Allow applications to retrieve the req payload (io-uring only)

With io-uring the req owns the payload buffer, the application
can directly access it and copy data into it.

fuse_buf_copy_one() already has a check for dstmem == srcmem
and skips data copies.

fuse_reply_data
   fuse_reply_data_uring
       fuse_buf_copy
           fuse_buf_copy_one

Signed-off-by: Bernd Schubert <bschubert@ddn.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/lib/fuse_uring.c b/lib/fuse_uring.c
index 104be14..ee68fab 100644
--- a/lib/fuse_uring.c
+++ b/lib/fuse_uring.c
@@ -190,6 +190,30 @@ static int fuse_uring_commit_sqe(struct fuse_ring_pool *ring_pool,
 	return 0;
 }
 
+int fuse_req_get_payload(fuse_req_t req, char **payload, size_t *payload_sz,
+			 void **mr)
+{
+	struct fuse_ring_ent *ring_ent;
+
+	/* Not possible without io-uring interface */
+	if (!req->is_uring)
+		return -EINVAL;
+
+	ring_ent = container_of(req, struct fuse_ring_ent, req);
+
+	*payload = ring_ent->op_payload;
+	*payload_sz = ring_ent->req_payload_sz;
+
+	/*
+	 * For now unused, but will be used later when the application can
+	 * allocate the buffers itself and register them for rdma.
+	 */
+	if (mr)
+		*mr = NULL;
+
+	return 0;
+}
+
 int send_reply_uring(fuse_req_t req, int error, const void *arg, size_t argsize)
 {
 	int res;