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git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux
Pull block updates from Jens Axboe:
- NVMe updates via Keith:
- Enable Clang context analysis for the nvme host driver, adding
context annotations across core, fabrics, rdma, tcp and pci
- nvmet reservation state exposed through a new namespace-level
debugfs directory, plus ABI documentation for the host sysfs and
target configfs interfaces
- nvme-tcp host memory disclosure fixes on the read path: reject a
read that transferred too few bytes, don't accept C2HData based
on blk_rq_payload_bytes() alone, and fix the R2T case for a read
command
- Parallelize nvme-rdma I/O queue allocation and startup (Surabhi)
- Apple nvme fixes and quirks: page aligned admin queue buffers,
destroy the admin queue on removal, and various DMA/NVMMU
correctness fixes
- A large pile of nvmet and host fixes for out-of-bounds reads,
refcount/resource leaks, and NULL derefs across auth, zns,
passthru, pci-epf, rdma and configfs
- Various other fixes and cleanups
- MD updates via Yu Kuai:
- llbitmap reshape support, the large series wiring exact bitmap
mapping and reshape lifecycle through raid5 and raid10, growing
the page cache in place, and remapping checkpointed bits as
reshape progresses
- raid5 fixes for lockless max_nr_stripes and recovery_offset
accesses, a reshape deadlock with more failed devices than max
degraded, and bitmap batch counter consistency
- Atomic write handling for raid1/raid10, and removal of the
REQ_NOWAIT support from raid1/10/456
- raid5-ppl use-after-free fix in ppl_do_flush()
- A batch of smaller fixes across md core and the bitmap code
- s390/dasd ESE full-track write support and the surrounding
infrastructure, plus enabling CONTEXT_ANALYSIS for s390/block
- RWF_DONTCACHE support for block devices, built on new task-context
bio completion infrastructure, and wiring it up for the iomap and
buffer dropbehind writeback paths
- Async io_uring zone reset all, plus zone management command cleanups
allowing REQ_NOWAIT and tightening conventional zone rejection
- Block integrity refactoring: lift BIP_CHECK_FLAGS to the shared
header, handle nogenerate/noverify properly in fs-integrity, and drop
the blk-integrity.h include from bdev.c
- Split out a new blk_plug.h header
- ublk improvements: add UBLK_F_IO_DESC_SIZE, split request validation
from io_desc init, reject non-power-of-2 zone sizes in SET_PARAMS,
and a series of hardening fixes around map/unmap and auto buf reg
- null_blk cleanups and configfs serialization fixes
- nbd queue freeze removal on the setup paths, and a new
pre_defined_connections module parameter for pre-created devices
- blk-cgroup fixes for the race between policy activation and blkg
destruction, and accounting per-cpu stats over possible CPUs across
blk-stat, iolatency, iocost and kyber
- Various dio fixes: leak on metadata mapping error, validate user
space vectors during extraction, and set dma_alignment from the
backing file for loop and zloop direct I/O
- bio cleanups
- Various other fixes and cleanups all over
* tag 'for-7.3/block-20260819' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux: (241 commits)
nbd: add pre_defined_connections module parameter for pre-created devices
nbd: remove queue freeze for newly created nbd from netlink path
nbd: factor out a nbd_genl_foreach_sock
nbd: skip queue freeze when setting size at device startup
nbd: remove queue freeze in nbd_add_socket
nbd: clear queue limits on disconnect
nbd: disallow NBD_SET_SOCK on an active device
nbd: simplify find_fallback() by removing redundant logic
blk-mq: add missing call to srcu_barrier() in blk_mq_free_tag_set()
block: mtip32xx: synchronize ioctls with device removal
ublk: avoid teardown retry loop on xarray allocation failure
null_blk: fix UBSAN shift-out-of-bounds when zone_size is 0 or overflows
block: don't include blk-integrity.h in bdev.c
xfs: avoid double deferrals for RWF_DONTCACHE writes
loop: Fix recently introduced lock inversion
block: set QUEUE_FLAG_DYING unconditionally in blk_mark_disk_dead()
swim3: Add missing MODULE_DESCRIPTION
selftests: ublk: add SET_PARAMS validation test
selftests: ublk: add helper for SET_PARAMS
ublk: reject non-power-of-2 zone sizes in SET_PARAMS
...
