[PATCH v5 2/4] io_uring/rsrc: split io_buffer_register_request() logic

Joanne Koong
2026-04-02T16:18:33Z

Split the main initialization logic in io_buffer_register_request() into
a helper function.

This is a preparatory patch for supporting kernel-populated buffers in
fuse io-uring, which will be reusing this logic.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
---
io_uring/rsrc.c | 84 ++++++++++++++++++++++++++++++-------------------
1 file changed, 51 insertions(+), 33 deletions(-)

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index ed5018c69d8d..5384fbbf684e 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -924,64 +924,82 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
return ret;
}

-int io_buffer_register_request(struct io_uring_cmd *cmd, struct request *rq,
- void (*release)(void *), unsigned int index,
- unsigned int issue_flags)
+static struct io_mapped_ubuf *io_kernel_buffer_init(struct io_ring_ctx *ctx,
+ unsigned int nr_bvecs,
+ unsigned int total_bytes,
+ u8 dir,
+ void (*release)(void *),
+ void *priv,
+ unsigned int index)
{
- struct io_ring_ctx *ctx = cmd_to_io_kiocb(cmd)->ctx;
struct io_rsrc_data *data = &ctx->buf_table;
- struct req_iterator rq_iter;
struct io_mapped_ubuf *imu;
struct io_rsrc_node *node;
- struct bio_vec bv;
- unsigned int nr_bvecs = 0;
- int ret = 0;

- io_ring_submit_lock(ctx, issue_flags);
- if (index >= data->nr) {
- ret = -EINVAL;
- goto unlock;
- }
+ if (index >= data->nr)
+ return ERR_PTR(-EINVAL);
index = array_index_nospec(index, data->nr);

- if (data->nodes[index]) {
- ret = -EBUSY;
- goto unlock;
- }
+ if (data->nodes[index])
+ return ERR_PTR(-EBUSY);

node = io_rsrc_node_alloc(ctx, IORING_RSRC_BUFFER);
- if (!node) {
- ret = -ENOMEM;
- goto unlock;
- }
+ if (!node)
+ return ERR_PTR(-ENOMEM);

- /*
- * blk_rq_nr_phys_segments() may overestimate the number of bvecs
- * but avoids needing to iterate over the bvecs
- */
- imu = io_alloc_imu(ctx, blk_rq_nr_phys_segments(rq));
+ imu = io_alloc_imu(ctx, nr_bvecs);
if (!imu) {
io_cache_free(&ctx->node_cache, node);
- ret = -ENOMEM;
- goto unlock;
+ return ERR_PTR(-ENOMEM);
}

imu->ubuf = 0;
- imu->len = blk_rq_bytes(rq);
+ imu->len = total_bytes;
imu->acct_pages = 0;
imu->folio_shift = PAGE_SHIFT;
+ imu->nr_bvecs = nr_bvecs;
refcount_set(&imu->refs, 1);
imu->release = release;
- imu->priv = rq;
+ imu->priv = priv;
+ imu->dir = dir;
imu->flags = IO_REGBUF_F_KBUF;
- imu->dir = 1 << rq_data_dir(rq);

+ node->buf = imu;
+ data->nodes[index] = node;
+
+ return imu;
+}
+
+int io_buffer_register_request(struct io_uring_cmd *cmd, struct request *rq,
+ void (*release)(void *), unsigned int index,
+ unsigned int issue_flags)
+{
+ struct io_ring_ctx *ctx = cmd_to_io_kiocb(cmd)->ctx;
+ struct req_iterator rq_iter;
+ struct io_mapped_ubuf *imu;
+ struct bio_vec bv;
+ /*
+ * blk_rq_nr_phys_segments() may overestimate the number of bvecs
+ * but avoids needing to iterate over the bvecs
+ */
+ unsigned int nr_bvecs = blk_rq_nr_phys_segments(rq);
+ unsigned int total_bytes = blk_rq_bytes(rq);
+ int ret = 0;
+
+ io_ring_submit_lock(ctx, issue_flags);
+
+ imu = io_kernel_buffer_init(ctx, nr_bvecs, total_bytes,
+ 1 << rq_data_dir(rq), release, rq, index);
+ if (IS_ERR(imu)) {
+ ret = PTR_ERR(imu);
+ goto unlock;
+ }
+
+ nr_bvecs = 0;
rq_for_each_bvec(bv, rq, rq_iter)
imu->bvec[nr_bvecs++] = bv;
imu->nr_bvecs = nr_bvecs;

- node->buf = imu;
- data->nodes[index] = node;
unlock:
io_ring_submit_unlock(ctx, issue_flags);
return ret;
--
2.52.0