commit 9b1d1dac181d8c1b9492e05cee660a985d035a06

commit 9b1d1dac181d8c1b9492e05cee660a985d035a06
Author: Paul Clements <paul.clements@steeleye.com>
Date:   Tue Oct 3 01:15:49 2006 -0700

    [PATCH] md: new sysfs interface for setting bits in the write-intent-bitmap

    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: Neil Brown <neilb@suse.de>
    Signed-off-by: Andrew Morton <akpm@osdl.org>
    Signed-off-by: Linus Torvalds <torvalds@osdl.org>