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 <kees@kernel.org>
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
...
The on-media cache_info index used sizeof(struct) instead of the
4K metadata stride, so gc_percent updates from dmsetup message
were written between slots and lost after reboot. Use
PCACHE_CACHE_INFO_SIZE in get_cache_info_addr() and align
info_index with the slot returned by pcache_meta_find_latest().
Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
Signed-off-by: Dongsheng Yang <dongsheng.yang@linux.dev>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Zheng Gu <cengku@gmail.com>
Cc: stable@vger.kernel.org # 6.18
In dm-pcache, in order to ensure crash-consistency, a dual-copy scheme
is used to alternately update metadata, and there is a slot index that
records the current slot. However, in the write path the current
implementation writes directly to the current slot indexed by slot
index, and then advances the slot — which ends up overwriting the
existing slot, violating the crash-consistency guarantee.
This patch fixes that behavior, preventing metadata from being
overwritten incorrectly.
In addition, this patch add a missing pmem_wmb() after memcpy_flushcache().
Signed-off-by: Dongsheng Yang <dongsheng.yang@linux.dev>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Zheng Gu <cengku@gmail.com>
Cc: stable@vger.kernel.org # 6.18
pcache_meta_find_latest() leaves whatever it last copied into the
caller’s buffer even when it returns NULL. For cache_info_init(),
that meant cache->cache_info could still contain CRC-bad garbage when
no valid metadata exists, leading later initialization paths to read
bogus flags.
Explicitly memset cache->cache_info in cache_info_init_default()
so new-cache paths start from a clean slate. The default sequence
number assignment becomes redundant with this reset, so it drops out.
Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
Reviewed-by: Zheng Gu <cengku@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
CONFIG_BCACHE is tristate, so dm-pcache can also be built-in.
Switch the Makefile to use obj-$(CONFIG_DM_PCACHE) so the target can be
linked into vmlinux instead of always being a loadable module.
Also rename cache_flush() to pcache_cache_flush() to avoid a global
symbol clash with sunrpc/cache.c's cache_flush().
Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
This patch introduces dm-pcache, a new DM target that places a DAX-
capable persistent-memory device in front of any slower block device and
uses it as a high-throughput, low-latency cache.
Design highlights
-----------------
- DAX data path – data is copied directly between DRAM and the pmem
mapping, bypassing the block layer’s overhead.
- Segmented, crash-consistent layout
- all layout metadata are dual-replicated CRC-protected.
- atomic kset flushes; key replay on mount guarantees cache integrity
even after power loss.
- Striped multi-tree index
- Multi‑tree indexing for high parallelism.
- overlap-resolution logic ensures non-intersecting cached extents.
- Background services
- write-back worker flushes dirty keys in order, preserving backing-device
crash consistency. This is important for checkpoint in cloud storage.
- garbage collector reclaims clean segments when utilisation exceeds a
tunable threshold.
- Data integrity – optional CRC32 on cached payload; metadata always protected.
Comparison with existing block-level caches
---------------------------------------------------------------------------------------------------------------------------------
| Feature | pcache (this patch) | bcache | dm-writecache |
|----------------------------------|---------------------------------|------------------------------|---------------------------|
| pmem access method | DAX | bio (block I/O) | DAX |
| Write latency (4 K rand-write) | ~5 µs | ~20 µs | ~5 µs |
| Concurrency | multi subtree index | global index tree | single tree + wc_lock |
| IOPS (4K randwrite, 32 numjobs) | 2.1 M | 352 K | 283 K |
| Read-cache support | YES | YES | NO |
| Deployment | no re-format of backend | backend devices must be | no re-format of backend |
| | | reformatted | |
| Write-back ordering | log-structured; | no ordering guarantee | no ordering guarantee |
| | preserves app-IO-order | | |
| Data integrity checks | metadata + data CRC(optional) | metadata CRC only | none |
---------------------------------------------------------------------------------------------------------------------------------
Signed-off-by: Dongsheng Yang <dongsheng.yang@linux.dev>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
