From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755164AbaCESeq (ORCPT ); Wed, 5 Mar 2014 13:34:46 -0500 Received: from out03.mta.xmission.com ([166.70.13.233]:54467 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751983AbaCESep (ORCPT ); Wed, 5 Mar 2014 13:34:45 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Greg Kroah-Hartman Cc: Richard Cochran , linux-kernel@vger.kernel.org, Tejun Heo , stable@vger.kernel.org References: <74f5a436ebf5c13ed89a81c47ba09a6549e385f6.1394035568.git.richardcochran@gmail.com> <20140305183042.GC9824@kroah.com> Date: Wed, 05 Mar 2014 10:34:38 -0800 In-Reply-To: <20140305183042.GC9824@kroah.com> (Greg Kroah-Hartman's message of "Wed, 5 Mar 2014 10:30:42 -0800") Message-ID: <87k3c8ze81.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-AID: U2FsdGVkX1+waJAhddAiUZ7VSMCxpnpKFZ5nplzIJjA= X-SA-Exim-Connect-IP: 98.207.154.105 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0008] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa04 1397; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: XMission; sa04 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Greg Kroah-Hartman X-Spam-Relay-Country: Subject: Re: [PATCH] kernfs: fix off by one error. X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Wed, 14 Nov 2012 14:26:46 -0700) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Greg Kroah-Hartman writes: > On Wed, Mar 05, 2014 at 05:10:52PM +0100, Richard Cochran wrote: >> The hash values 0 and 1 are reserved for magic directory entries, but >> the code only prevents names hashing to 0. This patch fixes the test >> to also prevent hash value 1. >> >> Signed-off-by: Richard Cochran >> Cc: >> --- >> fs/kernfs/dir.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) > > Is this for 3.14-final or 3.15-rc1? The bug has existed since I added that hash function in 3.4-rc1. It was named sysfs_name_hash then but the code has otherwise been unchanged. It is a very minor bug. commit 4e4d6d860b9393c5395ba5920edb5b4c5d43a3a3 Author: Eric W. Biederman Date: Sun Dec 18 20:05:43 2011 -0800 sysfs: Add s_hash to sysfs_dirent and order directory entries by hash Compute a 31 bit hash of directory entries (that can fit in a signed 32bit off_t) and index the sysfs directory entries by that hash, replacing the per directory indexes by name and by inode. Because we now only use a single rbtree this reduces the size of sysfs_dirent by 2 pointers. Because we have fewer cases to deal with the code is now simpler. For now I use the simple hash that the dcache uses as that is easy to use and seems simple enough. In addition to makeing the code simpler using a hash for the file position in readdir brings sysfs in line with other filesystems that have non-trivial directory structures. Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman Eric