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Subject[PATCH v3 4/4] io_uring: accept directly into fixed file table
Date
As done with open opcodes, allow accept to skip installing fd into
processes' file tables and put it directly into io_uring's fixed file
table. Same restrictions and design as for open.

Suggested-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 30 ++++++++++++++++++++++++------
1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index a54994a4f4ae..0323e947f403 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4759,10 +4759,11 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_accept *accept = &req->accept;
+ unsigned index;

if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
- if (sqe->ioprio || sqe->len || sqe->buf_index || sqe->splice_fd_in)
+ if (sqe->ioprio || sqe->len || sqe->buf_index)
return -EINVAL;

accept->addr = u64_to_user_ptr(READ_ONCE(sqe->addr));
@@ -4770,6 +4771,17 @@ static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
accept->flags = READ_ONCE(sqe->accept_flags);
accept->nofile = rlimit(RLIMIT_NOFILE);

+ index = READ_ONCE(sqe->file_index);
+ req->buf_index = index;
+ if (index) {
+ if (req->open.how.flags & O_CLOEXEC)
+ return -EINVAL;
+ if (req->buf_index != index)
+ return -EINVAL;
+ }
+
+ if (req->buf_index && (accept->flags & SOCK_CLOEXEC))
+ return -EINVAL;
if (accept->flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
return -EINVAL;
if (SOCK_NONBLOCK != O_NONBLOCK && (accept->flags & SOCK_NONBLOCK))
@@ -4782,28 +4794,34 @@ static int io_accept(struct io_kiocb *req, unsigned int issue_flags)
struct io_accept *accept = &req->accept;
bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
unsigned int file_flags = force_nonblock ? O_NONBLOCK : 0;
+ bool fixed = !!req->buf_index;
struct file *file;
int ret, fd;

if (req->file->f_flags & O_NONBLOCK)
req->flags |= REQ_F_NOWAIT;

- fd = __get_unused_fd_flags(accept->flags, accept->nofile);
- if (unlikely(fd < 0))
- return fd;
-
+ if (!fixed) {
+ fd = __get_unused_fd_flags(accept->flags, accept->nofile);
+ if (unlikely(fd < 0))
+ return fd;
+ }
file = do_accept(req->file, file_flags, accept->addr, accept->addr_len,
accept->flags);
if (IS_ERR(file)) {
+ if (!fixed)
+ put_unused_fd(fd);
ret = PTR_ERR(file);
if (ret == -EAGAIN && force_nonblock)
return -EAGAIN;
if (ret == -ERESTARTSYS)
ret = -EINTR;
req_set_fail(req);
- } else {
+ } else if (!fixed) {
fd_install(fd, file);
ret = fd;
+ } else {
+ ret = io_install_fixed_file(req, file, issue_flags);
}
__io_req_complete(req, issue_flags, ret, 0);
return 0;
--
2.32.0
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