GFS2: Add initialization for address space in super block

Spotted by Andy Price. This should fix the odd messages from
lockdep caused by 70d4ee94Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Andrew Price <anprice@redhat.com>

fs/gfs2/ops_fstype.c

@@ -102,6 +102,7 @@ static struct gfs2_sbd *init_sbd(struct super_block *sb)
 
 	mapping = &sdp->sd_aspace;
 
+	address_space_init_once(mapping);
 	mapping->a_ops = &gfs2_meta_aops;
 	mapping->host = sb->s_bdev->bd_inode;
 	mapping->flags = 0;