Commit fa247089 authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm: requeue IO if mapping table not yet available 



Update both bio-based and request-based DM to requeue IO if the
mapping table not available.

This race of IO being submitted before the DM device ready is so
narrow, yet possible for initial table load given that the DM device's
request_queue is created prior, that it best to requeue IO to handle
this unlikely case.

Reported-by: default avatarZhang Yi <yi.zhang@huawei.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent a6a4901a

drivers/md/dm-rq.c

+6 −1
Original line number Diff line number Diff line
@@ -491,8 +491,13 @@ static blk_status_t dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx, 


	if (unlikely(!ti)) {

		int srcu_idx;

		struct dm_table *map = dm_get_live_table(md, &srcu_idx);

		struct dm_table *map;



		map = dm_get_live_table(md, &srcu_idx);

		if (unlikely(!map)) {

			dm_put_live_table(md, srcu_idx);

			return BLK_STS_RESOURCE;

		}

		ti = dm_table_find_target(map, 0);

		dm_put_live_table(md, srcu_idx);

	}

drivers/md/dm.c

+3 −8
Original line number Diff line number Diff line
@@ -1533,15 +1533,10 @@ static void dm_submit_bio(struct bio *bio) 
	struct dm_table *map;



	map = dm_get_live_table(md, &srcu_idx);

	if (unlikely(!map)) {

		DMERR_LIMIT("%s: mapping table unavailable, erroring io",

			    dm_device_name(md));

		bio_io_error(bio);

		goto out;

	}



	/* If suspended, queue this IO for later */

	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {

	/* If suspended, or map not yet available, queue this IO for later */

	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) ||

	    unlikely(!map)) {

		if (bio->bi_opf & REQ_NOWAIT)

			bio_wouldblock_error(bio);

		else if (bio->bi_opf & REQ_RAHEAD)