mds: drain wrlocks before going from LOCK->SYNC in file_eval

This avoids excessive waits for the journal to flush on lock->sync
when a client request holds a wrlock.  There's no reason to hurry.. if
someone needs it sync we can to the transition then; otherwise, it'll
happen when the wrlock is dropped.

diff --git a/src/mds/Locker.cc b/src/mds/Locker.cc
index 0873a10fdc50c4ef6afd070e0402dd927662b1a5..3fae38eefc4490ef4bf874e053e445893e8885c2 100644 (file)
--- a/src/mds/Locker.cc
+++ b/src/mds/Locker.cc
@@ -3078,6 +3078,7 @@ void Locker::file_eval(ScatterLock *lock, bool *need_issue)
   
   // * -> sync?
   else if (lock->get_state() != LOCK_SYNC &&
+          !lock->is_wrlocked() &&   // drain wrlocks first!
           !in->filelock.is_waiter_for(SimpleLock::WAIT_WR) &&
           !(wanted & (CEPH_CAP_GWR|CEPH_CAP_GBUFFER)) &&
           !(in->get_state() == LOCK_MIX &&