[RFC 07/12] io_uring/rsrc: extended reg buffer registration
Pavel Begunkov
asml.silence at gmail.com
Fri Jun 27 08:10:34 PDT 2025
We'll need to pass extra information for buffer registration apart from
iovec, add a flag to struct io_uring_rsrc_update2 that tells that its
data fields points to an extended registration structure, i.e.
struct io_uring_reg_buffer. To do normal registration the user has to
set target_fd and dmabuf_fd fields to -1, and any other combination is
currently rejected.
Signed-off-by: Pavel Begunkov <asml.silence at gmail.com>
---
include/uapi/linux/io_uring.h | 13 ++++++++-
io_uring/rsrc.c | 53 +++++++++++++++++++++++++++--------
2 files changed, 54 insertions(+), 12 deletions(-)
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index cfd17e382082..596cb71bd214 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -725,15 +725,26 @@ struct io_uring_rsrc_update {
__aligned_u64 data;
};
+/* struct io_uring_rsrc_update2::flags */
+enum io_uring_rsrc_reg_flags {
+ IORING_RSRC_F_EXTENDED_UPDATE = 1,
+};
+
struct io_uring_rsrc_update2 {
__u32 offset;
- __u32 resv;
+ __u32 flags;
__aligned_u64 data;
__aligned_u64 tags;
__u32 nr;
__u32 resv2;
};
+struct io_uring_reg_buffer {
+ __aligned_u64 iov_uaddr;
+ __s32 target_fd;
+ __s32 dmabuf_fd;
+};
+
/* Skip updating fd indexes set to this value in the fd table */
#define IORING_REGISTER_FILES_SKIP (-2)
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index c592ceace97d..21f4932ecafa 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -26,7 +26,8 @@ struct io_rsrc_update {
u32 offset;
};
-static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,
+static struct io_rsrc_node *
+io_sqe_buffer_register(struct io_ring_ctx *ctx, struct io_uring_reg_buffer *rb,
struct iovec *iov, struct page **last_hpage);
/* only define max */
@@ -226,6 +227,8 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
if (!ctx->file_table.data.nr)
return -ENXIO;
+ if (up->flags)
+ return -EINVAL;
if (up->offset + nr_args > ctx->file_table.data.nr)
return -EINVAL;
@@ -280,10 +283,18 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
return done ? done : err;
}
+static inline void io_default_reg_buf(struct io_uring_reg_buffer *rb)
+{
+ memset(rb, 0, sizeof(*rb));
+ rb->target_fd = -1;
+ rb->dmabuf_fd = -1;
+}
+
static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
struct io_uring_rsrc_update2 *up,
unsigned int nr_args)
{
+ bool extended_entry = up->flags & IORING_RSRC_F_EXTENDED_UPDATE;
u64 __user *tags = u64_to_user_ptr(up->tags);
struct iovec fast_iov, *iov;
struct page *last_hpage = NULL;
@@ -294,14 +305,32 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
if (!ctx->buf_table.nr)
return -ENXIO;
+ if (up->flags & ~IORING_RSRC_F_EXTENDED_UPDATE)
+ return -EINVAL;
if (up->offset + nr_args > ctx->buf_table.nr)
return -EINVAL;
for (done = 0; done < nr_args; done++) {
+ struct io_uring_reg_buffer rb;
struct io_rsrc_node *node;
u64 tag = 0;
- uvec = u64_to_user_ptr(user_data);
+ if (extended_entry) {
+ if (copy_from_user(&rb, u64_to_user_ptr(user_data),
+ sizeof(rb)))
+ return -EFAULT;
+ user_data += sizeof(rb);
+ } else {
+ io_default_reg_buf(&rb);
+ rb.iov_uaddr = user_data;
+
+ if (ctx->compat)
+ user_data += sizeof(struct compat_iovec);
+ else
+ user_data += sizeof(struct iovec);
+ }
+
+ uvec = u64_to_user_ptr(rb.iov_uaddr);
iov = iovec_from_user(uvec, 1, 1, &fast_iov, ctx->compat);
if (IS_ERR(iov)) {
err = PTR_ERR(iov);
@@ -314,7 +343,7 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
err = io_buffer_validate(iov);
if (err)
break;
- node = io_sqe_buffer_register(ctx, iov, &last_hpage);
+ node = io_sqe_buffer_register(ctx, &rb, iov, &last_hpage);
if (IS_ERR(node)) {
err = PTR_ERR(node);
break;
@@ -329,10 +358,6 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
i = array_index_nospec(up->offset + done, ctx->buf_table.nr);
io_reset_rsrc_node(ctx, &ctx->buf_table, i);
ctx->buf_table.nodes[i] = node;
- if (ctx->compat)
- user_data += sizeof(struct compat_iovec);
- else
- user_data += sizeof(struct iovec);
}
return done ? done : err;
}
@@ -367,7 +392,7 @@ int io_register_files_update(struct io_ring_ctx *ctx, void __user *arg,
memset(&up, 0, sizeof(up));
if (copy_from_user(&up, arg, sizeof(struct io_uring_rsrc_update)))
return -EFAULT;
- if (up.resv || up.resv2)
+ if (up.resv2)
return -EINVAL;
return __io_register_rsrc_update(ctx, IORING_RSRC_FILE, &up, nr_args);
}
@@ -381,7 +406,7 @@ int io_register_rsrc_update(struct io_ring_ctx *ctx, void __user *arg,
return -EINVAL;
if (copy_from_user(&up, arg, sizeof(up)))
return -EFAULT;
- if (!up.nr || up.resv || up.resv2)
+ if (!up.nr || up.resv2)
return -EINVAL;
return __io_register_rsrc_update(ctx, type, &up, up.nr);
}
@@ -485,7 +510,7 @@ int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
up2.data = up->arg;
up2.nr = 0;
up2.tags = 0;
- up2.resv = 0;
+ up2.flags = 0;
up2.resv2 = 0;
if (up->offset == IORING_FILE_INDEX_ALLOC) {
@@ -769,6 +794,7 @@ bool io_check_coalesce_buffer(struct page **page_array, int nr_pages,
}
static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,
+ struct io_uring_reg_buffer *rb,
struct iovec *iov,
struct page **last_hpage)
{
@@ -781,6 +807,9 @@ static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,
struct io_imu_folio_data data;
bool coalesced = false;
+ if (rb->dmabuf_fd != -1 || rb->target_fd != -1)
+ return NULL;
+
if (!iov->iov_base)
return NULL;
@@ -872,6 +901,7 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
memset(iov, 0, sizeof(*iov));
for (i = 0; i < nr_args; i++) {
+ struct io_uring_reg_buffer rb;
struct io_rsrc_node *node;
u64 tag = 0;
@@ -898,7 +928,8 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
}
}
- node = io_sqe_buffer_register(ctx, iov, &last_hpage);
+ io_default_reg_buf(&rb);
+ node = io_sqe_buffer_register(ctx, &rb, iov, &last_hpage);
if (IS_ERR(node)) {
ret = PTR_ERR(node);
break;
--
2.49.0
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