sureshanaparti commented on code in PR #13877:
URL: https://github.com/apache/cloudstack/pull/13877#discussion_r4033613757
##########
plugins/backup/nas/src/main/java/org/apache/cloudstack/backup/NASBackupProvider.java:
##########
@@ -168,6 +208,330 @@ protected Host getVMHypervisorHost(VirtualMachine vm) {
return
resourceManager.findOneRandomRunningHostByHypervisor(Hypervisor.HypervisorType.KVM,
vm.getDataCenterId());
}
+ /**
+ * Returned by {@link #decideChain(VirtualMachine)} to describe the next
backup's place in
+ * the chain: full vs incremental, the bitmap name to create, and (for
incrementals) the
+ * parent bitmap and parent file path.
+ */
+ static final class ChainDecision {
+ final String mode; // "full" or "incremental"
+ final String bitmapNew;
+ final String bitmapParent; // null for full
+ // Per-volume parent backup file paths, one per current VM volume in
deviceId order.
+ // null/empty for full. Each volume needs its own parent file because
backup files
+ // are named after each volume's own UUID (root.<uuid>.qcow2 /
datadisk.<uuid>.qcow2).
+ final List<String> parentPaths;
+ final String chainId; // chain identifier this backup belongs
to
+ final int chainPosition; // 0 for full, N for the Nth incremental
in the chain
+
+ private ChainDecision(String mode, String bitmapNew, String
bitmapParent, List<String> parentPaths,
+ String chainId, int chainPosition) {
+ this.mode = mode;
+ this.bitmapNew = bitmapNew;
+ this.bitmapParent = bitmapParent;
+ this.parentPaths = parentPaths;
+ this.chainId = chainId;
+ this.chainPosition = chainPosition;
+ }
+
+ static ChainDecision fullStart(String bitmapName) {
+ return new ChainDecision(NASBackupChainKeys.TYPE_FULL, bitmapName,
null, null,
+ UUID.randomUUID().toString(), 0);
+ }
+
+ /**
+ * Decision used when the incremental feature is disabled: a plain
full backup that
+ * creates no bitmap and carries no chain identity, so nothing
chain/checkpoint-related
+ * is sent to the agent or persisted. Keeps the feature-off path
byte-for-byte legacy.
+ */
+ static ChainDecision legacyFull() {
+ return new ChainDecision(NASBackupChainKeys.TYPE_LEGACY_FULL,
null, null, null, null, 0);
+ }
+
+ static ChainDecision incremental(String bitmapNew, String
bitmapParent, List<String> parentPaths,
+ String chainId, int chainPosition) {
+ return new ChainDecision(NASBackupChainKeys.TYPE_INCREMENTAL,
bitmapNew, bitmapParent,
+ parentPaths, chainId, chainPosition);
+ }
+
+ boolean isIncremental() {
+ return NASBackupChainKeys.TYPE_INCREMENTAL.equals(mode);
+ }
+
+ boolean isLegacyFull() {
+ return NASBackupChainKeys.TYPE_LEGACY_FULL.equals(mode);
+ }
+ }
+
+ /**
+ * Decides whether the next backup for {@code vm} should be a fresh full
or an incremental
+ * appended to the existing chain. Stopped VMs are always full (libvirt
{@code backup-begin}
+ * requires a running QEMU process). The {@code nas.backup.full.every}
ConfigKey controls
+ * how many backups (full + incrementals) form one chain before a new full
is forced.
+ *
+ * <p>The decision is anchored on the VM's {@code
nas.active_checkpoint_id} detail, which
+ * records the bitmap that currently exists on the running QEMU. After a
restore that
+ * detail is cleared, so the next backup is automatically full — even
though there may be
+ * a more recent "last backup taken" row in the database. The decision
deliberately avoids
+ * relying on "last backup taken", because that row is misleading after a
restore.</p>
+ */
+ protected ChainDecision decideChain(VirtualMachine vm) {
+ // Master switch — when the operator disables incrementals at the zone
level the backup
+ // behaves exactly like the pre-incremental full-only path: no bitmap
is generated and no
+ // chain/checkpoint metadata is created, sent to the agent, or
persisted (legacy-full).
+ Boolean incrementalEnabled =
NASBackupIncrementalEnabled.valueIn(vm.getDataCenterId());
+ if (incrementalEnabled == null || !incrementalEnabled) {
+ return ChainDecision.legacyFull();
+ }
+
+ // Incremental backups rely on QEMU dirty bitmaps / libvirt
checkpoints, which only exist
+ // on file-based qcow2 storage. Storage such as Ceph-RBD and Linstor
cannot carry per-disk
+ // checkpoints, so a VM with any volume on such a pool must stay on
the full-only (legacy)
+ // path — otherwise an incremental attempt would fail or regress those
storages.
+ if (!allVolumesOnCheckpointCapableStorage(vm)) {
+ return ChainDecision.legacyFull();
+ }
+
+ final String newBitmap = "backup-" + System.currentTimeMillis() /
1000L;
+
+ // Stopped VMs cannot do incrementals — script will also fall back,
but we make the
+ // decision here so we register the right type up-front.
