GitHub-Mirror/linux-bl808
2
0
Fork 0
mirror of https://github.com/Fishwaldo/linux-bl808.git synced 2025-06-17 20:25:19 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

io_uring: add file set registration

Browse source 
We normally have to fget/fput for each IO we do on a file. Even with
the batching we do, the cost of the atomic inc/dec of the file usage
count adds up.

This adds IORING_REGISTER_FILES, and IORING_UNREGISTER_FILES opcodes
for the io_uring_register(2) system call. The arguments passed in must
be an array of __s32 holding file descriptors, and nr_args should hold
the number of file descriptors the application wishes to pin for the
duration of the io_uring instance (or until IORING_UNREGISTER_FILES is
called).

When used, the application must set IOSQE_FIXED_FILE in the sqe->flags
member. Then, instead of setting sqe->fd to the real fd, it sets sqe->fd
to the index in the array passed in to IORING_REGISTER_FILES.

Files are automatically unregistered when the io_uring instance is torn
down. An application need only unregister if it wishes to register a new
set of fds.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2019-01-10 22:13:58 -07:00
parent f4e65870e5
commit 6b06314c47
2 changed files with 288 additions and 32 deletions
Download patch file Download diff file Expand all files Collapse all files

9
include/uapi/linux/io_uring.h
View file

@ -16,7 +16,7 @@
*/
struct io_uring_sqe {
__u8 opcode; /* type of operation for this sqe */
__u8 flags; /* as of now unused */
__u8 flags; /* IOSQE_ flags */
__u16 ioprio; /* ioprio for the request */
__s32 fd; /* file descriptor to do IO on */
__u64 off; /* offset into file */
@ -33,6 +33,11 @@ struct io_uring_sqe {
};
};
/*
* sqe->flags
*/
#define IOSQE_FIXED_FILE (1U << 0) /* use fixed fileset */
/*
* io_uring_setup() flags
*/
@ -113,5 +118,7 @@ struct io_uring_params {
*/
#define IORING_REGISTER_BUFFERS 0
#define IORING_UNREGISTER_BUFFERS 1
#define IORING_REGISTER_FILES 2
#define IORING_UNREGISTER_FILES 3
#endif