kernel/linux.git/include/uapi/linux/ublk_cmd.h, branch v7.0-rc7

ublk: add UBLK_F_NO_AUTO_PART_SCAN feature flag

2026-01-31T13:36:41+00:00

Add a new feature flag UBLK_F_NO_AUTO_PART_SCAN to allow users to suppress automatic partition scanning when starting a ublk device. This is useful for some cases in which user don't want to scan partitions. Users still can manually trigger partition scanning later when appropriate using standard tools (e.g., partprobe, blockdev --rereadpt). Reported-by: Yoav Cohen Link: https://lore.kernel.org/linux-block/DM4PR12MB63280C5637917C071C2F0D65A9A8A@DM4PR12MB6328.namprd12.prod.outlook.com/ Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

ublk: add new feature UBLK_F_BATCH_IO

2026-01-23T03:05:40+00:00

Add new feature UBLK_F_BATCH_IO which replaces the following two per-io commands: - UBLK_U_IO_FETCH_REQ - UBLK_U_IO_COMMIT_AND_FETCH_REQ with three per-queue batch io uring_cmd: - UBLK_U_IO_PREP_IO_CMDS - UBLK_U_IO_COMMIT_IO_CMDS - UBLK_U_IO_FETCH_IO_CMDS Then ublk can deliver batch io commands to ublk server in single multishort uring_cmd, also allows to prepare & commit multiple commands in batch style via single uring_cmd, communication cost is reduced a lot. This feature also doesn't limit task context any more for all supported commands, so any allowed uring_cmd can be issued in any task context. ublk server implementation becomes much easier. Meantime load balance becomes much easier to support with this feature. The command `UBLK_U_IO_FETCH_IO_CMDS` can be issued from multiple task contexts, so each task can adjust this command's buffer length or number of inflight commands for controlling how much load is handled by current task. Later, priority parameter will be added to command `UBLK_U_IO_FETCH_IO_CMDS` for improving load balance support. UBLK_U_IO_NEED_GET_DATA isn't supported in batch io yet, but it may be enabled in future via its batch pair. Reviewed-by: Caleb Sander Mateos Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

ublk: add UBLK_U_IO_FETCH_IO_CMDS for batch I/O processing

2026-01-23T03:05:40+00:00

Add UBLK_U_IO_FETCH_IO_CMDS command to enable efficient batch processing of I/O requests. This multishot uring_cmd allows the ublk server to fetch multiple I/O commands in a single operation, significantly reducing submission overhead compared to individual FETCH_REQ* commands. Key Design Features: 1. Multishot Operation: One UBLK_U_IO_FETCH_IO_CMDS can fetch many I/O commands, with the batch size limited by the provided buffer length. 2. Dynamic Load Balancing: Multiple fetch commands can be submitted simultaneously, but only one is active at any time. This enables efficient load distribution across multiple server task contexts. 3. Implicit State Management: The implementation uses three key variables to track state: - evts_fifo: Queue of request tags awaiting processing - fcmd_head: List of available fetch commands - active_fcmd: Currently active fetch command (NULL = none active) States are derived implicitly: - IDLE: No fetch commands available - READY: Fetch commands available, none active - ACTIVE: One fetch command processing events 4. Lockless Reader Optimization: The active fetch command can read from evts_fifo without locking (single reader guarantee), while writers (ublk_queue_rq/ublk_queue_rqs) use evts_lock protection. The memory barrier pairing plays key role for the single lockless reader optimization. Implementation Details: - ublk_queue_rq() and ublk_queue_rqs() save request tags to evts_fifo - __ublk_acquire_fcmd() selects an available fetch command when events arrive and no command is currently active - ublk_batch_dispatch() moves tags from evts_fifo to the fetch command's buffer and posts completion via io_uring_mshot_cmd_post_cqe() - State transitions are coordinated via evts_lock to maintain consistency Reviewed-by: Caleb Sander Mateos Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

ublk: handle UBLK_U_IO_COMMIT_IO_CMDS

2026-01-23T03:05:40+00:00

Handle UBLK_U_IO_COMMIT_IO_CMDS by walking the uring_cmd fixed buffer: - read each element into one temp buffer in batch style - parse and apply each element for committing io result Reviewed-by: Caleb Sander Mateos Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

