[PATCH 1/5] liburing: support buffer registration updates

[Bijan Mottahedeh <bijan.mottahedeh@xxxxxxxxxx>]

Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@xxxxxxxxxx>
---
 src/include/liburing.h          | 12 ++++++++++++
 src/include/liburing/io_uring.h | 10 ++++++++--
 src/register.c                  | 27 ++++++++++++++++++++++++++-
 3 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/src/include/liburing.h b/src/include/liburing.h
index ebfc424..9648f8c 100644
--- a/src/include/liburing.h
+++ b/src/include/liburing.h
@@ -114,6 +114,9 @@ extern int io_uring_register_buffers(struct io_uring *ring,
 					const struct iovec *iovecs,
 					unsigned nr_iovecs);
 extern int io_uring_unregister_buffers(struct io_uring *ring);
+extern int io_uring_register_buffers_update(struct io_uring *ring, unsigned off,
+					struct iovec *iovecs,
+					unsigned nr_iovecs);
 extern int io_uring_register_files(struct io_uring *ring, const int *files,
 					unsigned nr_files);
 extern int io_uring_unregister_files(struct io_uring *ring);
@@ -373,6 +376,15 @@ static inline void io_uring_prep_files_update(struct io_uring_sqe *sqe,
 	io_uring_prep_rw(IORING_OP_FILES_UPDATE, sqe, -1, fds, nr_fds, offset);
 }
 
+static inline void io_uring_prep_buffers_update(struct io_uring_sqe *sqe,
+						struct iovec *iovs,
+						unsigned nr_iovs,
+						int offset)
+{
+	io_uring_prep_rw(IORING_OP_BUFFERS_UPDATE, sqe, -1, iovs, nr_iovs,
+			 offset);
+}
+
 static inline void io_uring_prep_fallocate(struct io_uring_sqe *sqe, int fd,
 					   int mode, off_t offset, off_t len)
 {
diff --git a/src/include/liburing/io_uring.h b/src/include/liburing/io_uring.h
index 0bb55b0..4e61817 100644
--- a/src/include/liburing/io_uring.h
+++ b/src/include/liburing/io_uring.h
@@ -141,6 +141,7 @@ enum {
 	IORING_OP_SHUTDOWN,
 	IORING_OP_RENAMEAT,
 	IORING_OP_UNLINKAT,
+	IORING_OP_BUFFERS_UPDATE,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,
@@ -284,15 +285,20 @@ enum {
 	IORING_UNREGISTER_PERSONALITY		= 10,
 	IORING_REGISTER_RESTRICTIONS		= 11,
 	IORING_REGISTER_ENABLE_RINGS		= 12,
+	IORING_REGISTER_BUFFERS_UPDATE		= 13,
 
 	/* this goes last */
 	IORING_REGISTER_LAST
 };
 
-struct io_uring_files_update {
+struct io_uring_rsrc_update {
 	__u32 offset;
 	__u32 resv;
-	__aligned_u64 /* __s32 * */ fds;
+	union {
+		__aligned_u64 /* __s32 * */ fds;
+		__aligned_u64 /* __s32 * */ iovs;
+		__aligned_u64 /* __s32 * */ rsrc;
+	};
 };
 
 #define IO_URING_OP_SUPPORTED	(1U << 0)
diff --git a/src/register.c b/src/register.c
index 994aaff..80292d9 100644
--- a/src/register.c
+++ b/src/register.c
@@ -14,6 +14,31 @@
 
 #include "syscall.h"
 
+/*
+ * Register an update for an existing buffer set. The updates will start at
+ * 'off' in the original array, and 'nr_iovecs' is the number of buffers we'll
+ * update.
+ *
+ * Returns number of files updated on success, -ERROR on failure.
+ */
+int io_uring_register_buffers_update(struct io_uring *ring, unsigned off,
+				     struct iovec *iovecs, unsigned nr_iovecs)
+{
+	struct io_uring_rsrc_update up = {
+		.offset	= off,
+		.iovs	= (unsigned long) iovecs,
+	};
+	int ret;
+
+	ret = __sys_io_uring_register(ring->ring_fd,
+					IORING_REGISTER_BUFFERS_UPDATE, &up,
+					nr_iovecs);
+	if (ret < 0)
+		return -errno;
+
+	return ret;
+}
+
 int io_uring_register_buffers(struct io_uring *ring, const struct iovec *iovecs,
 			      unsigned nr_iovecs)
 {
@@ -49,7 +74,7 @@ int io_uring_unregister_buffers(struct io_uring *ring)
 int io_uring_register_files_update(struct io_uring *ring, unsigned off,
 				   int *files, unsigned nr_files)
 {
-	struct io_uring_files_update up = {
+	struct io_uring_rsrc_update up = {
 		.offset	= off,
 		.fds	= (unsigned long) files,
 	};
-- 
1.8.3.1