btrfs: switch to use new generic UUID API

There are new types and helpers that are supposed to be used in new code.

As a preparation to get rid of legacy types and API functions do
the conversion here.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 702e0f2..ca61744 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1479,7 +1479,6 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	u64 index = 0;
 	u64 objectid;
 	u64 root_flags;
-	uuid_le new_uuid;
 
 	ASSERT(pending->path);
 	path = pending->path;
@@ -1572,8 +1571,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 
 	btrfs_set_root_generation_v2(new_root_item,
 			trans->transid);
-	uuid_le_gen(&new_uuid);
-	memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
+	generate_random_guid(new_root_item->uuid);
 	memcpy(new_root_item->parent_uuid, root->root_item.uuid,
 			BTRFS_UUID_SIZE);
 	if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
@@ -1684,7 +1682,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 		btrfs_abort_transaction(trans, ret);
 		goto fail;
 	}
-	ret = btrfs_uuid_tree_add(trans, new_uuid.b, BTRFS_UUID_KEY_SUBVOL,
+	ret = btrfs_uuid_tree_add(trans, new_root_item->uuid,
+				  BTRFS_UUID_KEY_SUBVOL,
 				  objectid);
 	if (ret) {
 		btrfs_abort_transaction(trans, ret);