refactor(backups/IncrementalRemoteWriter): reuse parent path from checkBaseVdis

@xen-orchestra/backups/_runners/_vmRunners/IncrementalXapi.mjs

@@ -78,6 +78,18 @@ export const IncrementalXapi = class IncrementalXapiVmBackupRunner extends Abstr
       'writer.transfer()'
     )
 
+    // we want to control the uuid of the vhd in the chain
+    // and ensure they are correctly chained
+    await this._callWriters(
+      writer =>
+        writer.updateUuidAndChain({
+          isVhdDifferencing,
+          timestamp,
+          vdis: deltaExport.vdis,
+        }),
+      'writer.updateUuidAndChain()'
+    )
+
     this._baseVm = exportedVm
 
     if (baseVm !== undefined) {

@xen-orchestra/backups/_runners/_writers/IncrementalRemoteWriter.mjs

@@ -6,11 +6,10 @@ import { chainVhd, openVhd } from 'vhd-lib'
 import { createLogger } from '@xen-orchestra/log'
 import { decorateClass } from '@vates/decorate-with'
 import { defer } from 'golike-defer'
-import { dirname } from 'node:path'
+import { dirname, basename } from 'node:path'
 
 import { formatFilenameDate } from '../../_filenameDate.mjs'
 import { getOldEntries } from '../../_getOldEntries.mjs'
-import { TAG_BASE_DELTA } from '../../_incrementalVm.mjs'
 import { Task } from '../../Task.mjs'
 
 import { MixinRemoteWriter } from './_MixinRemoteWriter.mjs'
@@ -125,6 +124,44 @@ export class IncrementalRemoteWriter extends MixinRemoteWriter(AbstractIncrement
     }
   }
 
+  async updateUuidAndChain({ isVhdDifferencing, vdis }) {
+    assert.notStrictEqual(
+      this.#vhds,
+      undefined,
+      '_transfer must be called before updateUuidAndChain for incremental backups'
+    )
+
+    const parentVdiPaths = this.#parentVdiPaths
+    const { handler } = this._adapter
+    const vhds = this.#vhds
+    await asyncEach(Object.entries(vdis), async ([id, vdi]) => {
+      const isDifferencing = isVhdDifferencing[`${id}.vhd`]
+      const path = `${this._vmBackupDir}/${vhds[id]}`
+      if (isDifferencing) {
+        assert.notStrictEqual(
+          parentVdiPaths,
+          'checkbasevdi must be called before updateUuidAndChain for incremental backups'
+        )
+        const parentPath = parentVdiPaths[dirname(path)]
+        // we are in a incremental backup
+        // we already computed the chain in checkBaseVdis
+        assert.notStrictEqual(parentPath, undefined, 'A differential VHD must have a parent')
+        // forbid any kind of loop
+        assert.ok(basename(parentPath) < basename(path), `vhd must be sorted to be chained`)
+        await chainVhd(handler, parentPath, handler, path)
+      }
+
+      // set the correct UUID in the VHD if needed
+      await Disposable.use(openVhd(handler, path), async vhd => {
+        if (!vhd.footer.uuid.equals(packUuid(vdi.uuid))) {
+          vhd.footer.uuid = packUuid(vdi.uuid)
+          await vhd.readBlockAllocationTable() // required by writeFooter()
+          await vhd.writeFooter()
+        }
+      })
+    })
+  }
+
   async _deleteOldEntries() {
     const adapter = this._adapter
     const oldEntries = this._oldEntries
@@ -143,16 +180,10 @@ export class IncrementalRemoteWriter extends MixinRemoteWriter(AbstractIncrement
     const jobId = job.id
     const handler = adapter.handler
 
-    let metadataContent = await this._isAlreadyTransferred(timestamp)
-    if (metadataContent !== undefined) {
-      // skip backup while being vigilant to not stuck the forked stream
-      Task.info('This backup has already been transfered')
-      Object.values(deltaExport.streams).forEach(stream => stream.destroy())
-      return { size: 0 }
-    }
-
     const basename = formatFilenameDate(timestamp)
-    const vhds = mapValues(
+    // update this.#vhds before eventually skipping transfer, so that
+    // updateUuidAndChain has all the mandatory data
+    const vhds = (this.#vhds = mapValues(
       deltaExport.vdis,
       vdi =>
         `vdis/${jobId}/${
@@ -162,7 +193,15 @@ export class IncrementalRemoteWriter extends MixinRemoteWriter(AbstractIncrement
               vdi.uuid
             : vdi.$snapshot_of$uuid
         }/${adapter.getVhdFileName(basename)}`
-    )
+    ))
+
+    let metadataContent = await this._isAlreadyTransferred(timestamp)
+    if (metadataContent !== undefined) {
+      // skip backup while being vigilant to not stuck the forked stream
+      Task.info('This backup has already been transfered')
+      Object.values(deltaExport.streams).forEach(stream => stream.destroy())
+      return { size: 0 }
+    }
 
