle_stripe_fill5 to continue
  */
-static int __handle_issuing_new_read_requests5(struct stripe_head *sh,
-                        struct stripe_head_state *s, int disk_idx, int disks)
+static int fetch_block5(struct stripe_head *sh, struct stripe_head_state *s,
+                        int disk_idx, int disks)
 {
         struct r5dev *dev = &sh->dev[disk_idx];
         struct r5dev *failed_dev = &sh->dev[s->failed_num];
 
-        /* don't schedule compute operations or reads on the parity block while
-         * a check is in flight
-         */
-        if ((disk_idx == sh->pd_idx) &&
-             test_bit(STRIPE_OP_CHECK, &sh->ops.pending))
-                return ~0;
-
         /* is the data in this block needed, and can we get it? */
         if (!test_bit(R5_LOCKED, &dev->flags) &&
-            !test_bit(R5_UPTODATE, &dev->flags) && (dev->toread ||
-            (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
-             s->syncing || s->expanding || (s->failed &&
-             (failed_dev->toread || (failed_dev->towrite &&
-             !test_bit(R5_OVERWRITE, &failed_dev->flags)
-             ))))) {
-                /* 1/ We would like to get this block, possibly by computing it,
-                 * but we might not be able to.
-                 *
-                 * 2/ Since parity check operations potentially make the parity
-                 * block !uptodate it will need to be refreshed before any
-                 * compute operations on data disks are scheduled.
-                 *
-                 * 3/ We hold off parity block re-reads until check operations
-                 * have quiesced.
+            !test_bit(R5_UPTODATE, &dev->flags) &&
+            (dev->toread ||
+             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
+             s->syncing || s->expanding ||
+             (s->failed &&
+              (failed_dev->toread ||
+               (failed_dev->towrite &&
+                !test_bit(R5_OVERWRITE, &failed_dev->flags)))))) {
+                /* We would like to get this block, possibly by computing it,
+                 * otherwise read it if the backing disk is insync
                  */
                 if ((s->uptodate == disks - 1) &&
-                    (s->failed && disk_idx == s->failed_num) &&
-                    !test_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
-                        set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
+                    (s->failed && disk_idx == s->failed_num)) {
+                        set_bit(STRIPE_COMPUTE_RUN, &sh->state);
+                        set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
                         set_bit(R5_Wantcompute, &dev->flags);
                         sh->ops.target = disk_idx;
                         s->req_compute = 1;
-                        sh->ops.count++;
                         /* Careful: from this point on 'uptodate' is in the eye
                          * of raid5_run_ops which services 'compute' operations
                          * before writes. R5_Wantcompute flags a block that will
@@ -2016,53 +1915,40 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh,
                          * subsequent operation.
                          */
                         s->uptodate++;
-                        return 0; /* uptodate + compute == disks */
+                        return 1; /* uptodate + compute == disks */
                 } else if (test_bit(R5_Insync, &dev->flags)) {
                         set_bit(R5_LOCKED, &dev->flags);
                         set_bit(R5_Wantread, &dev->flags);
-                        if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
-                                sh->ops.count++;
                         s->locked++;
                         pr_debug("Reading block %d (sync=%d)\n", disk_idx,
                                 s->syncing);
                 }
         }
 
-        return ~0;
+        return 0;
 }
 
-static void handle_issuing_new_read_requests5(struct stripe_head *sh,
+/**
+ * handle_stripe_fill5 - read or compute data to satisfy pending requests.
+ */
+static void handle_stripe_fill5(struct stripe_head *sh,
                         struct stripe_head_state *s, int disks)
 {
         int i;
 
-        /* Clear completed compute operations.  Parity recovery
-         * (STRIPE_OP_MOD_REPAIR_PD) implies a write-back which is handled
-         * later on in this routine
-         */
-        if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
-                !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
-                clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
-                clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);
-                clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
-        }
-
         /* look for blocks to read/compute, skip this if a compute
          * is already in flight, or if the stripe contents are in the
          * midst of changing due to a write
          */
-        if (!test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending) &&
-                !test_bit(STRIPE_OP_PREXOR, &sh->ops.pending) &&
-                !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
+        if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
+            !sh->reconstruct_state)
                 for (i = disks; i--; )
-                        if (__handle_issuing_new_read_requests5(
-                                sh, s, i, disks) == 0)
+                        if (fetch_block5(sh, s, i, disks))
                                 break;
-        }
         set_bit(STRIPE_HANDLE, &sh->state);
 }
 
-static void handle_issuing_new_read_requests6(struct stripe_head *sh,
+static void handle_stripe_fill6(struct stripe_head *sh,
                         struct stripe_head_state *s, struct r6_state *r6s,
                         int disks)
 {
@@ -2121,12 +2007,12 @@ static void handle_issuing_new_read_requests6(struct stripe_head *sh,
 }
 
 
-/* handle_completed_write_requests
+/* handle_stripe_clean_event
  * any written block on an uptodate or failed drive can be returned.
  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
  * never LOCKED, so we don't need to test 'failed' directly.
  */
-static void handle_completed_write_requests(raid5_conf_t *conf,
+static void handle_stripe_clean_event(raid5_conf_t *conf,
         struct stripe_head *sh, int disks, struct bio **return_bi)
 {
         int i;
@@ -2171,7 +2057,7 @@ static void handle_completed_write_requests(raid5_conf_t *conf,
                         md_wakeup_thread(conf->mddev->thread);
 }
 
