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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>
This commit is contained in:
Jens Axboe
parent
f4e65870e5
commit
6b06314c47
271
fs/io_uring.c
271
fs/io_uring.c
@ -49,6 +49,7 @@
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#include <linux/net.h>
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#include <net/sock.h>
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#include <net/af_unix.h>
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#include <net/scm.h>
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#include <linux/anon_inodes.h>
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#include <linux/sched/mm.h>
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#include <linux/uaccess.h>
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@ -61,6 +62,7 @@
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#include "internal.h"
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#define IORING_MAX_ENTRIES 4096
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#define IORING_MAX_FIXED_FILES 1024
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struct io_uring {
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u32 head ____cacheline_aligned_in_smp;
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@ -123,6 +125,14 @@ struct io_ring_ctx {
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struct fasync_struct *cq_fasync;
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} ____cacheline_aligned_in_smp;
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/*
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* If used, fixed file set. Writers must ensure that ->refs is dead,
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* readers must ensure that ->refs is alive as long as the file* is
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* used. Only updated through io_uring_register(2).
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*/
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struct file **user_files;
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unsigned nr_user_files;
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/* if used, fixed mapped user buffers */
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unsigned nr_user_bufs;
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struct io_mapped_ubuf *user_bufs;
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@ -170,6 +180,7 @@ struct io_kiocb {
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unsigned int flags;
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#define REQ_F_FORCE_NONBLOCK 1 /* inline submission attempt */
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#define REQ_F_IOPOLL_COMPLETED 2 /* polled IO has completed */
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#define REQ_F_FIXED_FILE 4 /* ctx owns file */
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u64 user_data;
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u64 error;
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@ -404,6 +415,7 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
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* Batched puts of the same file, to avoid dirtying the
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* file usage count multiple times, if avoidable.
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*/
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if (!(req->flags & REQ_F_FIXED_FILE)) {
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if (!file) {
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file = req->rw.ki_filp;
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file_count = 1;
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@ -414,6 +426,7 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
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file = req->rw.ki_filp;
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file_count = 1;
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}
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}
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if (to_free == ARRAY_SIZE(reqs))
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io_free_req_many(ctx, reqs, &to_free);
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@ -544,13 +557,19 @@ static void kiocb_end_write(struct kiocb *kiocb)
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}
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}
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static void io_fput(struct io_kiocb *req)
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{
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if (!(req->flags & REQ_F_FIXED_FILE))
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fput(req->rw.ki_filp);
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}
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static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
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{
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struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
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kiocb_end_write(kiocb);
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fput(kiocb->ki_filp);
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io_fput(req);
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io_cqring_add_event(req->ctx, req->user_data, res, 0);
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io_free_req(req);
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}
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@ -666,19 +685,29 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
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{
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struct io_ring_ctx *ctx = req->ctx;
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struct kiocb *kiocb = &req->rw;
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unsigned ioprio;
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unsigned ioprio, flags;
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int fd, ret;
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/* For -EAGAIN retry, everything is already prepped */
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if (kiocb->ki_filp)
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return 0;
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flags = READ_ONCE(sqe->flags);
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fd = READ_ONCE(sqe->fd);
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if (flags & IOSQE_FIXED_FILE) {
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if (unlikely(!ctx->user_files ||
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(unsigned) fd >= ctx->nr_user_files))
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return -EBADF;
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kiocb->ki_filp = ctx->user_files[fd];
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req->flags |= REQ_F_FIXED_FILE;
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} else {
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kiocb->ki_filp = io_file_get(state, fd);
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if (unlikely(!kiocb->ki_filp))
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return -EBADF;
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if (force_nonblock && !io_file_supports_async(kiocb->ki_filp))
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force_nonblock = false;
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}
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kiocb->ki_pos = READ_ONCE(sqe->off);
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kiocb->ki_flags = iocb_flags(kiocb->ki_filp);
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kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp));
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@ -718,10 +747,14 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
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}
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return 0;
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out_fput:
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/* in case of error, we didn't use this file reference. drop it. */
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if (!(flags & IOSQE_FIXED_FILE)) {
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/*
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* in case of error, we didn't use this file reference. drop it.
