Merge commit 'v2.6.27-rc8' into x86/setup

18 files changed, 1155 insertions, 860 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index b26927ce889..ac89a5deaca 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;
@@ -238,15 +238,47 @@ static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long inde
 
 }
 
+static mdk_rdev_t *next_active_rdev(mdk_rdev_t *rdev, mddev_t *mddev)
+{
+	/* Iterate the disks of an mddev, using rcu to protect access to the
+	 * linked list, and raising the refcount of devices we return to ensure
+	 * they don't disappear while in use.
+	 * As devices are only added or removed when raid_disk is < 0 and
+	 * nr_pending is 0 and In_sync is clear, the entries we return will
+	 * still be in the same position on the list when we re-enter
+	 * list_for_each_continue_rcu.
+	 */
+	struct list_head *pos;
+	rcu_read_lock();
+	if (rdev == NULL)
+		/* start at the beginning */
+		pos = &mddev->disks;
+	else {
+		/* release the previous rdev and start from there. */
+		rdev_dec_pending(rdev, mddev);
+		pos = &rdev->same_set;
+	}
+	list_for_each_continue_rcu(pos, &mddev->disks) {
+		rdev = list_entry(pos, mdk_rdev_t, same_set);
+		if (rdev->raid_disk >= 0 &&
+		    test_bit(In_sync, &rdev->flags) &&
+		    !test_bit(Faulty, &rdev->flags)) {
+			/* this is a usable devices */
+			atomic_inc(&rdev->nr_pending);
+			rcu_read_unlock();
+			return rdev;
+		}
+	}
+	rcu_read_unlock();
+	return NULL;
+}
+
 static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
 {
-	mdk_rdev_t *rdev;
-	struct list_head *tmp;
+	mdk_rdev_t *rdev = NULL;
 	mddev_t *mddev = bitmap->mddev;
 
-	rdev_for_each(rdev, tmp, mddev)
-		if (test_bit(In_sync, &rdev->flags)
-		    && !test_bit(Faulty, &rdev->flags)) {
+	while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {
 			int size = PAGE_SIZE;
 			if (page->index == bitmap->file_pages-1)
 				size = roundup(bitmap->last_page_size,
@@ -260,32 +292,36 @@ 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);
-		}
+	}
 
 	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 +490,11 @@ 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 +1124,19 @@ 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);
 		}
@@ -1216,7 +1265,7 @@ int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sect
 		case 0:
 			bitmap_file_set_bit(bitmap, offset);
 			bitmap_count_page(bitmap,offset, 1);
-			blk_plug_device(bitmap->mddev->queue);
+			blk_plug_device_unlocked(bitmap->mddev->queue);
 			/* fall through */
 		case 1:
 			*bmc = 2;
@@ -1257,6 +1306,12 @@ 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/dm-crypt.c b/drivers/md/dm-crypt.c
index ab6a61db63c..13956437bc8 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1216,9 +1216,24 @@ error:
 	return -EINVAL;
 }
 
+static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
+		       struct bio_vec *biovec, int max_size)
+{
+	struct crypt_config *cc = ti->private;
+	struct request_queue *q = bdev_get_queue(cc->dev->bdev);
+
+	if (!q->merge_bvec_fn)
+		return max_size;
+
+	bvm->bi_bdev = cc->dev->bdev;
+	bvm->bi_sector = cc->start + bvm->bi_sector - ti->begin;
+
+	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
+}
+
 static struct target_type crypt_target = {
 	.name   = "crypt",
-	.version= {1, 5, 0},
+	.version= {1, 6, 0},
 	.module = THIS_MODULE,
 	.ctr    = crypt_ctr,
 	.dtr    = crypt_dtr,
@@ -1228,6 +1243,7 @@ static struct target_type crypt_target = {
 	.preresume = crypt_preresume,
 	.resume = crypt_resume,
 	.message = crypt_message,
+	.merge  = crypt_merge,
 };
 
 static int __init dm_crypt_init(void)
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 17753d80ad2..6449bcdf84c 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -69,13 +69,25 @@ static void linear_dtr(struct dm_target *ti)
 	kfree(lc);
 }
 
-static int linear_map(struct dm_target *ti, struct bio *bio,
-		      union map_info *map_context)
+static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
 {
-	struct linear_c *lc = (struct linear_c *) ti->private;
+	struct linear_c *lc = ti->private;
+
+	return lc->start + (bi_sector - ti->begin);
+}
+
+static void linear_map_bio(struct dm_target *ti, struct bio *bio)
+{
+	struct linear_c *lc = ti->private;
 
 	bio->bi_bdev = lc->dev->bdev;
-	bio->bi_sector = lc->start + (bio->bi_sector - ti->begin);
+	bio->bi_sector = linear_map_sector(ti, bio->bi_sector);
+}
+
+static int linear_map(struct dm_target *ti, struct bio *bio,
+		      union map_info *map_context)
+{
+	linear_map_bio(ti, bio);
 
 	return DM_MAPIO_REMAPPED;
 }
@@ -114,15 +126,31 @@ static int linear_ioctl(struct dm_target *ti, struct inode *inode,
 	return blkdev_driver_ioctl(bdev->bd_inode, &fake_file, bdev->bd_disk, cmd, arg);
 }
 