-static void handle_issuing_new_write_requests5(raid5_conf_t *conf,
+static void handle_stripe_dirtying5(raid5_conf_t *conf,
                 struct stripe_head *sh, struct stripe_head_state *s, int disks)
 {
         int rmw = 0, rcw = 0, i;
@@ -2215,9 +2101,6 @@ static void handle_issuing_new_write_requests5(raid5_conf_t *conf,
                                                 "%d for r-m-w\n", i);
                                         set_bit(R5_LOCKED, &dev->flags);
                                         set_bit(R5_Wantread, &dev->flags);
-                                        if (!test_and_set_bit(
-                                                STRIPE_OP_IO, &sh->ops.pending))
-                                                sh->ops.count++;
                                         s->locked++;
                                 } else {
                                         set_bit(STRIPE_DELAYED, &sh->state);
@@ -2241,9 +2124,6 @@ static void handle_issuing_new_write_requests5(raid5_conf_t *conf,
                                                 "%d for Reconstruct\n", i);
                                         set_bit(R5_LOCKED, &dev->flags);
                                         set_bit(R5_Wantread, &dev->flags);
-                                        if (!test_and_set_bit(
-                                                STRIPE_OP_IO, &sh->ops.pending))
-                                                sh->ops.count++;
                                         s->locked++;
                                 } else {
                                         set_bit(STRIPE_DELAYED, &sh->state);
@@ -2261,14 +2141,13 @@ static void handle_issuing_new_write_requests5(raid5_conf_t *conf,
          * simultaneously.  If this is not the case then new writes need to be
          * held off until the compute completes.
          */
-        if ((s->req_compute ||
-            !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) &&
-                (s->locked == 0 && (rcw == 0 || rmw == 0) &&
-                !test_bit(STRIPE_BIT_DELAY, &sh->state)))
-                s->locked += handle_write_operations5(sh, rcw == 0, 0);
+        if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
+            (s->locked == 0 && (rcw == 0 || rmw == 0) &&
+            !test_bit(STRIPE_BIT_DELAY, &sh->state)))
+                schedule_reconstruction5(sh, s, rcw == 0, 0);
 }
 
-static void handle_issuing_new_write_requests6(raid5_conf_t *conf,
+static void handle_stripe_dirtying6(raid5_conf_t *conf,
                 struct stripe_head *sh, struct stripe_head_state *s,
                 struct r6_state *r6s, int disks)
 {
@@ -2371,92 +2250,86 @@ static void handle_issuing_new_write_requests6(raid5_conf_t *conf,
 static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
                                 struct stripe_head_state *s, int disks)
 {
-        int canceled_check = 0;
+        struct r5dev *dev = NULL;
 
         set_bit(STRIPE_HANDLE, &sh->state);
 
-        /* complete a check operation */
-        if (test_and_clear_bit(STRIPE_OP_CHECK, &sh->ops.complete)) {
-                clear_bit(STRIPE_OP_CHECK, &sh->ops.ack);
-                clear_bit(STRIPE_OP_CHECK, &sh->ops.pending);
+        switch (sh->check_state) {
+        case check_state_idle:
+                /* start a new check operation if there are no failures */
                 if (s->failed == 0) {
-                        if (sh->ops.zero_sum_result == 0)
-                                /* parity is correct (on disc,
-                                 * not in buffer any more)
-                                 */
-                                set_bit(STRIPE_INSYNC, &sh->state);
-                        else {
-                                conf->mddev->resync_mismatches +=
-                                        STRIPE_SECTORS;
-                                if (test_bit(
-                                     MD_RECOVERY_CHECK, &conf->mddev->recovery))
-                                        /* don't try to repair!! */
-                                        set_bit(STRIPE_INSYNC, &sh->state);
-                                else {
-                                        set_bit(STRIPE_OP_COMPUTE_BLK,
-                                                &sh->ops.pending);
-                                        set_bit(STRIPE_OP_MOD_REPAIR_PD,
-                                                &sh->ops.pending);
-                                        set_bit(R5_Wantcompute,
-                                                &sh->dev[sh->pd_idx].flags);
-                                        sh->ops.target = sh->pd_idx;
-                                        sh->ops.count++;
-                                        s->uptodate++;
-                                }
-                        }
-                } else
-                        canceled_check = 1; /* STRIPE_INSYNC is not set */
-        }
-
-        /* start a new check operation if there are no failures, the stripe is
-         * not insync, and a repair is not in flight
-         */
-        if (s->failed == 0 &&
-            !test_bit(STRIPE_INSYNC, &sh->state) &&
-            !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
-                if (!test_and_set_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
                         BUG_ON(s->uptodate != disks);
+                        sh->check_state = check_state_run;
+                        set_bit(STRIPE_OP_CHECK, &s->ops_request);
                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
-                        sh->ops.count++;
                         s->uptodate--;
+                        break;
                 }
-        }
-
-        /* check if we can clear a parity disk reconstruct */
-        if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
-            test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
-
-                clear_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending);
-                clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete);
-                clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack);
-                clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
-        }
-
+                dev = &sh->dev[s->failed_num];
+                /* fall through */
+        case check_state_compute_result:
+                sh->check_state = check_state_idle;
+                if (!dev)
+                        dev = &sh->dev[sh->pd_idx];
+
+                /* check that a write has not made the stripe insync */
+                if (test_bit(STRIPE_INSYNC, &sh->state))
+                        break;
 
