mds: avoid scatter writebehind from predirty_*

predirty_journal_parents does wrlock_start with
nowait=true.  Make sure we don't then simple_lock if
lock->is_updated(), as that will call scatter_writebehind,
which will barf if a log event is currently open (which
it is in this case).

diff --git a/src/mds/Locker.cc b/src/mds/Locker.cc
index b3f29089f19aa7feae9b479f3f0414fea655d4b2..9f31eb461f414b0a4b4052ce332571b162ed0488 100644 (file)
--- a/src/mds/Locker.cc
+++ b/src/mds/Locker.cc
@@ -813,8 +813,11 @@ bool Locker::wrlock_start(SimpleLock *lock, MDRequest *mut, bool nowait)
     if (in->is_auth()) {
       if (want_scatter)
        file_mixed((ScatterLock*)lock);
-      else 
+      else {
+       if (nowait && lock->is_updated())
+         return false;   // don't do nested lock, as that may scatter_writebehind in simple_lock!
        simple_lock(lock);
+      }
 
       if (nowait && !lock->can_wrlock(client))
        return false;