md: fix possible raid1/raid10 deadlock on read error during resync

[linux-2.6-omap-h63xx.git] / drivers / md / raid1.c

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 38f076a3400d6202aba4b7e7f460ff81a3d8c426..ff61b309129aa8ffa9dbd00987a71c1b6eb35bf5 100644 (file)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -704,13 +704,20 @@ static void freeze_array(conf_t *conf)
        /* stop syncio and normal IO and wait for everything to
         * go quite.
         * We increment barrier and nr_waiting, and then
-        * wait until barrier+nr_pending match nr_queued+2
+        * wait until nr_pending match nr_queued+1
+        * This is called in the context of one normal IO request
+        * that has failed. Thus any sync request that might be pending
+        * will be blocked by nr_pending, and we need to wait for
+        * pending IO requests to complete or be queued for re-try.
+        * Thus the number queued (nr_queued) plus this request (1)
+        * must match the number of pending IOs (nr_pending) before
+        * we continue.
         */
        spin_lock_irq(&conf->resync_lock);
        conf->barrier++;
        conf->nr_waiting++;
        wait_event_lock_irq(conf->wait_barrier,
-                           conf->barrier+conf->nr_pending == conf->nr_queued+2,
+                           conf->nr_pending == conf->nr_queued+1,
                            conf->resync_lock,
                            ({ flush_pending_writes(conf);
                               raid1_unplug(conf->mddev->queue); }));