• Paul Clements's avatar
    [PATCH] md: new sysfs interface for setting bits in the write-intent-bitmap · 9b1d1dac
    Paul Clements authored
    Add a new sysfs interface that allows the bitmap of an array to be dirtied.
    The interface is write-only, and is used as follows:
    
    echo "1000" > /sys/block/md2/md/bitmap
    
    (dirty the bit for chunk 1000 [offset 0] in the in-memory and on-disk
    bitmaps of array md2)
    
    echo "1000-2000" > /sys/block/md1/md/bitmap
    
    (dirty the bits for chunks 1000-2000 in md1's bitmap)
    
    This is useful, for example, in cluster environments where you may need to
    combine two disjoint bitmaps into one (following a server failure, after a
    secondary server has taken over the array).  By combining the bitmaps on
    the two servers, a full resync can be avoided (This was discussed on the
    list back on March 18, 2005, "[PATCH 1/2] md bitmap bug fixes" thread).
    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>
    9b1d1dac
bitmap.c 38.7 KB