From: Roman Penyaev rpenyaev@suse.de
[ Upstream commit c58c1f83436b501d45d4050fd1296d71a9760bcb ]
Non-mq devs do not honor REQ_NOWAIT so give a chance to the caller to repeat request gracefully on -EAGAIN error.
The problem is well reproduced using io_uring:
mkfs.ext4 /dev/ram0 mount /dev/ram0 /mnt
# Preallocate a file dd if=/dev/zero of=/mnt/file bs=1M count=1
# Start fio with io_uring and get -EIO fio --rw=write --ioengine=io_uring --size=1M --direct=1 --name=job --filename=/mnt/file
Signed-off-by: Roman Penyaev rpenyaev@suse.de Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-core.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c index d5e668ec751b..1075aaff606d 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -886,11 +886,14 @@ generic_make_request_checks(struct bio *bio) }
/* - * For a REQ_NOWAIT based request, return -EOPNOTSUPP - * if queue is not a request based queue. + * Non-mq queues do not honor REQ_NOWAIT, so complete a bio + * with BLK_STS_AGAIN status in order to catch -EAGAIN and + * to give a chance to the caller to repeat request gracefully. */ - if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q)) - goto not_supported; + if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q)) { + status = BLK_STS_AGAIN; + goto end_io; + }
if (should_fail_bio(bio)) goto end_io;