From be49866a150e04438cef971dec7948eaf34852fc Mon Sep 17 00:00:00 2001
From: Patrick Donnelly <pdonnell@redhat.com>
Date: Fri, 2 Aug 2019 13:22:51 -0700
Subject: [PATCH] mds: add explicit trim flag

So that the intent of the caller is clear to trim due to the cache being
too full.

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>
---
 src/mds/MDCache.cc |  2 +-
 src/mds/Server.cc  | 11 ++++++-----
 src/mds/Server.h   | 22 ++++++++++++++++++++--
 3 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/src/mds/MDCache.cc b/src/mds/MDCache.cc
index 722bb6d065c..df699f32b8d 100644
--- a/src/mds/MDCache.cc
+++ b/src/mds/MDCache.cc
@@ -7593,7 +7593,7 @@ void MDCache::check_memory_usage()
   mds->mlogger->set(l_mdm_heap, last.get_heap());
 
   if (cache_toofull()) {
-    mds->server->recall_client_state(nullptr);
+    mds->server->recall_client_state(nullptr, Server::RecallFlags::TRIM);
   }
 
   // If the cache size had exceeded its limit, but we're back in bounds
diff --git a/src/mds/Server.cc b/src/mds/Server.cc
index 07b95260111..a75811a2399 100644
--- a/src/mds/Server.cc
+++ b/src/mds/Server.cc
@@ -1566,8 +1566,9 @@ void Server::recover_filelocks(CInode *in, bufferlist locks, int64_t client)
 std::pair<bool, uint64_t> Server::recall_client_state(MDSGatherBuilder* gather, RecallFlags flags)
 {
   const auto now = clock::now();
-  const bool steady = flags&RecallFlags::STEADY;
-  const bool enforce_max = flags&RecallFlags::ENFORCE_MAX;
+  const bool steady = !!(flags&RecallFlags::STEADY);
+  const bool enforce_max = !!(flags&RecallFlags::ENFORCE_MAX);
+  const bool trim = !!(flags&RecallFlags::TRIM);
 
   const auto max_caps_per_client = g_conf().get_val<uint64_t>("mds_max_caps_per_client");
   const auto min_caps_per_client = g_conf().get_val<uint64_t>("mds_min_caps_per_client");
@@ -1579,14 +1580,14 @@ std::pair<bool, uint64_t> Server::recall_client_state(MDSGatherBuilder* gather,
            << " min=" << min_caps_per_client
            << " max=" << max_caps_per_client
            << " total=" << Capability::count()
-           << " flags=0x" << std::hex << flags
+           << " flags=" << flags
            << dendl;
 
   /* trim caps of sessions with the most caps first */
   std::multimap<uint64_t, Session*> caps_session;
-  auto f = [&caps_session, enforce_max, max_caps_per_client](auto& s) {
+  auto f = [&caps_session, enforce_max, trim, max_caps_per_client](auto& s) {
     auto num_caps = s->caps.size();
-    if (!enforce_max || num_caps > max_caps_per_client) {
+    if (trim || (enforce_max && num_caps > max_caps_per_client)) {
       caps_session.emplace(std::piecewise_construct, std::forward_as_tuple(num_caps), std::forward_as_tuple(s));
     }
   };
diff --git a/src/mds/Server.h b/src/mds/Server.h
index a5296a0a430..5a3aec0b1ca 100644
--- a/src/mds/Server.h
+++ b/src/mds/Server.h
@@ -169,12 +169,13 @@ public:
   void reconnect_tick();
   void recover_filelocks(CInode *in, bufferlist locks, int64_t client);
 
-  enum RecallFlags {
+  enum class RecallFlags : uint64_t {
     NONE = 0,
     STEADY = (1<<0),
     ENFORCE_MAX = (1<<1),
+    TRIM = (1<<2),
   };
-  std::pair<bool, uint64_t> recall_client_state(MDSGatherBuilder* gather, enum RecallFlags=RecallFlags::NONE);
+  std::pair<bool, uint64_t> recall_client_state(MDSGatherBuilder* gather, RecallFlags=RecallFlags::NONE);
   void force_clients_readonly();
 
   // -- requests --
@@ -353,4 +354,21 @@ private:
   time last_recall_state;
 };
 
+static inline constexpr auto operator|(Server::RecallFlags a, Server::RecallFlags b) {
+  using T = std::underlying_type<Server::RecallFlags>::type;
+  return static_cast<Server::RecallFlags>(static_cast<T>(a) | static_cast<T>(b));
+}
+static inline constexpr auto operator&(Server::RecallFlags a, Server::RecallFlags b) {
+  using T = std::underlying_type<Server::RecallFlags>::type;
+  return static_cast<Server::RecallFlags>(static_cast<T>(a) & static_cast<T>(b));
+}
+static inline std::ostream& operator<<(std::ostream& os, const Server::RecallFlags& f) {
+  using T = std::underlying_type<Server::RecallFlags>::type;
+  return os << "0x" << std::hex << static_cast<T>(f) << std::dec;
+}
+static inline constexpr bool operator!(const Server::RecallFlags& f) {
+  using T = std::underlying_type<Server::RecallFlags>::type;
+  return static_cast<T>(f) == static_cast<T>(0);
+}
+
 #endif
-- 
2.39.5