ublk: handle UBLK_U_IO_PREP_IO_CMDS

2026-01-23T03:05:40+00:00

This commit implements the handling of the UBLK_U_IO_PREP_IO_CMDS command, which allows userspace to prepare a batch of I/O requests. The core of this change is the `ublk_walk_cmd_buf` function, which iterates over the elements in the uring_cmd fixed buffer. For each element, it parses the I/O details, finds the corresponding `ublk_io` structure, and prepares it for future dispatch. Add per-io lock for protecting concurrent delivery and committing. Reviewed-by: Caleb Sander Mateos Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

ublk: add new batch command UBLK_U_IO_PREP_IO_CMDS & UBLK_U_IO_COMMIT_IO_CMDS

2026-01-23T03:05:40+00:00

Add new command UBLK_U_IO_PREP_IO_CMDS, which is the batch version of UBLK_IO_FETCH_REQ. Add new command UBLK_U_IO_COMMIT_IO_CMDS, which is for committing io command result only, still the batch version. The new command header type is `struct ublk_batch_io`. This patch doesn't actually implement these commands yet, just validates the SQE fields. Reviewed-by: Caleb Sander Mateos Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

ublk: add UBLK_CMD_TRY_STOP_DEV command

2026-01-12T22:07:31+00:00

Add a best-effort stop command, UBLK_CMD_TRY_STOP_DEV, which only stops a ublk device when it has no active openers. Unlike UBLK_CMD_STOP_DEV, this command does not disrupt existing users. New opens are blocked only after disk_openers has reached zero; if the device is busy, the command returns -EBUSY and leaves it running. The ub->block_open flag is used only to close a race with an in-progress open and does not otherwise change open behavior. Advertise support via the UBLK_F_SAFE_STOP_DEV feature flag. Signed-off-by: Yoav Cohen Reviewed-by: Ming Lei Signed-off-by: Jens Axboe

ublk: implement integrity user copy

2026-01-12T16:16:38+00:00

Add a function ublk_copy_user_integrity() to copy integrity information between a request and a user iov_iter. This mirrors the existing ublk_copy_user_pages() but operates on request integrity data instead of regular data. Check UBLKSRV_IO_INTEGRITY_FLAG in iocb->ki_pos in ublk_user_copy() to choose between copying data or integrity data. [csander: change offset units from data bytes to integrity data bytes, fix CONFIG_BLK_DEV_INTEGRITY=n build, rebase on user copy refactor] Signed-off-by: Stanley Zhang Signed-off-by: Caleb Sander Mateos Reviewed-by: Ming Lei Signed-off-by: Jens Axboe

ublk: set UBLK_IO_F_INTEGRITY in ublksrv_io_desc

2026-01-12T16:15:05+00:00

Indicate to the ublk server when an incoming request has integrity data by setting UBLK_IO_F_INTEGRITY in the ublksrv_io_desc's op_flags field. Signed-off-by: Caleb Sander Mateos Reviewed-by: Ming Lei Signed-off-by: Jens Axboe

ublk: support UBLK_PARAM_TYPE_INTEGRITY in device creation

2026-01-12T16:15:05+00:00

Add a feature flag UBLK_F_INTEGRITY for a ublk server to request integrity/metadata support when creating a ublk device. The ublk server can also check for the feature flag on the created device or the result of UBLK_U_CMD_GET_FEATURES to tell if the ublk driver supports it. UBLK_F_INTEGRITY requires UBLK_F_USER_COPY, as user copy is the only data copy mode initially supported for integrity data. Add UBLK_PARAM_TYPE_INTEGRITY and struct ublk_param_integrity to struct ublk_params to specify the integrity params of a ublk device. UBLK_PARAM_TYPE_INTEGRITY requires UBLK_F_INTEGRITY and a nonzero metadata_size. The LBMD_PI_CAP_* and LBMD_PI_CSUM_* values from the linux/fs.h UAPI header are used for the flags and csum_type fields. If the UBLK_PARAM_TYPE_INTEGRITY flag is set, validate the integrity parameters and apply them to the blk_integrity limits. The struct ublk_param_integrity validations are based on the checks in blk_validate_integrity_limits(). Any invalid parameters should be rejected before being applied to struct blk_integrity. [csander: drop redundant pi_tuple_size field, use block metadata UAPI constants, add param validation] Signed-off-by: Stanley Zhang Signed-off-by: Caleb Sander Mateos Reviewed-by: Ming Lei Signed-off-by: Jens Axboe