-        /* Wait for check parity and compute block operations to complete
-         * before write-back.  If a failure occurred while the check operation
-         * was in flight we need to cycle this stripe through handle_stripe
-         * since the parity block may not be uptodate
-         */
-        if (!canceled_check && !test_bit(STRIPE_INSYNC, &sh->state) &&
-            !test_bit(STRIPE_OP_CHECK, &sh->ops.pending) &&
-            !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) {
-                struct r5dev *dev;
                 /* either failed parity check, or recovery is happening */
-                if (s->failed == 0)
-                        s->failed_num = sh->pd_idx;
-                dev = &sh->dev[s->failed_num];
                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
                 BUG_ON(s->uptodate != disks);
 
                 set_bit(R5_LOCKED, &dev->flags);
+                s->locked++;
                 set_bit(R5_Wantwrite, &dev->flags);
-                if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
-                        sh->ops.count++;
 
                 clear_bit(STRIPE_DEGRADED, &sh->state);
-                s->locked++;
                 set_bit(STRIPE_INSYNC, &sh->state);
+                break;
+        case check_state_run:
+                break; /* we will be called again upon completion */
+        case check_state_check_result:
+                sh->check_state = check_state_idle;
+
+                /* if a failure occurred during the check operation, leave
+                 * STRIPE_INSYNC not set and let the stripe be handled again
+                 */
+                if (s->failed)
+                        break;
+
+                /* handle a successful check operation, if parity is correct
+                 * we are done.  Otherwise update the mismatch count and repair
+                 * parity if !MD_RECOVERY_CHECK
+                 */
+                if (sh->ops.zero_sum_result == 0)
+                        /* parity is correct (on disc,
+                         * not in buffer any more)
+                         */
+                        set_bit(STRIPE_INSYNC, &sh->state);
+                else {
+                        conf->mddev->resync_mismatches += STRIPE_SECTORS;
+                        if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
+                                /* don't try to repair!! */
+                                set_bit(STRIPE_INSYNC, &sh->state);
+                        else {
+                                sh->check_state = check_state_compute_run;
+                                set_bit(STRIPE_COMPUTE_RUN, &sh->state);
+                                set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
+                                set_bit(R5_Wantcompute,
+                                        &sh->dev[sh->pd_idx].flags);
+                                sh->ops.target = sh->pd_idx;
+                                s->uptodate++;
+                        }
+                }
+                break;
+        case check_state_compute_run:
+                break;
+        default:
+                printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
+                       __func__, sh->check_state,
+                       (unsigned long long) sh->sector);
+                BUG();
         }
 }
 
@@ -2641,15 +2514,14 @@ static void handle_stripe5(struct stripe_head *sh)
         struct bio *return_bi = NULL;
         struct stripe_head_state s;
         struct r5dev *dev;
-        unsigned long pending = 0;
         mdk_rdev_t *blocked_rdev = NULL;
         int prexor;
 
         memset(&s, 0, sizeof(s));
-        pr_debug("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d "
-                "ops=%lx:%lx:%lx\n", (unsigned long long)sh->sector, sh->state,
-                atomic_read(&sh->count), sh->pd_idx,
-                sh->ops.pending, sh->ops.ack, sh->ops.complete);
+        pr_debug("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d check:%d "
+                 "reconstruct:%d\n", (unsigned long long)sh->sector, sh->state,
+                 atomic_read(&sh->count), sh->pd_idx, sh->check_state,
+                 sh->reconstruct_state);
 
         spin_lock(&sh->lock);
         clear_bit(STRIPE_HANDLE, &sh->state);
@@ -2658,15 +2530,8 @@ static void handle_stripe5(struct stripe_head *sh)
         s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
         s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
         s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
-        /* Now to look around and see what can be done */
-
-        /* clean-up completed biofill operations */
-        if (test_bit(STRIPE_OP_BIOFILL, &sh->ops.complete)) {
-                clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
-                clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
-                clear_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
-        }
 
+        /* Now to look around and see what can be done */
         rcu_read_lock();
         for (i=disks; i--; ) {
                 mdk_rdev_t *rdev;
@@ -2680,10 +2545,10 @@ static void handle_stripe5(struct stripe_head *sh)
                 /* maybe we can request a biofill operation
                  *
                  * new wantfill requests are only permitted while
-                 * STRIPE_OP_BIOFILL is clear
+                 * ops_complete_biofill is guaranteed to be inactive
                  */
                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
-                        !test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
+                    !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
                         set_bit(R5_Wantfill, &dev->flags);
 
                 /* now count some things */
@@ -2727,8 +2592,10 @@ static void handle_stripe5(struct stripe_head *sh)
                 goto unlock;
         }
 
-        if (s.to_fill && !test_and_set_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
-                sh->ops.count++;
+        if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
+                set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
+                set_bit(STRIPE_BIOFILL_RUN, &sh->state);
+        }
 
         pr_debug("locked=%d uptodate=%d to_read=%d"
                 " to_write=%d failed=%d failed_num=%d\n",
@@ -2738,8 +2605,7 @@ static void handle_stripe5(struct stripe_head *sh)
          * need to be failed
          */
         if (s.failed > 1 && s.to_read+s.to_write+s.written)
-                handle_requests_to_failed_array(conf, sh, &s, disks,
-                                                &return_bi);
+                handle_failed_stripe(conf, sh, &s, disks, &return_bi);
         if (s.failed > 1 && s.syncing) {
                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
                 clear_bit(STRIPE_SYNCING, &sh->state);
@@ -2755,48 +2621,25 @@ static void handle_stripe5(struct stripe_head *sh)
                !test_bit(R5_LOCKED, &dev->flags) &&
                test_bit(R5_UPTODATE, &dev->flags)) ||
                (s.failed == 1 && s.failed_num == sh->pd_idx)))
-                handle_completed_write_requests(conf, sh, disks, &return_bi);
+                handle_stripe_clean_event(conf, sh, disks, &return_bi);
 
