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| author | Jens Axboe <axboe@kernel.dk> | 2022-05-07 14:18:44 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-05-13 06:28:42 -0600 |
| commit | 1339f24b336db5ded9811f3fe7b948e0de207785 (patch) | |
| tree | a53dff3d094d2847e56ee4ebb870555606c19801 | |
| parent | b70b8e3331d8134ab993368a6e0eb18c1acb1b1d (diff) | |
| download | linux-stable-1339f24b336db5ded9811f3fe7b948e0de207785.tar.gz linux-stable-1339f24b336db5ded9811f3fe7b948e0de207785.tar.bz2 linux-stable-1339f24b336db5ded9811f3fe7b948e0de207785.zip | |
io_uring: allow allocated fixed files for openat/openat2
If the application passes in IORING_FILE_INDEX_ALLOC as the file_slot,
then that's a hint to allocate a fixed file descriptor rather than have
one be passed in directly.
This can be useful for having io_uring manage the direct descriptor space.
Normal open direct requests will complete with 0 for success, and < 0
in case of error. If io_uring is asked to allocated the direct descriptor,
then the direct descriptor is returned in case of success.
Reviewed-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | fs/io_uring.c | 36 | ||||
| -rw-r--r-- | include/uapi/linux/io_uring.h | 9 |
2 files changed, 42 insertions, 3 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 8c40411a7e78..f448264a1067 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -4697,7 +4697,7 @@ static int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) return __io_openat_prep(req, sqe); } -static int __maybe_unused io_file_bitmap_get(struct io_ring_ctx *ctx) +static int io_file_bitmap_get(struct io_ring_ctx *ctx) { struct io_file_table *table = &ctx->file_table; unsigned long nr = ctx->nr_user_files; @@ -4722,6 +4722,36 @@ static int __maybe_unused io_file_bitmap_get(struct io_ring_ctx *ctx) return -ENFILE; } +static int io_fixed_fd_install(struct io_kiocb *req, unsigned int issue_flags, + struct file *file, unsigned int file_slot) +{ + bool alloc_slot = file_slot == IORING_FILE_INDEX_ALLOC; + struct io_ring_ctx *ctx = req->ctx; + int ret; + + if (alloc_slot) { + io_ring_submit_lock(ctx, issue_flags); + ret = io_file_bitmap_get(ctx); + if (unlikely(ret < 0)) { + io_ring_submit_unlock(ctx, issue_flags); + return ret; + } + + file_slot = ret; + } else { + file_slot--; + } + + ret = io_install_fixed_file(req, file, issue_flags, file_slot); + if (alloc_slot) { + io_ring_submit_unlock(ctx, issue_flags); + if (!ret) + return file_slot; + } + + return ret; +} + static int io_openat2(struct io_kiocb *req, unsigned int issue_flags) { struct open_flags op; @@ -4777,8 +4807,8 @@ static int io_openat2(struct io_kiocb *req, unsigned int issue_flags) if (!fixed) fd_install(ret, file); else - ret = io_install_fixed_file(req, file, issue_flags, - req->open.file_slot - 1); + ret = io_fixed_fd_install(req, issue_flags, file, + req->open.file_slot); err: putname(req->open.filename); req->flags &= ~REQ_F_NEED_CLEANUP; diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h index 06621a278cb6..b7f02a55032a 100644 --- a/include/uapi/linux/io_uring.h +++ b/include/uapi/linux/io_uring.h @@ -63,6 +63,15 @@ struct io_uring_sqe { __u64 __pad2[2]; }; +/* + * If sqe->file_index is set to this for opcodes that instantiate a new + * direct descriptor (like openat/openat2/accept), then io_uring will allocate + * an available direct descriptor instead of having the application pass one + * in. The picked direct descriptor will be returned in cqe->res, or -ENFILE + * if the space is full. + */ +#define IORING_FILE_INDEX_ALLOC (~0U) + enum { IOSQE_FIXED_FILE_BIT, IOSQE_IO_DRAIN_BIT, |