     metadataContent = {
       isVhdDifferencing,
@@ -178,38 +217,13 @@ export class IncrementalRemoteWriter extends MixinRemoteWriter(AbstractIncrement
       vm,
       vmSnapshot,
     }
+
     const { size } = await Task.run({ name: 'transfer' }, async () => {
       let transferSize = 0
       await asyncEach(
-        Object.entries(deltaExport.vdis),
-        async ([id, vdi]) => {
+        Object.keys(deltaExport.vdis),
+        async id => {
           const path = `${this._vmBackupDir}/${vhds[id]}`
-
-          const isDifferencing = isVhdDifferencing[`${id}.vhd`]
-          let parentPath
-          if (isDifferencing) {
-            const vdiDir = dirname(path)
-            parentPath = (
-              await handler.list(vdiDir, {
-                filter: filename => filename[0] !== '.' && filename.endsWith('.vhd'),
-                prependDir: true,
-              })
-            )
-              .sort()
-              .pop()
-
-            assert.notStrictEqual(
-              parentPath,
-              undefined,
-              `missing parent of ${id} in ${dirname(path)}, looking for ${vdi.other_config[TAG_BASE_DELTA]}`
-            )
-
-            parentPath = parentPath.slice(1) // remove leading slash
-
-            // TODO remove when this has been done before the export
-            await checkVhd(handler, parentPath)
-          }
-
           // don't write it as transferSize += await async function
           // since i += await asyncFun lead to race condition
           // as explained : https://eslint.org/docs/latest/rules/require-atomic-updates
@@ -221,17 +235,6 @@ export class IncrementalRemoteWriter extends MixinRemoteWriter(AbstractIncrement
             writeBlockConcurrency: this._config.writeBlockConcurrency,
           })
           transferSize += transferSizeOneDisk
-
-          if (isDifferencing) {
-            await chainVhd(handler, parentPath, handler, path)
-          }
-
-          // set the correct UUID in the VHD
-          await Disposable.use(openVhd(handler, path), async vhd => {
-            vhd.footer.uuid = packUuid(vdi.uuid)
-            await vhd.readBlockAllocationTable() // required by writeFooter()
-            await vhd.writeFooter()
-          })
         },
         {
           concurrency: settings.diskPerVmConcurrency,

@xen-orchestra/backups/_runners/_writers/IncrementalXapiWriter.mjs

@@ -38,7 +38,9 @@ export class IncrementalXapiWriter extends MixinXapiWriter(AbstractIncrementalWr
       }
     }
   }
-
+  updateUuidAndChain() {
+    // nothing to do, the chaining is not modified in this case
+  }
   prepare({ isFull }) {
     // create the task related to this export and ensure all methods are called in this context
     const task = new Task({

@xen-orchestra/backups/_runners/_writers/_AbstractIncrementalWriter.mjs

@@ -5,6 +5,10 @@ export class AbstractIncrementalWriter extends AbstractWriter {
     throw new Error('Not implemented')
   }
 
+  updateUuidAndChain() {
+    throw new Error('Not implemented')
+  }
+
   cleanup() {
     throw new Error('Not implemented')
   }

@xen-orchestra/backups/docs/VM backups/README.md

@@ -230,6 +230,7 @@ Settings are described in [`@xen-orchestra/backups/\_runners/VmsXapi.mjs``](http
     - `checkBaseVdis(baseUuidToSrcVdi, baseVm)`
     - `prepare({ isFull })`
     - `transfer({ timestamp, deltaExport, sizeContainers })`
+    - `updateUuidAndChain({ isVhdDifferencing, vdis })`
     - `cleanup()`
     - `healthCheck()` // is not executed if no health check sr or tag doesn't match
   - **Full**