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    Subject[PATCH 4/4] jbd2: don't dirty original metadata buffer on abort
    Currently, original metadata buffers are dirtied when they are
    unfiled whether the journal has aborted or not. Eventually these
    buffers will be written-back to the filesystem by pdflush. This
    means some metadata buffers are written to the filesystem without
    journaling if the journal aborts. So if both journal abort and
    system crash happen at the same time, the filesystem would become
    inconsistent state. Additionally, replaying journaled metadata
    can overwrite the latest metadata on the filesystem partly.
    Because, if the journal gets aborted, journaled metadata are
    preserved and replayed during the next mount not to lose
    uncheckpointed metadata. This would also break the consistency
    of the filesystem.

    This patch prevents original metadata buffers from being dirtied
    on abort by clearing BH_JBDDirty flag from those buffers. Thus,
    no metadata buffers are written to the filesystem without journaling.

    Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
    ---
    fs/jbd2/commit.c | 5 ++++-
    1 file changed, 4 insertions(+), 1 deletion(-)

    Index: linux-2.6.27-rc9-ex4-1/fs/jbd2/commit.c
    ===================================================================
    --- linux-2.6.27-rc9-ex4-1.orig/fs/jbd2/commit.c
    +++ linux-2.6.27-rc9-ex4-1/fs/jbd2/commit.c
    @@ -504,9 +504,10 @@ void jbd2_journal_commit_transaction(jou
    jh = commit_transaction->t_buffers;

    /* If we're in abort mode, we just un-journal the buffer and
    - release it for background writing. */
    + release it. */

    if (is_journal_aborted(journal)) {
    + clear_buffer_jbddirty(jh2bh(jh));
    JBUFFER_TRACE(jh, "journal is aborting: refile");
    jbd2_journal_refile_buffer(journal, jh);
    /* If that was the last one, we need to clean up
    @@ -884,6 +885,8 @@ restart_loop:
    if (buffer_jbddirty(bh)) {
    JBUFFER_TRACE(jh, "add to new checkpointing trans");
    __jbd2_journal_insert_checkpoint(jh, commit_transaction);
    + if (is_journal_aborted(journal))
    + clear_buffer_jbddirty(bh);
    JBUFFER_TRACE(jh, "refile for checkpoint writeback");
    __jbd2_journal_refile_buffer(jh);
    jbd_unlock_bh_state(bh);



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