From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1E9A7C433C1 for ; Sun, 28 Mar 2021 15:09:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D922D61948 for ; Sun, 28 Mar 2021 15:09:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231225AbhC1PIQ (ORCPT ); Sun, 28 Mar 2021 11:08:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231131AbhC1PHg (ORCPT ); Sun, 28 Mar 2021 11:07:36 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD65BC061756; Sun, 28 Mar 2021 08:07:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=U3VUBgSWmtuhj2eaOcurajScUzkTC8xyuO2uGbgOuaE=; b=aSLec8BLfvM6s8JuxKcmT1Wg2W m/And3P1jFN2IW/L1JYvNroaUyFxLz1W6U6oz2tM0c5Sp4BKZUJNortM4lqrYuDyQgFOu7KQfKV26 NE/GIoPujfo70lzZ3SrNV6WgavKVz7Mddbw9+fBhoAZuak+LqRB9jlhYNddifLa4BckCw1fK+2XZt zaMHXwj84B8anfi9sKC1D8iIJj788XdTVYqtxEE9t9kVqlZcoc9xa3IdPN4IA4PPLZ5iTdV+QRT+d bqgwGE1tdJzUh/NLuFafHWioh96XJcCZRhZ1Wg1yckv0WTHCdvtIBvJCBz4e0ODFl5hZk9rrMfG9V OVKMzBeg==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lQX0V-000CDn-KJ; Sun, 28 Mar 2021 15:07:20 +0000 Date: Sun, 28 Mar 2021 16:07:15 +0100 From: Matthew Wilcox To: =?iso-8859-1?Q?Andr=E9?= Almeida Cc: Alexander Viro , Theodore Ts'o , Andreas Dilger , Jaegeuk Kim , Chao Yu , krisman@collabora.com, kernel@collabora.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, Daniel Rosenberg , Chao Yu Subject: Re: [PATCH 1/3] fs/dcache: Add d_clear_dir_neg_dentries() Message-ID: <20210328150715.GA33249@casper.infradead.org> References: <20210328144356.12866-1-andrealmeid@collabora.com> <20210328144356.12866-2-andrealmeid@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210328144356.12866-2-andrealmeid@collabora.com> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Sun, Mar 28, 2021 at 11:43:54AM -0300, André Almeida wrote: > +/** > + * d_clear_dir_neg_dentries - Remove negative dentries in an inode > + * @dir: Directory to clear negative dentries > + * > + * For directories with negative dentries that are becoming case-insensitive > + * dirs, we need to remove all those negative dentries, otherwise they will > + * become dangling dentries. During the creation of a new file, if a d_hash > + * collision happens and the names match in a case-insensitive, the name of > + * the file will be the name defined at the negative dentry, that can be > + * different from the specified by the user. To prevent this from happening, we > + * need to remove all dentries in a directory. Given that the directory must be > + * empty before we call this function we are sure that all dentries there will > + * be negative. > + */ This is quite the landmine of a function. It _assumes_ that the directory is empty, and clears all dentries in it. > +void d_clear_dir_neg_dentries(struct inode *dir) > +{ > + struct dentry *alias, *dentry; > + > + hlist_for_each_entry(alias, &dir->i_dentry, d_u.d_alias) { > + list_for_each_entry(dentry, &alias->d_subdirs, d_child) { > + d_drop(dentry); > + dput(dentry); > + } I would be happier if it included a check for negativity. d_is_negative() or maybe this newfangled d_really_is_negative() (i haven't stayed up to speed on the precise difference between the two) > + } > +} > +EXPORT_SYMBOL(d_clear_dir_neg_dentries); I'd rather see this _GPL for such an internal thing.