[PATCH 6.18 200/957] dm cache: fix write hang in passthrough mode
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2026-05-20 17:24:43
Also in:
stable
Subsystem:
device-mapper (lvm), the rest · Maintainers:
Alasdair Kergon, Mike Snitzer, Mikulas Patocka, Benjamin Marzinski, Linus Torvalds
6.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ming-Hung Tsai <redacted>
[ Upstream commit 4ca8b8bd952df7c3ccdc68af9bd3419d0839a04b ]
The invalidate_remove() function has incomplete logic for handling write
hit bios after cache invalidation. It sets up the remapping for the
overwrite_bio but then drops it immediately without submission, causing
write operations to hang.
Fix by adding a new invalidate_committed() continuation that submits
the remapped writes to the cache origin after metadata commit completes,
while using the overwrite_endio hook to ensure proper completion
sequencing. This maintains existing coherency. Also improve error
handling in invalidate_complete() to preserve the original error status
instead of using bio_io_error() unconditionally.
Fixes: b29d4986d0da ("dm cache: significant rework to leverage dm-bio-prison-v2")
Signed-off-by: Ming-Hung Tsai <redacted>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/dm-cache-target.c | 30 +++++++++++++++++++++++++-----
1 file changed, 25 insertions(+), 5 deletions(-)
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 69fa2f6479318..b191ea1361b40 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c@@ -1467,8 +1467,14 @@ static void invalidate_complete(struct dm_cache_migration *mg, bool success) free_prison_cell(cache, mg->cell); } - if (!success && mg->overwrite_bio) - bio_io_error(mg->overwrite_bio); + if (mg->overwrite_bio) { + // Set generic error if the bio hasn't been issued yet, + // e.g., invalidation or metadata commit failed before bio + // submission. Otherwise preserve the bio's own error status. + if (!success && !mg->overwrite_bio->bi_status) + mg->overwrite_bio->bi_status = BLK_STS_IOERR; + bio_endio(mg->overwrite_bio); + } free_migration(mg); defer_bios(cache, &bios);
@@ -1508,6 +1514,22 @@ static int invalidate_cblock(struct cache *cache, dm_cblock_t cblock) return r; } +static void invalidate_committed(struct work_struct *ws) +{ + struct dm_cache_migration *mg = ws_to_mg(ws); + struct cache *cache = mg->cache; + struct bio *bio = mg->overwrite_bio; + struct per_bio_data *pb = get_per_bio_data(bio); + + if (mg->k.input) + invalidate_complete(mg, false); + + init_continuation(&mg->k, invalidate_completed); + remap_to_origin_clear_discard(cache, bio, mg->invalidate_oblock); + dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg); + dm_submit_bio_remap(bio, NULL); +} + static void invalidate_remove(struct work_struct *ws) { int r;
@@ -1520,10 +1542,8 @@ static void invalidate_remove(struct work_struct *ws) return; } - init_continuation(&mg->k, invalidate_completed); + init_continuation(&mg->k, invalidate_committed); continue_after_commit(&cache->committer, &mg->k); - remap_to_origin_clear_discard(cache, mg->overwrite_bio, mg->invalidate_oblock); - mg->overwrite_bio = NULL; schedule_commit(&cache->committer); }
--
2.53.0