+ if (VirtualMachine.State.Stopped.equals(vm.getState())) {
+ return ChainDecision.fullStart(newBitmap);
+ }
+
+ Integer fullEvery = NASBackupFullEvery.valueIn(vm.getDataCenterId());
+ if (fullEvery == null || fullEvery <= 1) {
+ // Disabled or every-backup-is-full mode.
+ return ChainDecision.fullStart(newBitmap);
+ }
+
+ // 1. If the VM has no active_checkpoint_id, there is no bitmap on the
host to use as
+ // a parent. This is the case after restore (we clear it), after VM
was just assigned
+ // to the offering, or on the very first backup.
+ String activeCheckpoint = readVmActiveCheckpoint(vm.getId());
+ if (activeCheckpoint == null) {
+ return ChainDecision.fullStart(newBitmap);
+ }
+
+ // 2. The most-recent BackedUp backup is the only safe parent — after
restore the
+ // next backup is always a fresh full, so anything older has a
rotated-out bitmap.
+ // If the latest backup's bitmap doesn't match the VM's
active_checkpoint_id, the
+ // chain is broken: force a full.
+ Backup parent = findLatestBackedUpBackup(vm.getId());
+ if (parent == null || !activeCheckpoint.equals(readDetail(parent,
NASBackupChainKeys.BITMAP_NAME))) {
+ LOG.debug("VM {} latest backup does not match
active_checkpoint_id={} — forcing full",
+ vm.getInstanceName(), activeCheckpoint);
+ return ChainDecision.fullStart(newBitmap);
+ }
+
+ String parentChainId = readDetail(parent, NASBackupChainKeys.CHAIN_ID);
+ int parentChainPosition = chainPosition(parent);
+ if (parentChainId == null || parentChainPosition == Integer.MAX_VALUE)
{
+ return ChainDecision.fullStart(newBitmap);
+ }
+
+ // Force a fresh full when the chain has reached the configured length.
+ if (parentChainPosition + 1 >= fullEvery) {
+ return ChainDecision.fullStart(newBitmap);
+ }
+
+ // The script needs the parent backup's on-NAS file path PER VOLUME so
it can rebase
+ // each new qcow2 onto the matching parent. The paths are stored
relative to the NAS
+ // mount root — the script resolves them inside its mount session.
When alignment
+ // fails (volume count changed, etc.) compose returns null and we fall
back to full
+ // so we don't risk corrupting the chain.
+ List<String> parentPaths = composeParentBackupPaths(parent,
vm.getId());
+ if (parentPaths == null) {
+ LOG.debug("VM {} parent backup {} volume layout no longer matches
current VM — forcing full",
+ vm.getInstanceName(), parent.getUuid());
+ return ChainDecision.fullStart(newBitmap);
+ }
+ return ChainDecision.incremental(newBitmap, activeCheckpoint,
parentPaths,
+ parentChainId, parentChainPosition + 1);
+ }
+
+ /**
+ * Incremental backups require QEMU dirty bitmaps / libvirt checkpoints,
which are only
+ * possible on file-based qcow2 storage. Returns {@code true} only when
EVERY volume of the
+ * VM sits on HOST-scope local, {@code SharedMountPoint}, or {@code
NetworkFilesystem} (NFS)
+ * storage. Ceph-RBD, Linstor, and any other pool that cannot carry a
per-disk checkpoint
+ * make this return {@code false} so the caller falls back to the legacy
full-only path. A
+ * volume whose pool can no longer be resolved is treated as incapable
(safe default).
+ */
+ protected boolean allVolumesOnCheckpointCapableStorage(VirtualMachine vm) {
+ List<VolumeVO> volumes = volumeDao.findByInstance(vm.getId());
+ if (volumes == null) {
+ return true;
+ }
+ for (VolumeVO volume : volumes) {
+ StoragePoolVO pool =
primaryDataStoreDao.findById(volume.getPoolId());
+ if (pool == null) {
+ LOG.debug("VM {} volume {} has no resolvable storage pool —
forcing legacy full",
+ vm.getInstanceName(), volume.getUuid());
+ return false;
+ }
+ boolean checkpointCapable = ScopeType.HOST.equals(pool.getScope())
+ ||
Storage.StoragePoolType.SharedMountPoint.equals(pool.getPoolType())
+ ||
Storage.StoragePoolType.NetworkFilesystem.equals(pool.getPoolType());
+ if (!checkpointCapable) {
+ LOG.debug("VM {} volume {} is on {} (scope {}) which cannot
carry checkpoints — forcing legacy full",
+ vm.getInstanceName(), volume.getUuid(),
pool.getPoolType(), pool.getScope());
+ return false;
+ }
+ }
+ return true;
+ }
+
+ /**
+ * Read the {@code nas.active_checkpoint_id} VM detail. Returns {@code
null} when no detail
+ * exists (post-restore, first backup, or after explicit reset).
+ */
+ private String readVmActiveCheckpoint(long vmId) {
+ VMInstanceDetailVO d = vmInstanceDetailsDao.findDetail(vmId,
NASBackupChainKeys.VM_ACTIVE_CHECKPOINT_ID);
+ if (d == null) {
+ return null;
+ }
+ String v = d.getValue();
+ return (v == null || v.isEmpty()) ? null : v;
Review Comment:
```suggestion
return (StringUtils.isBlank(v)) ? null : v;
```
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