From: Jens Axboe <axboe@kernel.dk>
Date: Thu, 28 May 2020 19:19:29 +0000 (-0600)
Subject: Revert "block: end bio with BLK_STS_AGAIN in case of non-mq devs and REQ_NOWAIT"
X-Git-Tag: block-5.7-2020-05-29^0
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=b0beb28097fa04177b3769f4bb7a0d0d9c4ae76e;p=linux-block.git

Revert "block: end bio with BLK_STS_AGAIN in case of non-mq devs and REQ_NOWAIT"

This reverts commit c58c1f83436b501d45d4050fd1296d71a9760bcb.

io_uring does do the right thing for this case, and we're still returning
-EAGAIN to userspace for the cases we don't support. Revert this change
to avoid doing endless spins of resubmits.

Cc: stable@vger.kernel.org # v5.6
Reported-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/blk-core.c b/block/blk-core.c
index 7e4a1da0715e..9bfaee050c82 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -891,14 +891,11 @@ generic_make_request_checks(struct bio *bio)
 	}
 
 	/*
-	 * 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.
+	 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
+	 * if queue is not a request based queue.
 	 */
-	if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q)) {
-		status = BLK_STS_AGAIN;
-		goto end_io;
-	}
+	if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q))
+		goto not_supported;
 
 	if (should_fail_bio(bio))
 		goto end_io;