ocfs2: Take the inode out of the metadata read/write paths.

We are really passing the inode into the ocfs2_read/write_blocks()
functions to get at the metadata cache.  This commit passes the cache
directly into the metadata block functions, divorcing them from the
inode.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 110bb57..fe15cee 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -2127,7 +2127,7 @@
 
 	/* This will discard any caching information we might have had
 	 * for the inode metadata. */
-	ocfs2_metadata_cache_purge(inode);
+	ocfs2_metadata_cache_purge(INODE_CACHE(inode));
 
 	ocfs2_extent_map_trunc(inode, 0);