From patchwork Sat Oct 8 07:54:16 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 118475 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 5FBFFB7150 for ; Sat, 8 Oct 2011 18:57:08 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752234Ab1JHH5B (ORCPT ); Sat, 8 Oct 2011 03:57:01 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:41694 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751343Ab1JHH46 (ORCPT ); Sat, 8 Oct 2011 03:56:58 -0400 Received: from d03relay05.boulder.ibm.com (d03relay05.boulder.ibm.com [9.17.195.107]) by e39.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id p987cP7P011530; Sat, 8 Oct 2011 01:38:25 -0600 Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d03relay05.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p987sJeu113496; Sat, 8 Oct 2011 01:54:19 -0600 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p987sHpQ013479; Sat, 8 Oct 2011 01:54:18 -0600 Received: from elm3c44.beaverton.ibm.com ([9.47.69.44]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id p987sGOq013456; Sat, 8 Oct 2011 01:54:16 -0600 Subject: [PATCH 05/28] ext4: Fix endian problem in MMP initialization To: Andreas Dilger , Theodore Tso , "Darrick J. Wong" From: "Darrick J. Wong" Cc: Sunil Mushran , Martin K Petersen , Greg Freemyer , Amir Goldstein , linux-kernel , Andi Kleen , Mingming Cao , Joel Becker , linux-fsdevel , linux-ext4@vger.kernel.org, Coly Li Date: Sat, 08 Oct 2011 00:54:16 -0700 Message-ID: <20111008075416.20506.12005.stgit@elm3c44.beaverton.ibm.com> In-Reply-To: <20111008075343.20506.23155.stgit@elm3c44.beaverton.ibm.com> References: <20111008075343.20506.23155.stgit@elm3c44.beaverton.ibm.com> User-Agent: StGit/0.15 MIME-Version: 1.0 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org As part of startup, the MMP initialization code does this: mmp->mmp_seq = seq = cpu_to_le32(mmp_new_seq()); Next, mmp->mmp_seq is written out to disk, a delay happens, and then the MMP block is read back in and the sequence value is tested: if (seq != le32_to_cpu(mmp->mmp_seq)) { /* fail the mount */ On a LE system such as x86, the *le32* functions do nothing and this works. Unfortunately, on a BE system such as ppc64, this comparison becomes: if (cpu_to_le32(new_seq) != le32_to_cpu(cpu_to_le32(new_seq)) { /* fail the mount */ Except for a few palindromic sequence numbers, this test always causes the mount to fail, which makes MMP filesystems generally unmountable on ppc64. The attached patch fixes this situation. Signed-off-by: Darrick J. Wong --- fs/ext4/mmp.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c index 9bdef3f..a7a4986 100644 --- a/fs/ext4/mmp.c +++ b/fs/ext4/mmp.c @@ -295,7 +295,8 @@ skip: /* * write a new random sequence number. */ - mmp->mmp_seq = seq = cpu_to_le32(mmp_new_seq()); + seq = mmp_new_seq(); + mmp->mmp_seq = cpu_to_le32(seq); retval = write_mmp_block(bh); if (retval)