From 65b7143cd431ae251540560540b0ec2f53fd9fc7 Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@redhat.com>
Date: Wed, 3 Jul 2019 13:29:15 -0500
Subject: [PATCH] osd: store purged_snaps history under separate object

We can't put this in the snapmapper object because filestore does not
allow multiple concurrent omap iterators on the same object.  (This is a
limitation that could be fixed with some read/write locking, but not
without some significant changes to DBObjectMap; since that is old crufty
legacy code let's avoid touching it!)

Signed-off-by: Sage Weil <sage@redhat.com>
---
 src/osd/OSD.cc        | 15 ++++++++++++---
 src/osd/OSD.h         |  6 ++++++
 src/osd/SnapMapper.cc |  4 ++--
 src/osd/SnapMapper.h  | 13 ++++++++-----
 4 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/src/osd/OSD.cc b/src/osd/OSD.cc
index 650adc9ca26..92c96a213d5 100644
--- a/src/osd/OSD.cc
+++ b/src/osd/OSD.cc
@@ -2883,6 +2883,14 @@ int OSD::init()
     if (r < 0)
       goto out;
   }
+  if (!store->exists(service.meta_ch, OSD::make_purged_snaps_oid())) {
+    dout(10) << "init creating/touching purged_snaps object" << dendl;
+    ObjectStore::Transaction t;
+    t.touch(coll_t::meta(), OSD::make_purged_snaps_oid());
+    r = store->queue_transaction(service.meta_ch, std::move(t));
+    if (r < 0)
+      goto out;
+  }
 
   class_handler = new ClassHandler(cct);
   cls_initialize(class_handler);
@@ -5529,7 +5537,7 @@ void OSD::handle_get_purged_snaps_reply(MMonGetPurgedSnapsReply *m)
     goto out;
   }
   SnapMapper::record_purged_snaps(cct, store, service.meta_ch,
-				  make_snapmapper_oid(), &t,
+				  make_purged_snaps_oid(), &t,
 				  m->purged_snaps);
   superblock.purged_snaps_last = m->last;
   write_superblock(t);
@@ -6633,7 +6641,8 @@ void OSD::scrub_purged_snaps()
   dout(10) << __func__ << dendl;
   ceph_assert(ceph_mutex_is_locked(osd_lock));
   SnapMapper::Scrubber s(cct, store, service.meta_ch,
-			 make_snapmapper_oid());
+			 make_snapmapper_oid(),
+			 make_purged_snaps_oid());
   clog->debug() << "purged_snaps scrub starts";
   osd_lock.unlock();
   s.run();
@@ -7812,7 +7821,7 @@ void OSD::handle_osd_map(MOSDMap *m)
   // record new purged_snaps
   if (superblock.purged_snaps_last == start - 1) {
     SnapMapper::record_purged_snaps(cct, store, service.meta_ch,
-				    make_snapmapper_oid(), &t,
+				    make_purged_snaps_oid(), &t,
 				    purged_snaps);
     superblock.purged_snaps_last = last;
   } else {
diff --git a/src/osd/OSD.h b/src/osd/OSD.h
index a64f7e25ceb..431404453a8 100644
--- a/src/osd/OSD.h
+++ b/src/osd/OSD.h
@@ -1184,6 +1184,12 @@ public:
 	object_t("snapmapper"),
 	0)));
   }
+  static ghobject_t make_purged_snaps_oid() {
+    return ghobject_t(hobject_t(
+      sobject_t(
+	object_t("purged_snaps"),
+	0)));
+  }
 
   static ghobject_t make_pg_log_oid(spg_t pg) {
     stringstream ss;
diff --git a/src/osd/SnapMapper.cc b/src/osd/SnapMapper.cc
index 65a8dac0264..2e23f1e9375 100644
--- a/src/osd/SnapMapper.cc
+++ b/src/osd/SnapMapper.cc
@@ -586,11 +586,11 @@ void SnapMapper::Scrubber::run()
 
   _init();
 
-  psit = store->get_omap_iterator(ch, hoid);
+  psit = store->get_omap_iterator(ch, purged_snaps_hoid);
   psit->upper_bound(PURGED_SNAP_PREFIX);
   _parse_p();
 
-  mapit = store->get_omap_iterator(ch, hoid);
+  mapit = store->get_omap_iterator(ch, mapping_hoid);
   mapit->upper_bound(MAPPING_PREFIX);
 
   while (_parse_m()) {
diff --git a/src/osd/SnapMapper.h b/src/osd/SnapMapper.h
index 3228feb1b22..552f6a35b9a 100644
--- a/src/osd/SnapMapper.h
+++ b/src/osd/SnapMapper.h
@@ -142,7 +142,8 @@ public:
     CephContext *cct;
     ObjectStore *store;
     ObjectStore::CollectionHandle ch;
-    ghobject_t hoid;
+    ghobject_t mapping_hoid;
+    ghobject_t purged_snaps_hoid;
 
     ObjectMap::ObjectMapIterator psit;
     int64_t pool;
@@ -162,12 +163,13 @@ public:
       CephContext *cct,
       ObjectStore *store,
       ObjectStore::CollectionHandle& ch,
-      ghobject_t hoid)
+      ghobject_t mapping_hoid,
+      ghobject_t purged_snaps_hoid)
       : cct(cct),
 	store(store),
 	ch(ch),
-	hoid(hoid) {}
-
+	mapping_hoid(mapping_hoid),
+	purged_snaps_hoid(purged_snaps_hoid) {}
 
     void _init();
     void run();
@@ -191,7 +193,8 @@ public:
     CephContext *cct,
     ObjectStore *store,
     ObjectStore::CollectionHandle& ch,
-    ghobject_t hoid);
+    ghobject_t mapper_hoid,
+    ghobject_t purged_snaps_hoid);
 
 private:
   static int _lookup_purged_snap(
-- 
2.39.5