+static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
+			struct bio_vec *biovec, int max_size)
+{
+	struct linear_c *lc = ti->private;
+	struct request_queue *q = bdev_get_queue(lc->dev->bdev);
+
+	if (!q->merge_bvec_fn)
+		return max_size;
+
+	bvm->bi_bdev = lc->dev->bdev;
+	bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector);
+
+	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
+}
+
 static struct target_type linear_target = {
 	.name   = "linear",
-	.version= {1, 0, 2},
+	.version= {1, 0, 3},
 	.module = THIS_MODULE,
 	.ctr    = linear_ctr,
 	.dtr    = linear_dtr,
 	.map    = linear_map,
 	.status = linear_status,
 	.ioctl  = linear_ioctl,
+	.merge  = linear_merge,
 };
 
 int __init dm_linear_init(void)
diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index 67a6f31b7fc..5b48478c79f 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -831,7 +831,7 @@ static struct dm_dirty_log_type _disk_type = {
 	.status = disk_status,
 };
 
-int __init dm_dirty_log_init(void)
+static int __init dm_dirty_log_init(void)
 {
 	int r;
 
@@ -848,7 +848,7 @@ int __init dm_dirty_log_init(void)
 	return r;
 }
 
-void __exit dm_dirty_log_exit(void)
+static void __exit dm_dirty_log_exit(void)
 {
 	dm_dirty_log_type_unregister(&_disk_type);
 	dm_dirty_log_type_unregister(&_core_type);
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 9f7302d4878..71dd65aa31b 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -147,9 +147,12 @@ static struct priority_group *alloc_priority_group(void)
 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
 {
 	struct pgpath *pgpath, *tmp;
+	struct multipath *m = ti->private;
 
 	list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
 		list_del(&pgpath->list);
+		if (m->hw_handler_name)
+			scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
 		dm_put_device(ti, pgpath->path.dev);
 		free_pgpath(pgpath);
 	}
@@ -525,8 +528,10 @@ static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
 	}
 
 	r = read_param(_params, shift(as), &ps_argc, &ti->error);
-	if (r)
+	if (r) {
+		dm_put_path_selector(pst);
 		return -EINVAL;
+	}
 
 	r = pst->create(&pg->ps, ps_argc, as->argv);
 	if (r) {
@@ -546,6 +551,7 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
 {
 	int r;
 	struct pgpath *p;
+	struct multipath *m = ti->private;
 
 	/* we need at least a path arg */
 	if (as->argc < 1) {
@@ -564,6 +570,15 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
 		goto bad;
 	}
 
+	if (m->hw_handler_name) {
+		r = scsi_dh_attach(bdev_get_queue(p->path.dev->bdev),
+				   m->hw_handler_name);
+		if (r < 0) {
+			dm_put_device(ti, p->path.dev);
+			goto bad;
+		}
+	}
+
 	r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
 	if (r) {
 		dm_put_device(ti, p->path.dev);
@@ -623,8 +638,10 @@ static struct priority_group *parse_priority_group(struct arg_set *as,
 		struct pgpath *pgpath;
 		struct arg_set path_args;
 
-		if (as->argc < nr_params)
+		if (as->argc < nr_params) {
+			ti->error = "not enough path parameters";
 			goto bad;
+		}
 
 		path_args.argc = nr_params;
 		path_args.argv = as->argv;
@@ -867,7 +884,7 @@ static int reinstate_path(struct pgpath *pgpath)
 	if (pgpath->path.is_active)
 		goto out;
 
-	if (!pgpath->pg->ps.type) {
+	if (!pgpath->pg->ps.type->reinstate_path) {
 		DMWARN("Reinstate path not supported by path selector %s",
 		       pgpath->pg->ps.type->name);
 		r = -EINVAL;
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 1ba8a47d61b..6e5528aecc9 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -40,6 +40,11 @@
  */
 #define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1)
 
+/*
+ * The size of the mempool used to track chunks in use.
+ */
+#define MIN_IOS 256
+
 static struct workqueue_struct *ksnapd;
 static void flush_queued_bios(struct work_struct *work);
 
