Add --rdonly_shmem_buf option to kublk that registers shared memory buffers with UBLK_SHMEM_BUF_READ_ONLY (read-only pinning without FOLL_WRITE) and mmaps with PROT_READ only. Add test_shmemzc_04.sh which exercises the new flag with a null target, hugetlbfs buffer, and write workload. Write I/O works because the server only reads from the shared buffer — the data flows from client to kernel to the shared pages, and the server reads them out. Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://patch.msgid.link/20260331153207.3635125-11-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add test_shmemzc_03.sh which exercises shmem_zc through the full filesystem stack: mkfs ext4 on the ublk device, mount it, then run fio verify on a file inside the filesystem with --mem=mmaphuge. Extend _mkfs_mount_test() to accept an optional command that runs between mount and umount. The function cd's into the mount directory so the command can use relative file paths. Existing callers that pass only the device are unaffected. Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://patch.msgid.link/20260331153207.3635125-10-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add test_shmem_zc_02.sh which tests the UBLK_IO_F_SHMEM_ZC zero-copy path on the loop target using a hugetlbfs shared buffer. Both kublk and fio mmap the same hugetlbfs file with MAP_SHARED, sharing physical pages. The kernel's PFN matching enables zero-copy — the loop target reads/writes directly from the shared buffer to the backing file. Uses standard fio --mem=mmaphuge:<path> (supported since fio 1.10), no patched fio required. Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://patch.msgid.link/20260331153207.3635125-9-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add test_shmem_zc_01.sh which tests UBLK_IO_F_SHMEM_ZC on the null target using a hugetlbfs shared buffer. Both kublk (--htlb) and fio (--mem=mmaphuge:<path>) mmap the same hugetlbfs file with MAP_SHARED, sharing physical pages. The kernel PFN match enables zero-copy I/O. Uses standard fio --mem=mmaphuge:<path> (supported since fio 1.10), no patched fio required. Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://patch.msgid.link/20260331153207.3635125-8-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add loop_queue_shmem_zc_io() which handles I/O requests marked with UBLK_IO_F_SHMEM_ZC. When the kernel sets this flag, the request data lives in a registered shared memory buffer — decode index + offset from iod->addr and use the server's mmap as the I/O buffer. The dispatch check in loop_queue_tgt_rw_io() routes SHMEM_ZC requests to this new function, bypassing the normal buffer registration path. Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://patch.msgid.link/20260331153207.3635125-7-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add infrastructure for UBLK_F_SHMEM_ZC shared memory zero-copy: - kublk.h: struct ublk_shmem_entry and table for tracking registered shared memory buffers - kublk.c: per-device unix socket listener that accepts memfd registrations from clients via SCM_RIGHTS fd passing. The listener mmaps the memfd and registers the VA range with the kernel for PFN matching. Also adds --shmem_zc command line option. - kublk.c: --htlb <path> option to open a pre-allocated hugetlbfs file, mmap it with MAP_SHARED|MAP_POPULATE, and register it with the kernel via ublk_ctrl_reg_buf(). Any process that mmaps the same hugetlbfs file shares the same physical pages, enabling zero-copy without socket-based fd passing. Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://patch.msgid.link/20260331153207.3635125-6-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Before the fix, teardown of a ublk server that was attempting to recover a device, but died when it had submitted a nonempty proper subset of the fetch commands to any queue would loop forever. Add a test to verify that, after the fix, teardown completes. This is done by: - Adding a new argument to the fault_inject target that causes it die after fetching a nonempty proper subset of the IOs to a queue - Using that argument in a new test while trying to recover an already-created device - Attempting to delete the ublk device at the end of the test; this hangs forever if teardown from the fault-injected ublk server never completed. It was manually verified that the test passes with the fix and hangs without it. Signed-off-by: Uday Shankar <ushankar@purestorage.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://patch.msgid.link/20260405-cancel-v2-2-02d711e643c2@purestorage.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull block updates from Jens Axboe:
- Support for batch request processing for ublk, improving the
efficiency of the kernel/ublk server communication. This can yield
nice 7-12% performance improvements
- Support for integrity data for ublk
- Various other ublk improvements and additions, including a ton of
selftests additions and updated
- Move the handling of blk-crypto software fallback from below the
block layer to above it. This reduces the complexity of dealing with
bio splitting
- Series fixing a number of potential deadlocks in blk-mq related to
the queue usage counter and writeback throttling and rq-qos debugfs
handling
- Add an async_depth queue attribute, to resolve a performance
regression that's been around for a qhilw related to the scheduler
depth handling
- Only use task_work for IOPOLL completions on NVMe, if it is necessary
to do so. An earlier fix for an issue resulted in all these
completions being punted to task_work, to guarantee that completions
were only run for a given io_uring ring when it was local to that
ring. With the new changes, we can detect if it's necessary to use
task_work or not, and avoid it if possible.
