Hi Xiaoguang,
On 5/26/22 20:38, Xiaoguang Wang wrote:
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)
How about allowing multiple fd update in IORING_FILES_UPDATE_INDEX_ALLOC
case? For example, using the sqe->addr(the fd array) to store the slots
we allocated, and let cqe return the number of slots allocated.
By the way, another way, we can levarage up->offset ==
IORING_FILE_INDEX_ALLOC
to do the mode check since seems it is not used in this mode. Though
I'm not sure that is better..
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))) {
^ (void __user *) ?
Regards,
Hao
