ocfs2: temporarily remove extent map caching

The code in extent_map.c is not prepared to deal with a subtree being
rotated between lookups. This can happen when filling holes in sparse files.
Instead of a lengthy patch to update the code (which would likely lose the
benefit of caching subtree roots), we remove most of the algorithms and
implement a simple path based lookup. A less ambitious extent caching scheme
will be added in a later patch.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 08d57a3..5ff8549 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -1003,9 +1003,6 @@
 			"Clear inode of %llu, inode has io markers\n",
 			(unsigned long long)oi->ip_blkno);
 
-	ocfs2_extent_map_drop(inode, 0);
-	ocfs2_extent_map_init(inode);
-
 	status = ocfs2_drop_inode_locks(inode);
 	if (status < 0)
 		mlog_errno(status);
@@ -1102,8 +1099,7 @@
 		return NULL;
 	}
 
-	tmperr = ocfs2_extent_map_get_blocks(inode, block, 1,
-					     &p_blkno, NULL);
+	tmperr = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL);
 	if (tmperr < 0) {
 		mlog_errno(tmperr);
 		goto fail;