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io_uring: introduce fixed buffer support for io_uring_cmd

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Add IORING_URING_CMD_FIXED flag that is to be used for sending io_uring
command with previously registered buffers. User-space passes the buffer
index in sqe->buf_index, same as done in read/write variants that uses
fixed buffers.

Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20220930062749.152261-3-anuj20.g@samsung.com
[axboe: shuffle valid flags check before acting on it]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Anuj Gupta 2022-09-30 11:57:39 +05:30 committed by Jens Axboe
parent a9216fac3e
commit 9cda70f622
3 changed files with 28 additions and 2 deletions
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2
include/linux/io_uring.h
View File

@ -28,7 +28,7 @@ struct io_uring_cmd {
void *cookie;
};
u32 cmd_op;
u32 pad;
u32 flags;
u8 pdu[32]; /* available inline for free use */
};

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

@ -56,6 +56,7 @@ struct io_uring_sqe {
__u32 hardlink_flags;
__u32 xattr_flags;
__u32 msg_ring_flags;
__u32 uring_cmd_flags;
};
__u64 user_data; /* data to be passed back at completion time */
/* pack this to avoid bogus arm OABI complaints */
@ -219,6 +220,14 @@ enum io_uring_op {
IORING_OP_LAST,
};
/*
* sqe->uring_cmd_flags
* IORING_URING_CMD_FIXED use registered buffer; pass thig flag
* along with setting sqe->buf_index.
*/
#define IORING_URING_CMD_FIXED (1U << 0)
/*
* sqe->fsync_flags
*/

19
io_uring/uring_cmd.c
View File

@ -4,6 +4,7 @@
#include <linux/file.h>
#include <linux/io_uring.h>
#include <linux/security.h>
#include <linux/nospec.h>
#include <uapi/linux/io_uring.h>
@ -77,8 +78,24 @@ int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd);
if (sqe->rw_flags || sqe->__pad1)
if (sqe->__pad1)
return -EINVAL;
ioucmd->flags = READ_ONCE(sqe->uring_cmd_flags);
if (ioucmd->flags & ~IORING_URING_CMD_FIXED)
return -EINVAL;
if (ioucmd->flags & IORING_URING_CMD_FIXED) {
struct io_ring_ctx *ctx = req->ctx;
u16 index;
req->buf_index = READ_ONCE(sqe->buf_index);
if (unlikely(req->buf_index >= ctx->nr_user_bufs))
return -EFAULT;
index = array_index_nospec(req->buf_index, ctx->nr_user_bufs);
req->imu = ctx->user_bufs[index];
io_req_set_rsrc_node(req, ctx, 0);
}
ioucmd->cmd = sqe->cmd;
ioucmd->cmd_op = READ_ONCE(sqe->cmd_op);
return 0;