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*/
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if (state)
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state->used_refs--;
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io_file_put(state, kiocb->ki_filp);
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}
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return ret;
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}
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@ -863,7 +896,7 @@ static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s,
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out_fput:
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/* Hold on to the file for -EAGAIN */
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if (unlikely(ret && ret != -EAGAIN))
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fput(file);
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io_fput(req);
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return ret;
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}
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@ -917,7 +950,7 @@ static ssize_t io_write(struct io_kiocb *req, const struct sqe_submit *s,
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kfree(iovec);
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out_fput:
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if (unlikely(ret))
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fput(file);
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io_fput(req);
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return ret;
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}
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@ -940,7 +973,7 @@ static int io_nop(struct io_kiocb *req, u64 user_data)
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*/
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if (req->rw.ki_filp) {
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err = -EBADF;
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fput(req->rw.ki_filp);
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io_fput(req);
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}
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io_cqring_add_event(ctx, user_data, err, 0);
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io_free_req(req);
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@ -949,21 +982,32 @@ static int io_nop(struct io_kiocb *req, u64 user_data)
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static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe)
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{
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struct io_ring_ctx *ctx = req->ctx;
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unsigned flags;
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int fd;
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/* Prep already done */
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if (req->rw.ki_filp)
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return 0;
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if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
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if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
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return -EINVAL;
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if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
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return -EINVAL;
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fd = READ_ONCE(sqe->fd);
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flags = READ_ONCE(sqe->flags);
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if (flags & IOSQE_FIXED_FILE) {
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if (unlikely(!ctx->user_files || fd >= ctx->nr_user_files))
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return -EBADF;
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req->rw.ki_filp = ctx->user_files[fd];
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req->flags |= REQ_F_FIXED_FILE;
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} else {
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req->rw.ki_filp = fget(fd);
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if (unlikely(!req->rw.ki_filp))
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return -EBADF;
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}
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return 0;
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}
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@ -993,7 +1037,7 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
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end > 0 ? end : LLONG_MAX,
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fsync_flags & IORING_FSYNC_DATASYNC);
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fput(req->rw.ki_filp);
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io_fput(req);
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io_cqring_add_event(req->ctx, sqe->user_data, ret, 0);
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io_free_req(req);
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return 0;
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@ -1132,7 +1176,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
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ssize_t ret;
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/* enforce forwards compatibility on users */
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if (unlikely(s->sqe->flags))
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if (unlikely(s->sqe->flags & ~IOSQE_FIXED_FILE))
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return -EINVAL;
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req = io_get_req(ctx, state);
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@ -1344,6 +1388,201 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
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return READ_ONCE(ring->r.head) == READ_ONCE(ring->r.tail) ? ret : 0;
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}
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static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
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{
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#if defined(CONFIG_UNIX)
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if (ctx->ring_sock) {
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struct sock *sock = ctx->ring_sock->sk;
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struct sk_buff *skb;
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while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
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kfree_skb(skb);
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}
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#else
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int i;
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for (i = 0; i < ctx->nr_user_files; i++)
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fput(ctx->user_files[i]);
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#endif
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}
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static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
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{
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if (!ctx->user_files)
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return -ENXIO;
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__io_sqe_files_unregister(ctx);
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kfree(ctx->user_files);
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ctx->user_files = NULL;
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ctx->nr_user_files = 0;
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return 0;
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}
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static void io_finish_async(struct io_ring_ctx *ctx)
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{
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if (ctx->sqo_wq) {
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destroy_workqueue(ctx->sqo_wq);
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ctx->sqo_wq = NULL;
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}
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}
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#if defined(CONFIG_UNIX)
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static void io_destruct_skb(struct sk_buff *skb)
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{
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struct io_ring_ctx *ctx = skb->sk->sk_user_data;
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io_finish_async(ctx);
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unix_destruct_scm(skb);
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}
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/*
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* Ensure the UNIX gc is aware of our file set, so we are certain that
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* the io_uring can be safely unregistered on process exit, even if we have
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* loops in the file referencing.
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*/
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static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
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{
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struct sock *sk = ctx->ring_sock->sk;
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struct scm_fp_list *fpl;
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struct sk_buff *skb;
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int i;
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if (!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
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unsigned long inflight = ctx->user->unix_inflight + nr;
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if (inflight > task_rlimit(current, RLIMIT_NOFILE))
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return -EMFILE;
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}
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fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
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if (!fpl)
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return -ENOMEM;
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skb = alloc_skb(0, GFP_KERNEL);
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if (!skb) {
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kfree(fpl);
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return -ENOMEM;
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}
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skb->sk = sk;
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skb->destructor = io_destruct_skb;
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fpl->user = get_uid(ctx->user);
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for (i = 0; i < nr; i++) {
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fpl->fp[i] = get_file(ctx->user_files[i + offset]);
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unix_inflight(fpl->user, fpl->fp[i]);
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}
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fpl->max = fpl->count = nr;
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UNIXCB(skb).fp = fpl;
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refcount_add(skb->truesize, &sk->sk_wmem_alloc);
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skb_queue_head(&sk->sk_receive_queue, skb);
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for (i = 0; i < nr; i++)
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fput(fpl->fp[i]);
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return 0;
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}
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/*
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* If UNIX sockets are enabled, fd passing can cause a reference cycle which
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* causes regular reference counting to break down. We rely on the UNIX
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* garbage collection to take care of this problem for us.
