kernel/linux.git/drivers/md/dm-ebs-target.c, branch v6.6.141

dm-ebs: Mark full buffer dirty even on partial write

2026-01-11T14:22:14+00:00

commit 7fa3e7d114abc9cc71cc35d768e116641074ddb4 upstream. When performing a read-modify-write(RMW) operation, any modification to a buffered block must cause the entire buffer to be marked dirty. Marking only a subrange as dirty is incorrect because the underlying device block size(ubs) defines the minimum read/write granularity. A lower device can perform I/O only on regions which are fully aligned and sized to ubs. This change ensures that write-back operations always occur in full ubs-sized chunks, matching the intended emulation semantics of the EBS target. As for user space visible impact, submitting sub-ubs and misaligned I/O for devices which are tuned to ubs sizes only, will reject such requests, therefore it can lead to losing data. Example: 1) Create a 8K nvme device in qemu by adding -device nvme,drive=drv0,serial=foo,logical_block_size=8192,physical_block_size=8192 2) Setup dm-ebs to emulate 512B to 8K mapping urezki@pc638:~/bin$ cat dmsetup.sh lower=/dev/nvme0n1 len=$(blockdev --getsz "$lower") echo "0 $len ebs $lower 0 1 16" | dmsetup create nvme-8k urezki@pc638:~/bin$ offset 0, ebs=1 and ubs=16(in sectors). 3) Create an ext4 filesystem(default 4K block size) urezki@pc638:~/bin$ sudo mkfs.ext4 -F /dev/dm-0 mke2fs 1.47.0 (5-Feb-2023) Discarding device blocks: done Creating filesystem with 2072576 4k blocks and 518144 inodes Filesystem UUID: bd0b6ca6-0506-4e31-86da-8d22c9d50b63 Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632 Allocating group tables: done Writing inode tables: done Creating journal (16384 blocks): done Writing superblocks and filesystem accounting information: mkfs.ext4: Input/output error while writing out and closing file system urezki@pc638:~/bin$ dmesg [ 1618.875449] buffer_io_error: 1028 callbacks suppressed [ 1618.875456] Buffer I/O error on dev dm-0, logical block 0, lost async page write [ 1618.875527] Buffer I/O error on dev dm-0, logical block 1, lost async page write [ 1618.875602] Buffer I/O error on dev dm-0, logical block 2, lost async page write [ 1618.875620] Buffer I/O error on dev dm-0, logical block 3, lost async page write [ 1618.875639] Buffer I/O error on dev dm-0, logical block 4, lost async page write [ 1618.894316] Buffer I/O error on dev dm-0, logical block 5, lost async page write [ 1618.894358] Buffer I/O error on dev dm-0, logical block 6, lost async page write [ 1618.894380] Buffer I/O error on dev dm-0, logical block 7, lost async page write [ 1618.894405] Buffer I/O error on dev dm-0, logical block 8, lost async page write [ 1618.894427] Buffer I/O error on dev dm-0, logical block 9, lost async page write Many I/O errors because the lower 8K device rejects sub-ubs/misaligned requests. with a patch: urezki@pc638:~/bin$ sudo mkfs.ext4 -F /dev/dm-0 mke2fs 1.47.0 (5-Feb-2023) Discarding device blocks: done Creating filesystem with 2072576 4k blocks and 518144 inodes Filesystem UUID: 9b54f44f-ef55-4bd4-9e40-c8b775a616ac Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632 Allocating group tables: done Writing inode tables: done Creating journal (16384 blocks): done Writing superblocks and filesystem accounting information: done urezki@pc638:~/bin$ sudo mount /dev/dm-0 /mnt/ urezki@pc638:~/bin$ ls -al /mnt/ total 24 drwxr-xr-x 3 root root 4096 Oct 17 15:13 . drwxr-xr-x 19 root root 4096 Jul 10 19:42 .. drwx------ 2 root root 16384 Oct 17 15:13 lost+found urezki@pc638:~/bin$ After this change: mkfs completes; mount succeeds. Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

dm-ebs: fix prefetch-vs-suspend race

2025-04-25T08:45:33+00:00

commit 9c565428788fb9b49066f94ab7b10efc686a0a4c upstream. There's a possible race condition in dm-ebs - dm bufio prefetch may be in progress while the device is suspended. Fix this by calling dm_bufio_client_reset in the postsuspend hook. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