         /* Now we might consider reading some blocks, either to check/generate
          * parity, or to satisfy requests
          * or to load a block that is being partially written.
          */
         if (s.to_read || s.non_overwrite ||
-            (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding ||
-            test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))
-                handle_issuing_new_read_requests5(sh, &s, disks);
+            (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding)
+                handle_stripe_fill5(sh, &s, disks);
 
         /* Now we check to see if any write operations have recently
          * completed
          */
-
-        /* leave prexor set until postxor is done, allows us to distinguish
-         * a rmw from a rcw during biodrain
-         */
         prexor = 0;
-        if (test_bit(STRIPE_OP_PREXOR, &sh->ops.complete) &&
-                test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
-
+        if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
                 prexor = 1;
-                clear_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
-                clear_bit(STRIPE_OP_PREXOR, &sh->ops.ack);
-                clear_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
-
-                for (i = disks; i--; )
-                        clear_bit(R5_Wantprexor, &sh->dev[i].flags);
-        }
-
-        /* if only POSTXOR is set then this is an 'expand' postxor */
-        if (test_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete) &&
-                test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
-
-                clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
-                clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.ack);
-                clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
-
-                clear_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
-                clear_bit(STRIPE_OP_POSTXOR, &sh->ops.ack);
-                clear_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
+        if (sh->reconstruct_state == reconstruct_state_drain_result ||
+            sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
+                sh->reconstruct_state = reconstruct_state_idle;
 
                 /* All the 'written' buffers and the parity block are ready to
                  * be written back to disk
@@ -2808,9 +2651,6 @@ static void handle_stripe5(struct stripe_head *sh)
                                 (i == sh->pd_idx || dev->written)) {
                                 pr_debug("Writing block %d\n", i);
                                 set_bit(R5_Wantwrite, &dev->flags);
-                                if (!test_and_set_bit(
-                                    STRIPE_OP_IO, &sh->ops.pending))
-                                        sh->ops.count++;
                                 if (prexor)
                                         continue;
                                 if (!test_bit(R5_Insync, &dev->flags) ||
@@ -2832,20 +2672,18 @@ static void handle_stripe5(struct stripe_head *sh)
          * 2/ A 'check' operation is in flight, as it may clobber the parity
          *    block.
          */
-        if (s.to_write && !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending) &&
-                          !test_bit(STRIPE_OP_CHECK, &sh->ops.pending))
-                handle_issuing_new_write_requests5(conf, sh, &s, disks);
+        if (s.to_write && !sh->reconstruct_state && !sh->check_state)
+                handle_stripe_dirtying5(conf, sh, &s, disks);
 
         /* maybe we need to check and possibly fix the parity for this stripe
          * Any reads will already have been scheduled, so we just see if enough
          * data is available.  The parity check is held off while parity
          * dependent operations are in flight.
          */
-        if ((s.syncing && s.locked == 0 &&
-             !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending) &&
-             !test_bit(STRIPE_INSYNC, &sh->state)) ||
-              test_bit(STRIPE_OP_CHECK, &sh->ops.pending) ||
-              test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending))
+        if (sh->check_state ||
+            (s.syncing && s.locked == 0 &&
+             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
+             !test_bit(STRIPE_INSYNC, &sh->state)))
                 handle_parity_checks5(conf, sh, &s, disks);
 
         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
@@ -2864,52 +2702,35 @@ static void handle_stripe5(struct stripe_head *sh)
                 dev = &sh->dev[s.failed_num];
                 if (!test_bit(R5_ReWrite, &dev->flags)) {
                         set_bit(R5_Wantwrite, &dev->flags);
-                        if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
-                                sh->ops.count++;
                         set_bit(R5_ReWrite, &dev->flags);
                         set_bit(R5_LOCKED, &dev->flags);
                         s.locked++;
                 } else {
                         /* let's read it back */
                         set_bit(R5_Wantread, &dev->flags);
-                        if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
-                                sh->ops.count++;
                         set_bit(R5_LOCKED, &dev->flags);
                         s.locked++;
                 }
         }
 
-        /* Finish postxor operations initiated by the expansion
-         * process
-         */
-        if (test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete) &&
-                !test_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending)) {
-
+        /* Finish reconstruct operations initiated by the expansion process */
+        if (sh->reconstruct_state == reconstruct_state_result) {
+                sh->reconstruct_state = reconstruct_state_idle;
                 clear_bit(STRIPE_EXPANDING, &sh->state);
-
-                clear_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
-                clear_bit(STRIPE_OP_POSTXOR, &sh->ops.ack);
-                clear_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
-
-                for (i = conf->raid_disks; i--; ) {
+                for (i = conf->raid_disks; i--; )
                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
                         set_bit(R5_LOCKED, &dev->flags);
                         s.locked++;
-                        if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
-                                sh->ops.count++;
-                }
         }
 
         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
-                !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
+            !sh->reconstruct_state) {
                 /* Need to write out all blocks after computing parity */
                 sh->disks = conf->raid_disks;
                 sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
                         conf->raid_disks);
-                s.locked += handle_write_operations5(sh, 1, 1);
-        } else if (s.expanded &&
-                   s.locked == 0 &&
-                !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
+                schedule_reconstruction5(sh, &s, 1, 1);
+        } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
                 atomic_dec(&conf->reshape_stripes);
                 wake_up(&conf->wait_for_overlap);
@@ -2917,12 +2738,9 @@ static void handle_stripe5(struct stripe_head *sh)
         }
 
         if (s.expanding && s.locked == 0 &&
-            !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))
+            !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
                 handle_stripe_expansion(conf, sh, NULL);
 
-        if (sh->ops.count)
-                pending = get_stripe_work(sh);
-
  unlock:
         spin_unlock(&sh->lock);
 
@@ -2930,11 +2748,12 @@ static void handle_stripe5(struct stripe_head *sh)
         if (unlikely(blocked_rdev))
                 md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
 
-        if (pending)
-                raid5_run_ops(sh, pending);
+        if (s.ops_request)
+                raid5_run_ops(sh, s.ops_request);
 
-        return_io(return_bi);
+        ops_run_io(sh, &s);
 
+        return_io(return_bi);
 }
 
 static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
@@ -3042,8 +2861,7 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
          * might need to be failed
          */
         if (s.failed > 2 && s.to_read+s.to_write+s.written)
-                handle_requests_to_failed_array(conf, sh, &s, disks,
-                                                &return_bi);
+                handle_failed_stripe(conf, sh, &s, disks, &return_bi);
         if (s.failed > 2 && s.syncing) {
                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
                 clear_bit(STRIPE_SYNCING, &sh->state);
@@ -3068,7 +2886,7 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
              ( r6s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
                              && !test_bit(R5_LOCKED, &qdev->flags)
                              && test_bit(R5_UPTODATE, &qdev->flags)))))
-                handle_completed_write_requests(conf, sh, disks, &return_bi);
+                handle_stripe_clean_event(conf, sh, disks, &return_bi);
 
         /* Now we might consider reading some blocks, either to check/generate
          * parity, or to satisfy requests
@@ -3076,11 +2894,11 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
          */
         if (s.to_read || s.non_overwrite || (s.to_write && s.failed) ||
             (s.syncing && (s.uptodate < disks)) || s.expanding)
-                handle_issuing_new_read_requests6(sh, &s, &r6s, disks);
+                handle_stripe_fill6(sh, &s, &r6s, disks);
 
         /* now to consider writing and what else, if anything should be read */
         if (s.to_write)
-                handle_issuing_new_write_requests6(conf, sh, &s, &r6s, disks);
+                handle_stripe_dirtying6(conf, sh, &s, &r6s, disks);
 
         /* maybe we need to check and possibly fix the parity for this stripe
          * Any reads will already have been scheduled, so we just see if enough
@@ -3136,7 +2954,7 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
         }
 
         if (s.expanding && s.locked == 0 &&
-            !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))
+            !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
                 handle_stripe_expansion(conf, sh, &r6s);
 
  unlock:
@@ -3146,68 +2964,9 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
         if (unlikely(blocked_rdev))
                 md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
 
-        return_io(return_bi);
-
-        for (i=disks; i-- ;) {
-                int rw;
-                struct bio *bi;
-                mdk_rdev_t *rdev;
-                if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
-                        rw = WRITE;
-                else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
-                        rw = READ;
-                else
-                        continue;
-
-                set_bit(STRIPE_IO_STARTED, &sh->state);
-
-                bi = &sh->dev[i].req;
-
-                bi->bi_rw = rw;
-                if (rw == WRITE)
-                        bi->bi_end_io = raid5_end_write_request;
-                else
-                        bi->bi_end_io = raid5_end_read_request;
-
-                rcu_read_lock();
-                rdev = rcu_dereference(conf->disks[i].rdev);
-                if (rdev && test_bit(Faulty, &rdev->flags))
-                        rdev = NULL;
-                if (rdev)
-                        atomic_inc(&rdev->nr_pending);
-                rcu_read_unlock();
+        ops_run_io(sh, &s);
 
-                if (rdev) {
-                        if (s.syncing || s.expanding || s.expanded)
-                                md_sync_acct(rdev->bdev, STRIPE_SECTORS);
-
-                        bi->bi_bdev = rdev->bdev;
-                        pr_debug("for %llu schedule op %ld on disc %d\n",
-                                (unsigned long long)sh->sector, bi->bi_rw, i);
-                        atomic_inc(&sh->count);
-                        bi->bi_sector = sh->sector + rdev->data_offset;
-                        bi->bi_flags = 1 << BIO_UPTODATE;
-                        bi->bi_vcnt = 1;
-                        bi->bi_max_vecs = 1;
-                        bi->bi_idx = 0;
-                        bi->bi_io_vec = &sh->dev[i].vec;
-                        bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
-                        bi->bi_io_vec[0].bv_offset = 0;
-                        bi->bi_size = STRIPE_SIZE;
-                        bi->bi_next = NULL;
-                        if (rw == WRITE &&
-                            test_bit(R5_ReWrite, &sh->dev[i].flags))
-                                atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
-                        generic_make_request(bi);
-                } else {
-                        if (rw == WRITE)
-                                set_bit(STRIPE_DEGRADED, &sh->state);
-                        pr_debug("skip op %ld on disc %d for sector %llu\n",
-                                bi->bi_rw, i, (unsigned long long)sh->sector);
-                        clear_bit(R5_LOCKED, &sh->dev[i].flags);
-                        set_bit(STRIPE_HANDLE, &sh->state);
-                }
-        }
+        return_io(return_bi);
 }
 
 static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
@@ -3697,9 +3456,7 @@ static int make_request(struct request_queue *q, struct bio * bi)
                 if ( rw == WRITE )
                         md_write_end(mddev);
 
-                bi->bi_end_io(bi,
-                              test_bit(BIO_UPTODATE, &bi->bi_flags)
-                                ? 0 : -EIO);
+                bio_endio(bi, 0);
         }
         return 0;
 }
@@ -3785,7 +3542,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
                             j == raid6_next_disk(sh->pd_idx, sh->disks))
                                 continue;
                         s = compute_blocknr(sh, j);
-                        if (s < (mddev->array_size<<1)) {
+                        if (s < mddev->array_sectors) {
                                 skipped = 1;
                                 continue;
                         }
@@ -4002,12 +3759,8 @@ static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
         spin_lock_irq(&conf->device_lock);
         remaining = --raid_bio->bi_phys_segments;
         spin_unlock_irq(&conf->device_lock);
-        if (remaining == 0) {
-
-                raid_bio->bi_end_io(raid_bio,
-                              test_bit(BIO_UPTODATE, &raid_bio->bi_flags)
-                                ? 0 : -EIO);
-        }
+        if (remaining == 0)
+                bio_endio(raid_bio, 0);
         if (atomic_dec_and_test(&conf->active_aligned_reads))
                 wake_up(&conf->wait_for_stripe);
         return handled;
@@ -4094,6 +3847,8 @@ raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
 {
         raid5_conf_t *conf = mddev_to_conf(mddev);
         unsigned long new;
+        int err;
+
         if (len >= PAGE_SIZE)
                 return -EINVAL;
         if (!conf)
@@ -4109,7 +3864,9 @@ raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
                 else
                         break;
         }
-        md_allow_write(mddev);
+        err = md_allow_write(mddev);
+        if (err)
+                return err;
         while (new > conf->max_nr_stripes) {
                 if (grow_one_stripe(conf))
                         conf->max_nr_stripes++;
@@ -4434,7 +4191,7 @@ static int run(mddev_t *mddev)
         mddev->queue->backing_dev_info.congested_data = mddev;
         mddev->queue->backing_dev_info.congested_fn = raid5_congested;
 
-        mddev->array_size =  mddev->size * (conf->previous_raid_disks -
+        mddev->array_sectors = 2 * mddev->size * (conf->previous_raid_disks -
                                             conf->max_degraded);
 
         blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
@@ -4609,35 +4366,41 @@ abort:
 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
 {
         raid5_conf_t *conf = mddev->private;
-        int found = 0;
+        int err = -EEXIST;
         int disk;
         struct disk_info *p;
+        int first = 0;
+        int last = conf->raid_disks - 1;
 
         if (mddev->degraded > conf->max_degraded)
                 /* no point adding a device */
-                return 0;
+                return -EINVAL;
+
+        if (rdev->raid_disk >= 0)
+                first = last = rdev->raid_disk;
 
         /*
          * find the disk ... but prefer rdev->saved_raid_disk
          * if possible.
          */
         if (rdev->saved_raid_disk >= 0 &&
+            rdev->saved_raid_disk >= first &&
             conf->disks[rdev->saved_raid_disk].rdev == NULL)
                 disk = rdev->saved_raid_disk;
         else
-                disk = 0;
-        for ( ; disk < conf->raid_disks; disk++)
+                disk = first;
+        for ( ; disk <= last ; disk++)
                 if ((p=conf->disks + disk)->rdev == NULL) {
                         clear_bit(In_sync, &rdev->flags);
                         rdev->raid_disk = disk;
-                        found = 1;
+                        err = 0;
                         if (rdev->saved_raid_disk != disk)
                                 conf->fullsync = 1;
                         rcu_assign_pointer(p->rdev, rdev);
                         break;
                 }
         print_raid5_conf(conf);
-        return found;
+        return err;
 }
 
 static int raid5_resize(mddev_t *mddev, sector_t sectors)
@@ -4652,8 +4415,9 @@ static int raid5_resize(mddev_t *mddev, sector_t sectors)
         raid5_conf_t *conf = mddev_to_conf(mddev);
 
         sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
-        mddev->array_size = (sectors * (mddev->raid_disks-conf->max_degraded))>>1;
-        set_capacity(mddev->gendisk, mddev->array_size << 1);
+        mddev->array_sectors = sectors * (mddev->raid_disks
+                                          - conf->max_degraded);
+        set_capacity(mddev->gendisk, mddev->array_sectors);
         mddev->changed = 1;
         if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
                 mddev->recovery_cp = mddev->size << 1;
@@ -4738,7 +4502,7 @@ static int raid5_start_reshape(mddev_t *mddev)
         rdev_for_each(rdev, rtmp, mddev)
                 if (rdev->raid_disk < 0 &&
                     !test_bit(Faulty, &rdev->flags)) {
-                        if (raid5_add_disk(mddev, rdev)) {
+                        if (raid5_add_disk(mddev, rdev) == 0) {
                                 char nm[20];
                                 set_bit(In_sync, &rdev->flags);
                                 added_devices++;
@@ -4786,15 +4550,16 @@ static void end_reshape(raid5_conf_t *conf)
         struct block_device *bdev;
 
         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
-                conf->mddev->array_size = conf->mddev->size *
+                conf->mddev->array_sectors = 2 * conf->mddev->size *
                         (conf->raid_disks - conf->max_degraded);
-                set_capacity(conf->mddev->gendisk, conf->mddev->array_size << 1);
+                set_capacity(conf->mddev->gendisk, conf->mddev->array_sectors);
                 conf->mddev->changed = 1;
 
                 bdev = bdget_disk(conf->mddev->gendisk, 0);
                 if (bdev) {
                         mutex_lock(&bdev->bd_inode->i_mutex);
-                        i_size_write(bdev->bd_inode, (loff_t)conf->mddev->array_size << 10);
+                        i_size_write(bdev->bd_inode,
+                                     (loff_t)conf->mddev->array_sectors << 9);
                         mutex_unlock(&bdev->bd_inode->i_mutex);
                         bdput(bdev);
                 }
diff --git a/include/linux/raid/bitmap.h b/include/linux/raid/bitmap.h
index 78bfdea24a8e..e98900671ca9 100644
--- a/include/linux/raid/bitmap.h
+++ b/include/linux/raid/bitmap.h
@@ -221,6 +221,7 @@ struct bitmap {
         unsigned long syncchunk;
 
