kernel.git/drivers/md/bcache/super.c, branch linux-rolling-stable

bcache: use bio cloning for detached device requests

2026-01-22T14:24:50Z

Previously, bcache hijacked the bi_end_io and bi_private fields of the incoming bio when the backing device was in a detached state. This is fragile and breaks if the bio is needed to be processed by other layers. This patch transitions to using a cloned bio embedded within a private structure. This ensures the original bio's metadata remains untouched. Fixes: 53280e398471 ("bcache: fix improper use of bi_end_io") Co-developed-by: Christoph Hellwig Signed-off-by: Christoph Hellwig Signed-off-by: Shida Zhang Acked-by: Coly Li Signed-off-by: Jens Axboe

bcache: WQ_PERCPU added to alloc_workqueue users

2025-11-13T16:18:06Z

Currently if a user enqueue a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This lack of consistentcy cannot be addressed without refactoring the API. alloc_workqueue() treats all queues as per-CPU by default, while unbound workqueues must opt-in via WQ_UNBOUND. This default is suboptimal: most workloads benefit from unbound queues, allowing the scheduler to place worker threads where they’re needed and reducing noise when CPUs are isolated. This patch continues the effort to refactor worqueue APIs, which has begun with the change introducing new workqueues and a new alloc_workqueue flag: commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq") commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag") This change adds a new WQ_PERCPU flag to explicitly request alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified. With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND), any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND must now use WQ_PERCPU. Once migration is complete, WQ_UNBOUND can be removed and unbound will become the implicit default. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Signed-off-by: Coly Li Signed-off-by: Jens Axboe

bcache: replace use of system_wq with system_percpu_wq

2025-11-13T16:18:06Z

Currently if a user enqueues a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This lack of consistency cannot be addressed without refactoring the API. This patch continues the effort to refactor worqueue APIs, which has begun with the change introducing new workqueues and a new alloc_workqueue flag: commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq") commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag") system_wq should be the per-cpu workqueue, yet in this name nothing makes that clear, so replace system_wq with system_percpu_wq. The old wq (system_wq) will be kept for a few release cycles. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Signed-off-by: Coly Li Signed-off-by: Jens Axboe

bcache: drop discard sysfs interface

2025-11-13T16:18:06Z

Since discard code is removed, now the sysfs interface to enable discard is useless. This patch removes the corresponding sysfs entry, and remove bool variable 'discard' from struct cache as well. Signed-off-by: Coly Li Signed-off-by: Jens Axboe

block: add a bio_init_inline helper

2025-09-09T13:31:59Z

Just a simpler wrapper around bio_init for callers that want to initialize a bio with inline bvecs. Signed-off-by: Christoph Hellwig Reviewed-by: John Garry Reviewed-by: Yu Kuai Signed-off-by: Jens Axboe

bcache: switch from pages to folios in read_super()

2025-07-03T00:56:42Z

Retrieve a folio from the page cache instead of a page. Removes a hidden call to compound_head(). Then be sure to call folio_put() instead of put_page() to release it. That doesn't save any calls to compound_head(), just moves them around. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Coly Li Acked-back: Coly Li Link: https://lore.kernel.org/r/20250702024848.343370-1-colyli@kernel.org [axboe: commit message massaging] Signed-off-by: Jens Axboe

Revert "bcache: remove heap-related macros and switch to generic min_heap"

2025-06-20T03:48:03Z

This reverts commit 866898efbb25bb44fd42848318e46db9e785973a. The generic bottom-up min_heap implementation causes performance regression in invalidate_buckets_lru(), a hot path in bcache. Before the cache is fully populated, new_bucket_prio() often returns zero, leading to many equal comparisons. In such cases, bottom-up sift_down performs up to 2 * log2(n) comparisons, while the original top-down approach completes with just O() comparisons, resulting in a measurable performance gap. The performance degradation is further worsened by the non-inlined min_heap API functions introduced in commit 92a8b224b833 ("lib/min_heap: introduce non-inline versions of min heap API functions"), adding function call overhead to this critical path. As reported by Robert, bcache now suffers from latency spikes, with P100 (max) latency increasing from 600 ms to 2.4 seconds every 5 minutes. These regressions degrade bcache's effectiveness as a low-latency cache layer and lead to frequent timeouts and application stalls in production environments. This revert aims to restore bcache's original low-latency behavior. Link: https://lore.kernel.org/lkml/CAJhEC05+0S69z+3+FB2Cd0hD+pCRyWTKLEOsc8BOmH73p1m+KQ@mail.gmail.com Link: https://lkml.kernel.org/r/20250614202353.1632957-3-visitorckw@gmail.com Fixes: 866898efbb25 ("bcache: remove heap-related macros and switch to generic min_heap") Fixes: 92a8b224b833 ("lib/min_heap: introduce non-inline versions of min heap API functions") Signed-off-by: Kuan-Wei Chiu Reported-by: Robert Pang Closes: https://lore.kernel.org/linux-bcache/CAJhEC06F_AtrPgw2-7CvCqZgeStgCtitbD-ryuPpXQA-JG5XXw@mail.gmail.com Acked-by: Coly Li Cc: Ching-Chun (Jim) Huang Cc: Kent Overstreet Cc: Signed-off-by: Andrew Morton

