[PATCH v6 11/13] io_uring/rsrc: add uncloneable regbuf flag

[Pavel Begunkov]

It's hard to implement cloning if the internal structure needs to be
mutable and/or relies on other ring resources. In preparation to such
buffer types, add a flag indicating that the buffer can't be cloned. It
might be possible to add cloning in the future for them, but that would
likely need reallocating the structure and reacquiring resources in case
by case manner.

Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
 io_uring/rsrc.c | 5 +++++
 io_uring/rsrc.h | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 83a7ad9f5bc7..0b526b094dc9 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -1434,6 +1434,11 @@ static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx
 		if (!src_node) {
 			dst_node = NULL;
 		} else {
+			if (src_node->buf->flags & IO_REGBUF_F_UNCLONEABLE) {
+				io_rsrc_data_free(ctx, &data);
+				return -ENOMEM;
+			}
+
 			dst_node = io_rsrc_node_alloc(ctx, IORING_RSRC_BUFFER);
 			if (!dst_node) {
 				io_rsrc_data_free(ctx, &data);
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 9ef88383b363..73d7b1ebf0b6 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -26,7 +26,8 @@ struct io_rsrc_node {
 };
 
 enum {
-	IO_REGBUF_F_KBUF		= 1,
+	IO_REGBUF_F_KBUF		= 1 << 0,
+	IO_REGBUF_F_UNCLONEABLE		= 1 << 1,
 };
 
 struct io_mapped_ubuf {
-- 
2.54.0