btrfs: simplify the send_in_progress check in btrfs_delete_subvolume

Only when send_in_progress, we have to do something different such as
btrfs_warn() and return -EPERM. Therefore, we could check
send_in_progress first and process error handling, after the
root_item_lock has been got.

Just for better readability. No functional change.
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/inode.c

@@ -4270,18 +4270,17 @@ int btrfs_delete_subvolume(struct inode *dir, struct dentry *dentry)
 	 * again is not run concurrently.
 	 */
 	spin_lock(&dest->root_item_lock);
-	root_flags = btrfs_root_flags(&dest->root_item);
-	if (dest->send_in_progress == 0) {
-		btrfs_set_root_flags(&dest->root_item,
-				root_flags | BTRFS_ROOT_SUBVOL_DEAD);
-		spin_unlock(&dest->root_item_lock);
-	} else {
+	if (dest->send_in_progress) {
 		spin_unlock(&dest->root_item_lock);
 		btrfs_warn(fs_info,
 			   "attempt to delete subvolume %llu during send",
 			   dest->root_key.objectid);
 		return -EPERM;
 	}
+	root_flags = btrfs_root_flags(&dest->root_item);
+	btrfs_set_root_flags(&dest->root_item,
+			     root_flags | BTRFS_ROOT_SUBVOL_DEAD);
+	spin_unlock(&dest->root_item_lock);
 
 	down_write(&fs_info->subvol_sem);