[PATCH] md: fix deadlock due to md thread processing delayed requests.

[safe/jmp/linux-2.6] / drivers / md / md.c

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 789b114..7075beb 100644 (file)
--- 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)) {