Merge tag 'block-6.16-20250606' of git://git.kernel.dk/linux

2025-06-06T20:12:50Z

Pull more block updates from Jens Axboe: - NVMe pull request via Christoph: - TCP error handling fix (Shin'ichiro Kawasaki) - TCP I/O stall handling fixes (Hannes Reinecke) - fix command limits status code (Keith Busch) - support vectored buffers also for passthrough (Pavel Begunkov) - spelling fixes (Yi Zhang) - MD pull request via Yu: - fix REQ_RAHEAD and REQ_NOWAIT IO err handling for raid1/10 - fix max_write_behind setting for dm-raid - some minor cleanups - Integrity data direction fix and cleanup - bcache NULL pointer fix - Fix for loop missing write start/end handling - Decouple hardware queues and IO threads in ublk - Slew of ublk selftests additions and updates * tag 'block-6.16-20250606' of git://git.kernel.dk/linux: (29 commits) nvme: spelling fixes nvme-tcp: fix I/O stalls on congested sockets nvme-tcp: sanitize request list handling nvme-tcp: remove tag set when second admin queue config fails nvme: enable vectored registered bufs for passthrough cmds nvme: fix implicit bool to flags conversion nvme: fix command limits status code selftests: ublk: kublk: improve behavior on init failure block: flip iter directions in blk_rq_integrity_map_user() block: drop direction param from bio_integrity_copy_user() selftests: ublk: cover PER_IO_DAEMON in more stress tests Documentation: ublk: document UBLK_F_PER_IO_DAEMON selftests: ublk: add stress test for per io daemons selftests: ublk: add functional test for per io daemons selftests: ublk: kublk: decouple ublk_queues from ublk server threads selftests: ublk: kublk: move per-thread data out of ublk_queue selftests: ublk: kublk: lift queue initialization out of thread selftests: ublk: kublk: tie sqe allocation to io instead of queue selftests: ublk: kublk: plumb q_id in io_uring user_data ublk: have a per-io daemon instead of a per-queue daemon ...

Merge tag 'hardening-v6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2025-05-28T14:47:10Z

Pull hardening updates from Kees Cook: - Update overflow helpers to ease refactoring of on-stack flex array instances (Gustavo A. R. Silva, Kees Cook) - lkdtm: Use SLAB_NO_MERGE instead of constructors (Harry Yoo) - Simplify CONFIG_CC_HAS_COUNTED_BY (Jan Hendrik Farr) - Disable u64 usercopy KUnit test on 32-bit SPARC (Thomas Weißschuh) - Add missed designated initializers now exposed by fixed randstruct (Nathan Chancellor, Kees Cook) - Document compilers versions for __builtin_dynamic_object_size - Remove ARM_SSP_PER_TASK GCC plugin - Fix GCC plugin randstruct, add selftests, and restore COMPILE_TEST builds - Kbuild: induce full rebuilds when dependencies change with GCC plugins, the Clang sanitizer .scl file, or the randstruct seed. - Kbuild: Switch from -Wvla to -Wvla-larger-than=1 - Correct several __nonstring uses for -Wunterminated-string-initialization * tag 'hardening-v6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (23 commits) Revert "hardening: Disable GCC randstruct for COMPILE_TEST" lib/tests: randstruct: Add deep function pointer layout test lib/tests: Add randstruct KUnit test randstruct: gcc-plugin: Remove bogus void member net: qede: Initialize qede_ll_ops with designated initializer scsi: qedf: Use designated initializer for struct qed_fcoe_cb_ops md/bcache: Mark __nonstring look-up table integer-wrap: Force full rebuild when .scl file changes randstruct: Force full rebuild when seed changes gcc-plugins: Force full rebuild when plugins change kbuild: Switch from -Wvla to -Wvla-larger-than=1 hardening: simplify CONFIG_CC_HAS_COUNTED_BY overflow: Fix direct struct member initialization in _DEFINE_FLEX() kunit/overflow: Add tests for STACK_FLEX_ARRAY_SIZE() helper overflow: Add STACK_FLEX_ARRAY_SIZE() helper input/joystick: magellan: Mark __nonstring look-up table const watchdog: exar: Shorten identity name to fit correctly mod_devicetable: Enlarge the maximum platform_device_id name length overflow: Clarify expectations for getting DEFINE_FLEX variable sizes compiler_types: Identify compiler versions for __builtin_dynamic_object_size ...

bcache: reserve more RESERVE_BTREE buckets to prevent allocator hang

2025-05-27T13:38:19Z

Reported an IO hang and unrecoverable error in our testing environment. After careful research, we found that bch_allocator_thread is stuck, the call stack is as follows: [<0>] __switch_to+0xbc/0x108 [<0>] __closure_sync+0x7c/0xbc [bcache] [<0>] bch_prio_write+0x430/0x448 [bcache] [<0>] bch_allocator_thread+0xb44/0xb70 [bcache] [<0>] kthread+0x124/0x130 [<0>] ret_from_fork+0x10/0x18 Moreover, the RESERVE_BTREE type bucket slot are empty and journal_full occurs at the same time. When the cache disk is first used, the sb.nJournal_buckets defaults to 0. So, only 8 RESERVE_BTREE type buckets are reserved. If RESERVE_BTREE type buckets used up or btree_check_reserve() failed when request handle btree split, the request will be repeatedly retried and wait for alloc thread to fill in. After the alloc thread fills the buckets, it will call bch_prio_write(). If journal_full occurs simultaneously at this time, journal_reclaim() and btree_flush_write() will be called sequentially, journal_write cannot be completed. This is a low probability event, we believe that reserve more RESERVE_BTREE buckets can avoid the worst situation. Fixes: 682811b3ce1a ("bcache: fix for allocator and register thread race") Signed-off-by: Mingzhe Zou Signed-off-by: Coly Li Link: https://lore.kernel.org/r/20250527051601.74407-4-colyli@kernel.org Signed-off-by: Jens Axboe