From 56f99b8d06ef1ed1c9730948f9f05ac2b930a20b Mon Sep 17 00:00:00 2001
From: Stefan Roesch <shr@fb.com>
Date: Mon, 12 Sep 2022 09:53:25 -0700
Subject: [PATCH] block: blk_queue_enter() / __bio_queue_enter() must return
-EAGAIN for nowait
Git-commit: 56f99b8d06ef1ed1c9730948f9f05ac2b930a20b
Patch-mainline: v6.0-rc6
References: git-fixes
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.
(Coly Li: rebased for Linux v5.14 based SUSE kernel)
Signed-off-by: Stefan Roesch <shr@fb.com>
Fixes: bfd343aa1718 ("blk-mq: don't wait in blk_mq_queue_enter() if __GFP_WAIT isn't set")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Coly Li <colyli@suse.de>
---
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 a0d1104c5590..651057c4146b 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;
}
/*
--
2.35.3