2015-05-01 16:59:49

by Shaohua Li

Subject: [PATCH] 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 <[email protected]>
---
include/linux/blk_types.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

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 @@ enum rq_flag_bits {

/* 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)
--
1.8.1

2015-05-04 19:11:08

by Jens Axboe

Subject: Re: [PATCH] blk-mq: fix FUA request hang

On 05/01/2015 10:59 AM, Shaohua Li wrote:
> 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.

Thanks, applied.

--
Jens Axboe