From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 67A44372B58; Wed, 20 May 2026 17:24:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779297892; cv=none; b=bhUXpakEhwsoCPVn6WlacuPjaaz6xCc3NWa3QrHuLAt/NepPoNr48uWx14faziz/R75KN2PkJI2WCKXVoU7ZM6xGRrplCqUJGfKh71ojp9OjwnoagAOr9LSit7vf5/eVLSXF5aoxXJ0y2JHL22eAEapUoygabPVgZl5O87qqKKE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779297892; c=relaxed/simple; bh=1FZSZZOvO7Dx8BFmM/Pzjb0QpzJmiQCsthWuNkQmxIM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YgaNk3icS+gDG7ILPb46S51QdtQKq/ZsG4mEDXOteAuhesd0e93ZODGP/7xyLIFTcYsyUhSnGXerpUZAgvDWkMJYFjEaR0zO3Jxmp2m4r+7LNK+nEy5X+PCiar2PI0JUGmMsJzOGyaIrAPZdP3X5fyeoWm/sFSojHcj1vCIYNek= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=jvBfpZV3; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="jvBfpZV3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D8891F000E9; Wed, 20 May 2026 17:24:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779297891; bh=n3PX7rOf/QxNX2YuBNsTQf6tpoN+pAyWbDkIx4HbWcY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jvBfpZV3Ydi2fAaxuh1M+QiuOY+ZGNSBgyZz35uH8odu84rm8VVov5G4sA9XTUV8F 1rKtvGODmB+kCEjRcTHieWrs2zuB+IOj3J66KUkmjAc0Zk/CPeLy5OzLvdQxvYimU1 YlDq4/bXKqENNw+qyiS6Kq0LFuV8kmZAsxrJ1eR4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ming-Hung Tsai , Mikulas Patocka , Sasha Levin Subject: [PATCH 6.18 202/957] dm cache: fix concurrent write failure in passthrough mode Date: Wed, 20 May 2026 18:11:25 +0200 Message-ID: <20260520162138.926237641@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162134.554764788@linuxfoundation.org> References: <20260520162134.554764788@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ming-Hung Tsai [ Upstream commit e4f66341779d0cf4c83c74793753a84094286d9e ] When bio prison cell lock acquisition fails due to concurrent writes to the same block in passthrough mode, dm-cache incorrectly returns an I/O error instead of properly handling the concurrency. This can occur in both process and workqueue contexts when invalidate_lock() is called for exclusive access to a data block. Fix this by deferring the write bios to ensure proper block device behavior. Reproduce steps: 1. Create a cache device dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" dmsetup create corig --table "0 262144 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" 2. Promote the first data block into cache fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k \ --direct=1 --size=64k 3. Reload the cache into passthrough mode dmsetup suspend cache dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0" dmsetup resume cache 4. Write to the first cached block concurrently. Sometimes one of the processes will receive I/O errors. fio --filename=/dev/mapper/cache --name test --rw=randwrite --bs=4k \ --randrepeat=0 --direct=1 --numjobs=2 --size 64k fio-3.41 fio: io_u error on file /dev/mapper/cache: Input/output error: write offset=4096, buflen=4096 fio: pid=106, err=5/file:io_u.c:2008, func=io_u error, error=Input/output error test: (groupid=0, jobs=1): err= 0: pid=105 test: (groupid=0, jobs=1): err= 5 (file:io_u.c:2008, func=io_u error, error=Input/output error): pid=106 Fixes: b29d4986d0da ("dm cache: significant rework to leverage dm-bio-prison-v2") Signed-off-by: Ming-Hung Tsai Signed-off-by: Mikulas Patocka Signed-off-by: Sasha Levin --- drivers/md/dm-cache-target.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index b191ea1361b40..e8709950dc49d 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -1561,6 +1561,15 @@ static int invalidate_lock(struct dm_cache_migration *mg) READ_WRITE_LOCK_LEVEL, prealloc, &mg->cell); if (r < 0) { free_prison_cell(cache, prealloc); + + /* Defer the bio for retrying the cell lock */ + if (mg->overwrite_bio) { + struct bio *bio = mg->overwrite_bio; + + mg->overwrite_bio = NULL; + defer_bio(cache, bio); + } + invalidate_complete(mg, false); return r; } -- 2.53.0