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libext2fs: Always swab the MMP block on big-endian systems machines

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The MMP code in libext2fs tries to gate MMP block swab'ing with this
test:

if (fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))

However, EXT2FS_ENABLE_SWAPFS never seems to be defined anywhere (all
possible 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.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Darrick J. Wong 2011-09-30 12:41:26 -07:00 committed by Theodore Ts'o
parent 1660034c0a
commit 9026b3db3a
1 changed files with 6 additions and 9 deletions
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15
lib/ext2fs/mmp.c
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@ -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 */