Commit d34e1e5b authored by Dylan Yudaken's avatar Dylan Yudaken Committed by Jens Axboe
Browse files

io_uring: update kiocb->ki_pos at execution time 



Update kiocb->ki_pos at execution time rather than in io_prep_rw().
io_prep_rw() happens before the job is enqueued to a worker and so the
offset might be read multiple times before being executed once.

Ensures that the file position in a set of _linked_ SQEs will be only
obtained after earlier SQEs have completed, and so will include their
incremented file position.

Signed-off-by: default avatarDylan Yudaken <dylany@fb.com>
Reviewed-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent af9c45ec

fs/io_uring.c

+18 −8
Original line number Diff line number Diff line
@@ -3020,14 +3020,6 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe) 
		req->flags |= io_file_get_flags(file) << REQ_F_SUPPORT_NOWAIT_BIT;



	kiocb->ki_pos = READ_ONCE(sqe->off);

	if (kiocb->ki_pos == -1) {

		if (!(file->f_mode & FMODE_STREAM)) {

			req->flags |= REQ_F_CUR_POS;

			kiocb->ki_pos = file->f_pos;

		} else {

			kiocb->ki_pos = 0;

		}

	}

	kiocb->ki_flags = iocb_flags(file);

	ret = kiocb_set_rw_flags(kiocb, READ_ONCE(sqe->rw_flags));

	if (unlikely(ret))
@@ -3094,6 +3086,20 @@ static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret) 
	}

}



static inline void io_kiocb_update_pos(struct io_kiocb *req)

{

	struct kiocb *kiocb = &req->rw.kiocb;



	if (kiocb->ki_pos == -1) {

		if (!(req->file->f_mode & FMODE_STREAM)) {

			req->flags |= REQ_F_CUR_POS;

			kiocb->ki_pos = req->file->f_pos;

		} else {

			kiocb->ki_pos = 0;

		}

	}

}



static void kiocb_done(struct io_kiocb *req, ssize_t ret,

		       unsigned int issue_flags)

{
@@ -3682,6 +3688,8 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags) 
		kiocb->ki_flags &= ~IOCB_NOWAIT;

	}



	io_kiocb_update_pos(req);



	ret = rw_verify_area(READ, req->file, io_kiocb_ppos(kiocb), req->result);

	if (unlikely(ret)) {

		kfree(iovec);
@@ -3811,6 +3819,8 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags) 
		kiocb->ki_flags &= ~IOCB_NOWAIT;

	}



	io_kiocb_update_pos(req);



	ret = rw_verify_area(WRITE, req->file, io_kiocb_ppos(kiocb), req->result);

	if (unlikely(ret))

		goto out_free;