From 147f25a4547b98ae66b44f11c72e539e6648f2ba Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@newdream.net>
Date: Mon, 14 Sep 2009 15:34:47 -0700
Subject: [PATCH] mds: flush log in caller(s), not scatter_writebehind

Otherwise scatter_tick(), in particular, will call scatter_writebehind
a zillion times and generate lots of small log flushes.  Instead, flush
at the end of the whole tick.
---
 src/mds/Locker.cc  | 6 +++++-
 src/mds/journal.cc | 1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/mds/Locker.cc b/src/mds/Locker.cc
index 614994518bbb1..bb7ac65aab7f5 100644
--- a/src/mds/Locker.cc
+++ b/src/mds/Locker.cc
@@ -487,6 +487,7 @@ void Locker::eval_gather(SimpleLock *lock, bool first, bool *need_issue)
 
       if (lock->is_updated()) {
 	scatter_writebehind((ScatterLock*)lock);
+	mds->mdlog->flush();
 	return;
       }
       
@@ -2562,6 +2563,7 @@ bool Locker::simple_sync(SimpleLock *lock, bool *need_issue)
     if (!gather && lock->is_updated()) {
       lock->get_parent()->auth_pin(lock);
       scatter_writebehind((ScatterLock*)lock);
+      mds->mdlog->flush();
       return false;
     }
 
@@ -2685,6 +2687,7 @@ void Locker::simple_lock(SimpleLock *lock, bool *need_issue)
   if (!gather && lock->is_updated()) {
     lock->get_parent()->auth_pin(lock);
     scatter_writebehind((ScatterLock*)lock);
+    mds->mdlog->flush();
     return;
   }
 
@@ -2824,7 +2827,6 @@ void Locker::scatter_writebehind(ScatterLock *lock)
   
   mds->mdlog->submit_entry(le);
   mds->mdlog->wait_for_sync(new C_Locker_ScatterWB(this, lock, mut));
-  mds->mdlog->flush();
 }
 
 void Locker::scatter_writebehind_finish(ScatterLock *lock, Mutation *mut)
@@ -3003,6 +3005,7 @@ void Locker::scatter_tick()
     updated_scatterlocks.pop_front();
     scatter_nudge(lock, 0);
   }
+  mds->mdlog->flush();
 }
 
 
@@ -3543,6 +3546,7 @@ void Locker::handle_file_lock(ScatterLock *lock, MLock *m)
       dout(7) << "handle_file_lock trying nudge on " << *lock
 	      << " on " << *lock->get_parent() << dendl;
       scatter_nudge(lock, 0);
+      mds->mdlog->flush();
     } else {
       dout(7) << "handle_file_lock IGNORING nudge on non-auth " << *lock
 	      << " on " << *lock->get_parent() << dendl;
diff --git a/src/mds/journal.cc b/src/mds/journal.cc
index 2cb4750c0e1fa..4112be7202e48 100644
--- a/src/mds/journal.cc
+++ b/src/mds/journal.cc
@@ -273,6 +273,7 @@ C_Gather *LogSegment::try_to_expire(MDS *mds)
 
   if (gather) {
     dout(6) << "LogSegment(" << offset << ").try_to_expire waiting" << dendl;
+    mds->mdlog->flush();
   } else {
     dout(6) << "LogSegment(" << offset << ").try_to_expire success" << dendl;
   }
-- 
2.39.5