block: disable discard request merge temporarily

The SCSI discard request merge never worked, and looks no solution
for in future, let's disable it temporarily.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index dc632975d54fd07f02c5bf8aceccaf55015b8908..4a2ab7c85393df48fd8d93e085f3b7ead5de7be2 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -601,7 +601,7 @@ static inline void blk_clear_rl_full(struct request_list *rl, bool sync)
  * it already be started by driver.
  */
 #define RQ_NOMERGE_FLAGS       \
-       (REQ_NOMERGE | REQ_STARTED | REQ_SOFTBARRIER | REQ_FLUSH | REQ_FUA)
+       (REQ_NOMERGE | REQ_STARTED | REQ_SOFTBARRIER | REQ_FLUSH | REQ_FUA | REQ_DISCARD)
 #define rq_mergeable(rq)       \
        (!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && \
         (((rq)->cmd_flags & REQ_DISCARD) || \