         __u64   events_cleared;
+        int need_sync;
 
         /* bitmap spinlock */
         spinlock_t lock;
diff --git a/include/linux/raid/linear.h b/include/linux/raid/linear.h
index ba15469daf11..7e375111d007 100644
--- a/include/linux/raid/linear.h
+++ b/include/linux/raid/linear.h
@@ -16,7 +16,7 @@ struct linear_private_data
         struct linear_private_data *prev;       /* earlier version */
         dev_info_t              **hash_table;
         sector_t                hash_spacing;
-        sector_t                array_size;
+        sector_t                array_sectors;
         int                     preshift; /* shift before dividing by hash_spacing */
         dev_info_t              disks[0];
 };
diff --git a/include/linux/raid/md.h b/include/linux/raid/md.h
index b7386ae9d288..dc0e3fcb9f28 100644
--- a/include/linux/raid/md.h
+++ b/include/linux/raid/md.h
@@ -95,7 +95,7 @@ extern int sync_page_io(struct block_device *bdev, sector_t sector, int size,
                         struct page *page, int rw);
 extern void md_do_sync(mddev_t *mddev);
 extern void md_new_event(mddev_t *mddev);
-extern void md_allow_write(mddev_t *mddev);
+extern int md_allow_write(mddev_t *mddev);
 extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 
 #endif /* CONFIG_MD */
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index 3dea9f545c8f..9f2549ac0e2d 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -59,7 +59,7 @@ struct mdk_rdev_s
         int             sb_loaded;
         __u64           sb_events;
         sector_t        data_offset;    /* start of data in array */
-        sector_t        sb_offset;
+        sector_t        sb_start;       /* offset of the super block (in 512byte sectors) */
         int             sb_size;        /* bytes in the superblock */
         int             preferred_minor;        /* autorun support */
 
@@ -87,6 +87,9 @@ struct mdk_rdev_s
 #define Blocked         8               /* An error occured on an externally
                                          * managed array, don't allow writes
                                          * until it is cleared */
+#define StateChanged    9               /* Faulty or Blocked has changed during
+                                         * interrupt, so it needs to be
+                                         * notified by the thread */
         wait_queue_head_t blocked_wait;
 
         int desc_nr;                    /* descriptor index in the superblock */
@@ -147,7 +150,7 @@ struct mddev_s
         int                             raid_disks;
         int                             max_disks;
         sector_t                        size; /* used size of component devices */
-        sector_t                        array_size; /* exported array size */
+        sector_t                        array_sectors; /* exported array size */
         __u64                           events;
 
         char                            uuid[16];
@@ -188,6 +191,7 @@ struct mddev_s
          * NEEDED:   we might need to start a resync/recover
          * RUNNING:  a thread is running, or about to be started
          * SYNC:     actually doing a resync, not a recovery
+         * RECOVER:  doing recovery, or need to try it.
          * INTR:     resync needs to be aborted for some reason
          * DONE:     thread is done and is waiting to be reaped
          * REQUEST:  user-space has requested a sync (used with SYNC)
@@ -198,6 +202,7 @@ struct mddev_s
          */
 #define MD_RECOVERY_RUNNING     0
 #define MD_RECOVERY_SYNC        1
+#define MD_RECOVERY_RECOVER     2
 #define MD_RECOVERY_INTR        3
 #define MD_RECOVERY_DONE        4
 #define MD_RECOVERY_NEEDED      5
@@ -210,7 +215,8 @@ struct mddev_s
 
         int                             in_sync;        /* know to not need resync */
         struct mutex                    reconfig_mutex;
-        atomic_t                        active;
+        atomic_t                        active;         /* general refcount */
+        atomic_t                        openers;        /* number of active opens */
 
         int                             changed;        /* true if we might need to reread partition info */
         int                             degraded;       /* whether md should consider
@@ -227,6 +233,8 @@ struct mddev_s
         atomic_t                        recovery_active; /* blocks scheduled, but not written */
         wait_queue_head_t               recovery_wait;
         sector_t                        recovery_cp;
+        sector_t                        resync_min;     /* user requested sync
+                                                         * starts here */
         sector_t                        resync_max;     /* resync should pause
                                                          * when it gets here */
 
@@ -331,6 +339,9 @@ static inline char * mdname (mddev_t * mddev)
 #define rdev_for_each(rdev, tmp, mddev)                         \
         rdev_for_each_list(rdev, tmp, (mddev)->disks)
 
+#define rdev_for_each_rcu(rdev, mddev)                          \
+        list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
+
 typedef struct mdk_thread_s {
         void                    (*run) (mddev_t *mddev);
         mddev_t                 *mddev;
diff --git a/include/linux/raid/md_p.h b/include/linux/raid/md_p.h
index 3f2cd98c508b..8b4de4a41ff1 100644
--- a/include/linux/raid/md_p.h
+++ b/include/linux/raid/md_p.h
@@ -43,14 +43,11 @@
  */
 #define MD_RESERVED_BYTES               (64 * 1024)
 #define MD_RESERVED_SECTORS             (MD_RESERVED_BYTES / 512)
-#define MD_RESERVED_BLOCKS              (MD_RESERVED_BYTES / BLOCK_SIZE)
 