- rnbd fixes:
- Fix refcount underflow in device unmap path
- Handle PREFLUSH and NOUNMAP flags properly in protocol
- Fix server-side bi_size for special IOs
- Zero response buffer before use
- Fix trace format for flags
- Add .release to rnbd_dev_ktype
- MD pull requests via Yu Kuai
- Fix raid5_run() to return error when log_init() fails
- Fix IO hang with degraded array with llbitmap
- Fix percpu_ref not resurrected on suspend timeout in llbitmap
- Fix GPF in write_page caused by resize race
- Fix NULL pointer dereference in process_metadata_update
- Fix hang when stopping arrays with metadata through dm-raid
- Fix any_working flag handling in raid10_sync_request
- Refactor sync/recovery code path, improve error handling for
badblocks, and remove unused recovery_disabled field
- Consolidate mddev boolean fields into mddev_flags
- Use mempool to allocate stripe_request_ctx and make sure
max_sectors is not less than io_opt in raid5
- Fix return value of mddev_trylock
- Fix memory leak in raid1_run()
- Add Li Nan as mdraid reviewer
- Move phys_vec definitions to the kernel types, mostly in preparation
for some VFIO and RDMA changes
- Improve the speed for secure erase for some devices
- Various little rust updates
- Various other minor fixes, improvements, and cleanups
* tag 'for-7.0/block-20260206' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux: (162 commits)
blk-mq: ABI/sysfs-block: fix docs build warnings
selftests: ublk: organize test directories by test ID
block: decouple secure erase size limit from discard size limit
block: remove redundant kill_bdev() call in set_blocksize()
blk-mq: add documentation for new queue attribute async_dpeth
block, bfq: convert to use request_queue->async_depth
mq-deadline: covert to use request_queue->async_depth
kyber: covert to use request_queue->async_depth
blk-mq: add a new queue sysfs attribute async_depth
blk-mq: factor out a helper blk_mq_limit_depth()
blk-mq-sched: unify elevators checking for async requests
block: convert nr_requests to unsigned int
block: don't use strcpy to copy blockdev name
blk-mq-debugfs: warn about possible deadlock
blk-mq-debugfs: add missing debugfs_mutex in blk_mq_debugfs_register_hctxs()
blk-mq-debugfs: remove blk_mq_debugfs_unregister_rqos()
blk-mq-debugfs: make blk_mq_debugfs_register_rqos() static
blk-rq-qos: fix possible debugfs_mutex deadlock
blk-mq-debugfs: factor out a helper to register debugfs for all rq_qos
blk-wbt: fix possible deadlock to nest pcpu_alloc_mutex under q_usage_counter
...
Pull kselftest updates from Shuah Khan: "resctrl test: - fix division by zero error on Hygon - fix non-contiguous CBM check for Hygon - define CPU vendor IDs as bits to match usage - add CPU vendor detection for Hygon misc: - coredeump test: use __builtin_trap() instead of a null pointer - anon_inode: replace null pointers with empty arrays - kublk: include message in _Static_assert for C11 compatibility - run_kselftest.sh: add `--skip` argument option - pidfd: fix typo in comment" * tag 'linux_kselftest-next-6.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: selftests/pidfd: fix typo in comment selftests/run_kselftest.sh: Add `--skip` argument option selftests/resctrl: Fix non-contiguous CBM check for Hygon selftests/resctrl: Add CPU vendor detection for Hygon selftests/resctrl: Define CPU vendor IDs as bits to match usage selftests/resctrl: Fix a division by zero error on Hygon kselftest/kublk: include message in _Static_assert for C11 compatibility kselftest/anon_inode: replace null pointers with empty arrays kselftest/coredump: use __builtin_trap() instead of null pointer
Set UBLK_TEST_DIR to ${TMPDIR:-./ublktest-dir}/${TID}.XXXXXX to create
per-test subdirectories organized by test ID. This makes it easier to
identify and debug specific test runs.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>