@@ -91,7 +96,63 @@ struct dm_snap_pending_exception {
  */
 static struct kmem_cache *exception_cache;
 static struct kmem_cache *pending_cache;
-static mempool_t *pending_pool;
+
+struct dm_snap_tracked_chunk {
+	struct hlist_node node;
+	chunk_t chunk;
+};
+
+static struct kmem_cache *tracked_chunk_cache;
+
+static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s,
+						 chunk_t chunk)
+{
+	struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool,
+							GFP_NOIO);
+	unsigned long flags;
+
+	c->chunk = chunk;
+
+	spin_lock_irqsave(&s->tracked_chunk_lock, flags);
+	hlist_add_head(&c->node,
+		       &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]);
+	spin_unlock_irqrestore(&s->tracked_chunk_lock, flags);
+
+	return c;
+}
+
+static void stop_tracking_chunk(struct dm_snapshot *s,
+				struct dm_snap_tracked_chunk *c)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&s->tracked_chunk_lock, flags);
+	hlist_del(&c->node);
+	spin_unlock_irqrestore(&s->tracked_chunk_lock, flags);
+
+	mempool_free(c, s->tracked_chunk_pool);
+}
+
+static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk)
+{
+	struct dm_snap_tracked_chunk *c;
+	struct hlist_node *hn;
+	int found = 0;
+
+	spin_lock_irq(&s->tracked_chunk_lock);
+
+	hlist_for_each_entry(c, hn,
+	    &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) {
+		if (c->chunk == chunk) {
+			found = 1;
+			break;
+		}
+	}
+
+	spin_unlock_irq(&s->tracked_chunk_lock);
+
+	return found;
+}
 
 /*
  * One of these per registered origin, held in the snapshot_origins hash
@@ -302,14 +363,19 @@ static void free_exception(struct dm_snap_exception *e)
 	kmem_cache_free(exception_cache, e);
 }
 
-static struct dm_snap_pending_exception *alloc_pending_exception(void)
+static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s)
 {
-	return mempool_alloc(pending_pool, GFP_NOIO);
+	struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool,
+							     GFP_NOIO);
+
+	pe->snap = s;
+
+	return pe;
 }
 
 static void free_pending_exception(struct dm_snap_pending_exception *pe)
 {
-	mempool_free(pe, pending_pool);
+	mempool_free(pe, pe->snap->pending_pool);
 }
 
 static void insert_completed_exception(struct dm_snapshot *s,
@@ -482,6 +548,7 @@ static int set_chunk_size(struct dm_snapshot *s, const char *chunk_size_arg,
 static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
 	struct dm_snapshot *s;
+	int i;
 	int r = -EINVAL;
 	char persistent;
 	char *origin_path;
@@ -564,11 +631,30 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		goto bad5;
 	}
 
+	s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache);
+	if (!s->pending_pool) {
+		ti->error = "Could not allocate mempool for pending exceptions";
+		goto bad6;
+	}
+
+	s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS,
+							 tracked_chunk_cache);
+	if (!s->tracked_chunk_pool) {
+		ti->error = "Could not allocate tracked_chunk mempool for "
+			    "tracking reads";
+		goto bad_tracked_chunk_pool;
+	}
+
+	for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
+		INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]);
+
+	spin_lock_init(&s->tracked_chunk_lock);
+
 	/* Metadata must only be loaded into one table at once */
 	r = s->store.read_metadata(&s->store);
 	if (r < 0) {
 		ti->error = "Failed to read snapshot metadata";
-		goto bad6;
+		goto bad_load_and_register;
 	} else if (r > 0) {
 		s->valid = 0;
 		DMWARN("Snapshot is marked invalid.");
@@ -582,7 +668,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	if (register_snapshot(s)) {
 		r = -EINVAL;
 		ti->error = "Cannot register snapshot origin";
-		goto bad6;
+		goto bad_load_and_register;
 	}
 
 	ti->private = s;
@@ -590,6 +676,12 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 	return 0;
 
+ bad_load_and_register:
+	mempool_destroy(s->tracked_chunk_pool);
+
+ bad_tracked_chunk_pool:
+	mempool_destroy(s->pending_pool);
+
  bad6:
 	dm_kcopyd_client_destroy(s->kcopyd_client);
 
@@ -624,6 +716,9 @@ static void __free_exceptions(struct dm_snapshot *s)
 
 static void snapshot_dtr(struct dm_target *ti)
 {
+#ifdef CONFIG_DM_DEBUG
+	int i;
+#endif
 	struct dm_snapshot *s = ti->private;
 
 	flush_workqueue(ksnapd);
@@ -632,8 +727,17 @@ static void snapshot_dtr(struct dm_target *ti)
 	/* After this returns there can be no new kcopyd jobs. */
 	unregister_snapshot(s);
 
+#ifdef CONFIG_DM_DEBUG
+	for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
+		BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i]));
+#endif
+
+	mempool_destroy(s->tracked_chunk_pool);
+
 	__free_exceptions(s);
 
+	mempool_destroy(s->pending_pool);
+
 	dm_put_device(ti, s->origin);
 	dm_put_device(ti, s->cow);
 
@@ -772,6 +876,13 @@ static void pending_complete(struct dm_snap_pending_exception *pe, int success)
 	}
 
