7 files changed, 23 insertions, 39 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 789b114f860a..7075bebb7f37 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -224,8 +224,8 @@ 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);
+        init_waitqueue_head(&new->sb_wait);
 
         new->queue = blk_alloc_queue(GFP_KERNEL);
         if (!new->queue) {
@@ -1307,6 +1307,7 @@ repeat:
         if (!mddev->persistent) {
                 mddev->sb_dirty = 0;
                 spin_unlock(&mddev->write_lock);
+                wake_up(&mddev->sb_wait);
                 return;
         }
         spin_unlock(&mddev->write_lock);
@@ -1348,6 +1349,7 @@ repeat:
         }
         mddev->sb_dirty = 0;
         spin_unlock(&mddev->write_lock);
+        wake_up(&mddev->sb_wait);
 
 }
 
@@ -3368,29 +3370,26 @@ void md_done_sync(mddev_t *mddev, int blocks, int ok)
 
 /* 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
+ * in superblock) before writing, schedule a superblock update
+ * and wait for it to complete.
  */
-int md_write_start(mddev_t *mddev, struct bio *bi)
+void md_write_start(mddev_t *mddev, struct bio *bi)
 {
+        DEFINE_WAIT(w);
         if (bio_data_dir(bi) != WRITE)
-                return 1;
+                return;
 
         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_lock(&mddev->write_lock);
+                if (mddev->in_sync) {
+                        mddev->in_sync = 0;
+                        mddev->sb_dirty = 1;
+                        md_wakeup_thread(mddev->thread);
+                }
+                spin_unlock(&mddev->write_lock);
         }
-        spin_unlock(&mddev->write_lock);
-        md_wakeup_thread(mddev->thread);
-        return 0;
+        wait_event(mddev->sb_wait, mddev->sb_dirty==0);
 }
 
 void md_write_end(mddev_t *mddev)
@@ -3685,7 +3684,6 @@ 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)
@@ -3694,7 +3692,6 @@ 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) &&
@@ -3704,21 +3701,11 @@ 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)) {
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 3f5234fe3593..98b09773e79e 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -561,8 +561,8 @@ 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;
+        md_write_start(mddev, bio); /* wait on superblock update early */
+
         spin_lock_irq(&conf->resync_lock);
         wait_event_lock_irq(conf->wait_resume, !conf->barrier, conf->resync_lock, );
         conf->nr_pending++;
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 8476515bfdc7..fd7324a86d13 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -700,8 +700,7 @@ static int make_request(request_queue_t *q, struct bio * bio)
                 return 0;
         }
 
-        if (md_write_start(mddev, bio) == 0)
-                return 0;
+        md_write_start(mddev, bio);
 
         /*
          * Register the new request and wait if the reconstruction
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 1ce3f5aaa984..93a9726cc2d6 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1411,8 +1411,7 @@ 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;
+        md_write_start(mddev, bi);
 
         if (bio_data_dir(bi)==WRITE) {
                 disk_stat_inc(mddev->gendisk, writes);
diff --git a/drivers/md/raid6main.c b/drivers/md/raid6main.c
index d9c385496dc5..f62ea1a73d0d 100644
--- a/drivers/md/raid6main.c
+++ b/drivers/md/raid6main.c
@@ -1570,8 +1570,7 @@ 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;
+        md_write_start(mddev, bi);
 
         if (bio_data_dir(bi)==WRITE) {
                 disk_stat_inc(mddev->gendisk, writes);
diff --git a/include/linux/raid/md.h b/include/linux/raid/md.h
index cfde8f497d6d..75f41d8faed2 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 int md_write_start(mddev_t *mddev, struct bio *bi);
+extern void 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 6cdcb4434c6c..3e977025cf43 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -261,7 +261,7 @@ struct mddev_s
         sector_t                        recovery_cp;
 
         spinlock_t                      write_lock;
-        struct bio_list                 write_list;
+        wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
 
         unsigned int                    safemode;       /* if set, update "clean" superblock
                                                          * when no writes pending.