From: Patrick Donnelly <pdonnell@redhat.com>
Date: Tue, 9 Jun 2020 23:49:20 +0000 (-0700)
Subject: mds: add maximum random ephemeral pin percentage
X-Git-Tag: v15.2.5~172^2~7
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=d5c905392ad6729e2551d700da52fa0a9e593dee;p=ceph.git

mds: add maximum random ephemeral pin percentage

This new config is designed to prevent creating too many subtrees from a
random ephemeral pinning policy.

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>
(cherry picked from commit c8d343d592de92af91c6f9eecb6aab0ebed54657)
---

diff --git a/src/common/options.cc b/src/common/options.cc
index c456ea173a8..c0941ceb503 100644
--- a/src/common/options.cc
+++ b/src/common/options.cc
@@ -7837,6 +7837,13 @@ std::vector<Option> get_mds_options() {
     .set_description("allow ephemeral random pinning of the loaded subtrees")
     .set_long_description("probabilistically pin the loaded directory inode and the subtree beneath it to an MDS based on the consistent hash of the inode number. The higher this value the more likely the loaded subtrees get pinned"),
 
+    Option("mds_export_ephemeral_random_max", Option::TYPE_FLOAT, Option::LEVEL_ADVANCED)
+    .set_default(0.01)
+    .set_flag(Option::FLAG_RUNTIME)
+    .set_description("the maximum percent permitted for random ephemeral pin policy")
+    .set_min_max(0.0, 1.0)
+    .add_see_also("mds_export_ephemeral_random"),
+
     Option("mds_export_ephemeral_distributed", Option::TYPE_BOOL, Option::LEVEL_ADVANCED)
     .set_default(false)
     .set_flag(Option::FLAG_RUNTIME)
diff --git a/src/mds/CInode.cc b/src/mds/CInode.cc
index e8b0b69e46f..f543fa730f6 100644
--- a/src/mds/CInode.cc
+++ b/src/mds/CInode.cc
@@ -5474,6 +5474,7 @@ double CInode::get_ephemeral_rand(bool inherit) const
    * have a parent yet.
    */
   const CInode *in = this;
+  double max = mdcache->export_ephemeral_random_max;
   while (true) {
     if (in->is_system())
       break;
@@ -5485,7 +5486,7 @@ double CInode::get_ephemeral_rand(bool inherit) const
       break;
 
     if (in->get_inode().export_ephemeral_random_pin > 0.0)
-      return in->get_inode().export_ephemeral_random_pin;
+      return std::min(in->get_inode().export_ephemeral_random_pin, max);
 
     /* An export_pin overrides only if no closer parent (incl. this one) has a
      * random pin set.
diff --git a/src/mds/MDCache.cc b/src/mds/MDCache.cc
index 6a9b314c92b..88eece19f00 100644
--- a/src/mds/MDCache.cc
+++ b/src/mds/MDCache.cc
@@ -155,6 +155,7 @@ MDCache::MDCache(MDSRank *m, PurgeQueue &purge_queue_) :
 
   export_ephemeral_distributed_config =  g_conf().get_val<bool>("mds_export_ephemeral_distributed");
   export_ephemeral_random_config =  g_conf().get_val<bool>("mds_export_ephemeral_random");
+  export_ephemeral_random_max = g_conf().get_val<double>("mds_export_ephemeral_random_max");
 
   lru.lru_set_midpoint(g_conf().get_val<double>("mds_cache_mid"));
 
@@ -243,6 +244,9 @@ void MDCache::handle_conf_change(const std::set<std::string>& changed, const MDS
     }
     mds->balancer->handle_export_pins();
   }
+  if (changed.count("mds_export_ephemeral_random_max")) {
+    export_ephemeral_random_max = g_conf().get_val<double>("mds_export_ephemeral_random_max");
+  }
   if (changed.count("mds_health_cache_threshold"))
     cache_health_threshold = g_conf().get_val<double>("mds_health_cache_threshold");
   if (changed.count("mds_cache_mid"))
diff --git a/src/mds/MDCache.h b/src/mds/MDCache.h
index 20f946c60ff..38fac4235db 100644
--- a/src/mds/MDCache.h
+++ b/src/mds/MDCache.h
@@ -1004,6 +1004,8 @@ class MDCache {
 
   OpenFileTable open_file_table;
 
+  double export_ephemeral_random_max = 0.0;
+
  protected:
   // track master requests whose slaves haven't acknowledged commit
   struct umaster {
diff --git a/src/mds/MDSRank.cc b/src/mds/MDSRank.cc
index 4b267319a6b..69e98db1c34 100644
--- a/src/mds/MDSRank.cc
+++ b/src/mds/MDSRank.cc
@@ -3525,6 +3525,7 @@ const char** MDSRankDispatcher::get_tracked_conf_keys() const
     "mds_dump_cache_threshold_formatter",
     "mds_enable_op_tracker",
     "mds_export_ephemeral_random",
+    "mds_export_ephemeral_random_max",
     "mds_export_ephemeral_distributed",
     "mds_health_cache_threshold",
     "mds_inject_migrator_session_race",
diff --git a/src/mds/Server.cc b/src/mds/Server.cc
index 2899031a880..d636646807d 100644
--- a/src/mds/Server.cc
+++ b/src/mds/Server.cc
@@ -5640,6 +5640,14 @@ void Server::handle_set_vxattr(MDRequestRef& mdr, CInode *cur)
       return;
     }
 
+    if (val < 0.0 || 1.0 < val) {
+      respond_to_request(mdr, -EDOM);
+      return;
+    } else if (mdcache->export_ephemeral_random_max < val) {
+      respond_to_request(mdr, -EINVAL);
+      return;
+    }
+
     if (!xlock_policylock(mdr, cur))
       return;