Commit 958148a6 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: check BLK_FEAT_POLL under q_usage_count 



Otherwise feature reconfiguration can race with I/O submission.

Also drop the bio_clear_polled in the error path, as the flag does not
matter for instant error completions, it is a left over from when we
allowed polled I/O to proceed unpolled in this case.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Reviewed-by: default avatarNilay Shroff <nilay@linux.ibm.com>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20250110054726.1499538-4-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent aa427d7b

block/blk-core.c

+12 −10
Original line number Diff line number Diff line
@@ -630,7 +630,13 @@ static void __submit_bio(struct bio *bio) 
	} else if (likely(bio_queue_enter(bio) == 0)) {

		struct gendisk *disk = bio->bi_bdev->bd_disk;

	

		if ((bio->bi_opf & REQ_POLLED) &&

		    !(disk->queue->limits.features & BLK_FEAT_POLL)) {

			bio->bi_status = BLK_STS_NOTSUPP;

			bio_endio(bio);

		} else {

			disk->fops->submit_bio(bio);

		}

		blk_queue_exit(disk->queue);

	}
@@ -805,12 +811,6 @@ void submit_bio_noacct(struct bio *bio) 
		}

	}



	if (!(q->limits.features & BLK_FEAT_POLL) &&

			(bio->bi_opf & REQ_POLLED)) {

		bio_clear_polled(bio);

		goto not_supported;

	}



	switch (bio_op(bio)) {

	case REQ_OP_READ:

		break;
@@ -935,7 +935,7 @@ int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags) 
		return 0;



	q = bdev_get_queue(bdev);

	if (cookie == BLK_QC_T_NONE || !(q->limits.features & BLK_FEAT_POLL))

	if (cookie == BLK_QC_T_NONE)

		return 0;



	blk_flush_plug(current->plug, false);
@@ -951,7 +951,9 @@ int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags) 
	 */

	if (!percpu_ref_tryget(&q->q_usage_counter))

		return 0;

	if (queue_is_mq(q)) {

	if (!(q->limits.features & BLK_FEAT_POLL)) {

		ret = 0;

	} else if (queue_is_mq(q)) {

		ret = blk_mq_poll(q, cookie, iob, flags);

	} else {

		struct gendisk *disk = q->disk;

block/blk-mq.c

+10 −2
Original line number Diff line number Diff line
@@ -3096,14 +3096,22 @@ void blk_mq_submit_bio(struct bio *bio) 
	}



	/*

	 * Device reconfiguration may change logical block size, so alignment

	 * check has to be done with queue usage counter held

	 * Device reconfiguration may change logical block size or reduce the

	 * number of poll queues, so the checks for alignment and poll support

	 * have to be done with queue usage counter held.

	 */

	if (unlikely(bio_unaligned(bio, q))) {

		bio_io_error(bio);

		goto queue_exit;

	}



	if ((bio->bi_opf & REQ_POLLED) &&

	    !(q->limits.features & BLK_FEAT_POLL)) {

		bio->bi_status = BLK_STS_NOTSUPP;

		bio_endio(bio);

		goto queue_exit;

	}



	bio = __bio_split_to_limits(bio, &q->limits, &nr_segs);

	if (!bio)

		goto queue_exit;