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struct bvec_iter::bi_bvec_done is used an offset in the current bvec,
let's rename it accordingly for better clarity. I also plan to use it
for non-bvec based iteration in the future like dma-buf, so drop the
"bvec" part.
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/4e4c21858705a200bd8848ffe4080522e3eb5c1c.1786018753.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The 'cache' parameter is never used in the function body, remove it.
Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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This function is declared but never defined or called anywhere.
The miss read completion is handled via miss_read_end_req callback
instead. Remove the orphan declaration.
Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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The 'allocated' variable is never non-zero when its value is consumed.
'to_alloc' was always equal to key->len, so replace them with key->len
directly.
Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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Some editors interpret tabs as 4 spaces while others use 2, causing
ASCII art diagrams in comments to misalign and hurt readability.
Replace tabs with spaces to ensure consistent display across all editors.
Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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In kset_replay, when key->seg_gen is stale (key->seg_gen <
key->cache_pos.cache_seg->gen), cache_key_put(key) is called but then
key->cache_pos.cache_seg is accessed as the argument to cache_seg_get().
This is a use-after-free on the freed key memory. Although mempool
recycled memory is not immediately reclaimed or overwritten in practice,
this is still a potential UAF bug.
Additionally, for expired invalid keys, setting the cache->seg_map bit
and calling cache_seg_get() is unreasonable since the corresponding
segment data is no longer valid.
Fix both issues by moving cache_seg_get() and __set_bit() after the
gen check, so they only execute for valid keys, and using continue to
skip invalid keys.
Cc: stable@vger.kernel.org
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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When setting gc_percent via message, kstrtoul parses the input into an
unsigned long, which is then implicitly truncated to u8 when passed to
pcache_cache_set_gc_percent(). For example, value 266 (0x10A) silently
truncates to 10 (0x0A), successfully bypassing the > 90 upper bound
check in pcache_cache_set_gc_percent(), and setting a different value
than the user intended.
Use kstrtou8 directly instead of kstrtoul, so that overflow values are
properly rejected.
Cc: stable@vger.kernel.org
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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get_cache_segment() scans the segment map up to cache->n_segs, the
physical device segment count, but cache_segs_init() only initializes
the first cache_info->n_segs segments. A crafted image with
cache_info->n_segs smaller than the device count leaves the remaining
pcache_cache_segment structs zeroed (segment.data == NULL), and the
allocator can hand one to cache_kset_close(), which writes through the
returned segment's data pointer with no NULL check.
Bound the allocator's search to cache_info->n_segs so only initialized
segments are ever returned. A conforming cache sets n_segs equal to the
device segment count, so this rejects nothing legitimate.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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The writeback worker follows the persisted dirty_tail chain, which is
decoded from the cache device independently of the key_tail chain that
cache_replay() walks and bounds. A crafted image, whose on-media fields are
authenticated only by a crc32c with a fixed seed, can aim dirty_tail at a
chain of last ksets that never terminates, so cache_writeback_fn() re-arms
itself with no delay forever.
Walk the dirty_tail chain once at load with the same hop cap cache_replay()
uses and fail the table load with -EIO if it does not reach an end within
n_segs hops.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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seg_num is read from the crc32c-only superblock, so whoever supplies the
cache device on a table load (CAP_SYS_ADMIN) controls it. It sizes
cache->segments[] and is the value every later on-media segment id is
bounded against, yet it is never checked against the device. Because
cache_dev->mapping is the direct map of the pmem, CACHE_DEV_SEGMENT() for
a segment id past the device resolves to ordinary kernel memory beyond
the mapping; a new-cache init reaching such an id has cache_seg_init() ->
cache_dev_zero_range() memset() 12 KiB over that memory -- an
out-of-bounds write into the kernel heap at table load. A zero seg_num
makes the segment allocations ZERO_SIZE_PTR.
Reject a seg_num that is zero, larger than the device can hold, or larger
than PCACHE_CACHE_SEGS_MAX before it is used.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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The tail-kset read in cache_replay(), the writeback worker and the GC
worker bounds its length by PCACHE_SEG_SIZE - seg_off, the raw segment
size rather than the data region. A tail near the segment end reads past
the segment data into the following control area.
