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    Subject[PATCH 05/28] ext4: Fix endian problem in MMP initialization
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    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 <djwong@us.ibm.com>
    ---
    fs/ext4/mmp.c | 3 ++-
    1 files changed, 2 insertions(+), 1 deletions(-)


    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)


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