[PATCH v3 08/10] io_uring/rsrc: introduce buf registration structure

Pavel Begunkov
2026-04-29T15:27:01Z

In preparation to following changes, instead of passing an iovec for
buffer registration introduce a new structure. It'll be moved to uapi
later, but for now it's initialised early from a user provided iovec.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
io_uring/rsrc.c | 50 +++++++++++++++++++++++++++++++++----------------
1 file changed, 34 insertions(+), 16 deletions(-)

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index c4a7a77d1ee9..ba00238941ed 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -27,8 +27,14 @@ struct io_rsrc_update {
u32 offset;
};

+struct io_uring_regbuf_desc {
+ __u64 uaddr;
+ __u64 size;
+};
+
static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,
- struct iovec *iov, struct page **last_hpage);
+ struct io_uring_regbuf_desc *desc,
+ struct page **last_hpage);

/* only define max */
#define IORING_MAX_FIXED_FILES (1U << 20)
@@ -36,6 +42,15 @@ static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,

#define IO_CACHED_BVECS_SEGS 32

+static void io_iov_to_regbuf_desc(const struct iovec *iov,
+ struct io_uring_regbuf_desc *desc)
+{
+ *desc = (struct io_uring_regbuf_desc) {
+ .uaddr = (u64)iov->iov_base,
+ .size = iov->iov_len,
+ };
+}
+
int __io_account_mem(struct user_struct *user, unsigned long nr_pages)
{
unsigned long page_limit, cur_pages, new_pages;
@@ -291,6 +306,7 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
return -EINVAL;

for (done = 0; done < nr_args; done++) {
+ struct io_uring_regbuf_desc desc;
struct io_rsrc_node *node;
u64 tag = 0;

@@ -304,7 +320,9 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
err = -EFAULT;
break;
}
- node = io_sqe_buffer_register(ctx, iov, &last_hpage);
+
+ io_iov_to_regbuf_desc(iov, &desc);
+ node = io_sqe_buffer_register(ctx, &desc, &last_hpage);
if (IS_ERR(node)) {
err = PTR_ERR(node);
break;
@@ -760,27 +778,27 @@ 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 iovec *iov,
- struct page **last_hpage)
+ struct io_uring_regbuf_desc *desc,
+ struct page **last_hpage)
{
+ unsigned long uaddr = (unsigned long)desc->uaddr;
+ size_t size = desc->size;
struct io_mapped_ubuf *imu = NULL;
struct page **pages = NULL;
struct io_rsrc_node *node;
unsigned long off;
- size_t size;
int ret, nr_pages, i;
struct io_imu_folio_data data;
bool coalesced = false;

- if (!iov->iov_base) {
- if (iov->iov_len)
+ if (!uaddr) {
+ if (size)
return ERR_PTR(-EFAULT);
/* remove the buffer without installing a new one */
return NULL;
}

- ret = io_validate_user_buf_range((unsigned long)iov->iov_base,
- iov->iov_len);
+ ret = io_validate_user_buf_range(uaddr, size);
if (ret)
return ERR_PTR(ret);

@@ -789,8 +807,7 @@ static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,
return ERR_PTR(-ENOMEM);

ret = -ENOMEM;
- pages = io_pin_pages((unsigned long) iov->iov_base, iov->iov_len,
- &nr_pages);
+ pages = io_pin_pages(uaddr, size, &nr_pages);
if (IS_ERR(pages)) {
ret = PTR_ERR(pages);
pages = NULL;
@@ -812,10 +829,9 @@ static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,
if (ret)
goto done;

- size = iov->iov_len;
/* store original address for later verification */
- imu->ubuf = (unsigned long) iov->iov_base;
- imu->len = iov->iov_len;
+ imu->ubuf = uaddr;
+ imu->len = size;
imu->folio_shift = PAGE_SHIFT;
imu->release = io_release_ubuf;
imu->priv = imu;
@@ -825,7 +841,7 @@ static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,
imu->folio_shift = data.folio_shift;
refcount_set(&imu->refs, 1);

- off = (unsigned long)iov->iov_base & ~PAGE_MASK;
+ off = uaddr & ~PAGE_MASK;
if (coalesced)
off += data.first_folio_page_idx << PAGE_SHIFT;

@@ -878,6 +894,7 @@ 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_regbuf_desc desc;
struct io_rsrc_node *node;
u64 tag = 0;

@@ -901,7 +918,8 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
}
}

- node = io_sqe_buffer_register(ctx, iov, &last_hpage);
+ io_iov_to_regbuf_desc(iov, &desc);
+ node = io_sqe_buffer_register(ctx, &desc, &last_hpage);
if (IS_ERR(node)) {
ret = PTR_ERR(node);
break;
--
2.53.0