[PATCH 5/8] btrfs-progs: Introduce function change_device_uuid().

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

This function just change a device item's uuid.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 btrfstune.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/btrfstune.c b/btrfstune.c
index 9c1b7aa..6706cd7 100644
--- a/btrfstune.c
+++ b/btrfstune.c
@@ -198,6 +198,27 @@ out:
 	return ret;
 }
 
+static int change_device_uuid(struct btrfs_root *root, struct extent_buffer *eb,
+			      int slot)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_dev_item *di;
+	int ret = 0;
+
+	di = btrfs_item_ptr(eb, slot, struct btrfs_dev_item);
+	if (fs_info->new_fsid) {
+		if (!memcmp_extent_buffer(eb, fs_info->new_fsid,
+					  (unsigned long)btrfs_device_fsid(di),
+					  BTRFS_FSID_SIZE))
+			return ret;
+		write_extent_buffer(eb, fs_info->new_fsid,
+				    (unsigned long)btrfs_device_fsid(di),
+				    BTRFS_FSID_SIZE);
+		ret = write_tree_block(NULL, root, eb);
+	}
+	return ret;
+}
+
 static void print_usage(void)
 {
 	fprintf(stderr, "usage: btrfstune [options] device\n");
-- 
2.3.7