221c5eb233
This is basically a direct port of bfe4037e72, which implements a
one-shot poll command through aio. Description below is based on that
commit as well. However, instead of adding a POLL command and relying
on io_cancel(2) to remove it, we mimic the epoll(2) interface of
having a command to add a poll notification, IORING_OP_POLL_ADD,
and one to remove it again, IORING_OP_POLL_REMOVE.
To poll for a file descriptor the application should submit an sqe of
type IORING_OP_POLL. It will poll the fd for the events specified in the
poll_events field.
Unlike poll or epoll without EPOLLONESHOT this interface always works in
one shot mode, that is once the sqe is completed, it will have to be
resubmitted.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Based-on-code-from: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
138 lines
2.9 KiB
C
138 lines
2.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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/*
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* Header file for the io_uring interface.
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*
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* Copyright (C) 2019 Jens Axboe
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* Copyright (C) 2019 Christoph Hellwig
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*/
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#ifndef LINUX_IO_URING_H
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#define LINUX_IO_URING_H
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#include <linux/fs.h>
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#include <linux/types.h>
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/*
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* IO submission data structure (Submission Queue Entry)
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*/
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struct io_uring_sqe {
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__u8 opcode; /* type of operation for this sqe */
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__u8 flags; /* IOSQE_ flags */
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__u16 ioprio; /* ioprio for the request */
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__s32 fd; /* file descriptor to do IO on */
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__u64 off; /* offset into file */
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__u64 addr; /* pointer to buffer or iovecs */
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__u32 len; /* buffer size or number of iovecs */
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union {
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__kernel_rwf_t rw_flags;
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__u32 fsync_flags;
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__u16 poll_events;
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};
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__u64 user_data; /* data to be passed back at completion time */
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union {
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__u16 buf_index; /* index into fixed buffers, if used */
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__u64 __pad2[3];
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};
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};
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/*
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* sqe->flags
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*/
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#define IOSQE_FIXED_FILE (1U << 0) /* use fixed fileset */
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/*
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* io_uring_setup() flags
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*/
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#define IORING_SETUP_IOPOLL (1U << 0) /* io_context is polled */
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#define IORING_SETUP_SQPOLL (1U << 1) /* SQ poll thread */
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#define IORING_SETUP_SQ_AFF (1U << 2) /* sq_thread_cpu is valid */
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#define IORING_OP_NOP 0
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#define IORING_OP_READV 1
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#define IORING_OP_WRITEV 2
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#define IORING_OP_FSYNC 3
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#define IORING_OP_READ_FIXED 4
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#define IORING_OP_WRITE_FIXED 5
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#define IORING_OP_POLL_ADD 6
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#define IORING_OP_POLL_REMOVE 7
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/*
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* sqe->fsync_flags
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*/
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#define IORING_FSYNC_DATASYNC (1U << 0)
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/*
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* IO completion data structure (Completion Queue Entry)
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*/
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struct io_uring_cqe {
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__u64 user_data; /* sqe->data submission passed back */
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__s32 res; /* result code for this event */
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__u32 flags;
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};
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/*
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* Magic offsets for the application to mmap the data it needs
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*/
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#define IORING_OFF_SQ_RING 0ULL
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#define IORING_OFF_CQ_RING 0x8000000ULL
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#define IORING_OFF_SQES 0x10000000ULL
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/*
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* Filled with the offset for mmap(2)
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*/
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struct io_sqring_offsets {
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__u32 head;
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__u32 tail;
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__u32 ring_mask;
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__u32 ring_entries;
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__u32 flags;
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__u32 dropped;
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__u32 array;
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__u32 resv1;
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__u64 resv2;
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};
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/*
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* sq_ring->flags
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*/
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#define IORING_SQ_NEED_WAKEUP (1U << 0) /* needs io_uring_enter wakeup */
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struct io_cqring_offsets {
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__u32 head;
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__u32 tail;
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__u32 ring_mask;
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__u32 ring_entries;
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__u32 overflow;
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__u32 cqes;
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__u64 resv[2];
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};
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/*
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* io_uring_enter(2) flags
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*/
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#define IORING_ENTER_GETEVENTS (1U << 0)
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#define IORING_ENTER_SQ_WAKEUP (1U << 1)
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/*
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* Passed in for io_uring_setup(2). Copied back with updated info on success
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*/
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struct io_uring_params {
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__u32 sq_entries;
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__u32 cq_entries;
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__u32 flags;
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__u32 sq_thread_cpu;
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__u32 sq_thread_idle;
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__u32 resv[5];
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struct io_sqring_offsets sq_off;
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struct io_cqring_offsets cq_off;
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};
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/*
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* io_uring_register(2) opcodes and arguments
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*/
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#define IORING_REGISTER_BUFFERS 0
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#define IORING_UNREGISTER_BUFFERS 1
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#define IORING_REGISTER_FILES 2
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#define IORING_UNREGISTER_FILES 3
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#endif
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