linux-stable/include/uapi/linux/io_uring.h
Jens Axboe 6b06314c47 io_uring: add file set registration
We normally have to fget/fput for each IO we do on a file. Even with
the batching we do, the cost of the atomic inc/dec of the file usage
count adds up.

This adds IORING_REGISTER_FILES, and IORING_UNREGISTER_FILES opcodes
for the io_uring_register(2) system call. The arguments passed in must
be an array of __s32 holding file descriptors, and nr_args should hold
the number of file descriptors the application wishes to pin for the
duration of the io_uring instance (or until IORING_UNREGISTER_FILES is
called).

When used, the application must set IOSQE_FIXED_FILE in the sqe->flags
member. Then, instead of setting sqe->fd to the real fd, it sets sqe->fd
to the index in the array passed in to IORING_REGISTER_FILES.

Files are automatically unregistered when the io_uring instance is torn
down. An application need only unregister if it wishes to register a new
set of fds.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-02-28 08:24:23 -07:00

124 lines
2.5 KiB
C

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/*
* Header file for the io_uring interface.
*
* Copyright (C) 2019 Jens Axboe
* Copyright (C) 2019 Christoph Hellwig
*/
#ifndef LINUX_IO_URING_H
#define LINUX_IO_URING_H
#include <linux/fs.h>
#include <linux/types.h>
/*
* IO submission data structure (Submission Queue Entry)
*/
struct io_uring_sqe {
__u8 opcode; /* type of operation for this sqe */
__u8 flags; /* IOSQE_ flags */
__u16 ioprio; /* ioprio for the request */
__s32 fd; /* file descriptor to do IO on */
__u64 off; /* offset into file */
__u64 addr; /* pointer to buffer or iovecs */
__u32 len; /* buffer size or number of iovecs */
union {
__kernel_rwf_t rw_flags;
__u32 fsync_flags;
};
__u64 user_data; /* data to be passed back at completion time */
union {
__u16 buf_index; /* index into fixed buffers, if used */
__u64 __pad2[3];
};
};
/*
* sqe->flags
*/
#define IOSQE_FIXED_FILE (1U << 0) /* use fixed fileset */
/*
* io_uring_setup() flags
*/
#define IORING_SETUP_IOPOLL (1U << 0) /* io_context is polled */
#define IORING_OP_NOP 0
#define IORING_OP_READV 1
#define IORING_OP_WRITEV 2
#define IORING_OP_FSYNC 3
#define IORING_OP_READ_FIXED 4
#define IORING_OP_WRITE_FIXED 5
/*
* sqe->fsync_flags
*/
#define IORING_FSYNC_DATASYNC (1U << 0)
/*
* IO completion data structure (Completion Queue Entry)
*/
struct io_uring_cqe {
__u64 user_data; /* sqe->data submission passed back */
__s32 res; /* result code for this event */
__u32 flags;
};
/*
* Magic offsets for the application to mmap the data it needs
*/
#define IORING_OFF_SQ_RING 0ULL
#define IORING_OFF_CQ_RING 0x8000000ULL
#define IORING_OFF_SQES 0x10000000ULL
/*
* Filled with the offset for mmap(2)
*/
struct io_sqring_offsets {
__u32 head;
__u32 tail;
__u32 ring_mask;
__u32 ring_entries;
__u32 flags;
__u32 dropped;
__u32 array;
__u32 resv1;
__u64 resv2;
};
struct io_cqring_offsets {
__u32 head;
__u32 tail;
__u32 ring_mask;
__u32 ring_entries;
__u32 overflow;
__u32 cqes;
__u64 resv[2];
};
/*
* io_uring_enter(2) flags
*/
#define IORING_ENTER_GETEVENTS (1U << 0)
/*
* Passed in for io_uring_setup(2). Copied back with updated info on success
*/
struct io_uring_params {
__u32 sq_entries;
__u32 cq_entries;
__u32 flags;
__u32 resv[7];
struct io_sqring_offsets sq_off;
struct io_cqring_offsets cq_off;
};
/*
* io_uring_register(2) opcodes and arguments
*/
#define IORING_REGISTER_BUFFERS 0
#define IORING_UNREGISTER_BUFFERS 1
#define IORING_REGISTER_FILES 2
#define IORING_UNREGISTER_FILES 3
#endif