[Backport] [2.x] Fixed the SnapshotsInProgress error during index deletion (#4570)

CHANGELOG.md

@@ -45,6 +45,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Fixed flaky test `ResourceAwareTasksTests.testTaskIdPersistsInThreadContext` ([#4484](https://github.com/opensearch-project/OpenSearch/pull/4484))
 - Fixed the ignore_malformed setting to also ignore objects ([#4494](https://github.com/opensearch-project/OpenSearch/pull/4494))
 - [Bug]: Fixed invalid location of JDK dependency for arm64 architecture([#4613](https://github.com/opensearch-project/OpenSearch/pull/4613))
+- Fixed the SnapshotsInProgress error during index deletion ([#4570](https://github.com/opensearch-project/OpenSearch/pull/4570))
 
 ### Security
 - CVE-2022-25857 org.yaml:snakeyaml DOS vulnerability ([#4341](https://github.com/opensearch-project/OpenSearch/pull/4341))

server/src/internalClusterTest/java/org/opensearch/snapshots/DedicatedClusterSnapshotRestoreIT.java

@@ -1475,6 +1475,31 @@ public void testSnapshotDeleteRelocatingPrimaryIndex() throws Exception {
         logger.info("--> done");
     }
 
+    public void testIndexDeletionDuringSnapshotCreationInQueue() throws Exception {
+        assertAcked(prepareCreate("test-idx", 1, indexSettingsNoReplicas(1)));
+        ensureGreen();
+        indexRandomDocs("test-idx", 100);
+        createRepository("test-repo", "fs");
+        createSnapshot("test-repo", "test-snap", Collections.singletonList("test-idx"));
+
+        logger.info("--> create snapshot to be deleted and then delete");
+        createSnapshot("test-repo", "test-snap-delete", Collections.singletonList("test-idx"));
+        clusterAdmin().prepareDeleteSnapshot("test-repo", "test-snap-delete").execute();
+
+        logger.info("--> create snapshot before index deletion during above snapshot deletion");
+        clusterAdmin().prepareCreateSnapshot("test-repo", "test-snap-2")
+            .setWaitForCompletion(false)
+            .setPartial(true)
+            .setIndices("test-idx")
+            .get();
+
+        logger.info("delete index during snapshot creation");
+        assertAcked(admin().indices().prepareDelete("test-idx"));
+
+        clusterAdmin().prepareRestoreSnapshot("test-repo", "test-snap").get();
+        ensureGreen("test-idx");
+    }
+
     private long calculateTotalFilesSize(List<Path> files) {
         return files.stream().mapToLong(f -> {
             try {

server/src/main/java/org/opensearch/snapshots/SnapshotsService.java

@@ -2965,8 +2965,14 @@ private SnapshotsInProgress updatedSnapshotsInProgress(ClusterState currentState
                                     updatedAssignmentsBuilder.put(shardId, updated);
                                 }
                             }
-                            snapshotEntries.add(entry.withStartedShards(updatedAssignmentsBuilder.build()));
+                            final SnapshotsInProgress.Entry updatedEntry = entry.withShardStates(updatedAssignmentsBuilder.build());
+                            snapshotEntries.add(updatedEntry);
                             changed = true;
+                            // When all the required shards for a snapshot are missing, the snapshot state will be "completed"
+                            // need to finalize it.
+                            if (updatedEntry.state().completed()) {
+                                newFinalizations.add(entry);
+                            }
                         }
                     } else {
                         // Entry is already completed so we will finalize it now that the delete doesn't block us after