From 56f99b8d06ef1ed1c9730948f9f05ac2b930a20b Mon Sep 17 00:00:00 2001 From: Stefan Roesch Date: Mon, 12 Sep 2022 09:53:25 -0700 Subject: [PATCH] block: blk_queue_enter() / __bio_queue_enter() must return -EAGAIN for nowait Today blk_queue_enter() and __bio_queue_enter() return -EBUSY for the nowait code path. This is not correct: they should return -EAGAIN instead. This problem was detected by fio. The following command exposed the above problem: t/io_uring -p0 -d128 -b4096 -s32 -c32 -F1 -B0 -R0 -X1 -n24 -P1 -u1 -O0 /dev/ng0n1 By applying the patch, the retry case is handled correctly in the slow path. Signed-off-by: Stefan Roesch Fixes: bfd343aa1718 ("blk-mq: don't wait in blk_mq_queue_enter() if __GFP_WAIT isn't set") Signed-off-by: Jens Axboe --- block/blk-core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index a0d1104..651057c 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -295,7 +295,7 @@ int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) while (!blk_try_enter_queue(q, pm)) { if (flags & BLK_MQ_REQ_NOWAIT) - return -EBUSY; + return -EAGAIN; /* * read pair of barrier in blk_freeze_queue_start(), we need to @@ -325,7 +325,7 @@ int __bio_queue_enter(struct request_queue *q, struct bio *bio) if (test_bit(GD_DEAD, &disk->state)) goto dead; bio_wouldblock_error(bio); - return -EBUSY; + return -EAGAIN; } /* -- 2.7.4