1 files changed, 59 insertions, 14 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index c842e34d850e..177d2a7d7cea 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 */