From: "Darrick J. Wong" Subject: [PATCH] libext2fs: Always swab MMP block on BE machines Date: Fri, 30 Sep 2011 12:41:26 -0700 Message-ID: <20110930194126.GU12086@tux1.beaverton.ibm.com> Reply-To: djwong@us.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4 To: "Theodore Ts'o" Return-path: Received: from e4.ny.us.ibm.com ([32.97.182.144]:58269 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932073Ab1I3TlR (ORCPT ); Fri, 30 Sep 2011 15:41:17 -0400 Received: from d01relay05.pok.ibm.com (d01relay05.pok.ibm.com [9.56.227.237]) by e4.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id p8UJHCoD021068 for ; Fri, 30 Sep 2011 15:17:12 -0400 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay05.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p8UJfGoT193176 for ; Fri, 30 Sep 2011 15:41:16 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p8UJfFJX007276 for ; Fri, 30 Sep 2011 15:41:16 -0400 Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: The MMP code in libext2fs tries to gate MMP block swab'ing with this test: #ifdef EXT2FS_ENABLE_SWAPFS if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) However, EXT2FS_ENABLE_SWAPFS never seems to be defined anywhere (all possible #define's were cleaned out of e2fsprogs ages ago), and even if any still existed, the field fs->super->s_magic is always in host byteorder, so the test always fails. So, we can change the #ifdef to WORDS_BIGENDIAN (which is conditionally defined on BE platforms) and get rid of the broken if test. (This fix came up while testing the metadata checksumming patchset) Signed-off-by: Darrick J. Wong --- lib/ext2fs/mmp.c | 15 ++++++--------- 1 files changed, 6 insertions(+), 9 deletions(-) diff --git a/lib/ext2fs/mmp.c b/lib/ext2fs/mmp.c index ed6ee42..91f4fb2 100644 --- a/lib/ext2fs/mmp.c +++ b/lib/ext2fs/mmp.c @@ -91,9 +91,8 @@ errcode_t ext2fs_mmp_read(ext2_filsys fs, blk64_t mmp_blk, void *buf) } mmp_cmp = fs->mmp_cmp; -#ifdef EXT2FS_ENABLE_SWAPFS - if (fs->flags & EXT2_FLAG_SWAP_BYTES) - ext2fs_swap_mmp(mmp_cmp); +#ifdef WORDS_BIGENDIAN + ext2fs_swap_mmp(mmp_cmp); #endif if (buf != NULL && buf != fs->mmp_cmp) @@ -122,18 +121,16 @@ errcode_t ext2fs_mmp_write(ext2_filsys fs, blk64_t mmp_blk, void *buf) fs->super->s_mmp_block > ext2fs_blocks_count(fs->super)) return EXT2_ET_MMP_BAD_BLOCK; -#ifdef EXT2FS_ENABLE_SWAPFS - if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) - ext2fs_swap_mmp(mmp_s); +#ifdef WORDS_BIGENDIAN + ext2fs_swap_mmp(mmp_s); #endif /* I was tempted to make this use O_DIRECT and the mmp_fd, but * this caused no end of grief, while leaving it as-is works. */ retval = io_channel_write_blk64(fs->io, mmp_blk, -fs->blocksize, buf); -#ifdef EXT2FS_ENABLE_SWAPFS - if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) - ext2fs_swap_mmp(mmp_s); +#ifdef WORDS_BIGENDIAN + ext2fs_swap_mmp(mmp_s); #endif /* Make sure the block gets to disk quickly */