dm-ebs: don't set the flag DM_TARGET_PASSES_INTEGRITY

2025-01-17T12:36:17+00:00

commit 47f33c27fc9565fb0bc7dfb76be08d445cd3d236 upstream. dm-ebs uses dm-bufio to process requests that are not aligned on logical sector size. dm-bufio doesn't support passing integrity data (and it is unclear how should it do it), so we shouldn't set the DM_TARGET_PASSES_INTEGRITY flag. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Fixes: d3c7b35c20d6 ("dm: add emulated block size target") Signed-off-by: Greg Kroah-Hartman

dm: add helper macro for simple DM target module init and exit

2023-04-11T16:09:08+00:00

Eliminate duplicate boilerplate code for simple modules that contain a single DM target driver without any additional setup code. Add a new module_dm() macro, which replaces the module_init() and module_exit() with template functions that call dm_register_target() and dm_unregister_target() respectively. Signed-off-by: Yangtao Li Signed-off-by: Mike Snitzer

dm: push error reporting down to dm_register_target()

2023-04-11T16:01:01+00:00

Simplifies each DM target's init method by making dm_register_target() responsible for its error reporting (on behalf of targets). Signed-off-by: Yangtao Li Signed-off-by: Mike Snitzer

dm: avoid spaces before function arguments or in favour of tabs

2023-02-14T19:23:06+00:00

Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer

dm: change "unsigned" to "unsigned int"

2023-02-14T19:23:06+00:00

Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer

dm: add missing SPDX-License-Indentifiers

2023-02-14T19:23:06+00:00

'GPL-2.0-only' is used instead of 'GPL-2.0' because SPDX has deprecated its use. Suggested-by: John Wiele Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer

Merge tag 'for-6.0/dm-changes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

2022-08-06T18:09:55+00:00

Pull more device mapper updates from Mike Snitzer: - Add flags argument to dm_bufio_client_create and introduce DM_BUFIO_CLIENT_NO_SLEEP flag to have dm-bufio use spinlock rather than mutex for its locking. - Add optional "try_verify_in_tasklet" feature to DM verity target. This feature gives users the option to improve IO latency by using a tasklet to verify, using hashes in bufio's cache, rather than wait to schedule a work item via workqueue. But if there is a bufio cache miss, or an error, then the tasklet will fallback to using workqueue. - Incremental changes to both dm-bufio and the DM verity target to use jump_label to minimize cost of branching associated with the niche "try_verify_in_tasklet" feature. DM-bufio in particular is used by quite a few other DM targets so it doesn't make sense to incur additional bufio cost in those targets purely for the benefit of this niche verity feature if the feature isn't ever used. - Optimize verity_verify_io, which is used by both workqueue and tasklet based verification, if FEC is not configured or tasklet based verification isn't used. - Remove DM verity target's verify_wq's use of the WQ_CPU_INTENSIVE flag since it uses WQ_UNBOUND. Also, use the WQ_HIGHPRI flag if "try_verify_in_tasklet" is specified. * tag 'for-6.0/dm-changes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm verity: have verify_wq use WQ_HIGHPRI if "try_verify_in_tasklet" dm verity: remove WQ_CPU_INTENSIVE flag since using WQ_UNBOUND dm verity: only copy bvec_iter in verity_verify_io if in_tasklet dm verity: optimize verity_verify_io if FEC not configured dm verity: conditionally enable branching for "try_verify_in_tasklet" dm bufio: conditionally enable branching for DM_BUFIO_CLIENT_NO_SLEEP dm verity: allow optional args to alter primary args handling dm verity: Add optional "try_verify_in_tasklet" feature dm bufio: Add DM_BUFIO_CLIENT_NO_SLEEP flag dm bufio: Add flags argument to dm_bufio_client_create

dm bufio: Add flags argument to dm_bufio_client_create

2022-07-28T21:46:14+00:00

Add a flags argument to dm_bufio_client_create and update all the callers. This is in preparation to add the DM_BUFIO_NO_SLEEP flag. Signed-off-by: Nathan Huckleberry Signed-off-by: Mike Snitzer