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*/
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static int io_sqe_files_scm(struct io_ring_ctx *ctx)
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{
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unsigned left, total;
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int ret = 0;
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total = 0;
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left = ctx->nr_user_files;
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while (left) {
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unsigned this_files = min_t(unsigned, left, SCM_MAX_FD);
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int ret;
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ret = __io_sqe_files_scm(ctx, this_files, total);
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if (ret)
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break;
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left -= this_files;
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total += this_files;
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}
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if (!ret)
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return 0;
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while (total < ctx->nr_user_files) {
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fput(ctx->user_files[total]);
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total++;
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}
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return ret;
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}
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#else
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static int io_sqe_files_scm(struct io_ring_ctx *ctx)
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{
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return 0;
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}
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#endif
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static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
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unsigned nr_args)
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{
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__s32 __user *fds = (__s32 __user *) arg;
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int fd, ret = 0;
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unsigned i;
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if (ctx->user_files)
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return -EBUSY;
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if (!nr_args)
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return -EINVAL;
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if (nr_args > IORING_MAX_FIXED_FILES)
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return -EMFILE;
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ctx->user_files = kcalloc(nr_args, sizeof(struct file *), GFP_KERNEL);
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if (!ctx->user_files)
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return -ENOMEM;
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for (i = 0; i < nr_args; i++) {
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ret = -EFAULT;
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if (copy_from_user(&fd, &fds[i], sizeof(fd)))
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break;
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ctx->user_files[i] = fget(fd);
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ret = -EBADF;
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if (!ctx->user_files[i])
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break;
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/*
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* Don't allow io_uring instances to be registered. If UNIX
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* isn't enabled, then this causes a reference cycle and this
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* instance can never get freed. If UNIX is enabled we'll
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* handle it just fine, but there's still no point in allowing
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* a ring fd as it doesn't support regular read/write anyway.
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*/
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if (ctx->user_files[i]->f_op == &io_uring_fops) {
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fput(ctx->user_files[i]);
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break;
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}
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ctx->nr_user_files++;
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ret = 0;
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}
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if (ret) {
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for (i = 0; i < ctx->nr_user_files; i++)
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fput(ctx->user_files[i]);
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kfree(ctx->user_files);
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ctx->nr_user_files = 0;
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return ret;
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}
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ret = io_sqe_files_scm(ctx);
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if (ret)
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io_sqe_files_unregister(ctx);
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return ret;
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}
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static int io_sq_offload_start(struct io_ring_ctx *ctx)
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{
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int ret;
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@ -1612,13 +1851,13 @@ err:
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static void io_ring_ctx_free(struct io_ring_ctx *ctx)
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{
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if (ctx->sqo_wq)
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destroy_workqueue(ctx->sqo_wq);
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io_finish_async(ctx);
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if (ctx->sqo_mm)
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mmdrop(ctx->sqo_mm);
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io_iopoll_reap_events(ctx);
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io_sqe_buffer_unregister(ctx);
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io_sqe_files_unregister(ctx);
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#if defined(CONFIG_UNIX)
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if (ctx->ring_sock)
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@ -1858,6 +2097,7 @@ static int io_uring_get_fd(struct io_ring_ctx *ctx)
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#if defined(CONFIG_UNIX)
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ctx->ring_sock->file = file;
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ctx->ring_sock->sk->sk_user_data = ctx;
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#endif
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fd_install(ret, file);
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return ret;
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@ -2001,6 +2241,15 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
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break;
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ret = io_sqe_buffer_unregister(ctx);
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break;
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case IORING_REGISTER_FILES:
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ret = io_sqe_files_register(ctx, arg, nr_args);
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break;
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case IORING_UNREGISTER_FILES:
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ret = -EINVAL;
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if (arg || nr_args)
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break;
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ret = io_sqe_files_unregister(ctx);
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break;
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default:
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ret = -EINVAL;
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break;
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@ -16,7 +16,7 @@
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*/
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struct io_uring_sqe {
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__u8 opcode; /* type of operation for this sqe */
|
||||
__u8 flags; /* as of now unused */
|
||||
__u8 flags; /* IOSQE_ flags */
|
||||
__u16 ioprio; /* ioprio for the request */
|
||||
__s32 fd; /* file descriptor to do IO on */
|
||||
__u64 off; /* offset into file */
|
||||
@ -33,6 +33,11 @@ struct io_uring_sqe {
|
||||
};
|
||||
};
|
||||
|
||||
/*
|
||||
* sqe->flags
|
||||
*/
|
||||
#define IOSQE_FIXED_FILE (1U << 0) /* use fixed fileset */
|
||||
|
||||
/*
|
||||
* io_uring_setup() flags
|
||||
*/
|
||||
@ -113,5 +118,7 @@ struct io_uring_params {
|
||||
*/
|
||||
#define IORING_REGISTER_BUFFERS 0
|
||||
#define IORING_UNREGISTER_BUFFERS 1
|
||||
#define IORING_REGISTER_FILES 2
|
||||
#define IORING_UNREGISTER_FILES 3
|
||||
|
||||
#endif
|
||||
|
||||
Loading…
Reference in New Issue
Block a user