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    Subject[ 53/79] bcache: Journal replay fix
    Date
    3.10-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Kent Overstreet <kmo@daterainc.com>

    commit faa5673617656ee58369a3cfe4a312cfcdc59c81 upstream.

    The journal replay code starts by finding something that looks like a
    valid journal entry, then it does a binary search over the unchecked
    region of the journal for the journal entries with the highest sequence
    numbers.

    Trouble is, the logic was wrong - journal_read_bucket() returns true if
    it found journal entries we need, but if the range of journal entries
    we're looking for loops around the end of the journal - in that case
    journal_read_bucket() could return true when it hadn't found the highest
    sequence number we'd seen yet, and in that case the binary search did
    the wrong thing. Whoops.

    Signed-off-by: Kent Overstreet <kmo@daterainc.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/md/bcache/journal.c | 7 ++++++-
    1 file changed, 6 insertions(+), 1 deletion(-)

    --- a/drivers/md/bcache/journal.c
    +++ b/drivers/md/bcache/journal.c
    @@ -182,9 +182,14 @@ bsearch:
    pr_debug("starting binary search, l %u r %u", l, r);

    while (l + 1 < r) {
    + seq = list_entry(list->prev, struct journal_replay,
    + list)->j.seq;
    +
    m = (l + r) >> 1;
    + read_bucket(m);

    - if (read_bucket(m))
    + if (seq != list_entry(list->prev, struct journal_replay,
    + list)->j.seq)
    l = m;
    else
    r = m;



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