f2fs: fix a redundant call to f2fs_balance_fs if an error occurs

The  uninitialized variable dn.node_changed does not get set when a
call to f2fs_get_node_page fails.  This uninitialized value gets used
in the call to f2fs_balance_fs() that may or not may not balances
dirty node and dentry pages depending on the uninitialized state of
the variable. Fix this by only calling f2fs_balance_fs if err is
not set.

Thanks to Jaegeuk Kim for suggesting an appropriate fix.

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: 2a34076070 ("f2fs: call f2fs_balance_fs only when node was changed")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/inline.c

@@ -219,7 +219,8 @@ out:
 
 	f2fs_put_page(page, 1);
 
-	f2fs_balance_fs(sbi, dn.node_changed);
+	if (!err)
+		f2fs_balance_fs(sbi, dn.node_changed);
 
 	return err;
 }