From 1bb65373dfbb3ad1a4d76c5b58cfb855608648f8 Mon Sep 17 00:00:00 2001
From: Mike Ryan <mike.ryan@inktank.com>
Date: Wed, 31 Oct 2012 11:36:49 -0700
Subject: [PATCH] PG: requeue snap_trimmer after scrub finishes

Previously the snap_trimmer would continuously requeue itself until the
end of scrub. This degrades performance and fills up logs for No Good
Reason.

Signed-off-by: Mike Ryan <mike.ryan@inktank.com>
---
 src/osd/PG.cc           | 5 +++++
 src/osd/PG.h            | 6 ++++--
 src/osd/ReplicatedPG.cc | 7 ++++---
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/osd/PG.cc b/src/osd/PG.cc
index 1e66d93b303..ec9a495074b 100644
--- a/src/osd/PG.cc
+++ b/src/osd/PG.cc
@@ -3743,6 +3743,11 @@ void PG::scrub_clear_state()
 
   requeue_ops(waiting_for_active);
 
+  if (scrubber.queue_snap_trim) {
+    dout(10) << "scrub finished, requeuing snap_trimmer" << dendl;
+    queue_snap_trim();
+  }
+
   scrubber.reset();
 
   // type-specific state clear
diff --git a/src/osd/PG.h b/src/osd/PG.h
index cf0173352da..15a00610731 100644
--- a/src/osd/PG.h
+++ b/src/osd/PG.h
@@ -791,8 +791,8 @@ public:
     Scrubber() :
       reserved(false), reserve_failed(false),
       epoch_start(0),
-      block_writes(false), active(false), waiting_on(0),
-      errors(0), fixed(0), active_rep_scrub(0),
+      block_writes(false), active(false), queue_snap_trim(false),
+      waiting_on(0), errors(0), fixed(0), active_rep_scrub(0),
       finalizing(false), is_chunky(false), state(INACTIVE),
       deep(false)
     {
@@ -806,6 +806,7 @@ public:
     // common to both scrubs
     bool block_writes;
     bool active;
+    bool queue_snap_trim;
     int waiting_on;
     set<int> waiting_on_whom;
     int errors;
@@ -860,6 +861,7 @@ public:
       finalizing = false;
       block_writes = false;
       active = false;
+      queue_snap_trim = false;
       waiting_on = 0;
       waiting_on_whom.clear();
       if (active_rep_scrub) {
diff --git a/src/osd/ReplicatedPG.cc b/src/osd/ReplicatedPG.cc
index 5763c43d985..c7225f5aa90 100644
--- a/src/osd/ReplicatedPG.cc
+++ b/src/osd/ReplicatedPG.cc
@@ -1468,9 +1468,10 @@ void ReplicatedPG::snap_trimmer()
   dout(10) << "snap_trimmer entry" << dendl;
   if (is_primary()) {
     entity_inst_t nobody;
-    if (!mode.try_write(nobody) || scrubber.active) {
-      dout(10) << " can't write, requeueing" << dendl;
-      queue_snap_trim();
+    assert(mode.try_write(nobody));
+    if (scrubber.active) {
+      dout(10) << " scrubbing, will requeue snap_trimmer after" << dendl;
+      scrubber.queue_snap_trim = true;
       unlock();
       return;
     }