os/bluestore: alert on fm/bdev size mismatch

Relates to: https://tracker.ceph.com/issues/39151

Signed-off-by: Igor Fedotov <ifedotov@suse.com>
(cherry picked from commit a3ab32e)

src/mon/PGMap.cc

@@ -2996,6 +2996,8 @@ void PGMap::get_health_checks(
 	summary = "BlueStore compression broken";
       } else if (asum.first == "BLUESTORE_LEGACY_STATFS") {
 	summary = "Legacy BlueStore stats reporting detected";
+      } else if (asum.first == "BLUESTORE_DISK_SIZE_MISMATCH") {
+	summary = "BlueStore has dangerous mismatch between block device and free list sizes";
       }
       summary += " on ";
       summary += stringify(asum.second.first);

src/os/bluestore/BlueStore.cc

@@ -4822,6 +4822,19 @@ int BlueStore::_open_fm(KeyValueDB::Transaction t)
     fm = NULL;
     return r;
   }
+  // if space size tracked by free list manager is that higher than actual
+  // dev size one can hit out-of-space allocation which will result
+  // in data loss and/or assertions
+  // Probably user altered the device size somehow.
+  // The only fix for now is to redeploy OSD.
+  if (fm->get_size() >= bdev->get_size() + min_alloc_size) {
+    ostringstream ss;
+    ss << "slow device size mismatch detected, "
+	<< " fm size(" << fm->get_size()
+	<< ") > slow device size(" << bdev->get_size()
+	<< "), Please stop using this OSD as it might cause data loss.";
+    _set_disk_size_mismatch_alert(ss.str());
+  }
   return 0;
 }
 
@@ -13803,6 +13816,11 @@ void BlueStore::_log_alerts(osd_alert_list_t& alerts)
 {
   std::lock_guard l(qlock);
 
+  if (!disk_size_mismatch_alert.empty()) {
+    alerts.emplace(
+      "BLUESTORE_DISK_SIZE_MISMATCH",
+      disk_size_mismatch_alert);
+  }
   if (!legacy_statfs_alert.empty()) {
     alerts.emplace(
       "BLUESTORE_LEGACY_STATFS",

src/os/bluestore/BlueStore.h

@@ -2698,6 +2698,7 @@ class BlueStore : public ObjectStore,
   set<string> failed_compressors;
   string spillover_alert;
   string legacy_statfs_alert;
+  string disk_size_mismatch_alert;
 
   void _log_alerts(osd_alert_list_t& alerts);
   bool _set_compression_alert(bool cmode, const char* s) {
@@ -2725,6 +2726,10 @@ class BlueStore : public ObjectStore,
   }
 
   void _check_legacy_statfs_alert();
+  void _set_disk_size_mismatch_alert(const string& s) {
+    std::lock_guard l(qlock);
+    disk_size_mismatch_alert = s;
+  }
 
 private: