1 files changed, 9 insertions, 0 deletions

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 6b5173ac8131..c99b46354859 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -340,6 +340,15 @@ unsigned blk_ordered_req_seq(struct request *rq)
         if (rq == &q->post_flush_rq)
                 return QUEUE_ORDSEQ_POSTFLUSH;
 
+        /*
+         * !fs requests don't need to follow barrier ordering.  Always
+         * put them at the front.  This fixes the following deadlock.
+         *
+         * http://thread.gmane.org/gmane.linux.kernel/537473
+         */
+        if (!blk_fs_request(rq))
+                return QUEUE_ORDSEQ_DRAIN;
+
         if ((rq->cmd_flags & REQ_ORDERED_COLOR) ==
             (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR))
                 return QUEUE_ORDSEQ_DRAIN;