diff --git a/drivers/md/md.c b/drivers/md/md.c
index c842e34d850..177d2a7d7ce 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -218,6 +218,8 @@ static mddev_t * mddev_find(dev_t unit)
 	INIT_LIST_HEAD(&new->all_mddevs);
 	init_timer(&new->safemode_timer);
 	atomic_set(&new->active, 1);
+	bio_list_init(&new->write_list);
+	spin_lock_init(&new->write_lock);
 
 	new->queue = blk_alloc_queue(GFP_KERNEL);
 	if (!new->queue) {
@@ -1251,9 +1253,11 @@ static void md_update_sb(mddev_t * mddev)
 	int err, count = 100;
 	struct list_head *tmp;
 	mdk_rdev_t *rdev;
+	int sync_req;
 
-	mddev->sb_dirty = 0;
 repeat:
+	spin_lock(&mddev->write_lock);
+	sync_req = mddev->in_sync;
 	mddev->utime = get_seconds();
 	mddev->events ++;
 
@@ -1272,8 +1276,12 @@ repeat:
 	 * do not write anything to disk if using
 	 * nonpersistent superblocks
 	 */
-	if (!mddev->persistent)
+	if (!mddev->persistent) {
+		mddev->sb_dirty = 0;
+		spin_unlock(&mddev->write_lock);
 		return;
+	}
+	spin_unlock(&mddev->write_lock);
 
 	dprintk(KERN_INFO 
 		"md: updating %s RAID superblock on device (in sync %d)\n",
@@ -1304,6 +1312,15 @@ repeat:
 		printk(KERN_ERR \
 			"md: excessive errors occurred during superblock update, exiting\n");
 	}
+	spin_lock(&mddev->write_lock);
+	if (mddev->in_sync != sync_req) {
+		/* have to write it out again */
+		spin_unlock(&mddev->write_lock);
+		goto repeat;
+	}
+	mddev->sb_dirty = 0;
+	spin_unlock(&mddev->write_lock);
+
 }
 
 /*
@@ -3178,19 +3195,31 @@ void md_done_sync(mddev_t *mddev, int blocks, int ok)
 }
 
 
-void md_write_start(mddev_t *mddev)
+/* md_write_start(mddev, bi)
+ * If we need to update some array metadata (e.g. 'active' flag
+ * in superblock) before writing, queue bi for later writing
+ * and return 0, else return 1 and it will be written now
+ */
+int md_write_start(mddev_t *mddev, struct bio *bi)
 {
-	if (!atomic_read(&mddev->writes_pending)) {
-		mddev_lock_uninterruptible(mddev);
-		if (mddev->in_sync) {
-			mddev->in_sync = 0;
- 			del_timer(&mddev->safemode_timer);
-			md_update_sb(mddev);
-		}
-		atomic_inc(&mddev->writes_pending);
-		mddev_unlock(mddev);
-	} else
-		atomic_inc(&mddev->writes_pending);
+	if (bio_data_dir(bi) != WRITE)
+		return 1;
+
+	atomic_inc(&mddev->writes_pending);
+	spin_lock(&mddev->write_lock);
+	if (mddev->in_sync == 0 && mddev->sb_dirty == 0) {
+		spin_unlock(&mddev->write_lock);
+		return 1;
+	}
+	bio_list_add(&mddev->write_list, bi);
+
+	if (mddev->in_sync) {
+		mddev->in_sync = 0;
+		mddev->sb_dirty = 1;
+	}
+	spin_unlock(&mddev->write_lock);
+	md_wakeup_thread(mddev->thread);
+	return 0;
 }
 
 void md_write_end(mddev_t *mddev)
@@ -3472,6 +3501,7 @@ void md_check_recovery(mddev_t *mddev)
 		mddev->sb_dirty ||
 		test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
 		test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
+		mddev->write_list.head ||
 		(mddev->safemode == 1) ||
 		(mddev->safemode == 2 && ! atomic_read(&mddev->writes_pending)
 		 && !mddev->in_sync && mddev->recovery_cp == MaxSector)
@@ -3480,7 +3510,9 @@ void md_check_recovery(mddev_t *mddev)
 
 	if (mddev_trylock(mddev)==0) {
 		int spares =0;
+		struct bio *blist;
 
+		spin_lock(&mddev->write_lock);
 		if (mddev->safemode && !atomic_read(&mddev->writes_pending) &&
 		    !mddev->in_sync && mddev->recovery_cp == MaxSector) {
 			mddev->in_sync = 1;
@@ -3488,9 +3520,22 @@ void md_check_recovery(mddev_t *mddev)
 		}
 		if (mddev->safemode == 1)
 			mddev->safemode = 0;
+		blist = bio_list_get(&mddev->write_list);
+		spin_unlock(&mddev->write_lock);
 
