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-rw-r--r--block/ll_rw_blk.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 6b5173ac813..c99b4635485 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;