Clamp the read to cache_seg_remain(), the data region.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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cache_key_decode() takes a key's logical off from the cache device and
later indexes req_key_tree->subtrees[] by it in get_subtree(). An off
past the device forms a subtree pointer outside the array, which
rb_insert() writes through during replay.
Reject a key of zero length, or whose off+len (computed in 64 bits)
exceeds the device size, before it is used.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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cache_replay() follows the on-media last-kset chain by next_cache_seg_id
with no cond_resched(). A forged chain that points back into a segment it
has already visited makes the replay loop follow it forever.
Cap the last-kset hops at cache->n_segs; a valid chain visits each segment
at most once.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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cache_replay(), the writeback worker and the GC worker read a kset of
get_kset_onmedia_size() bytes and advance the position by it. A forged
key_num makes that size exceed the segment's remaining space, so the
advance walks past the segment and trips the cache_pos_advance() BUG_ON.
Reject a kset whose on-media size exceeds cache_seg_remain() before use.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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cache_pos_decode() takes the persisted key_tail and dirty_tail seg_off from
the cache device and addresses within the segment with it. A seg_off at or
past the segment data_size, controllable by whoever supplies the device
(CAP_SYS_ADMIN), reads past the segment data.
Reject a decoded seg_off that is not below the segment data_size.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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Two more fields decoded from the cache device go unbounded. The kset
key_num drives cache_kset_crc() and the replay loop in cache_replay(),
the writeback worker and the GC worker, but only the magic and a
fixed-seed CRC are checked first, so a non-last kset whose key_num exceeds
the PCACHE_KSET_KEYS_MAX buffer reads past its end before the CRC compare.
A key's intra-segment offset and length in cache_key_decode() are taken
verbatim, so a key running past its segment is replayed into the cache
tree and the data CRC check and every later read hit then copy adjacent
persistent memory into the caller's bio -- an out-of-bounds read that
leaks to user space. Both fields are controlled by whoever supplies the
cache device (CAP_SYS_ADMIN); the CRC seed is public.
Add kset_onmedia_valid() to bound key_num before any kset read, and
reject a key whose offset plus length, computed in 64 bits, exceeds the
segment data_size. Valid metadata is unaffected.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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cache_segs_init() iterates cache_info->n_segs times indexing
cache->segments[], which is sized to the cache device geometry, and
get_seg_id() takes each segment id from the on-media cache_info and the
per-segment next_seg link. Both come from cache device metadata that is
only CRC-protected with a fixed public seed, so whoever supplies the
cache device on a table load (CAP_SYS_ADMIN) controls them: an oversized
n_segs or an out-of-range id drives an out-of-bounds access of
cache->segments[] and a wild CACHE_DEV_SEGMENT() pointer into the device
mapping -- an out-of-bounds read and write from on-disk data.
Reject an n_segs that exceeds the device segment count and a segment id
that is out of range before either is used. Valid metadata is unaffected.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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cache_pos_decode(), cache_key_decode() and the last-kset branches of
cache_replay(), the writeback worker and the GC worker take a cache
segment id from the cache device metadata and index cache->segments[]
with it without checking it against cache->n_segs. That metadata is only
CRC-protected with a fixed public seed, so whoever supplies the cache
device on a table load (CAP_SYS_ADMIN) controls the id; an out-of-range
value forms a wild pcache_cache_segment pointer that is dereferenced and
written through -- an out-of-bounds read and write driven by on-disk data.
Add cache_seg_id_valid() and reject an out-of-range id at each decode
site, failing the operation with -EIO instead of indexing past the array.
Bound the id against the initialized-segment count (cache_info.n_segs)
rather than the physical device total. A forged cache_info.n_segs below
seg_num otherwise leaves segments[cache_info.n_segs..seg_num) as zeroed
structs whose data pointer is NULL, so a forged id in that window would
still be dereferenced. A later patch guarantees cache_info.n_segs <=
seg_num, and a driver-created cache sets the two equal, so valid images
are unaffected.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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The pcache target parses optional arguments as name/value pairs. A
table that advertises one optional argument and supplies only a
recognized option name, for example "cache_mode", reaches
parse_cache_opts() with argc == 1. The parser consumes the name,
decrements argc to zero, then calls dm_shift_arg() again for the value.
dm_shift_arg() returns NULL when no arguments remain, and the following
strcmp() dereferences that NULL pointer.
