filestore: don't start commit if nothing new is _applied_

We were starting a commit if we had started a new op, but that left a
window in which the op could be being journaled, and nothing new has been
applied to disk.  With this fix we only commit if committing/committed
will increase.  Now the check matches the

 committing_seq = applied_seq;

a few lines down, and all is well.

The actual crash this fixes was:

2010-10-07 16:20:36.245301 7f07e66d3710 filestore(/mnt/osd3) taking snap 'snap_23230'
2010-10-07 16:20:36.245428 7f07e66d3710 filestore(/mnt/osd3) snap create 'snap_23230' got -1 File exists
os/FileStore.cc: In function 'void FileStore::sync_entry()':
os/FileStore.cc:1738: FAILED assert(r == 0)
 ceph version 0.22~rc (1d77c14bc310aed31d6cfeb2c87e87187d3527ea)
 1: (FileStore::sync_entry()+0x6ee) [0x793148]
 2: (FileStore::SyncThread::entry()+0x19) [0x761d43]
 3: (Thread::_entry_func(void*)+0x20) [0x667822]
 4: (()+0x68ba) [0x7f07eac248ba]
 5: (clone()+0x6d) [0x7f07e9bd802d]

Signed-off-by: Sage Weil <sage@newdream.net>

diff --git a/src/os/JournalingObjectStore.cc b/src/os/JournalingObjectStore.cc
index c82dc3f91c545b822eedc18652d565f2022673cc..e152c08496984d7fc03449a5167de9ffa9da76d6 100644 (file)
--- a/src/os/JournalingObjectStore.cc
+++ b/src/os/JournalingObjectStore.cc
@@ -148,14 +148,16 @@ bool JournalingObjectStore::commit_start()
   // suspend new ops...
   Mutex::Locker l(lock);
 
-  dout(10) << "commit_start" << dendl;
+  dout(10) << "commit_start op_seq " << op_seq
+          << ", applied_seq " << applied_seq
+          << ", committed_seq " << committed_seq << dendl;
   blocked = true;
   while (open_ops > 0) {
     dout(10) << "commit_start blocked, waiting for " << open_ops << " open ops" << dendl;
     cond.Wait(lock);
   }
   
-  if (op_seq == committed_seq) {
+  if (applied_seq == committed_seq) {
     dout(10) << "commit_start nothing to do" << dendl;
     blocked = false;
     cond.Signal();