[PATCH 4/6] block: clear BIO_PERCPU_CACHE flag if polling isn't supported

From: Jens Axboe <axboe@kernel.dk>
To: io-uring@vger.kernel.org
Cc: linux-block@vger.kernel.org, hch@infradead.org,
	Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 4/6] block: clear BIO_PERCPU_CACHE flag if polling isn't supported
Date: Wed, 11 Aug 2021 13:35:31 -0600	[thread overview]
Message-ID: <20210811193533.766613-5-axboe@kernel.dk> (raw)
In-Reply-To: <20210811193533.766613-1-axboe@kernel.dk>

The bio alloc cache relies on the fact that a polled bio will complete
in process context, clear the cacheable flag if we disable polling
for a given bio.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 04477697ee4b..c130206e9961 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -833,8 +833,11 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio)
 		}
 	}
 
-	if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+	if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) {
+		/* can't support alloc cache if we turn off polling */
+		bio_clear_flag(bio, BIO_PERCPU_CACHE);
 		bio->bi_opf &= ~REQ_HIPRI;
+	}
 
 	switch (bio_op(bio)) {
 	case REQ_OP_DISCARD:
-- 
2.32.0

