• NeilBrown's avatar
    [PATCH] md: Don't write dirty/clean update to spares - leave them alone · 42543769
    NeilBrown authored
    - record the 'event' count on each individual device (they
      might sometimes be slightly different now)
    - add a new value for 'sb_dirty': '3' means that the super
      block only needs to be updated to record a clean<->dirty
      transition.
    - Prefer odd event numbers for dirty states and even numbers
      for clean states
    - Using all the above, don't update the superblock on
      a spare device if the update is just doing a clean-dirty
      transition.  To accomodate this, a transition from
      dirty back to clean might now decrement the events counter
      if nothing else has changed.
    
    The net effect of this is that spare drives will not see any IO requests
    during normal running of the array, so they can go to sleep if that is what
    they want to do.
    Signed-off-by: default avatarNeil Brown <neilb@suse.de>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    42543769
md.c 133 KB