 	/*
+	 * Check for conflicting reads. This is extremely improbable,
+	 * so yield() is sufficient and there is no need for a wait queue.
+	 */
+	while (__chunk_is_tracked(s, pe->e.old_chunk))
+		yield();
+
+	/*
 	 * Add a proper exception, and remove the
 	 * in-flight exception from the list.
 	 */
@@ -873,7 +984,7 @@ __find_pending_exception(struct dm_snapshot *s, struct bio *bio)
 	 * to hold the lock while we do this.
 	 */
 	up_write(&s->lock);
-	pe = alloc_pending_exception();
+	pe = alloc_pending_exception(s);
 	down_write(&s->lock);
 
 	if (!s->valid) {
@@ -893,7 +1004,6 @@ __find_pending_exception(struct dm_snapshot *s, struct bio *bio)
 	bio_list_init(&pe->snapshot_bios);
 	pe->primary_pe = NULL;
 	atomic_set(&pe->ref_count, 0);
-	pe->snap = s;
 	pe->started = 0;
 
 	if (s->store.prepare_exception(&s->store, &pe->e)) {
@@ -974,14 +1084,10 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
 			start_copy(pe);
 			goto out;
 		}
-	} else
-		/*
-		 * FIXME: this read path scares me because we
-		 * always use the origin when we have a pending
-		 * exception.  However I can't think of a
-		 * situation where this is wrong - ejt.
-		 */
+	} else {
 		bio->bi_bdev = s->origin->bdev;
+		map_context->ptr = track_chunk(s, chunk);
+	}
 
  out_unlock:
 	up_write(&s->lock);
@@ -989,6 +1095,18 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
 	return r;
 }
 
+static int snapshot_end_io(struct dm_target *ti, struct bio *bio,
+			   int error, union map_info *map_context)
+{
+	struct dm_snapshot *s = ti->private;
+	struct dm_snap_tracked_chunk *c = map_context->ptr;
+
+	if (c)
+		stop_tracking_chunk(s, c);
+
+	return 0;
+}
+
 static void snapshot_resume(struct dm_target *ti)
 {
 	struct dm_snapshot *s = ti->private;
@@ -1266,6 +1384,7 @@ static struct target_type snapshot_target = {
 	.ctr     = snapshot_ctr,
 	.dtr     = snapshot_dtr,
 	.map     = snapshot_map,
+	.end_io  = snapshot_end_io,
 	.resume  = snapshot_resume,
 	.status  = snapshot_status,
 };
@@ -1306,9 +1425,9 @@ static int __init dm_snapshot_init(void)
 		goto bad4;
 	}
 
-	pending_pool = mempool_create_slab_pool(128, pending_cache);
-	if (!pending_pool) {
-		DMERR("Couldn't create pending pool.");
+	tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0);
+	if (!tracked_chunk_cache) {
+		DMERR("Couldn't create cache to track chunks in use.");
 		r = -ENOMEM;
 		goto bad5;
 	}
@@ -1317,13 +1436,13 @@ static int __init dm_snapshot_init(void)
 	if (!ksnapd) {
 		DMERR("Failed to create ksnapd workqueue.");
 		r = -ENOMEM;
-		goto bad6;
+		goto bad_pending_pool;
 	}
 
 	return 0;
 
-      bad6:
-	mempool_destroy(pending_pool);
+      bad_pending_pool:
+	kmem_cache_destroy(tracked_chunk_cache);
       bad5:
 	kmem_cache_destroy(pending_cache);
       bad4:
@@ -1352,9 +1471,9 @@ static void __exit dm_snapshot_exit(void)
 		DMERR("origin unregister failed %d", r);
 
 	exit_origin_hash();
-	mempool_destroy(pending_pool);
 	kmem_cache_destroy(pending_cache);
 	kmem_cache_destroy(exception_cache);
+	kmem_cache_destroy(tracked_chunk_cache);
 }
 
 /* Module hooks */
diff --git a/drivers/md/dm-snap.h b/drivers/md/dm-snap.h
index 24f9fb73b98..292c15609ae 100644
--- a/drivers/md/dm-snap.h
+++ b/drivers/md/dm-snap.h
@@ -130,6 +130,10 @@ struct exception_store {
 	void *context;
 };
 
+#define DM_TRACKED_CHUNK_HASH_SIZE	16
+#define DM_TRACKED_CHUNK_HASH(x)	((unsigned long)(x) & \
+					 (DM_TRACKED_CHUNK_HASH_SIZE - 1))
+
 struct dm_snapshot {
 	struct rw_semaphore lock;
 	struct dm_target *ti;
@@ -157,6 +161,8 @@ struct dm_snapshot {
 	/* The last percentage we notified */
 	int last_percent;
 
+	mempool_t *pending_pool;
+
 	struct exception_table pending;
 	struct exception_table complete;
 
@@ -174,6 +180,11 @@ struct dm_snapshot {
 	/* Queue of snapshot writes for ksnapd to flush */
 	struct bio_list queued_bios;
 	struct work_struct queued_bios_work;
+
+	/* Chunks with outstanding reads */
+	mempool_t *tracked_chunk_pool;
+	spinlock_t tracked_chunk_lock;
+	struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE];
 };
 
 /*
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 94116eaf470..61f44140923 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -316,29 +316,12 @@ static inline int check_space(struct dm_table *t)
  */
 static int lookup_device(const char *path, dev_t *dev)
 {
-	int r;
-	struct nameidata nd;
-	struct inode *inode;
-
-	if ((r = path_lookup(path, LOOKUP_FOLLOW, &nd)))
-		return r;
-
-	inode = nd.path.dentry->d_inode;
-	if (!inode) {
-		r = -ENOENT;
-		goto out;
-	}
-
-	if (!S_ISBLK(inode->i_mode)) {
-		r = -ENOTBLK;
-		goto out;
-	}
-
-	*dev = inode->i_rdev;
-
- out:
-	path_put(&nd.path);
-	return r;
+	struct block_device *bdev = lookup_bdev(path);
+	if (IS_ERR(bdev))
+		return PTR_ERR(bdev);
+	*dev = bdev->bd_dev;
+	bdput(bdev);
+	return 0;
 }
 
 /*
@@ -506,14 +489,13 @@ void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev)
 	rs->max_sectors =
 		min_not_zero(rs->max_sectors, q->max_sectors);
 
-	/* FIXME: Device-Mapper on top of RAID-0 breaks because DM
-	 *        currently doesn't honor MD's merge_bvec_fn routine.
-	 *        In this case, we'll force DM to use PAGE_SIZE or
-	 *        smaller I/O, just to be safe. A better fix is in the
-	 *        works, but add this for the time being so it will at
-	 *        least operate correctly.
+	/*
+	 * Check if merge fn is supported.
+	 * If not we'll force DM to use PAGE_SIZE or
+	 * smaller I/O, just to be safe.
 	 */
-	if (q->merge_bvec_fn)
+
+	if (q->merge_bvec_fn && !ti->type->merge)
 		rs->max_sectors =
 			min_not_zero(rs->max_sectors,
 				     (unsigned int) (PAGE_SIZE >> 9));
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 372369b1cc2..bca448e1187 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -37,8 +37,8 @@ static DEFINE_SPINLOCK(_minor_lock);
 struct dm_io {
 	struct mapped_device *md;
 	int error;
-	struct bio *bio;
 	atomic_t io_count;
+	struct bio *bio;
 	unsigned long start_time;
 };
 
@@ -829,6 +829,49 @@ static int __split_bio(struct mapped_device *md, struct bio *bio)
  * CRUD END
  *---------------------------------------------------------------*/
 
+static int dm_merge_bvec(struct request_queue *q,
+			 struct bvec_merge_data *bvm,
+			 struct bio_vec *biovec)
+{
+	struct mapped_device *md = q->queuedata;
+	struct dm_table *map = dm_get_table(md);
+	struct dm_target *ti;
+	sector_t max_sectors;
+	int max_size;
+
+	if (unlikely(!map))
+		return 0;
+
+	ti = dm_table_find_target(map, bvm->bi_sector);
+
+	/*
+	 * Find maximum amount of I/O that won't need splitting
+	 */
+	max_sectors = min(max_io_len(md, bvm->bi_sector, ti),
+			  (sector_t) BIO_MAX_SECTORS);
+	max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
+	if (max_size < 0)
+		max_size = 0;
+
+	/*
+	 * merge_bvec_fn() returns number of bytes
+	 * it can accept at this offset
+	 * max is precomputed maximal io size
+	 */
+	if (max_size && ti->type->merge)
+		max_size = ti->type->merge(ti, bvm, biovec, max_size);
+
+	/*
+	 * Always allow an entire first page
+	 */
+	if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
+		max_size = biovec->bv_len;
+
+	dm_table_put(map);
+
+	return max_size;
+}
+
 /*
  * The request function that just remaps the bio built up by
  * dm_merge_bvec.
@@ -1032,6 +1075,7 @@ static struct mapped_device *alloc_dev(int minor)
 	blk_queue_make_request(md->queue, dm_request);
 	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
 	md->queue->unplug_fn = dm_unplug_all;
+	blk_queue_merge_bvec(md->queue, dm_merge_bvec);
 
 	md->io_pool = mempool_create_slab_pool(MIN_IOS, _io_cache);
 	if (!md->io_pool)
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 8c03b634e62..1e59a0b0a78 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -100,12 +100,6 @@ int dm_lock_for_deletion(struct mapped_device *md);
 
 void dm_kobject_uevent(struct mapped_device *md);
 
-/*
- * Dirty log
- */
-int dm_dirty_log_init(void);
-void dm_dirty_log_exit(void);
-
 int dm_kcopyd_init(void);
 void dm_kcopyd_exit(void);
 
diff --git a/drivers/md/faulty.c b/drivers/md/faulty.c
index d107ddceefc..268547dbfbd 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 6a866d7c8ae..b1eebf88c20 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 2580ac1b9b0..deeac4b4417 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;
 }
 
@@ -2293,6 +2393,8 @@ static void analyze_sbs(mddev_t * mddev)
 