 #define MD_NEW_SIZE_SECTORS(x)          ((x & ~(MD_RESERVED_SECTORS - 1)) - MD_RESERVED_SECTORS)
-#define MD_NEW_SIZE_BLOCKS(x)           ((x & ~(MD_RESERVED_BLOCKS - 1)) - MD_RESERVED_BLOCKS)
 
 #define MD_SB_BYTES                     4096
 #define MD_SB_WORDS                     (MD_SB_BYTES / 4)
-#define MD_SB_BLOCKS                    (MD_SB_BYTES / BLOCK_SIZE)
 #define MD_SB_SECTORS                   (MD_SB_BYTES / 512)
 
 /*
diff --git a/include/linux/raid/raid5.h b/include/linux/raid/raid5.h
index f0827d31ae6f..3b2672792457 100644
--- a/include/linux/raid/raid5.h
+++ b/include/linux/raid/raid5.h
@@ -158,6 +158,43 @@
  *    the compute block completes.
  */
 
+/*
+ * Operations state - intermediate states that are visible outside of sh->lock
+ * In general _idle indicates nothing is running, _run indicates a data
+ * processing operation is active, and _result means the data processing result
+ * is stable and can be acted upon.  For simple operations like biofill and
+ * compute that only have an _idle and _run state they are indicated with
+ * sh->state flags (STRIPE_BIOFILL_RUN and STRIPE_COMPUTE_RUN)
+ */
+/**
+ * enum check_states - handles syncing / repairing a stripe
+ * @check_state_idle - check operations are quiesced
+ * @check_state_run - check operation is running
+ * @check_state_result - set outside lock when check result is valid
+ * @check_state_compute_run - check failed and we are repairing
+ * @check_state_compute_result - set outside lock when compute result is valid
+ */
+enum check_states {
+        check_state_idle = 0,
+        check_state_run, /* parity check */
+        check_state_check_result,
+        check_state_compute_run, /* parity repair */
+        check_state_compute_result,
+};
+
+/**
+ * enum reconstruct_states - handles writing or expanding a stripe
+ */
+enum reconstruct_states {
+        reconstruct_state_idle = 0,
+        reconstruct_state_prexor_drain_run,     /* prexor-write */
+        reconstruct_state_drain_run,            /* write */
+        reconstruct_state_run,                  /* expand */
+        reconstruct_state_prexor_drain_result,
+        reconstruct_state_drain_result,
+        reconstruct_state_result,
+};
+
 struct stripe_head {
         struct hlist_node       hash;
         struct list_head        lru;                    /* inactive_list or handle_list */
@@ -169,19 +206,13 @@ struct stripe_head {
         spinlock_t              lock;
         int                     bm_seq; /* sequence number for bitmap flushes */
         int                     disks;                  /* disks in stripe */
+        enum check_states       check_state;
+        enum reconstruct_states reconstruct_state;
         /* stripe_operations
-         * @pending - pending ops flags (set for request->issue->complete)
-         * @ack - submitted ops flags (set for issue->complete)
-         * @complete - completed ops flags (set for complete)
          * @target - STRIPE_OP_COMPUTE_BLK target
-         * @count - raid5_runs_ops is set to run when this is non-zero
          */
         struct stripe_operations {
-                unsigned long      pending;
-                unsigned long      ack;
-                unsigned long      complete;
                 int                target;
-                int                count;
                 u32                zero_sum_result;
         } ops;
         struct r5dev {
@@ -202,6 +233,7 @@ struct stripe_head_state {
         int locked, uptodate, to_read, to_write, failed, written;
         int to_fill, compute, req_compute, non_overwrite;
         int failed_num;
+        unsigned long ops_request;
 };
 
 /* r6_state - extra state data only relevant to r6 */
@@ -228,9 +260,7 @@ struct r6_state {
 #define R5_Wantfill     12 /* dev->toread contains a bio that needs
                                     * filling
                                     */
-#define R5_Wantprexor   13 /* distinguish blocks ready for rmw from
-                                    * other "towrites"
-                                    */
+#define R5_Wantdrain    13 /* dev->towrite needs to be drained */
 /*
  * Write method
  */
@@ -254,8 +284,10 @@ struct r6_state {
 #define STRIPE_EXPAND_READY     11
 #define STRIPE_IO_STARTED       12 /* do not count towards 'bypass_count' */
 #define STRIPE_FULL_WRITE       13 /* all blocks are set to be overwritten */
+#define STRIPE_BIOFILL_RUN      14
+#define STRIPE_COMPUTE_RUN      15
 /*
- * Operations flags (in issue order)
+ * Operation request flags
  */
 #define STRIPE_OP_BIOFILL       0
 #define STRIPE_OP_COMPUTE_BLK   1
@@ -263,14 +295,6 @@ struct r6_state {
 #define STRIPE_OP_BIODRAIN      3
 #define STRIPE_OP_POSTXOR       4
 #define STRIPE_OP_CHECK 5
-#define STRIPE_OP_IO            6
-
-/* modifiers to the base operations
- * STRIPE_OP_MOD_REPAIR_PD - compute the parity block and write it back
- * STRIPE_OP_MOD_DMA_CHECK - parity is not corrupted by the check
- */
-#define STRIPE_OP_MOD_REPAIR_PD 7
-#define STRIPE_OP_MOD_DMA_CHECK 8
 
 /*
  * Plugging: