blk-mq: fix FUA request hang
When a FUA request enters its DATA stage of flush pipeline, the
request is added to mq requeue list, the request will then be added to
ctx->rq_list. blk_mq_attempt_merge() might merge the request with a bio.
Later when the request is finished the flush pipeline, the
request->__data_len is 0. Then I only saw the bio gets endio called, the
original request never finish.
Adding REQ_FLUSH_SEQ into REQ_NOMERGE_FLAGS looks an easy fix.
stable: 3.15+
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index a1b25e3..b7299fe 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -220,7 +220,7 @@
/* This mask is used for both bio and request merge checking */
#define REQ_NOMERGE_FLAGS \
- (REQ_NOMERGE | REQ_STARTED | REQ_SOFTBARRIER | REQ_FLUSH | REQ_FUA)
+ (REQ_NOMERGE | REQ_STARTED | REQ_SOFTBARRIER | REQ_FLUSH | REQ_FUA | REQ_FLUSH_SEQ)
#define REQ_RAHEAD (1ULL << __REQ_RAHEAD)
#define REQ_THROTTLED (1ULL << __REQ_THROTTLED)