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

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>

diff --git a/lib/ext2fs/mmp.c b/lib/ext2fs/mmp.c
index ed6ee425b23014ba1b10e95fb06baf552227707a..91f4fb283f0a152e20818c19a2f67485102522de 100644 (file)
--- 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 */