ceph: clean up send_mds_reconnect interface

Pass a ceph_mds_session, since the caller has it.

Remove the dead code for sending empty reconnects.  It used to be used
when the MDS contacted _us_ to solicit a reconnect, and we could reply
saying "go away, I have no session."  Now we only send reconnects based
on the mds map, and only when we do in fact have an open session.
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/mds_client.c

@@ -2177,33 +2177,27 @@ static int encode_caps_cb(struct inode *inode, struct ceph_cap *cap,
  *
  * called with mdsc->mutex held.
  */
-static void send_mds_reconnect(struct ceph_mds_client *mdsc, int mds)
+static void send_mds_reconnect(struct ceph_mds_client *mdsc,
+			       struct ceph_mds_session *session)
 {
-	struct ceph_mds_session *session = NULL;
 	struct ceph_msg *reply;
 	struct rb_node *p;
+	int mds = session->s_mds;
 	int err = -ENOMEM;
 	struct ceph_pagelist *pagelist;
 
-	pr_info("reconnect to recovering mds%d\n", mds);
+	pr_info("mds%d reconnect start\n", mds);
 
 	pagelist = kmalloc(sizeof(*pagelist), GFP_NOFS);
 	if (!pagelist)
 		goto fail_nopagelist;
 	ceph_pagelist_init(pagelist);
 
-	err = -ENOMEM;
 	reply = ceph_msg_new(CEPH_MSG_CLIENT_RECONNECT, 0);
 	if (!reply)
 		goto fail_nomsg;
 
-	/* find session */
-	session = __ceph_lookup_mds_session(mdsc, mds);
-	mutex_unlock(&mdsc->mutex);    /* drop lock for duration */
-
-	if (session) {
 	mutex_lock(&session->s_mutex);
-
 	session->s_state = CEPH_MDS_SESSION_RECONNECTING;
 	session->s_seq = 0;
 
@@ -2212,15 +2206,9 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc, int mds)
 
 	/* replay unsafe requests */
 	replay_unsafe_requests(mdsc, session);
-	} else {
-		dout("no session for mds%d, will send short reconnect\n",
-		     mds);
-	}
 
 	down_read(&mdsc->snap_rwsem);
 
-	if (!session)
-		goto send;
 	dout("session %p state %s\n", session,
 	     session_state_name(session->s_state));
 
@@ -2255,7 +2243,6 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc, int mds)
 			goto fail;
 	}
 
-send:
 	reply->pagelist = pagelist;
 	reply->hdr.data_len = cpu_to_le32(pagelist->length);
 	reply->nr_pages = calc_pages_for(0, pagelist->length);
@@ -2267,23 +2254,18 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc, int mds)
 	__wake_requests(mdsc, &session->s_waiting);
 	mutex_unlock(&mdsc->mutex);
 
-	ceph_put_mds_session(session);
-
 	up_read(&mdsc->snap_rwsem);
-	mutex_lock(&mdsc->mutex);
 	return;
 
 fail:
 	ceph_msg_put(reply);
 	up_read(&mdsc->snap_rwsem);
 	mutex_unlock(&session->s_mutex);
-	ceph_put_mds_session(session);
 fail_nomsg:
 	ceph_pagelist_release(pagelist);
 	kfree(pagelist);
 fail_nopagelist:
 	pr_err("error %d preparing reconnect for mds%d\n", err, mds);
-	mutex_lock(&mdsc->mutex);
 	return;
 }
 
@@ -2345,8 +2327,11 @@ static void check_new_map(struct ceph_mds_client *mdsc,
 		 * send reconnect?
 		 */
 		if (s->s_state == CEPH_MDS_SESSION_RESTARTING &&
-		    newstate >= CEPH_MDS_STATE_RECONNECT)
-			send_mds_reconnect(mdsc, i);
+		    newstate >= CEPH_MDS_STATE_RECONNECT) {
+			mutex_unlock(&mdsc->mutex);
+			send_mds_reconnect(mdsc, s);
+			mutex_lock(&mdsc->mutex);
+		}
 
 		/*
 		 * kick request on any mds that has gone active.