[PATCH] md: extend md sysfs support to component devices.

Each device in an md array how has a corresponding
  /sys/block/mdX/md/devNN/
directory which can contain attributes.  Currently there is only 'state' which
summarises the state, nd 'super' which has a copy of the superblock, and
'block' which is a symlink to the block device.

Also, /sys/block/mdX/md/rdNN represents slot 'NN' in the array, and is a
symlink to the relevant 'devNN'.  Obviously spare devices do not have a slot
in the array, and so don't have such a symlink.

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index a9b0e47..d1dad32 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -105,6 +105,8 @@
 	int		sb_size;	/* bytes in the superblock */
 	int		preferred_minor;	/* autorun support */
 
+	struct kobject	kobj;
+
 	/* A device can be in one of three states based on two flags:
 	 * Not working:   faulty==1 in_sync==0
 	 * Fully working: faulty==0 in_sync==1