ceph: check inode caps in ceph_d_revalidate

Some inodes in readdir reply may have no caps. Getattr mds request
for these inodes can return -ESTALE. The fix is consider dentry that
links to inode with no caps as invalid. Invalid dentry causes a
lookup request to send to the mds, the MDS will send caps back.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index d2154d6..d65ff33 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -891,6 +891,18 @@
 	return !RB_EMPTY_ROOT(&ci->i_caps) || ci->i_cap_exporting_mds >= 0;
 }
 
+int ceph_is_any_caps(struct inode *inode)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	int ret;
+
+	spin_lock(&ci->i_ceph_lock);
+	ret = __ceph_is_any_caps(ci);
+	spin_unlock(&ci->i_ceph_lock);
+
+	return ret;
+}
+
 /*
  * Remove a cap.  Take steps to deal with a racing iterate_session_caps.
  *