kernel/linux.git/drivers/md/dm-verity-fec.c, branch v7.0-rc2

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

dm-verity: correctly handle dm_bufio_client_create() failure

2026-01-04T19:35:32+00:00

If either of the calls to dm_bufio_client_create() in verity_fec_ctr() fails, then dm_bufio_client_destroy() is later called with an ERR_PTR() argument. That causes a crash. Fix this. Fixes: a739ff3f543a ("dm verity: add support for forward error correction") Cc: stable@vger.kernel.org Reviewed-by: Sami Tolvanen Signed-off-by: Eric Biggers Signed-off-by: Mikulas Patocka

dm-verity: make verity_fec_is_enabled() an inline function

2026-01-04T19:35:32+00:00

verity_fec_is_enabled() is very short and is called in quite a few places, so make it an inline function. Reviewed-by: Sami Tolvanen Signed-off-by: Eric Biggers Signed-off-by: Mikulas Patocka

dm-verity: make dm_verity_fec_io::bufs variable-length

2026-01-04T19:35:32+00:00

When correcting a data block, the FEC code performs optimally when it has enough buffers to hold all the needed RS blocks. That number of buffers is '1 << (v->data_dev_block_bits - DM_VERITY_FEC_BUF_RS_BITS)'. However, since v->data_dev_block_bits isn't a compile-time constant, the code actually used PAGE_SHIFT instead. With the traditional PAGE_SIZE == data_block_size == 4096, this was fine. However, when PAGE_SIZE > data_block_size, this wastes space. E.g., with data_block_size == 4096 && PAGE_SIZE == 16384, struct dm_verity_fec_io is 9240 bytes, when in fact only 3096 bytes are needed. Fix this by making dm_verity_fec_io::bufs a variable-length array. This makes the macros DM_VERITY_FEC_BUF_MAX and fec_for_each_extra_buffer() no longer apply, so remove them. For consistency, and because DM_VERITY_FEC_BUF_PREALLOC is fixed at 1 and was already assumed to be 1 (considering that mempool_alloc() shouldn't be called in a loop), also remove the related macros DM_VERITY_FEC_BUF_PREALLOC and fec_for_each_prealloc_buffer(). Signed-off-by: Eric Biggers Reviewed-by: Sami Tolvanen Signed-off-by: Mikulas Patocka

dm-verity: move dm_verity_fec_io to mempool

2026-01-04T19:35:32+00:00

Currently, struct dm_verity_fec_io is allocated in the front padding of struct bio using dm_target::per_io_data_size. Unfortunately, struct dm_verity_fec_io is very large: 3096 bytes when CONFIG_64BIT=y && PAGE_SIZE == 4096, or 9240 bytes when CONFIG_64BIT=y && PAGE_SIZE == 16384. This makes the bio size very large. Moreover, most of dm_verity_fec_io gets iterated over up to three times, even on I/O requests that don't require any error correction: 1. To zero the memory on allocation, if init_on_alloc=1. (This happens when the bio is allocated, not in dm-verity itself.) 2. To zero the buffers array in verity_fec_init_io(). 3. To free the buffers in verity_fec_finish_io(). Fix all of these inefficiencies by moving dm_verity_fec_io to a mempool. Replace the embedded dm_verity_fec_io with a pointer dm_verity_io::fec_io. verity_fec_init_io() initializes it to NULL, verity_fec_decode() allocates it on the first call, and verity_fec_finish_io() cleans it up. The normal case is that the pointer simply stays NULL, so the overhead becomes negligible. Reviewed-by: Sami Tolvanen Signed-off-by: Eric Biggers Signed-off-by: Mikulas Patocka

Merge tag 'for-6.19/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

2025-12-11T03:13:29+00:00

Pull device mapper updates from Mikulas Patocka: - convert crypto_shash users to direct crypto library use with simpler and faster code and reduced stack usage (Eric Biggers): - the dm-verity SHA-256 conversion also teaches it to do two-way interleaved hashing for added performance - dm-crypt MD5 conversion (used for Loop-AES compatibility) - added document for for takeover/reshape raid1 -> raid5 examples (Heinz Mauelshagen) - fix dm-vdo kerneldoc warnings (Matthew Sakai) - various random fixes and cleanups * tag 'for-6.19/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (29 commits) dm pcache: fix segment info indexing dm pcache: fix cache info indexing dm-pcache: advance slot index before writing slot dm raid: add documentation for takeover/reshape raid1 -> raid5 table line examples dm log-writes: Add missing set_freezable() for freezable kthread dm-raid: fix possible NULL dereference with undefined raid type dm-snapshot: fix 'scheduling while atomic' on real-time kernels dm: ignore discard return value MAINTAINERS: add Benjamin Marzinski as a device mapper maintainer dm-mpath: Simplify the setup_scsi_dh code dm vdo: fix kerneldoc warnings dm-bufio: align write boundary on physical block size dm-crypt: enable DM_TARGET_ATOMIC_WRITES dm: test for REQ_ATOMIC in dm_accept_partial_bio() dm-verity: remove useless mempool dm-verity: disable recursive forward error correction dm-ebs: Mark full buffer dirty even on partial write dm mpath: enable DM_TARGET_ATOMIC_WRITES dm verity fec: Expose corrected block count via status dm: Don't warn if IMA_DISABLE_HTABLE is not enabled ...

dm-verity: remove useless mempool

2025-12-10T18:28:12+00:00

v->fec->extra_pool has zero reserved entries, so we can remove it and use the kernel cache directly. Signed-off-by: Mikulas Patocka Reviewed-by: Eric Biggers

dm-verity: disable recursive forward error correction

2025-12-10T18:27:59+00:00

There are two problems with the recursive correction: 1. It may cause denial-of-service. In fec_read_bufs, there is a loop that has 253 iterations. For each iteration, we may call verity_hash_for_block recursively. There is a limit of 4 nested recursions - that means that there may be at most 253^4 (4 billion) iterations. Red Hat QE team actually created an image that pushes dm-verity to this limit - and this image just makes the udev-worker process get stuck in the 'D' state. 2. It doesn't work. In fec_read_bufs we store data into the variable "fio->bufs", but fio bufs is shared between recursive invocations, if "verity_hash_for_block" invoked correction recursively, it would overwrite partially filled fio->bufs. Signed-off-by: Mikulas Patocka Reported-by: Guangwu Zhang Reviewed-by: Sami Tolvanen Reviewed-by: Eric Biggers

dm-verity: fix unreliable memory allocation

2025-11-21T11:51:41+00:00

GFP_NOWAIT allocation may fail anytime. It needs to be changed to GFP_NOIO. There's no need to handle an error because mempool_alloc with GFP_NOIO can't fail. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Reviewed-by: Eric Biggers