From: Yufen Yu yuyufen@huawei.com
[ 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@kernel.org Signed-off-by: Yufen Yu yuyufen@huawei.com Reviewed-by: Ming Lei ming.lei@redhat.com Link: https://lore.kernel.org/r/20210331115359.1125679-1-yuyufen@huawei.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/bio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
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;