btrfs: make btrfs_destroy_delayed_refs() return void

btrfs_destroy_delayed_refs() always returns 0 and its single caller does
not check its return value, as it also returns void, and so does the
callers' caller and so on. This is because we are in the transaction abort
path, where we have no way to deal with errors (we are in a critical
situation) and all cleanup of resources works in a best effort fashion.
So make btrfs_destroy_delayed_refs() return void.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -4562,13 +4562,12 @@ static void btrfs_destroy_all_ordered_extents(struct btrfs_fs_info *fs_info)
 	btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 }
 
-static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
-				      struct btrfs_fs_info *fs_info)
+static void btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
+				       struct btrfs_fs_info *fs_info)
 {
 	struct rb_node *node;
 	struct btrfs_delayed_ref_root *delayed_refs;
 	struct btrfs_delayed_ref_node *ref;
-	int ret = 0;
 
 	delayed_refs = &trans->delayed_refs;
 
@@ -4576,7 +4575,7 @@ static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
 	if (atomic_read(&delayed_refs->num_entries) == 0) {
 		spin_unlock(&delayed_refs->lock);
 		btrfs_debug(fs_info, "delayed_refs has NO entry");
-		return ret;
+		return;
 	}
 
 	while ((node = rb_first_cached(&delayed_refs->href_root)) != NULL) {
@@ -4637,8 +4636,6 @@ static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
 	btrfs_qgroup_destroy_extent_records(trans);
 
 	spin_unlock(&delayed_refs->lock);
-
-	return ret;
 }
 
 static void btrfs_destroy_delalloc_inodes(struct btrfs_root *root)