Revert "SERVER-38356 added functionality to forbid dropping the oplog, modified tests to get around Evergreen issue"

This reverts commit 58e4edb8237288f45f55cd8a59ea96a955489353.

5 files changed, 10 insertions, 106 deletions

diff --git a/jstests/auth/lib/commands_lib.js b/jstests/auth/lib/commands_lib.js
index c98964c5bfd..5d91ae32500 100644
--- a/jstests/auth/lib/commands_lib.js
+++ b/jstests/auth/lib/commands_lib.js
@@ -4230,22 +4230,10 @@ var authCommandsLib = {
           command: {insert: "oplog.rs", documents: [{ts: Timestamp()}]},
           skipSharded: true,
           setup: function(db) {
-              load("jstests/libs/storage_engine_utils.js");
-              if (!db.getCollectionNames().includes("oplog.rs")) {
-                  assert.commandWorked(
-                      db.runCommand({create: "oplog.rs", capped: true, size: 10000}));
-              } else {
-                  if (storageEngineIsWiredTigerOrInMemory()) {
-                      assert.commandWorked(db.adminCommand({replSetResizeOplog: 1, size: 10000}));
-                  } else {
-                      assert.commandWorked(db.runCommand({drop: "oplog.rs"}));
-                      assert.commandWorked(
-                          db.runCommand({create: "oplog.rs", capped: true, size: 10000}));
-                  }
-              }
+              db.createCollection("oplog.rs", {capped: true, size: 10000});
           },
           teardown: function(db) {
-              assert.commandWorked(db.oplog.rs.runCommand('emptycapped'));
+              db.oplog.rs.drop();
           },
           testcases: [
               {
diff --git a/jstests/libs/storage_engine_utils.js b/jstests/libs/storage_engine_utils.js
deleted file mode 100644
index 7c6f2d1309e..00000000000
--- a/jstests/libs/storage_engine_utils.js
+++ /dev/null
@@ -1,12 +0,0 @@
-function storageEngineIsWiredTigerOrInMemory() {
-    // We assume that WiredTiger is the default storage engine, if the storage engine is
-    // unspecified in the test options.
-    return !jsTest.options().storageEngine || jsTest.options().storageEngine === "wiredTiger" ||
-        jsTest.options().storageEngine === "inMemory";
-}
-
-function storageEngineIsWiredTiger() {
-    // We assume that WiredTiger is the default storage engine, if the storage engine is
-    // unspecified in the test options.
-    return !jsTest.options().storageEngine || jsTest.options().storageEngine === "wiredTiger";
-}
\ No newline at end of file
diff --git a/jstests/noPassthroughWithMongod/query_oplogreplay.js b/jstests/noPassthroughWithMongod/query_oplogreplay.js
index 9b42f7ea705..c264e211ef6 100644
--- a/jstests/noPassthroughWithMongod/query_oplogreplay.js
+++ b/jstests/noPassthroughWithMongod/query_oplogreplay.js
@@ -5,28 +5,11 @@
     "use strict";
 
     load("jstests/libs/analyze_plan.js");
-    load("jstests/libs/storage_engine_utils.js");
 
     function test(t) {
-        const isOplog = t.getName().startsWith("oplog.");
-
-        if (storageEngineIsWiredTigerOrInMemory() && isOplog) {
-            // We forbid dropping the oplog when using the WiredTiger or in-memory storage engines
-            // and so we can't drop the oplog here. Because Evergreen reuses nodes for testing,
-            // the oplog may already exist on the test node; in this case, trying to create the
-            // oplog once again would fail.
-            // To ensure we are working with a clean oplog (an oplog without entries), we resort
-            // to truncating the oplog instead.
-            if (!t.getDB().getCollectionNames().includes(t.getName())) {
-                t.getDB().createCollection(t.getName(), {capped: true, size: 16 * 1024});
-            }
-            t.runCommand('emptycapped');
-            t.getDB().adminCommand({replSetResizeOplog: 1, size: 16 * 1024});
-        } else {
-            t.drop();
-            assert.commandWorked(
-                t.getDB().createCollection(t.getName(), {capped: true, size: 16 * 1024}));
-        }
+        t.drop();
+        assert.commandWorked(
+            t.getDB().createCollection(t.getName(), {capped: true, size: 16 * 1024}));
 
