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 40AED3D1CA0; Wed, 20 May 2026 18:33:02 +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=1779301985; cv=none; b=oHXlS7cjpktm6eV5jOQD69k7sSQqmigIrhn5pazbcSLjmDyolK1Z51KgM/baJAAX+REsiCIcjCs1qVnKqsc5fqVtFG3E0cEoYN8S1DlNl7vhW7jSdLeLVxajR6zj9g60r8L8jYwrbBZ2DLaiZs3m8M/Y6sOMWKvZc39dcO316jY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779301985; c=relaxed/simple; bh=Tp4w6JTeGIKqSdM1obEC60f5AxqRXCLBYvm8j+xB63Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=o6Q/+UhI0RsD0ey4JmoZ2i8qNs0rA+j801EON8xYi8TEUe66j0M5AfewExSUznaBWKp46rUN1XMy+HRKoLe/HOfZSGHMPhSLLTTiucx7ikgdJkmG/0Hwf3vbAjDyPBBMYJDXyl4frOMKkpFN8wy/uI/a4DYAO5OzOs0AYqgnJMs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=uO1W9TDT; 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="uO1W9TDT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4C2A91F00893; Wed, 20 May 2026 18:33:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779301982; bh=z6ALsnKOLfQyO657F/ybn5oQdgzybOHuSByBlp2Z0os=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=uO1W9TDTpbdwmSzDQNC9PZjZIEmNMl5Y7XEb0cM5eilioEi6ZB4vp0TypN/b0GqxJ xZMm+0picUtz+XI6jRoMhAZuGXzfZi0FTHB0tmg5OuDDDpdpc5Fw+ZRqkFWhT3/ZzJ uVFOpByQKs75ZfATPl0qoRS5khnU3zUVhFMI6O7U= 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 6.6 095/508] dm cache: fix concurrent write failure in passthrough mode Date: Wed, 20 May 2026 18:18:38 +0200 Message-ID: <20260520162100.672922024@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162058.573354582@linuxfoundation.org> References: <20260520162058.573354582@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 6.6-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 a3a8623eff297..65ae94f64c11b 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -1557,6 +1557,15 @@ 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