ceph: include time stamp in every MDS request

We recently modified the client/MDS protocol to include a timestamp in the
client request.  This allows ctime updates to follow the client's clock
in most cases, which avoids subtle problems when clocks are out of sync
and timestamps are updated sometimes by the MDS clock (for most requests)
and sometimes by the client clock (for cap writeback).
Signed-off-by: Sage Weil <sage@inktank.com>

fs/ceph/mds_client.c

@@ -1558,6 +1558,8 @@ ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode)
 	init_completion(&req->r_safe_completion);
 	INIT_LIST_HEAD(&req->r_unsafe_item);
 
+	req->r_stamp = CURRENT_TIME;
+
 	req->r_op = op;
 	req->r_direct_mode = mode;
 	return req;
@@ -1783,7 +1785,8 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
 	}
 
 	len = sizeof(*head) +
-		pathlen1 + pathlen2 + 2*(1 + sizeof(u32) + sizeof(u64));
+		pathlen1 + pathlen2 + 2*(1 + sizeof(u32) + sizeof(u64)) +
+		sizeof(struct timespec);
 
 	/* calculate (max) length for cap releases */
 	len += sizeof(struct ceph_mds_request_release) *
@@ -1800,6 +1803,7 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
 		goto out_free2;
 	}
 
+	msg->hdr.version = 2;
 	msg->hdr.tid = cpu_to_le64(req->r_tid);
 
 	head = msg->front.iov_base;
@@ -1836,6 +1840,9 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
 		      mds, req->r_old_inode_drop, req->r_old_inode_unless, 0);
 	head->num_releases = cpu_to_le16(releases);
 
+	/* time stamp */
+	ceph_encode_copy(&p, &req->r_stamp, sizeof(req->r_stamp));
+
 	BUG_ON(p > end);
 	msg->front.iov_len = p - msg->front.iov_base;
 	msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);

fs/ceph/mds_client.h

@@ -194,6 +194,7 @@ struct ceph_mds_request {
 	int r_fmode;        /* file mode, if expecting cap */
 	kuid_t r_uid;
 	kgid_t r_gid;
+	struct timespec r_stamp;
 
 	/* for choosing which mds to send this request to */
 	int r_direct_mode;