Commit b16e920a authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring/rsrc: allow cloning at an offset 



Right now buffer cloning is an all-or-nothing kind of thing - either the
whole table is cloned from a source to a destination ring, or nothing at
all.

However, it's not always desired to clone the whole thing. Allow for
the application to specify a source and destination offset, and a
number of buffers to clone. If the destination offset is non-zero, then
allocate sparse nodes upfront.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d50f94d7

include/uapi/linux/io_uring.h

+4 −1
Original line number Diff line number Diff line
@@ -719,7 +719,10 @@ enum { 
struct io_uring_clone_buffers {

	__u32	src_fd;

	__u32	flags;

	__u32	pad[6];

	__u32	src_off;

	__u32	dst_off;

	__u32	nr;

	__u32	pad[3];

};



struct io_uring_buf {

io_uring/rsrc.c

+26 −6
Original line number Diff line number Diff line
@@ -927,10 +927,11 @@ int io_import_fixed(int ddir, struct iov_iter *iter, 
	return 0;

}



static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx)

static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx,

			    struct io_uring_clone_buffers *arg)

{

	int i, ret, nbufs, off, nr;

	struct io_rsrc_data data;

	int i, ret, nbufs;



	/*

	 * Drop our own lock here. We'll setup the data we need and reference
@@ -943,11 +944,29 @@ static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx 
	nbufs = src_ctx->buf_table.nr;

	if (!nbufs)

		goto out_unlock;

	ret = io_rsrc_data_alloc(&data, nbufs);

	ret = -EINVAL;

	if (!arg->nr)

		arg->nr = nbufs;

	else if (arg->nr > nbufs)

		goto out_unlock;

	ret = -EOVERFLOW;

	if (check_add_overflow(arg->nr, arg->src_off, &off))

		goto out_unlock;

	if (off > nbufs)

		goto out_unlock;

	if (check_add_overflow(arg->nr, arg->dst_off, &off))

		goto out_unlock;

	ret = -EINVAL;

	if (off > IORING_MAX_REG_BUFFERS)

		goto out_unlock;

	ret = io_rsrc_data_alloc(&data, off);

	if (ret)

		goto out_unlock;



	for (i = 0; i < nbufs; i++) {

	off = arg->dst_off;

	i = arg->src_off;

	nr = arg->nr;

	while (nr--) {

		struct io_rsrc_node *dst_node, *src_node;



		src_node = io_rsrc_node_lookup(&src_ctx->buf_table, i);
@@ -963,7 +982,8 @@ static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx 
			refcount_inc(&src_node->buf->refs);

			dst_node->buf = src_node->buf;

		}

		data.nodes[i] = dst_node;

		data.nodes[off++] = dst_node;

		i++;

	}



	/* Have a ref on the bufs now, drop src lock and re-grab our own lock */
@@ -1018,7 +1038,7 @@ int io_register_clone_buffers(struct io_ring_ctx *ctx, void __user *arg) 
	file = io_uring_register_get_file(buf.src_fd, registered_src);

	if (IS_ERR(file))

		return PTR_ERR(file);

	ret = io_clone_buffers(ctx, file->private_data);

	ret = io_clone_buffers(ctx, file->private_data, &buf);

	if (!registered_src)

		fput(file);

	return ret;