Commit a8da73a3 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: add flag for allocating a fully sparse direct descriptor space 



Currently to setup a fully sparse descriptor space upfront, the app needs
to alloate an array of the full size and memset it to -1 and then pass
that in. Make this a bit easier by allowing a flag that simply does
this internally rather than needing to copy each slot separately.

This works with IORING_REGISTER_FILES2 as the flag is set in struct
io_uring_rsrc_register, and is only allow when the type is
IORING_RSRC_FILE as this doesn't make sense for registered buffers.

Reviewed-by: default avatarHao Xu <howeyxu@tencent.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 09893e15

fs/io_uring.c

+12 −3
Original line number Diff line number Diff line
@@ -9111,12 +9111,12 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg, 
	for (i = 0; i < nr_args; i++, ctx->nr_user_files++) {

		struct io_fixed_file *file_slot;



		if (copy_from_user(&fd, &fds[i], sizeof(fd))) {

		if (fds && copy_from_user(&fd, &fds[i], sizeof(fd))) {

			ret = -EFAULT;

			goto fail;

		}

		/* allow sparse sets */

		if (fd == -1) {

		if (!fds || fd == -1) {

			ret = -EINVAL;

			if (unlikely(*io_get_tag_slot(ctx->file_data, i)))

				goto fail;
@@ -11759,14 +11759,20 @@ static __cold int io_register_rsrc(struct io_ring_ctx *ctx, void __user *arg, 
	memset(&rr, 0, sizeof(rr));

	if (copy_from_user(&rr, arg, size))

		return -EFAULT;

	if (!rr.nr || rr.resv || rr.resv2)

	if (!rr.nr || rr.resv2)

		return -EINVAL;

	if (rr.flags & ~IORING_RSRC_REGISTER_SPARSE)

		return -EINVAL;



	switch (type) {

	case IORING_RSRC_FILE:

		if (rr.flags & IORING_RSRC_REGISTER_SPARSE && rr.data)

			break;

		return io_sqe_files_register(ctx, u64_to_user_ptr(rr.data),

					     rr.nr, u64_to_user_ptr(rr.tags));

	case IORING_RSRC_BUFFER:

		if (rr.flags & IORING_RSRC_REGISTER_SPARSE)

			break;

		return io_sqe_buffers_register(ctx, u64_to_user_ptr(rr.data),

					       rr.nr, u64_to_user_ptr(rr.tags));

	}
@@ -11935,6 +11941,9 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode, 
		ret = io_sqe_buffers_unregister(ctx);

		break;

	case IORING_REGISTER_FILES:

		ret = -EFAULT;

		if (!arg)

			break;

		ret = io_sqe_files_register(ctx, arg, nr_args, NULL);

		break;

	case IORING_UNREGISTER_FILES:

include/uapi/linux/io_uring.h

+7 −1
Original line number Diff line number Diff line
@@ -396,9 +396,15 @@ struct io_uring_files_update { 
	__aligned_u64 /* __s32 * */ fds;

};



/*

 * Register a fully sparse file space, rather than pass in an array of all

 * -1 file descriptors.

 */

#define IORING_RSRC_REGISTER_SPARSE	(1U << 0)



struct io_uring_rsrc_register {

	__u32 nr;

	__u32 resv;

	__u32 flags;

	__u64 resv2;

	__aligned_u64 data;

	__aligned_u64 tags;