mds/FSMap: assign v16.2.4 compat to pre-v16.2.5 standby daemons

With v16.2.5, the monitors store an MDS's CompatSet with its mds_info_t
in the MDSMap. If an older MDS fails and rejoins the cluster, it gets
assigned the empty CompatSet. This is problematic during upgrades as an
MDS failure may prevent the upgrade process from continuing and cause
file system unavailability.

This patch makes it so the mons will assign a reasonable default: a
CompatSet used since v14.2.0 until v16.2.5.

Fixes: https://tracker.ceph.com/issues/53150
Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>

diff --git a/src/mds/FSMap.cc b/src/mds/FSMap.cc
index e258cc139ada41a2b684299f83c355f8d1ea5aec..6a5b84b91e478ce81e068d7255357ab73f92accd 100644 (file)
--- a/src/mds/FSMap.cc
+++ b/src/mds/FSMap.cc
@@ -1054,10 +1054,18 @@ bool FSMap::undamaged(const fs_cluster_id_t fscid, const mds_rank_t rank)
 
 void FSMap::insert(const MDSMap::mds_info_t &new_info)
 {
+  static const CompatSet empty;
+
   ceph_assert(new_info.state == MDSMap::STATE_STANDBY);
   ceph_assert(new_info.rank == MDS_RANK_NONE);
   mds_roles[new_info.global_id] = FS_CLUSTER_ID_NONE;
-  standby_daemons[new_info.global_id] = new_info;
+  auto& info = standby_daemons[new_info.global_id];
+  info = new_info;
+  if (empty.compare(info.compat) == 0) {
+    // bootstrap old compat: boot beacon contains empty compat on old (v16.2.4
+    // or older) MDS.
+    info.compat = MDSMap::get_compat_set_v16_2_4();
+  }
   standby_epochs[new_info.global_id] = epoch;
 }
 

diff --git a/src/mds/MDSMap.cc b/src/mds/MDSMap.cc
index 956dff2d9303dd651a26a8c357aaabb390829a64..8aea8d01982548162260bf930e3126b795892a0b 100644 (file)
--- a/src/mds/MDSMap.cc
+++ b/src/mds/MDSMap.cc
@@ -83,6 +83,23 @@ CompatSet MDSMap::get_compat_set_base() {
   return CompatSet(feature_compat_base, feature_ro_compat_base, feature_incompat_base);
 }
 
+// pre-v16.2.5 CompatSet in MDS beacon
+CompatSet MDSMap::get_compat_set_v16_2_4() {
+  CompatSet::FeatureSet feature_compat;
+  CompatSet::FeatureSet feature_ro_compat;
+  CompatSet::FeatureSet feature_incompat;
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_BASE);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_CLIENTRANGES);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_FILELAYOUT);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_DIRINODE);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_ENCODING);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_OMAPDIRFRAG);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_NOANCHOR);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_FILE_LAYOUT_V2);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_SNAPREALM_V2);
+  return CompatSet(feature_compat, feature_ro_compat, feature_incompat);
+}
+
 void MDSMap::mds_info_t::dump(Formatter *f) const
 {
   f->dump_unsigned("gid", global_id);
@@ -638,6 +655,8 @@ void MDSMap::mds_info_t::decode(bufferlist::const_iterator& bl)
   }
   if (struct_v >= 10) {
     decode(compat, bl);
+  } else {
+    compat = MDSMap::get_compat_set_v16_2_4();
   }
   DECODE_FINISH(bl);
 }

diff --git a/src/mds/MDSMap.h b/src/mds/MDSMap.h
index 2b4021ba1f49260201aeb49980af0c7e88b8d1fa..b9f3c6cabe1ed29764f4c3c163707bcdafe2cbe6 100644 (file)
--- a/src/mds/MDSMap.h
+++ b/src/mds/MDSMap.h
@@ -168,6 +168,7 @@ public:
   static CompatSet get_compat_set_all();
   static CompatSet get_compat_set_default();
   static CompatSet get_compat_set_base(); // pre v0.20
+  static CompatSet get_compat_set_v16_2_4(); // pre-v16.2.5 CompatSet in MDS beacon
 
   static MDSMap create_null_mdsmap() {
     MDSMap null_map;