 		if (mddev->sb_dirty)
 			md_update_sb(mddev);
+
+		while (blist) {
+			struct bio *b = blist;
+			blist = blist->bi_next;
+			b->bi_next = NULL;
+			generic_make_request(b);
+			/* we already counted this, so need to un-count */
+			md_write_end(mddev);
+		}
+
+
 		if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
 		    !test_bit(MD_RECOVERY_DONE, &mddev->recovery)) {
 			/* resync/recovery still happening */
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index b34ad56362d..3f1280bbaf3 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -530,6 +530,8 @@ static int make_request(request_queue_t *q, struct bio * bio)
 	 * thread has put up a bar for new requests.
 	 * Continue immediately if no resync is active currently.
 	 */
+	if (md_write_start(mddev, bio)==0)
+		return 0;
 	spin_lock_irq(&conf->resync_lock);
 	wait_event_lock_irq(conf->wait_resume, !conf->barrier, conf->resync_lock, );
 	conf->nr_pending++;
@@ -611,7 +613,7 @@ static int make_request(request_queue_t *q, struct bio * bio)
 	rcu_read_unlock();
 
 	atomic_set(&r1_bio->remaining, 1);
-	md_write_start(mddev);
+
 	for (i = 0; i < disks; i++) {
 		struct bio *mbio;
 		if (!r1_bio->bios[i])
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 9ae21504db8..bfc9f52f0ec 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -700,6 +700,9 @@ static int make_request(request_queue_t *q, struct bio * bio)
 		return 0;
 	}
 
+	if (md_write_start(mddev, bio) == 0)
+		return 0;
+
 	/*
 	 * Register the new request and wait if the reconstruction
 	 * thread has put up a bar for new requests.
@@ -774,7 +777,7 @@ static int make_request(request_queue_t *q, struct bio * bio)
 	rcu_read_unlock();
 
 	atomic_set(&r10_bio->remaining, 1);
-	md_write_start(mddev);
+
 	for (i = 0; i < conf->copies; i++) {
 		struct bio *mbio;
 		int d = r10_bio->devs[i].devnum;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 63b1c59d36f..677ce49078d 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1411,6 +1411,9 @@ static int make_request (request_queue_t *q, struct bio * bi)
 	sector_t logical_sector, last_sector;
 	struct stripe_head *sh;
 
+	if (md_write_start(mddev, bi)==0)
+		return 0;
+
 	if (bio_data_dir(bi)==WRITE) {
 		disk_stat_inc(mddev->gendisk, writes);
 		disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bi));
@@ -1423,8 +1426,7 @@ static int make_request (request_queue_t *q, struct bio * bi)
 	last_sector = bi->bi_sector + (bi->bi_size>>9);
 	bi->bi_next = NULL;
 	bi->bi_phys_segments = 1;	/* over-loaded to count active stripes */
-	if ( bio_data_dir(bi) == WRITE )
-		md_write_start(mddev);
+
 	for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
 		DEFINE_WAIT(w);
 		
diff --git a/drivers/md/raid6main.c b/drivers/md/raid6main.c
index 9d0e0e42a3b..fede16c4e8f 100644
--- a/drivers/md/raid6main.c
+++ b/drivers/md/raid6main.c
@@ -1570,6 +1570,9 @@ static int make_request (request_queue_t *q, struct bio * bi)
 	sector_t logical_sector, last_sector;
 	struct stripe_head *sh;
 
+	if (md_write_start(mddev, bi)==0)
+		return 0;
+
 	if (bio_data_dir(bi)==WRITE) {
 		disk_stat_inc(mddev->gendisk, writes);
 		disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bi));
@@ -1583,8 +1586,7 @@ static int make_request (request_queue_t *q, struct bio * bi)
 
 	bi->bi_next = NULL;
 	bi->bi_phys_segments = 1;	/* over-loaded to count active stripes */
-	if ( bio_data_dir(bi) == WRITE )
-		md_write_start(mddev);
+
 	for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
 		DEFINE_WAIT(w);
 
diff --git a/include/linux/raid/md.h b/include/linux/raid/md.h
index a6a67d102bf..cfde8f497d6 100644
--- a/include/linux/raid/md.h
+++ b/include/linux/raid/md.h
@@ -69,7 +69,7 @@ extern mdk_thread_t * md_register_thread (void (*run) (mddev_t *mddev),
 extern void md_unregister_thread (mdk_thread_t *thread);
 extern void md_wakeup_thread(mdk_thread_t *thread);
 extern void md_check_recovery(mddev_t *mddev);
-extern void md_write_start(mddev_t *mddev);
+extern int md_write_start(mddev_t *mddev, struct bio *bi);
 extern void md_write_end(mddev_t *mddev);
 extern void md_handle_safemode(mddev_t *mddev);
 extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index c9a0d4013be..d92db54255a 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -15,6 +15,9 @@
 #ifndef _MD_K_H
 #define _MD_K_H
 
+/* and dm-bio-list.h is not under include/linux because.... ??? */
+#include "../../../drivers/md/dm-bio-list.h"
+
 #define MD_RESERVED       0UL
 #define LINEAR            1UL
 #define RAID0             2UL
@@ -252,6 +255,10 @@ struct mddev_s
 	atomic_t			recovery_active; /* blocks scheduled, but not written */
 	wait_queue_head_t		recovery_wait;
 	sector_t			recovery_cp;
+
+	spinlock_t			write_lock;
+	struct bio_list			write_list;
+
 	unsigned int			safemode;	/* if set, update "clean" superblock
 							 * when no writes pending.
 							 */