For synchronous polling to work, the bio must be issued to the driver from the submit_bio call, otherwise ->bi_cookie won't be set. Based on a patch from Ming Lei. Reported-by: Changhui Zhong <czhong@xxxxxxxxxx> Signed-off-by: Christoph Hellwig <hch@xxxxxx> --- block/blk-mq.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index ed3ed86f7dd24..bcc7e3d11296c 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2851,7 +2851,13 @@ void blk_mq_submit_bio(struct bio *bio) return; } - if (plug) + /* + * We can't plug for synchronously polled submissions, otherwise + * bio->bi_cookie won't be set directly after submission, which is the + * indicator used by the submitter to check if a bio needs polling. + */ + if (plug && + (rq->bio->bi_opf & (REQ_POLLED | REQ_NOWAIT)) != REQ_POLLED) blk_add_rq_to_plug(plug, rq); else if ((rq->rq_flags & RQF_ELV) || (rq->mq_hctx->dispatch_busy && -- 2.30.2
