kvm: ref-count secondary storage pool usage (apache#9498)

If a secondary storage pool is used by e.g.
2 concurrent snapshot->template actions,
if the first action finished it removed the netfs mount
point for the other action.
Now the storage pools are usage ref-counted and will only
deleted if there are no more users.

Author: rp-

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/IscsiAdmStorageAdaptor.java

@@ -43,7 +43,7 @@ public class IscsiAdmStorageAdaptor implements StorageAdaptor {
     private static final Map<String, KVMStoragePool> MapStorageUuidToStoragePool = new HashMap<>();
 
     @Override
-    public KVMStoragePool createStoragePool(String uuid, String host, int port, String path, String userInfo, StoragePoolType storagePoolType, Map<String, String> details) {
+    public KVMStoragePool createStoragePool(String uuid, String host, int port, String path, String userInfo, StoragePoolType storagePoolType, Map<String, String> details, boolean isPrimaryStorage) {
         IscsiAdmStoragePool storagePool = new IscsiAdmStoragePool(uuid, host, port, storagePoolType, this);
 
         MapStorageUuidToStoragePool.put(uuid, storagePool);

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/KVMStoragePoolManager.java

@@ -389,7 +389,7 @@ public KVMStoragePool createStoragePool(String name, String host, int port, Stri
     //Note: due to bug CLOUDSTACK-4459, createStoragepool can be called in parallel, so need to be synced.
     private synchronized KVMStoragePool createStoragePool(String name, String host, int port, String path, String userInfo, StoragePoolType type, Map<String, String> details, boolean primaryStorage) {
         StorageAdaptor adaptor = getStorageAdaptor(type);
-        KVMStoragePool pool = adaptor.createStoragePool(name, host, port, path, userInfo, type, details);
+        KVMStoragePool pool = adaptor.createStoragePool(name, host, port, path, userInfo, type, details, primaryStorage);
 
         // LibvirtStorageAdaptor-specific statement
         if (type == StoragePoolType.NetworkFilesystem && primaryStorage) {

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/LibvirtStorageAdaptor.java

@@ -75,6 +75,7 @@
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Collectors;
 
 
@@ -83,6 +84,7 @@ public class LibvirtStorageAdaptor implements StorageAdaptor {
     private StorageLayer _storageLayer;
     private String _mountPoint = "/mnt";
     private String _manageSnapshotPath;
+    private static final ConcurrentHashMap<String, Integer> storagePoolRefCounts = new ConcurrentHashMap<>();
 
     private String rbdTemplateSnapName = "cloudstack-base-snap";
     private static final int RBD_FEATURE_LAYERING = 1;
@@ -684,8 +686,44 @@ public KVMPhysicalDisk getPhysicalDisk(String volumeUuid, KVMStoragePool pool) {
         }
     }
 
+    /**
+     * adjust refcount
+     */
+    private int adjustStoragePoolRefCount(String uuid, int adjustment) {
+        final String mutexKey = storagePoolRefCounts.keySet().stream()
+                .filter(k -> k.equals(uuid))
+                .findFirst()
+                .orElse(uuid);
+        synchronized (mutexKey) {
+            // some access on the storagePoolRefCounts.key(mutexKey) element
+            int refCount = storagePoolRefCounts.computeIfAbsent(mutexKey, k -> 0);
+            refCount += adjustment;
+            if (refCount < 1) {
+                storagePoolRefCounts.remove(mutexKey);
+            } else {
+                storagePoolRefCounts.put(mutexKey, refCount);
+            }
+            return refCount;
+        }
+    }
+    /**
+     * Thread-safe increment storage pool usage refcount
+     * @param uuid UUID of the storage pool to increment the count
+     */
+    private void incStoragePoolRefCount(String uuid) {
+        adjustStoragePoolRefCount(uuid, 1);
+    }
+    /**
+     * Thread-safe decrement storage pool usage refcount for the given uuid and return if storage pool still in use.
+     * @param uuid UUID of the storage pool to decrement the count
+     * @return true if the storage pool is still used, else false.
+     */
+    private boolean decStoragePoolRefCount(String uuid) {
+        return adjustStoragePoolRefCount(uuid, -1) > 0;
+    }
+
     @Override
-    public KVMStoragePool createStoragePool(String name, String host, int port, String path, String userInfo, StoragePoolType type, Map<String, String> details) {
+    public KVMStoragePool createStoragePool(String name, String host, int port, String path, String userInfo, StoragePoolType type, Map<String, String> details, boolean isPrimaryStorage) {
         logger.info("Attempting to create storage pool " + name + " (" + type.toString() + ") in libvirt");
 
         // gluefs mount script call
@@ -805,6 +843,12 @@ public KVMStoragePool createStoragePool(String name, String host, int port, Stri
         }
 
         try {
+            if (!isPrimaryStorage) {
+                // only ref count storage pools for secondary storage, as primary storage is assumed
+                // to be always mounted, as long the primary storage isn't fully deleted.
+                incStoragePoolRefCount(name);
+            }
+
             if (sp.isActive() == 0) {
                 logger.debug("Attempting to activate pool " + name);
                 sp.create(0);
@@ -816,6 +860,7 @@ public KVMStoragePool createStoragePool(String name, String host, int port, Stri
 
             return getStoragePool(name);
         } catch (LibvirtException e) {
+            decStoragePoolRefCount(name);
             String error = e.toString();
             if (error.contains("Storage source conflict")) {
                 throw new CloudRuntimeException("A pool matching this location already exists in libvirt, " +
@@ -866,7 +911,14 @@ private boolean destroyStoragePoolHandleException(Connect conn, String uuid)
     @Override
     public boolean deleteStoragePool(String uuid) {
         logger.info("Attempting to remove storage pool " + uuid + " from libvirt");
-        Connect conn = null;
+
+        // decrement and check if storage pool still in use
+        if (decStoragePoolRefCount(uuid)) {
+            s_logger.info(String.format("deleteStoragePool: Storage pool %s still in use", uuid));
+            return true;
+        }
+
+        Connect conn;
         try {
             conn = LibvirtConnection.getConnection();
         } catch (LibvirtException e) {

