One big issue with file registration feature is that it needs user
space apps to maintain free slot info about io_uring's fixed file
table, which really is a burden for development. Now since io_uring
starts to choose free file slot for user space apps by using
IORING_FILE_INDEX_ALLOC flag in accept or open operations, but they
need app to uses direct accept or direct open, which as far as I know,
some apps are not prepared to use direct accept or open yet.
To support apps, who still need real fds, use registration feature
easier, let IORING_OP_FILES_UPDATE support to choose fixed file slot,
which will return free file slot in cqe->res.
TODO list:
Need to prepare liburing corresponding helpers.
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx>
---
fs/io_uring.c | 50 ++++++++++++++++++++++++++++++++++---------
include/uapi/linux/io_uring.h | 1 +
2 files changed, 41 insertions(+), 10 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 9f1c682d7caf..d77e6bbec81c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -680,6 +680,7 @@ struct io_rsrc_update {
u64 arg;
u32 nr_args;
u32 offset;
+ u32 flags;
};
struct io_fadvise {
@@ -7970,14 +7971,23 @@ static int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
return 0;
}
+#define IORING_FILES_UPDATE_INDEX_ALLOC 1
+
static int io_rsrc_update_prep(struct io_kiocb *req,
const struct io_uring_sqe *sqe)
{
+ u32 flags = READ_ONCE(sqe->files_update_flags);
+
if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
return -EINVAL;
- if (sqe->rw_flags || sqe->splice_fd_in)
+ if (sqe->splice_fd_in)
+ return -EINVAL;
+ if (flags & ~IORING_FILES_UPDATE_INDEX_ALLOC)
+ return -EINVAL;
+ if ((flags & IORING_FILES_UPDATE_INDEX_ALLOC) && READ_ONCE(sqe->len) != 1)
return -EINVAL;
+ req->rsrc_update.flags = flags;
req->rsrc_update.offset = READ_ONCE(sqe->off);
req->rsrc_update.nr_args = READ_ONCE(sqe->len);
if (!req->rsrc_update.nr_args)
@@ -7990,18 +8000,38 @@ static int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_ring_ctx *ctx = req->ctx;
struct io_uring_rsrc_update2 up;
+ struct file *file;
int ret;
- up.offset = req->rsrc_update.offset;
- up.data = req->rsrc_update.arg;
- up.nr = 0;
- up.tags = 0;
- up.resv = 0;
- up.resv2 = 0;
+ if (req->rsrc_update.flags & IORING_FILES_UPDATE_INDEX_ALLOC) {
+ int fd;
- io_ring_submit_lock(ctx, issue_flags);
- ret = __io_register_rsrc_update(ctx, IORING_RSRC_FILE,
- &up, req->rsrc_update.nr_args);
+ if (copy_from_user(&fd, (int *)req->rsrc_update.arg, sizeof(fd))) {
+ ret = -EFAULT;
+ goto out;
+ }
+ file = fget(fd);
+ if (!file) {
+ ret = -EBADF;
+ goto out;
+ }
+ ret = io_fixed_fd_install(req, issue_flags, file,
+ IORING_FILE_INDEX_ALLOC);
+ } else {
+ up.offset = req->rsrc_update.offset;
+ up.data = req->rsrc_update.arg;
+ up.nr = 0;
+ up.tags = 0;
+ up.resv = 0;
+ up.resv2 = 0;
+
+ io_ring_submit_lock(ctx, issue_flags);
+ ret = __io_register_rsrc_update(ctx, IORING_RSRC_FILE,
+ &up, req->rsrc_update.nr_args);
+ io_ring_submit_unlock(ctx, issue_flags);
+ }
+
+out:
io_ring_submit_unlock(ctx, issue_flags);
if (ret < 0)
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 53e7dae92e42..b4af01d56d7c 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -47,6 +47,7 @@ struct io_uring_sqe {
__u32 unlink_flags;
__u32 hardlink_flags;
__u32 xattr_flags;
+ __u32 files_update_flags;
};
__u64 user_data; /* data to be passed back at completion time */
/* pack this to avoid bogus arm OABI complaints */
--
2.14.4.44.g2045bb6
