[libvirt] [PATCH 1/2] Introduce btrfsCloneFile for btrfs COW copy
Signed-off-by: Chen Hanxiao <chenhanxiao(a)cn.fujitsu.com>
---
src/storage/storage_backend.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
index b990a82..5ce3566 100644
--- a/src/storage/storage_backend.c
+++ b/src/storage/storage_backend.c
@@ -156,6 +156,32 @@ enum {
#define READ_BLOCK_SIZE_DEFAULT (1024 * 1024)
#define WRITE_BLOCK_SIZE_DEFAULT (4 * 1024)
+/*
+ * Perform the O(1) btrfs clone operation, if possible.
+ * Upon success, return 0. Otherwise, return -1 and set errno.
+ */
+#if !defined(BTRFS_IOCTL_MAGIC)
+# define BTRFS_IOCTL_MAGIC 0x94
+#endif
+
+#define BTRFS_IOC_CLONE _IOW (BTRFS_IOCTL_MAGIC, 9, int)
+
+#if defined(__linux__)
+static inline int
+btrfsCloneFile(int dest_fd, int src_fd)
+{
+ return ioctl(dest_fd, BTRFS_IOC_CLONE, src_fd);
+}
+#else
+static inline int
+btrfsCloneFile(int dest_fd ATTRIBUTE_UNUSED,
+ int src_fd ATTRIBUTE_UNUSED)
+{
+ errno = ENOTSUP;
+ return -1;
+}
+#endif
+
static int ATTRIBUTE_NONNULL(2)
virStorageBackendCopyToFD(virStorageVolDefPtr vol,
virStorageVolDefPtr inputvol,
--
1.9.3