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/ManagedNfsStorageAdaptor.java

@@ -56,7 +56,7 @@ public ManagedNfsStorageAdaptor(StorageLayer storagelayer) {
     }
 
     @Override
-    public KVMStoragePool createStoragePool(String uuid, String host, int port, String path, String userInfo, StoragePoolType storagePoolType, Map<String, String> details) {
+    public KVMStoragePool createStoragePool(String uuid, String host, int port, String path, String userInfo, StoragePoolType storagePoolType, Map<String, String> details, boolean isPrimaryStorage) {
 
         LibvirtStoragePool storagePool = new LibvirtStoragePool(uuid, path, StoragePoolType.ManagedNFS, this, null);
         storagePool.setSourceHost(host);

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/MultipathSCSIAdapterBase.java

@@ -169,7 +169,7 @@ private KVMPhysicalDisk getPhysicalDisk(AddressInfo address, KVMStoragePool pool
     }
 
     @Override
-    public KVMStoragePool createStoragePool(String uuid, String host, int port, String path, String userInfo, Storage.StoragePoolType type, Map<String, String> details) {
+    public KVMStoragePool createStoragePool(String uuid, String host, int port, String path, String userInfo, Storage.StoragePoolType type, Map<String, String> details, boolean isPrimaryStorage) {
         LOGGER.info(String.format("createStoragePool(uuid,host,port,path,type) called with args (%s, %s, %s, %s, %s)", uuid, host, ""+port, path, type));
         MultipathSCSIPool storagePool = new MultipathSCSIPool(uuid, host, port, path, type, details, this);
         MapStorageUuidToStoragePool.put(uuid, storagePool);

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/ScaleIOStorageAdaptor.java

@@ -146,7 +146,7 @@ public KVMPhysicalDisk getPhysicalDisk(String volumePath, KVMStoragePool pool) {
     }
 
     @Override
-    public KVMStoragePool createStoragePool(String uuid, String host, int port, String path, String userInfo, Storage.StoragePoolType type, Map<String, String> details) {
+    public KVMStoragePool createStoragePool(String uuid, String host, int port, String path, String userInfo, Storage.StoragePoolType type, Map<String, String> details, boolean isPrimaryStorage) {
         ScaleIOStoragePool storagePool = new ScaleIOStoragePool(uuid, host, port, path, type, details, this);
         MapStorageUuidToStoragePool.put(uuid, storagePool);
         return storagePool;

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/StorageAdaptor.java

@@ -40,7 +40,7 @@ public interface StorageAdaptor {
     // it with info from local disk, and return it
     public KVMPhysicalDisk getPhysicalDisk(String volumeUuid, KVMStoragePool pool);
 
-    public KVMStoragePool createStoragePool(String name, String host, int port, String path, String userInfo, StoragePoolType type, Map<String, String> details);
+    public KVMStoragePool createStoragePool(String name, String host, int port, String path, String userInfo, StoragePoolType type, Map<String, String> details, boolean isPrimaryStorage);
 
     public boolean deleteStoragePool(String uuid);
 

plugins/hypervisors/kvm/src/test/java/com/cloud/hypervisor/kvm/storage/LibvirtStorageAdaptorTest.java

@@ -86,6 +86,6 @@ public void testCreateStoragePoolWithNFSMountOpts() throws Exception {
 
         Map<String, String> details = new HashMap<>();
         details.put("nfsmountopts", "vers=4.1, nconnect=4");
-        KVMStoragePool pool = libvirtStorageAdaptor.createStoragePool(uuid, null, 0, dir, null, Storage.StoragePoolType.NetworkFilesystem, details);
+        KVMStoragePool pool = libvirtStorageAdaptor.createStoragePool(uuid, null, 0, dir, null, Storage.StoragePoolType.NetworkFilesystem, details, true);
     }
 }

plugins/storage/volume/storpool/src/main/java/com/cloud/hypervisor/kvm/storage/StorPoolStorageAdaptor.java

@@ -57,7 +57,7 @@ public static void SP_LOG(String fmt, Object... args) {
     private static final Map<String, KVMStoragePool> storageUuidToStoragePool = new HashMap<String, KVMStoragePool>();
 
     @Override
-    public KVMStoragePool createStoragePool(String uuid, String host, int port, String path, String userInfo, StoragePoolType storagePoolType, Map<String, String> details) {
+    public KVMStoragePool createStoragePool(String uuid, String host, int port, String path, String userInfo, StoragePoolType storagePoolType, Map<String, String> details, boolean isPrimaryStorage) {
         SP_LOG("StorPoolStorageAdaptor.createStoragePool: uuid=%s, host=%s:%d, path=%s, userInfo=%s, type=%s", uuid, host, port, path, userInfo, storagePoolType);
 
         StorPoolStoragePool storagePool = new StorPoolStoragePool(uuid, host, port, storagePoolType, this);