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    md: simplify updating of event count to sometimes avoid updating spares. · a8707c08
    NeilBrown 提交于
    When updating the event count for a simple clean <-> dirty transition,
    we try to avoid updating the spares so they can safely spin-down.
    As the event_counts across an array must be +/- 1, this means
    decrementing the event_count on a dirty->clean transition.
    This is not always safe and we have to avoid the unsafe time.
    We current do this with a misguided idea about it being safe or
    not depending on whether the event_count is odd or even.  This
    approach only works reliably in a few common instances, but easily
    falls down.
    
    So instead, simply keep internal state concerning whether it is safe
    or not, and always assume it is not safe when an array is first
    assembled.
    Signed-off-by: NNeilBrown <neilb@suse.de>
    a8707c08
md.h 15.5 KB