From: John Spray <john.spray@redhat.com>
Date: Thu, 4 Sep 2014 12:04:18 +0000 (+0100)
Subject: mds: add state for tracking RECALL progress
X-Git-Tag: v0.86~68^2~6
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=8c0f2555fe6275c330b8db146d1a3822a28d2ccc;p=ceph.git

mds: add state for tracking RECALL progress

To be used later for generating health metrics
for clients which are failing to promptly service
CEPH_SESSION_RECALL_STATE messages.

Signed-off-by: John Spray <john.spray@redhat.com>
---

diff --git a/src/mds/Locker.cc b/src/mds/Locker.cc
index 5efbfa9c366..d42f452a56e 100644
--- a/src/mds/Locker.cc
+++ b/src/mds/Locker.cc
@@ -99,6 +99,7 @@ void Locker::dispatch(Message *m)
     // client sync
   case CEPH_MSG_CLIENT_CAPS:
     handle_client_caps(static_cast<MClientCaps*>(m));
+
     break;
   case CEPH_MSG_CLIENT_CAPRELEASE:
     handle_client_cap_release(static_cast<MClientCapRelease*>(m));
@@ -3121,8 +3122,15 @@ void Locker::handle_client_cap_release(MClientCapRelease *m)
     return;
   }
 
-  for (vector<ceph_mds_cap_item>::iterator p = m->caps.begin(); p != m->caps.end(); ++p)
+  Session *session = static_cast<Session *>(m->get_connection()->get_priv());
+
+  for (vector<ceph_mds_cap_item>::iterator p = m->caps.begin(); p != m->caps.end(); ++p) {
     _do_cap_release(client, inodeno_t((uint64_t)p->ino) , p->cap_id, p->migrate_seq, p->seq);
+  }
+
+  if (session) {
+    session->notify_cap_release(m->caps.size());
+  }
 
   m->put();
 }
diff --git a/src/mds/Server.cc b/src/mds/Server.cc
index beb469647f3..09ef3510aa0 100644
--- a/src/mds/Server.cc
+++ b/src/mds/Server.cc
@@ -781,6 +781,12 @@ void Server::recover_filelocks(CInode *in, bufferlist locks, int64_t client)
   }
 }
 
+
+/**
+ * Call this when the MDCache is oversized, to send requests to the clients
+ * to trim some caps, and consequently unpin some inodes in the MDCache so
+ * that it can trim too.
+ */
 void Server::recall_client_state(float ratio)
 {
   int max_caps_per_client = (int)(g_conf->mds_cache_size * .8);
@@ -806,15 +812,15 @@ void Server::recall_client_state(float ratio)
 	     << dendl;
 
     if (session->caps.size() > min_caps_per_client) {	
-      int newlim = (int)(session->caps.size() * ratio);
-      if (newlim > max_caps_per_client)
-	newlim = max_caps_per_client;
-      MClientSession *m = new MClientSession(CEPH_SESSION_RECALL_STATE);
-      m->head.max_caps = newlim;
-      mds->send_message_client(m, session);
+      int newlim = MIN((int)(session->caps.size() * ratio), max_caps_per_client);
+      if (session->caps.size() > newlim) {
+          MClientSession *m = new MClientSession(CEPH_SESSION_RECALL_STATE);
+          m->head.max_caps = newlim;
+          mds->send_message_client(m, session);
+          session->notify_recall_sent(newlim);
+      }
     }
   }
- 
 }
 
 
diff --git a/src/mds/SessionMap.cc b/src/mds/SessionMap.cc
index 4f4071ef532..bf53badf3c3 100644
--- a/src/mds/SessionMap.cc
+++ b/src/mds/SessionMap.cc
@@ -341,3 +341,39 @@ void SessionMap::touch_session(Session *session)
   session->last_cap_renew = ceph_clock_now(g_ceph_context);
 }
 
+/**
+ * Capped in response to a CEPH_MSG_CLIENT_CAPRELEASE message,
+ * with n_caps equal to the number of caps that were released
+ * in the message.  Used to update state about how many caps a
+ * client has released since it was last instructed to RECALL_STATE.
+ */
+void Session::notify_cap_release(size_t n_caps)
+{
+  if (!recalled_at.is_zero()) {
+    recall_release_count += n_caps;
+    if (recall_release_count >= recall_count) {
+      recalled_at = utime_t();
+      recall_count = 0;
+      recall_release_count = 0;
+    }
+  }
+}
+
+/**
+ * Called when a CEPH_MSG_CLIENT_SESSION->CEPH_SESSION_RECALL_STATE
+ * message is sent to the client.  Update our recall-related state
+ * in order to generate health metrics if the session doesn't see
+ * a commensurate number of calls to ::notify_cap_release
+ */
+void Session::notify_recall_sent(int const new_limit)
+{
+  if (recalled_at.is_zero()) {
+    // Entering recall phase, set up counters so we can later
+    // judge whether the client has respected the recall request
+    recalled_at = ceph_clock_now(g_ceph_context);
+    assert (new_limit < caps.size());  // Behaviour of Server::recall_client_state
+    recall_count = caps.size() - new_limit;
+    recall_release_count = 0;
+  }
+}
+
diff --git a/src/mds/SessionMap.h b/src/mds/SessionMap.h
index b1adcb77fc7..c95af0a3ff0 100644
--- a/src/mds/SessionMap.h
+++ b/src/mds/SessionMap.h
@@ -80,6 +80,12 @@ private:
   uint64_t state_seq;
   int importing_count;
   friend class SessionMap;
+
+  // Ephemeral state for tracking progress of capability recalls
+  utime_t recalled_at;  // When was I asked to SESSION_RECALL?
+  uint32_t recall_count;  // How many caps was I asked to SESSION_RECALL?
+  uint32_t recall_release_count;  // How many caps have I actually revoked?
+
 public:
   session_info_t info;                         ///< durable bits
 
@@ -93,6 +99,9 @@ public:
 
   interval_set<inodeno_t> pending_prealloc_inos; // journaling prealloc, will be added to prealloc_inos
 
+  void notify_cap_release(size_t n_caps);
+  void notify_recall_sent(int const new_limit);
+
   inodeno_t next_ino() {
     if (info.prealloc_inos.empty())
       return 0;
@@ -203,6 +212,7 @@ public:
 
   Session() : 
     state(STATE_CLOSED), state_seq(0), importing_count(0),
+    recalled_at(), recall_count(0), recall_release_count(0),
     connection(NULL), item_session_list(this),
     requests(0),  // member_offset passed to front() manually
     cap_push_seq(0),