ext4: check the return value of ext4_xattr_inode_dec_ref()

Check the return value of ext4_xattr_inode_dec_ref(), which could
return error code and need to be warned.
Signed-off-by: Li Zhong <floridsleeves@gmail.com>
Link: https://lore.kernel.org/r/20220917002816.3804400-1-floridsleeves@gmail.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/xattr.c

@@ -1540,7 +1540,8 @@ static int ext4_xattr_inode_lookup_create(handle_t *handle, struct inode *inode,
 
 	err = ext4_xattr_inode_write(handle, ea_inode, value, value_len);
 	if (err) {
-		ext4_xattr_inode_dec_ref(handle, ea_inode);
+		if (ext4_xattr_inode_dec_ref(handle, ea_inode))
+			ext4_warning_inode(ea_inode, "cleanup dec ref error %d", err);
 		iput(ea_inode);
 		return err;
 	}