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>
diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 1c9713c..a47750d 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -1112,7 +1112,7 @@
 	ocfs2_lock_res_free(&oi->ip_inode_lockres);
 	ocfs2_lock_res_free(&oi->ip_open_lockres);
 
-	ocfs2_metadata_cache_purge(INODE_CACHE(inode));
+	ocfs2_metadata_cache_exit(INODE_CACHE(inode));
 
 	mlog_bug_on_msg(INODE_CACHE(inode)->ci_num_cached,
 			"Clear inode of %llu, inode has %u cache items\n",
@@ -1148,7 +1148,6 @@
 	/* Clear all other flags. */
 	oi->ip_flags = 0;
 	oi->ip_created_trans = 0;
-	oi->ip_last_trans = 0;
 	oi->ip_dir_start_lookup = 0;
 	oi->ip_blkno = 0ULL;