ceph: initial CEPH_FEATURE_FS_FILE_LAYOUT_V2 support

Add support for the format change of MClientReply/MclientCaps.
Also add code that denies access to inodes with pool_ns layouts.

Signed-off-by: Yan, Zheng <[email protected]>
Reviewed-by: Sage Weil <[email protected]>
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index ccf11ef..37712cc 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -44,6 +44,7 @@
 	u64 inline_version;
 	u32 inline_len;
 	char *inline_data;
+	u32 pool_ns_len;
 };
 
 /*