 }
 
+static void md_safemode_timeout(unsigned long data);
+
 static ssize_t
 safe_delay_show(mddev_t *mddev, char *page)
 {
@@ -2332,9 +2434,12 @@ safe_delay_store(mddev_t *mddev, const char *cbuf, size_t len)
 	if (msec == 0)
 		mddev->safemode_delay = 0;
 	else {
+		unsigned long old_delay = mddev->safemode_delay;
 		mddev->safemode_delay = (msec*HZ)/1000;
 		if (mddev->safemode_delay == 0)
 			mddev->safemode_delay = 1;
+		if (mddev->safemode_delay < old_delay)
+			md_safemode_timeout((unsigned long)mddev);
 	}
 	return len;
 }
@@ -2512,7 +2617,7 @@ __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 +2690,7 @@ 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 +2704,16 @@ 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 +2721,7 @@ 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 +2731,7 @@ 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 +2786,10 @@ 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 +2892,7 @@ 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 +2909,7 @@ 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 +3006,7 @@ 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 +3028,19 @@ 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, "reshape")) {
+	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")) {
 		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 +3051,7 @@ 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 +3161,11 @@ 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 +3187,36 @@ 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 +3231,10 @@ 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 +3365,7 @@ 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 +3470,9 @@ 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 +3485,11 @@ 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)
+			set_bit(MD_NOTIFY_ARRAY_STATE, &mddev->flags);
+	}
 	md_wakeup_thread(mddev->thread);
 }
 
@@ -3432,22 +3580,23 @@ 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 +3668,9 @@ 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 +3679,6 @@ 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 +3713,7 @@ 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 +3758,9 @@ 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 +3768,25 @@ 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 +3820,17 @@ 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);
@@ -3700,8 +3841,6 @@ static int do_md_stop(mddev_t * mddev, int mode)
 
 		del_timer_sync(&mddev->safemode_timer);
 
-		invalidate_partition(disk, 0);
-
 		switch(mode) {
 		case 1: /* readonly */
 			err  = -ENXIO;
@@ -3773,10 +3912,11 @@ 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 +3951,7 @@ 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 +3977,7 @@ 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 +4068,10 @@ 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 +4152,11 @@ 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 +4189,12 @@ 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 +4314,12 @@ 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 +4358,10 @@ 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 +4378,6 @@ 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 +4400,6 @@ 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 +4427,11 @@ 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 
@@ -4476,44 +4616,50 @@ 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;
+	if (mddev->bitmap)
+		/* Sorry, cannot grow a bitmap yet, just remove it,
+		 * grow, and re-add.
+		 */
+		return -EBUSY;
 	rdev_for_each(rdev, tmp, mddev) {
 		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 +4734,7 @@ 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 +4787,12 @@ 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 +4937,13 @@ 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 +4953,12 @@ 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 +5028,7 @@ 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 +5041,7 @@ 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 +5176,9 @@ 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 +5408,11 @@ 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 +5542,12 @@ 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 +5579,7 @@ static int is_mddev_idle(mddev_t *mddev)
 			idle = 0;
 		}
 	}
+	rcu_read_unlock();
 	return idle;
 }
 
@@ -5451,6 +5603,7 @@ 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 +5614,7 @@ 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 +5625,12 @@ 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 +5651,18 @@ 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 +5673,14 @@ 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);
 
@@ -5600,7 +5761,11 @@ void md_do_sync(mddev_t *mddev)
 					 * time 'round when curr_resync == 2
 					 */
 					continue;
-				prepare_to_wait(&resync_wait, &wq, TASK_UNINTERRUPTIBLE);
+				/* We need to wait 'interruptible' so as not to
+				 * contribute to the load average, and not to
+				 * be caught by 'softlockup'
+				 */
+				prepare_to_wait(&resync_wait, &wq, TASK_INTERRUPTIBLE);
 				if (!kthread_should_stop() &&
 				    mddev2->curr_resync >= mddev->curr_resync) {
 					printk(KERN_INFO "md: delaying %s of %s"
@@ -5608,6 +5773,8 @@ void md_do_sync(mddev_t *mddev)
 					       " share one or more physical units)\n",
 					       desc, mdname(mddev), mdname(mddev2));
 					mddev_put(mddev2);
+					if (signal_pending(current))
+						flush_signals(current);
 					schedule();
 					finish_wait(&resync_wait, &wq);
 					goto try_again;
@@ -5625,9 +5792,11 @@ 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 +5965,7 @@ 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);
@@ -5837,15 +6007,17 @@ static int remove_and_add_spares(mddev_t *mddev)
 			}
 		}
 
-	if (mddev->degraded) {
+	if (mddev->degraded && ! mddev->ro) {
 		rdev_for_each(rdev, rtmp, mddev) {
 			if (rdev->raid_disk >= 0 &&
-			    !test_bit(In_sync, &rdev->flags))
+			    !test_bit(In_sync, &rdev->flags) &&
+			    !test_bit(Blocked, &rdev->flags))
 				spares++;
 			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,
@@ -5894,6 +6066,9 @@ void md_check_recovery(mddev_t *mddev)
 	if (mddev->bitmap)
 		bitmap_daemon_work(mddev->bitmap);
 
