dm: requeue IO if mapping table not yet available

[ Upstream commit fa247089de9936a46e290d4724cb5f0b845600f5 ]

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: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index a896dea9750e434655b9ebef4363da84b59be91e..53a9b16c7b2e69675ce6facf1933efe759f07b24 100644 (file)
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -500,8 +500,13 @@ 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);
        }

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 443478a0885782f5bc43a0c797767e85b1745df3..36449422e7e07bb362027aac09c8a84a50ac744e 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1594,15 +1594,10 @@ static blk_qc_t 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)