linux/io_uring/openclose.h
Jens Axboe dc18b89ab1 io_uring/openclose: add support for IORING_OP_FIXED_FD_INSTALL
io_uring can currently open/close regular files or fixed/direct
descriptors. Or you can instantiate a fixed descriptor from a regular
one, and then close the regular descriptor. But you currently can't turn
a purely fixed/direct descriptor into a regular file descriptor.

IORING_OP_FIXED_FD_INSTALL adds support for installing a direct
descriptor into the normal file table, just like receiving a file
descriptor or opening a new file would do. This is all nicely abstracted
into receive_fd(), and hence adding support for this is truly trivial.

Since direct descriptors are only usable within io_uring itself, it can
be useful to turn them into real file descriptors if they ever need to
be accessed via normal syscalls. This can either be a transitory thing,
or just a permanent transition for a given direct descriptor.

By default, new fds are installed with O_CLOEXEC set. The application
can disable O_CLOEXEC by setting IORING_FIXED_FD_NO_CLOEXEC in the
sqe->install_fd_flags member.

Suggested-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-12-12 07:42:57 -07:00

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754 B
C

// SPDX-License-Identifier: GPL-2.0
int __io_close_fixed(struct io_ring_ctx *ctx, unsigned int issue_flags,
unsigned int offset);
int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
int io_openat(struct io_kiocb *req, unsigned int issue_flags);
void io_open_cleanup(struct io_kiocb *req);
int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
int io_openat2(struct io_kiocb *req, unsigned int issue_flags);
int io_close_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
int io_close(struct io_kiocb *req, unsigned int issue_flags);
int io_install_fixed_fd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
int io_install_fixed_fd(struct io_kiocb *req, unsigned int issue_flags);