         /**
          * Helper function for making timestamps with the property that if i < j, then makeTS(i) <
diff --git a/jstests/replsets/drop_oplog_should_fail_if_storage_engine_supports_replSetResizeOplog_command.js b/jstests/replsets/drop_oplog_should_fail_if_storage_engine_supports_replSetResizeOplog_command.js
deleted file mode 100644
index 4ba1be0dbdc..00000000000
--- a/jstests/replsets/drop_oplog_should_fail_if_storage_engine_supports_replSetResizeOplog_command.js
+++ /dev/null
@@ -1,44 +0,0 @@
-/* Tests that dropping the oplog is forbidden on standalone nodes with storage engines
- * that support the command "replSetResizeOplog". The support for this command is
- * provided only by the WiredTiger storage engine.
- * Therefore, attempts to drop the oplog when using these storage engines should fail.
- * Also, nodes running in a replica set will forbid dropping the oplog, but
- * for a different reason.
- * Note: We detect whether a storage engine supports the replSetResizeOplog command
- * by checking whether it supportsRecoveryTimestamp().
- *
- * @tags: [requires_persistence]
- */
-
-(function() {
-    "use strict";
-
-    load("jstests/libs/storage_engine_utils.js");
-
-    const rt = new ReplSetTest({
-        name: "drop_oplog_should_fail_if_storage_engine_supports_replSetResizeOplog_command",
-        nodes: 1
-    });
-
-    // Start as a standalone node.
-    rt.start(0, {noReplSet: true});
-
-    let master = rt.getPrimary();
-    let localDB = master.getDB('local');
-
-    // Standalone nodes don't start with an oplog; create one. The size of the oplog doesn't
-    // matter. We are capping the oplog because some storage engines do not allow the creation
-    // of uncapped oplog collections.
-    assert.commandWorked(localDB.runCommand({create: 'oplog.rs', capped: true, size: 1000}));
-
-    if (storageEngineIsWiredTiger()) {
-        const ret = assert.commandFailed(localDB.runCommand({drop: 'oplog.rs'}));
-        assert.eq("can't drop oplog on storage engines that support replSetResizeOplog command",
-                  ret.errmsg);
-    } else {
-        assert.commandWorked(localDB.runCommand({drop: 'oplog.rs'}));
-    }
-
-    rt.stopSet();
-
-}());
\ No newline at end of file
diff --git a/src/mongo/db/commands/dbcommands.cpp b/src/mongo/db/commands/dbcommands.cpp
index 5f9628912c6..615f4fbe3c5 100644
--- a/src/mongo/db/commands/dbcommands.cpp
+++ b/src/mongo/db/commands/dbcommands.cpp
@@ -305,22 +305,11 @@ public:
             return false;
         }
 
-        if (nsToDrop.isOplog()) {
-            if (repl::ReplicationCoordinator::get(opCtx)->isReplEnabled()) {
-                errmsg = "can't drop live oplog while replicating";
-                return false;
-            }
-
-            auto storageEngine = opCtx->getServiceContext()->getStorageEngine();
-            invariant(storageEngine);
-            if (storageEngine->supportsRecoveryTimestamp()) {
-                // We use the method supportsRecoveryTimestamp() to detect whether we are using
-                // the WiredTiger storage engine, which is currently only storage engine that
-                // supports the replSetResizeOplog command.
-                errmsg =
-                    "can't drop oplog on storage engines that support replSetResizeOplog command";
-                return false;
-            }
+        if ((repl::ReplicationCoordinator::get(opCtx)->getReplicationMode() !=
+             repl::ReplicationCoordinator::modeNone) &&
+            nsToDrop.isOplog()) {
+            errmsg = "can't drop live oplog while replicating";
+            return false;
         }
 
         uassertStatusOK(