• Tejun Heo's avatar
    blkcg: implement blkg_[rw]stat_recursive_sum() and blkg_[rw]stat_merge() · 16b3de66
    Tejun Heo authored
    
    
    Implement blkg_[rw]stat_recursive_sum() and blkg_[rw]stat_merge().
    The former two collect the [rw]stats designated by the target policy
    data and offset from the pd's subtree.  The latter two add one
    [rw]stat to another.
    
    Note that the recursive sum functions require the queue lock to be
    held on entry to make blkg online test reliable.  This is necessary to
    properly handle stats of a dying blkg.
    
    These will be used to implement hierarchical stats.
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
    16b3de66