os/bluestore/BlueFS: compact log even when sync_metadata sees no work

It's possible that when sync_metadata() is called there won't be any new
log data to flush because it was already flushed for other reasons (e.g.,
because fsync was called).  However, the log may still be large and in
need of compaction.

Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/src/os/bluestore/BlueFS.cc b/src/os/bluestore/BlueFS.cc
index 36e883de7442fc355a9f12bea6b0fb3e2b3d5894..b94ae7651d4e6ebb663de4f7676368a787f23a1e 100644 (file)
--- a/src/os/bluestore/BlueFS.cc
+++ b/src/os/bluestore/BlueFS.cc
@@ -1882,18 +1882,21 @@ void BlueFS::sync_metadata()
   std::unique_lock<std::mutex> l(lock);
   if (log_t.empty()) {
     dout(10) << __func__ << " - no pending log events" << dendl;
-    return;
-  }
-  dout(10) << __func__ << dendl;
-  utime_t start = ceph_clock_now();
-  vector<interval_set<uint64_t>> to_release(pending_release.size());
-  to_release.swap(pending_release);
-  flush_bdev(); // FIXME?
-  _flush_and_sync_log(l);
-  for (unsigned i = 0; i < to_release.size(); ++i) {
-    for (auto p = to_release[i].begin(); p != to_release[i].end(); ++p) {
-      alloc[i]->release(p.get_start(), p.get_len());
+  } else {
+    dout(10) << __func__ << dendl;
+    utime_t start = ceph_clock_now();
+    vector<interval_set<uint64_t>> to_release(pending_release.size());
+    to_release.swap(pending_release);
+    flush_bdev(); // FIXME?
+    _flush_and_sync_log(l);
+    for (unsigned i = 0; i < to_release.size(); ++i) {
+      for (auto p = to_release[i].begin(); p != to_release[i].end(); ++p) {
+       alloc[i]->release(p.get_start(), p.get_len());
+      }
     }
+    utime_t end = ceph_clock_now();
+    utime_t dur = end - start;
+    dout(10) << __func__ << " done in " << dur << dendl;
   }
 
   if (_should_compact_log()) {
@@ -1903,10 +1906,6 @@ void BlueFS::sync_metadata()
       _compact_log_async(l);
     }
   }
-
-  utime_t end = ceph_clock_now();
-  utime_t dur = end - start;
-  dout(10) << __func__ << " done in " << dur << dendl;
 }
 
 int BlueFS::open_for_write(