[PATCH] md: Fix device-size updates in md

As 'array_size' is a 'sector_t', it may overflow inappropriately when shifted
10 bits.  So We should cast it to a loff_t first.

There are two places with this problem, but the second (in update_raid_disks)
isn't needed so just remove it:
  The only personality that handles ->reshape currently is raid1,
  and it doesn't change the size of the array.
  When added for raid5/6, reshape again won't change the size of the array,
  at least not straight away.
  This code might be need for reshaping 'linear' but linear->shape,
  if implemented, should probably do the i_size_write itself.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/md.c

@@ -3465,7 +3465,7 @@ static int update_size(mddev_t *mddev, unsigned long size)
 		bdev = bdget_disk(mddev->gendisk, 0);
 		if (bdev) {
 			mutex_lock(&bdev->bd_inode->i_mutex);
-			i_size_write(bdev->bd_inode, mddev->array_size << 10);
+			i_size_write(bdev->bd_inode, (loff_t)mddev->array_size << 10);
 			mutex_unlock(&bdev->bd_inode->i_mutex);
 			bdput(bdev);
 		}
@@ -3485,17 +3485,6 @@ static int update_raid_disks(mddev_t *mddev, int raid_disks)
 	if (mddev->sync_thread)
 		return -EBUSY;
 	rv = mddev->pers->reshape(mddev, raid_disks);
-	if (!rv) {
-		struct block_device *bdev;
-
-		bdev = bdget_disk(mddev->gendisk, 0);
-		if (bdev) {
-			mutex_lock(&bdev->bd_inode->i_mutex);
-			i_size_write(bdev->bd_inode, mddev->array_size << 10);
-			mutex_unlock(&bdev->bd_inode->i_mutex);
-			bdput(bdev);
-		}
-	}
 	return rv;
 }