ceph: implement DIRLAYOUTHASH feature to get dir layout from MDS

This implements the DIRLAYOUTHASH protocol feature, which passes the dir
layout over the wire from the MDS.  This gives the client knowledge
of the correct hash function to use for mapping dentries among dir
fragments.

Note that if this feature is _not_ present on the client but is on the
MDS, the client may misdirect requests.  This will result in a forward
and degrade performance.  It may also result in inaccurate NFS filehandle
generation, which will prevent fh resolution when the inode is not present
in the client cache and the parent directories have been fragmented.

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index aabe563b54d..f8f27f6eaa9 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -35,6 +35,7 @@ struct ceph_cap;
  */
 struct ceph_mds_reply_info_in {
 	struct ceph_mds_reply_inode *in;
+	struct ceph_dir_layout dir_layout;
 	u32 symlink_len;
 	char *symlink;
 	u32 xattr_len;