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 8ABC0356754; Wed, 20 May 2026 16:37:31 +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=1779295053; cv=none; b=dPvTg4vki9hEZ74u6UhyP/kB51h813TeIz4n8S3iFnvoh9nkpdnWBewSk/V38GJ+Z+koilj0p8+WeoX2WsxLACMaMfCUY2tstb0eRQ6dxM8YmtSkVnRbzuoJMhzoHeyaikZ8Iw81YxQLiiSTtZn5UCdIHA719+UUw2wl4UExKJk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779295053; c=relaxed/simple; bh=GBjRhF79gpGn9q7otPnmLnkVmdlurmqINal1ZcHZE+s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=k7c8V8uG7oF9i/F+3OjjS8imR15HsQXSDI0jaSQ6Q/x0V4IqZopeITWRV2bh537cudVq4IA92q6SyUl7RcV/t1rtGn9czEXBCNmDrWN/SfHl28GkE81tEl1PjHbBolsYhjHBazi08j7GO+WVgpUU9Zs5laVLRGKcmYxsWXL7K+c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pA2yaGKR; 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="pA2yaGKR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1127E1F000E9; Wed, 20 May 2026 16:37:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779295050; bh=SoXaFUe/M/Pbnu/Y/othf/7lP+8xJLg0Cdj2msUEvxM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=pA2yaGKRWswbD+LmwACTtVqqjLXU3iC4FM7W13sn+8TA3x0pWUsNZ6QtBUOnefn3x boNByYwQibkStOkgECInJAeBi93POLXWswKBzGWc1YZtEBQD2/Yw91OYqL8mZuLUYA DEYDAjbBq2o+J8vQ0wULfUdS+NQocgPHX73JbZQE= 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 7.0 0255/1146] dm cache: fix dirty mapping checking in passthrough mode switching Date: Wed, 20 May 2026 18:08:25 +0200 Message-ID: <20260520162154.003735959@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162148.390695140@linuxfoundation.org> References: <20260520162148.390695140@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ming-Hung Tsai [ Upstream commit 322586745bd1a0e5f3559fd1635fdeb4dbd1d6b8 ] As mentioned in commit 9b1cc9f251af ("dm cache: share cache-metadata object across inactive and active DM tables"), dm-cache assumed table reload occurs after suspension, while LVM's table preload breaks this assumption. The dirty mapping check for passthrough mode was designed around this assumption and is performed during table creation, causing the check to fail with preload while metadata updates are ongoing. This risks loading dirty mappings into passthrough mode, resulting in data loss. Reproduce steps: 1. Create a writeback cache with zero migration_threshold to produce dirty mappings 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 writeback smq \ 2 migration_threshold 0" 2. Preload a table in passthrough mode dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0" 3. Write to the first cache block to make it dirty fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k \ --direct=1 --size=64k 4. Resume the inactive table. Now it's possible to load the dirty block into passthrough mode. dmsetup resume cache Fix by moving the checks to the preresume phase to support table preloading. Also remove the unused function dm_cache_metadata_all_clean. Fixes: 2ee57d587357 ("dm cache: add passthrough mode") Signed-off-by: Ming-Hung Tsai Signed-off-by: Mikulas Patocka Signed-off-by: Sasha Levin --- drivers/md/dm-cache-metadata.c | 11 ----------- drivers/md/dm-cache-metadata.h | 5 ----- drivers/md/dm-cache-target.c | 25 ++++++++----------------- 3 files changed, 8 insertions(+), 33 deletions(-) diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c index 57158c02d096e..1b86e80c89cca 100644 --- a/drivers/md/dm-cache-metadata.c +++ b/drivers/md/dm-cache-metadata.c @@ -1714,17 +1714,6 @@ int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy * return r; } -int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result) -{ - int r; - - READ_LOCK(cmd); - r = blocks_are_unmapped_or_clean(cmd, 0, cmd->cache_blocks, result); - READ_UNLOCK(cmd); - - return r; -} - void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd) { WRITE_LOCK_VOID(cmd); diff --git a/drivers/md/dm-cache-metadata.h b/drivers/md/dm-cache-metadata.h index 5f77890207fed..2f107e7c67d0a 100644 --- a/drivers/md/dm-cache-metadata.h +++ b/drivers/md/dm-cache-metadata.h @@ -135,11 +135,6 @@ int dm_cache_get_metadata_dev_size(struct dm_cache_metadata *cmd, */ int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *p); -/* - * Query method. Are all the blocks in the cache clean? - */ -int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result); - int dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd, bool *result); int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd); void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd); diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 32d22c7b9a07d..e479ac22b97cc 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -2499,23 +2499,8 @@ static int cache_create(struct cache_args *ca, struct cache **result) goto bad; } - if (passthrough_mode(cache)) { - bool all_clean; - - r = dm_cache_metadata_all_clean(cache->cmd, &all_clean); - if (r) { - *error = "dm_cache_metadata_all_clean() failed"; - goto bad; - } - - if (!all_clean) { - *error = "Cannot enter passthrough mode unless all blocks are clean"; - r = -EINVAL; - goto bad; - } - + if (passthrough_mode(cache)) policy_allow_migrations(cache->policy, false); - } spin_lock_init(&cache->lock); bio_list_init(&cache->deferred_bios); @@ -2842,6 +2827,12 @@ static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock, struct cache *cache = context; if (dirty) { + if (passthrough_mode(cache)) { + DMERR("%s: cannot enter passthrough mode unless all blocks are clean", + cache_device_name(cache)); + return -EBUSY; + } + set_bit(from_cblock(cblock), cache->dirty_bitset); atomic_inc(&cache->nr_dirty); } else @@ -3075,7 +3066,7 @@ static int cache_preresume(struct dm_target *ti) load_filtered_mapping, cache); if (r) { DMERR("%s: could not load cache mappings", cache_device_name(cache)); - if (r != -EFBIG) + if (r != -EFBIG && r != -EBUSY) metadata_operation_failed(cache, "dm_cache_load_mappings", r); return r; } -- 2.53.0