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: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index b75a49d..3621898 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -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:
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index b7f02a5..36ec43d 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -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;
