osd: release backoffs during merge

When we merge PGs, ensure that backoffs release messages are sent to
the client before the victim PG is destroyed.  This is /almost/ handled
by on_shutdown(), except that the shutdown code is aggressive about
tearing down backoff state in order to manage the PGRef lifecycle
carefully--and because in the shutdown (or normal PG/pool deletion) case
it doesn't matter what (if anything) we tell the client.

Fix this by simply queuing the backoff release prior to shutting down the
merge source PG.

An alternative appraoch would be to rejigger the PGRef release timing, but
that code is very fragile and this is a more targetted fix for this issue.
We might consider a more careful look in the future... or not!

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

diff --git a/src/osd/OSD.cc b/src/osd/OSD.cc
index 6b592ff85bfa314d216a16fe762fd976c52bb00e..591c019d969ea03887f340ea61feae8c3be228ae 100644 (file)
--- a/src/osd/OSD.cc
+++ b/src/osd/OSD.cc
@@ -8440,6 +8440,11 @@ bool OSD::advance_pg(
          pg->write_if_dirty(rctx);
          dispatch_context(rctx, pg, pg->get_osdmap(), &handle);
          pg->ch->flush();
+         // release backoffs explicitly, since the on_shutdown path
+         // aggressively tears down backoff state.
+         if (pg->is_primary()) {
+           pg->release_pg_backoffs();
+         }
          pg->on_shutdown();
          OSDShard *sdata = pg->osd_shard;
          {

diff --git a/src/osd/PG.h b/src/osd/PG.h
index 1ed490a0a9aff310aa29fae82ec45a05509e9636..d1d4b124144b759d9d12400f57b6a7dcaf48fc49 100644 (file)
--- a/src/osd/PG.h
+++ b/src/osd/PG.h
@@ -1085,11 +1085,13 @@ protected:
     hobject_t end = info.pgid.pgid.get_hobj_end(pool.info.get_pg_num());
     add_backoff(s, begin, end);
   }
+public:
   void release_pg_backoffs() {
     hobject_t begin = info.pgid.pgid.get_hobj_start();
     hobject_t end = info.pgid.pgid.get_hobj_end(pool.info.get_pg_num());
     release_backoffs(begin, end);
   }
+protected:
 
   // -- scrub --
 public: