[PATCH] md: write-intent bitmap support for raid6

This is a direct port of the raid5 patch.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/md.c

@@ -645,7 +645,7 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 
 		if (sb->state & (1<<MD_SB_BITMAP_PRESENT) &&
 		    mddev->bitmap_file == NULL) {
-			if (mddev->level != 1 && mddev->level != 5) {
+			if (mddev->level != 1 && mddev->level != 5 && mddev->level != 6) {
 				/* FIXME use a better test */
 				printk(KERN_WARNING "md: bitmaps only support for raid1\n");
 				return -EINVAL;