This is a note to let you know that I've just added the patch titled
block: only update parent bi_status when bio fail
to the 5.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
block-only-update-parent-bi_status-when-bio-fail.patch
and it can be found in the queue-5.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b99daf06da51973f9a86bea2e7a6a483d8edf9d0
Author: Yufen Yu <yuyufen@xxxxxxxxxx>
Date: Wed Mar 31 07:53:59 2021 -0400
block: only update parent bi_status when bio fail
[ Upstream commit 3edf5346e4f2ce2fa0c94651a90a8dda169565ee ]
For multiple split bios, if one of the bio is fail, the whole
should return error to application. But we found there is a race
between bio_integrity_verify_fn and bio complete, which return
io success to application after one of the bio fail. The race as
following:
split bio(READ) kworker
nvme_complete_rq
blk_update_request //split error=0
bio_endio
bio_integrity_endio
queue_work(kintegrityd_wq, &bip->bip_work);
bio_integrity_verify_fn
bio_endio //split bio
__bio_chain_endio
if (!parent->bi_status)
<interrupt entry>
nvme_irq
blk_update_request //parent error=7
req_bio_endio
bio->bi_status = 7 //parent bio
<interrupt exit>
parent->bi_status = 0
parent->bi_end_io() // return bi_status=0
The bio has been split as two: split and parent. When split
bio completed, it depends on kworker to do endio, while
bio_integrity_verify_fn have been interrupted by parent bio
complete irq handler. Then, parent bio->bi_status which have
been set in irq handler will overwrite by kworker.
In fact, even without the above race, we also need to conside
the concurrency beteen mulitple split bio complete and update
the same parent bi_status. Normally, multiple split bios will
be issued to the same hctx and complete from the same irq
vector. But if we have updated queue map between multiple split
bios, these bios may complete on different hw queue and different
irq vector. Then the concurrency update parent bi_status may
cause the final status error.
Suggested-by: Keith Busch <kbusch@xxxxxxxxxx>
Signed-off-by: Yufen Yu <yuyufen@xxxxxxxxxx>
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210331115359.1125679-1-yuyufen@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/block/bio.c b/block/bio.c
index 1f2cc1fbe283..3209d865828a 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -313,7 +313,7 @@ static struct bio *__bio_chain_endio(struct bio *bio)
{
struct bio *parent = bio->bi_private;
- if (!parent->bi_status)
+ if (bio->bi_status && !parent->bi_status)
parent->bi_status = bio->bi_status;
bio_put(bio);
return parent;
