ocfs2: move ip_last_trans to struct ocfs2_caching_info

We have the read side of metadata caching isolated to struct
ocfs2_caching_info, now we need the write side.  This means the journal
functions.  The journal only does a couple of things with struct inode.

This change moves the ip_last_trans field onto struct
ocfs2_caching_info as ci_last_trans.  This field tells the journal
whether a pending journal flush is required.

Signed-off-by: Joel Becker <joel.becker@oracle.com>

fs/ocfs2/super.c

@@ -1669,7 +1669,6 @@ static void ocfs2_inode_init_once(void *data)
 	ocfs2_extent_map_init(&oi->vfs_inode);
 	INIT_LIST_HEAD(&oi->ip_io_markers);
 	oi->ip_created_trans = 0;
-	oi->ip_last_trans = 0;
 	oi->ip_dir_start_lookup = 0;
 
 	init_rwsem(&oi->ip_alloc_sem);