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 <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
vieko · Dec 7, 2020 · f6f371f · f6f371f
1 parent 926f75f
commit f6f371f
Showing 1 changed file with 3 additions and 2 deletions.
diff --git 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++;