ceph: use fpos_cmp() to compare dentry positions

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 8c7f90b..fb4f7a2 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -141,7 +141,7 @@
 
 	/* start at beginning? */
 	if (ctx->pos == 2 || last == NULL ||
-	    ctx->pos < ceph_dentry(last)->offset) {
+	    fpos_cmp(ctx->pos, ceph_dentry(last)->offset) < 0) {
 		if (list_empty(&parent->d_subdirs))
 			goto out_unlock;
 		p = parent->d_subdirs.prev;