From mboxrd@z Thu Jan 1 00:00:00 1970 From: bugzilla-daemon@bugzilla.kernel.org Subject: [Bug 48251] Sorting directory entries Date: Wed, 3 Oct 2012 16:29:50 +0000 (UTC) Message-ID: <20121003162950.83D6111FB3D@bugzilla.kernel.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" To: linux-ext4@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.19.201]:46218 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932530Ab2JCQ3y (ORCPT ); Wed, 3 Oct 2012 12:29:54 -0400 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 193D920524 for ; Wed, 3 Oct 2012 16:29:52 +0000 (UTC) Received: from bugzilla.kernel.org (bugzilla.kernel.org [198.145.19.217]) by mail.kernel.org (Postfix) with ESMTP id 31A612051E for ; Wed, 3 Oct 2012 16:29:51 +0000 (UTC) In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: https://bugzilla.kernel.org/show_bug.cgi?id=48251 Theodore Tso changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED CC| |tytso@mit.edu Resolution| |INVALID --- Comment #1 from Theodore Tso 2012-10-03 16:29:50 --- There is never a guarantee that directory entries are listed in the same order that they are created. If you are writing a program where you are making this assumption --- don't. It's something which has never been true, for any file system. With ext3 if the directory hashing feature is enabled (which it is by default), the directory entries are returned in hash order. This was needed so we could meet POSIX requirements for how readdir() behaves in the face of telldir() and seekdir(), as well as files being created while iterating through the directory entries using readdir(). (The short version is once you use a tree, if you do a node split due to a file being created, and where half of the directory entries in the node are copied to a new leaf block, it still must be the case that each directory entry which was created before starting the readdir() pass must be returned once and only once. In order to guarantee this, we traverse the tree in hash order.) If you disable the directory hashing feature, then the files will be returned _roughly_ in creation order; however, once you start deleting directory entries, new files can get inserted into the unallocated portion of the directory, which means readdir() won't be returning the files in creation order, even though previously it would appear to be returning files in creation order before any files had been deleted. -- Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug.