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    md: remove ability to explicit set an inactive array to 'clean'. · 5bf29597
    NeilBrown 提交于
    Being able to write 'clean' to an 'array_state' of an inactive array
    to activate it in 'clean' mode is both unnecessary and inconvenient.
    
    It is unnecessary because the same can be achieved by writing
    'active'.  This activates and array, but it still remains 'clean'
    until the first write.
    
    It is inconvenient because writing 'clean' is more often used to
    cause an 'active' array to revert to 'clean' mode (thus blocking
    any writes until a 'write-pending' is promoted to 'active').
    
    Allowing 'clean' to both activate an array and mark an active array as
    clean can lead to races:  One program writes 'clean' to mark the
    active array as clean at the same time as another program writes
    'inactive' to deactivate (stop) and active array.  Depending on which
    writes first, the array could be deactivated and immediately
    reactivated which isn't what was desired.
    
    So just disable the use of 'clean' to activate an array.
    
    This avoids a race that can be triggered with mdadm-3.0 and external
    metadata, so it suitable for -stable.
    Reported-by: NRafal Marszewski <rafal.marszewski@intel.com>
    Acked-by: NDan Williams <dan.j.williams@intel.com>
    Cc: <stable@kernel.org>
    Signed-off-by: NNeilBrown <neilb@suse.de>
    5bf29597
md.c 177.2 KB