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 579ab6183d4d811c5c6697b60ecb21a44ade2a52..dffeb47a9efbc835b6676dc9881781546e0127d3 100644 (file)
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -499,8 +499,13 @@ 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 5fd3660e07b5cecd6e31baa0ed03a41b91754407..af12c0accb5908da9bac72f47cb335823228d438 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1587,15 +1587,10 @@ 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)