+	if (test_and_clear_bit(MD_NOTIFY_ARRAY_STATE, &mddev->flags))
+		sysfs_notify(&mddev->kobj, NULL, "array_state");
+
 	if (mddev->ro)
 		return;
 
@@ -5906,6 +6081,8 @@ void md_check_recovery(mddev_t *mddev)
 		flush_signals(current);
 	}
 
+	if (mddev->ro && !test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
+		return;
 	if ( ! (
 		(mddev->flags && !mddev->external) ||
 		test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
@@ -5919,24 +6096,41 @@ void md_check_recovery(mddev_t *mddev)
 	if (mddev_trylock(mddev)) {
 		int spares = 0;
 
+		if (mddev->ro) {
+			/* Only thing we do on a ro array is remove
+			 * failed devices.
+			 */
+			remove_and_add_spares(mddev);
+			clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+			goto unlock;
+		}
+
 		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)) {
@@ -5948,10 +6142,13 @@ void md_check_recovery(mddev_t *mddev)
 			/* resync has finished, collect result */
 			md_unregister_thread(mddev->sync_thread);
 			mddev->sync_thread = NULL;
-			if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
+			if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
+			    !test_bit(MD_RECOVERY_REQUESTED, &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 +6162,18 @@ 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 +6191,20 @@ 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);
+			clear_bit(MD_RECOVERY_REQUESTED, &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 +6223,16 @@ 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 +6259,11 @@ static int md_notify_reboot(struct notifier_block *this,
 
 		for_each_mddev(mddev, tmp)
 			if (mddev_trylock(mddev)) {
-				do_md_stop (mddev, 1);
+				/* Force a switch to readonly even array
+				 * appears to still be in use.  Hence
+				 * the '100'.
+				 */
+				do_md_stop (mddev, 1, 100);
 				mddev_unlock(mddev);
 			}
 		/*
diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index e968116e0de..c4779ccba1c 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 bcbb82594a1..18361063566 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 c610b947218..03a5ab705c2 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 22bb2b1b886..e34cd0e6247 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -76,11 +76,13 @@ static void r10bio_pool_free(void *r10_bio, void *data)
 	kfree(r10_bio);
 }
 
+/* Maximum size of each resync request */
 #define RESYNC_BLOCK_SIZE (64*1024)
-//#define RESYNC_BLOCK_SIZE PAGE_SIZE
-#define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
-#define RESYNC_WINDOW (2048*1024)
+/* amount of memory to reserve for resync requests */
+#define RESYNC_WINDOW (1024*1024)
+/* maximum number of concurrent requests, memory permitting */
+#define RESYNC_DEPTH (32*1024*1024/RESYNC_BLOCK_SIZE)
 
 /*
  * When performing a resync, we need to read and compare, so
@@ -215,6 +217,9 @@ static void reschedule_retry(r10bio_t *r10_bio)
 	conf->nr_queued ++;
 	spin_unlock_irqrestore(&conf->device_lock, flags);
 
+	/* wake up frozen array... */
+	wake_up(&conf->wait_barrier);
+
 	md_wakeup_thread(mddev->thread);
 }
 
@@ -687,7 +692,6 @@ static int flush_pending_writes(conf_t *conf)
  *    there is no normal IO happeing.  It must arrange to call
  *    lower_barrier when the particular background IO completes.
  */
-#define RESYNC_DEPTH 32
 
 static void raise_barrier(conf_t *conf, int force)
 {
@@ -1114,24 +1118,30 @@ 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 +1156,7 @@ 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 +1164,7 @@ 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 +2169,7 @@ 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 9ce7154845c..224de022e7c 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();
 	}
 }
 
@@ -2634,22 +2507,21 @@ static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
  *
  */
 
-static void handle_stripe5(struct stripe_head *sh)
+static bool handle_stripe5(struct stripe_head *sh)
 {
 	raid5_conf_t *conf = sh->raid_conf;
 	int disks = sh->disks, i;
 	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 */
@@ -2703,10 +2568,10 @@ static void handle_stripe5(struct stripe_head *sh)
 		if (dev->written)
 			s.written++;
 		rdev = rcu_dereference(conf->disks[i].rdev);
-		if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
+		if (blocked_rdev == NULL &&
+		    rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
 			blocked_rdev = rdev;
 			atomic_inc(&rdev->nr_pending);
-			break;
 		}
 		if (!rdev || !test_bit(In_sync, &rdev->flags)) {
 			/* The ReadError flag will just be confusing now */
@@ -2723,12 +2588,20 @@ static void handle_stripe5(struct stripe_head *sh)
 	rcu_read_unlock();
 
 	if (unlikely(blocked_rdev)) {
-		set_bit(STRIPE_HANDLE, &sh->state);
-		goto unlock;
+		if (s.syncing || s.expanding || s.expanded ||
+		    s.to_write || s.written) {
+			set_bit(STRIPE_HANDLE, &sh->state);
+			goto unlock;
+		}
+		/* There is nothing for the blocked_rdev to block */
+		rdev_dec_pending(blocked_rdev, conf->mddev);
+		blocked_rdev = NULL;
 	}
 
