From 8a0cc5f3446a324b13f62020eeddb32d6ba1c2db Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 30 Sep 2026 21:42:03 +0200 Subject: [PATCH] dm-writecache: fix uncommitted_blocks underflow Revert the commit 39495b12ef1cf602e6abd350dce2ef4199906531 writecache_bio_copy_ssd sets wc->uncommitted_blocks = 0; and then queues the flush work: queue_work(wc->writeback_wq, &wc->flush_work); It may be possible that discard is dispatched in this window, and the discard would decrement wc->uncommitted_blocks to -1U. Note that this bug is benign - wc->uncommitted_blocks is only used to trigged autocommit, so decrementing it to -1U will trigger a spurious autocommit, but won't cause any data corruption. Signed-off-by: Mikulas Patocka Assisted-by: Claude:claude-opus-5 Fixes: 39495b12ef1c ("dm writecache: correct uncommitted_block when discarding uncommitted entry") Cc: stable@vger.kernel.org --- drivers/md/dm-writecache.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c index 2b3950dd45e8..a38780a7b1be 100644 --- a/drivers/md/dm-writecache.c +++ b/drivers/md/dm-writecache.c @@ -901,8 +901,6 @@ static void writecache_discard(struct dm_writecache *wc, sector_t start, sector_ } discarded_something = true; } - if (!writecache_entry_is_committed(wc, e)) - wc->uncommitted_blocks--; writecache_free_entry(wc, e); }