blk-mq: skip hybrid polling if iopoll doesn't spin

If blk_poll() is not going to spin (i.e. @spin=false), it also must not
sleep in hybrid polling, otherwise it might be pretty suprising for
users trying to do a quick check and expecting no-wait behaviour.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index cf3916e..2881a45 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3865,9 +3865,10 @@ int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
         * the state. Like for the other success return cases, the
         * caller is responsible for checking if the IO completed. If
         * the IO isn't complete, we'll get called again and will go
-        * straight to the busy poll loop.
+        * straight to the busy poll loop. If specified not to spin,
+        * we also should not sleep.
         */
-       if (blk_mq_poll_hybrid(q, hctx, cookie))
+       if (spin && blk_mq_poll_hybrid(q, hctx, cookie))
                return 1;
 
        hctx->poll_considered++;