-	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 +2611,7 @@ 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 +2627,25 @@ 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 +2657,6 @@ 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 +2678,18 @@ 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 +2708,36 @@ 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--; ) {
 			set_bit(R5_Wantwrite, &sh->dev[i].flags);
-			set_bit(R5_LOCKED, &dev->flags);
+			set_bit(R5_LOCKED, &sh->dev[i].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 +2745,9 @@ 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);
 
@@ -2930,14 +2755,17 @@ 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);
+
+	ops_run_io(sh, &s);
 
 	return_io(return_bi);
 
+	return blocked_rdev == NULL;
 }
 
-static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
+static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 {
 	raid6_conf_t *conf = sh->raid_conf;
 	int disks = sh->disks;
@@ -3010,10 +2838,10 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 		if (dev->written)
 			s.written++;
 		rdev = rcu_dereference(conf->disks[i].rdev);
-		if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
+		if (blocked_rdev == NULL &&
+		    rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
 			blocked_rdev = rdev;
 			atomic_inc(&rdev->nr_pending);
-			break;
 		}
 		if (!rdev || !test_bit(In_sync, &rdev->flags)) {
 			/* The ReadError flag will just be confusing now */
@@ -3031,9 +2859,16 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
 	rcu_read_unlock();
 
 	if (unlikely(blocked_rdev)) {
-		set_bit(STRIPE_HANDLE, &sh->state);
-		goto unlock;
+		if (s.syncing || s.expanding || s.expanded ||
+		    s.to_write || s.written) {
+			set_bit(STRIPE_HANDLE, &sh->state);
+			goto unlock;
+		}
+		/* There is nothing for the blocked_rdev to block */
+		rdev_dec_pending(blocked_rdev, conf->mddev);
+		blocked_rdev = NULL;
 	}
+
 	pr_debug("locked=%d uptodate=%d to_read=%d"
 	       " to_write=%d failed=%d failed_num=%d,%d\n",
 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
@@ -3042,8 +2877,7 @@ 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 +2902,7 @@ 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 +2910,11 @@ 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 +2970,7 @@ 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:
@@ -3146,76 +2980,20 @@ 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);
+	return_io(return_bi);
 
-			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 blocked_rdev == NULL;
 }
 
-static void handle_stripe(struct stripe_head *sh, struct page *tmp_page)
+/* returns true if the stripe was handled */
+static bool handle_stripe(struct stripe_head *sh, struct page *tmp_page)
 {
 	if (sh->raid_conf->level == 6)
-		handle_stripe6(sh, tmp_page);
+		return handle_stripe6(sh, tmp_page);
 	else
-		handle_stripe5(sh);
+		return handle_stripe5(sh);
 }
 
 
@@ -3697,9 +3475,7 @@ 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 +3561,7 @@ 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;
 			}
@@ -3935,7 +3711,9 @@ static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *ski
 	clear_bit(STRIPE_INSYNC, &sh->state);
 	spin_unlock(&sh->lock);
 
-	handle_stripe(sh, NULL);
+	/* wait for any blocked device to be handled */
+	while(unlikely(!handle_stripe(sh, NULL)))
+		;
 	release_stripe(sh);
 
 	return STRIPE_SECTORS;
@@ -4002,12 +3780,8 @@ 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;
@@ -4058,10 +3832,8 @@ static void raid5d(mddev_t *mddev)
 
 		sh = __get_priority_stripe(conf);
 
-		if (!sh) {
-			async_tx_issue_pending_all();
+		if (!sh)
 			break;
-		}
 		spin_unlock_irq(&conf->device_lock);
 		
 		handled++;
@@ -4074,6 +3846,7 @@ static void raid5d(mddev_t *mddev)
 
 	spin_unlock_irq(&conf->device_lock);
 
+	async_tx_issue_pending_all();
 	unplug_slaves(mddev);
 
 	pr_debug("--- raid5d inactive\n");
@@ -4094,6 +3867,8 @@ 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 +3884,9 @@ 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 +4211,7 @@ 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 +4386,41 @@ 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 +4435,9 @@ 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;
@@ -4675,6 +4459,9 @@ static int raid5_check_reshape(mddev_t *mddev)
 		return -EINVAL; /* Cannot shrink array or change level yet */
 	if (mddev->delta_disks == 0)
 		return 0; /* nothing to do */
+	if (mddev->bitmap)
+		/* Cannot grow a bitmap yet */
+		return -EBUSY;
 
 	/* Can only proceed if there are plenty of stripe_heads.
 	 * We need a minimum of one full stripe,, and for sensible progress
@@ -4738,7 +4525,7 @@ 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 +4573,16 @@ 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);
 		}