Check that each recognized option has a value before consuming it. This
keeps valid "cache_mode writeback" and "data_crc true/false" tables
unchanged while making malformed tables fail during target construction
with a precise missing-value error.
Assisted-by: Codex:gpt-5.5-cyber-preview
Signed-off-by: Samuel Moelius <sam.moelius@trailofbits.com>
Reviewed-by: Zheng Gu <cengku@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: stable@vger.kernel.org
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Conversion performed via this Coccinelle script:
// SPDX-License-Identifier: GPL-2.0-only
// Options: --include-headers-for-types --all-includes --include-headers --keep-comments
virtual patch
@gfp depends on patch && !(file in "tools") && !(file in "samples")@
identifier ALLOC = {kmalloc_obj,kmalloc_objs,kmalloc_flex,
kzalloc_obj,kzalloc_objs,kzalloc_flex,
kvmalloc_obj,kvmalloc_objs,kvmalloc_flex,
kvzalloc_obj,kvzalloc_objs,kvzalloc_flex};
@@
ALLOC(...
- , GFP_KERNEL
)
$ make coccicheck MODE=patch COCCI=gfp.cocci
Build and boot tested x86_64 with Fedora 42's GCC and Clang:
Linux version 6.19.0+ (user@host) (gcc (GCC) 15.2.1 20260123 (Red Hat 15.2.1-7), GNU ld version 2.44-12.fc42) #1 SMP PREEMPT_DYNAMIC 1970-01-01
Linux version 6.19.0+ (user@host) (clang version 20.1.8 (Fedora 20.1.8-4.fc42), LLD 20.1.8) #1 SMP PREEMPT_DYNAMIC 1970-01-01
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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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>
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git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
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
...
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Segment info indexing also used sizeof(struct) instead of the
4K metadata stride, so info_index could point between slots and
subsequent writes would advance incorrectly. Derive info_index
from the pointer returned by the segment meta search using
PCACHE_SEG_INFO_SIZE and advance to the next slot for future
updates.
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
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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
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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
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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>
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pcache_meta_find_latest() already computes the metadata address as
meta_addr. Reuse that instead of recomputing.
Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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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>
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Change the 'ret' variable from u32 to int to store negative error codes or
zero returned by cache_kset_close().
Storing the negative error codes in unsigned type, doesn't cause an issue
at runtime but it's ugly. Additionally, assigning negative error codes to
unsigned type may trigger a GCC warning when the -Wsign-conversion flag
is enabled.
No effect on runtime.
Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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A patch from a few days ago fixed the division issue on 32-bit machines,
but it introduced a coding style problem.
WARNING: Missing a blank line after declarations
+ u32 rem;
+ div_u64_rem(off >> PCACHE_CACHE_SUBTREE_SIZE_SHIFT,
cache->n_ksets, &rem);
total: 0 errors, 1 warnings, 634 lines checked
Signed-off-by: Dongsheng Yang <dongsheng.yang@linux.dev>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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The smatch checker reports a “scheduler in atomic context” problem in
the following call chain:
miss_read_end_req()
-> cache_seg_put()
-> cache_seg_invalidate()
-> cache_seg_gen_increase()
-> mutex_lock(&cache_seg->ctrl_lock);
In practice, this `mutex_lock` will not actually schedule, because it is
only called when `cache_seg_put()` drops the last reference, which is
single-threaded. That is also why the issue never shows up during real
testing.
However, the code is still buggy. The original purpose of `ctrl_lock`
was to prevent read/write conflicts on the cache segment control
information. Looking at the current usage, all control information
accesses are single-threaded: reads only occur during the init phase,
where no conflicts are possible, and writes happen once in the init
phase (also single-threaded) and once when `cache_seg_put()` drops the
last reference (again single-threaded).
Therefore, this patch removes `ctrl_lock` entirely and adds comments in
the appropriate places to document this logic.
Signed-off-by: Dongsheng Yang <dongsheng.yang@linux.dev>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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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>
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