• Artem Bityutskiy's avatar
    UBIFS: seek journal heads to the latest bud in replay · 52c6e6f9
    Artem Bityutskiy authored
    This is the second fix of the following symptom:
    
    UBIFS error (pid 34456): could not find an empty LEB
    
    which sometimes happens after power cuts when we mount the file-system - UBIFS
    refuses it with the above error message which comes from the
    'ubifs_rcvry_gc_commit()' function. I can reproduce this using the integck test
    with the UBIFS power cut emulation enabled.
    
    Analysis of the problem.
    
    Currently UBIFS replay seeks the journal heads to the last _replayed_ bud.
    But the buds are replayed out-of-order, so the replay basically seeks journal
    heads to the "random" bud belonging to this head, and not to the _last_ one.
    
    The result of this is that the GC head may be seeked to a full LEB with no free
    space, or very little free space. And 'ubifs_rcvry_gc_commit()' tries to find a
    fully or mostly dirty LEB to match the current GC head (because we need to
    garbage-collect that dirty LEB at one go, because we do not have @c->gc_lnum).
    So 'ubifs_find_dirty_leb()' fails and we fall back to finding an empty LEB and
    also fail. As a result - recovery fails and mounting fails.
    
    This patch teaches the replay to initialize the GC heads exactly to the latest
    buds, i.e. the buds which have the largest sequence number in corresponding
    log reference nodes.
    Signed-off-by: default avatarArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
    Cc: stable@kernel.org
    52c6e6f9
replay.c 28.2 KB