BF-532: Revert "SERVER-14668: Replace uses of DBWrite lock with DBLock"

This reverts commit ae333bc94a7d89d3220dcae9579fcaf68aa2e290.
This reverts commit 962f959a09b63aa0482d7e0c9bad89363d1e1194.

38 files changed, 127 insertions, 124 deletions

diff --git a/src/mongo/db/client.cpp b/src/mongo/db/client.cpp
index 812e062ede9..17901be98de 100644
--- a/src/mongo/db/client.cpp
+++ b/src/mongo/db/client.cpp
@@ -238,7 +238,7 @@ namespace mongo {
 
     Client::WriteContext::WriteContext(
                 OperationContext* opCtx, const std::string& ns, bool doVersion)
-        : _lk(opCtx->lockState(), nsToDatabaseSubstring(ns), newlm::MODE_X),
+        : _lk(opCtx->lockState(), ns),
           _wunit(opCtx),
           _c(opCtx, ns, doVersion) {
     }
diff --git a/src/mongo/db/client.h b/src/mongo/db/client.h
index 265b8439037..ef78f899154 100644
--- a/src/mongo/db/client.h
+++ b/src/mongo/db/client.h
@@ -204,7 +204,7 @@ namespace mongo {
             Context& ctx() { return _c; }
 
         private:
-            Lock::DBLock _lk;
+            Lock::DBWrite _lk;
             WriteUnitOfWork _wunit;
             Context _c;
         };
diff --git a/src/mongo/db/cloner.cpp b/src/mongo/db/cloner.cpp
index 67c76b071e9..1686cfe2c10 100644
--- a/src/mongo/db/cloner.cpp
+++ b/src/mongo/db/cloner.cpp
@@ -308,15 +308,15 @@ namespace mongo {
                                 bool logForRepl) {
 
         const NamespaceString nss(ns);
-        const string dbname = nss.db().toString();
+        Lock::DBWrite dbWrite(txn->lockState(), nss.db());
 
-        Lock::DBLock dbWrite(txn->lockState(), dbname, newlm::MODE_X);
+        const string dbName = nss.db().toString();
 
         bool unused;
-        Database* db = dbHolder().getOrCreate(txn, dbname, unused);
+        Database* db = dbHolder().getOrCreate(txn, dbName, unused);
 
         // config
-        string temp = dbname + ".system.namespaces";
+        string temp = dbName + ".system.namespaces";
         BSONObj config = _conn->findOne(temp , BSON("name" << ns));
         if (config["options"].isABSONObj()) {
             WriteUnitOfWork wunit(txn);
@@ -329,7 +329,7 @@ namespace mongo {
         }
 
         // main data
-        copy(txn, dbname,
+        copy(txn, dbName,
              nss, nss,
              logForRepl, false, true, mayYield, mayBeInterrupted,
              Query(query).snapshot());
@@ -340,7 +340,7 @@ namespace mongo {
         }
 
         // indexes
-        copyIndexes(txn, dbname,
+        copyIndexes(txn, dbName,
                     NamespaceString(ns), NamespaceString(ns),
                     logForRepl, false, true, mayYield,
                     mayBeInterrupted);
diff --git a/src/mongo/db/commands/apply_ops.cpp b/src/mongo/db/commands/apply_ops.cpp
index cc760412120..c0a1f398e56 100644
--- a/src/mongo/db/commands/apply_ops.cpp
+++ b/src/mongo/db/commands/apply_ops.cpp
@@ -126,26 +126,26 @@ namespace mongo {
 
                 string ns = temp["ns"].String();
 
-                // Run operations under a nested lock as a hack to prevent yielding.
+                // Run operations under a nested lock as a hack to prevent them from yielding.
                 //
-                // The list of operations is supposed to be applied atomically; yielding
-                // would break atomicity by allowing an interruption or a shutdown to occur
-                // after only some operations are applied.  We are already locked globally
-                // at this point, so taking a DBLock on the namespace creates a nested lock,
-                // and yields are disallowed for operations that hold a nested lock.
+                // The list of operations is supposed to be applied atomically; yielding would break
+                // atomicity by allowing an interruption or a shutdown to occur after only some
+                // operations are applied.  We are already locked globally at this point, so taking
+                // a DBWrite on the namespace creates a nested lock, and yields are disallowed for
+                // operations that hold a nested lock.
                 //
-                // We do not have a wrapping WriteUnitOfWork so it is possible for a journal
-                // commit to happen with a subset of ops applied.
+                // We do not have a wrapping WriteUnitOfWork so it is possible for a journal commit
+                // to happen with a subset of ops applied.
                 // TODO figure out what to do about this.
-                Lock::DBLock lk(txn->lockState(), nsToDatabaseSubstring(ns), newlm::MODE_X);
+                Lock::DBWrite lk(txn->lockState(), ns);
                 invariant(txn->lockState()->isRecursive());
 
                 Client::Context ctx(txn, ns);
                 bool failed = repl::applyOperation_inlock(txn,
-                                                          ctx.db(),
-                                                          temp,
-                                                          false,
-                                                          alwaysUpsert);
+                                                             ctx.db(),
+                                                             temp,
+                                                             false,
+                                                             alwaysUpsert);
                 ab.append(!failed);
                 if ( failed )
                     errors++;
diff --git a/src/mongo/db/commands/clone.cpp b/src/mongo/db/commands/clone.cpp
index 0b73001e559..a25deba9e32 100644
--- a/src/mongo/db/commands/clone.cpp
+++ b/src/mongo/db/commands/clone.cpp
@@ -115,7 +115,7 @@ namespace mongo {
 
             set<string> clonedColls;
 
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
 
             Cloner cloner;
             bool rval = cloner.go(txn, dbname, from, opts, &clonedColls, errmsg);
diff --git a/src/mongo/db/commands/collection_to_capped.cpp b/src/mongo/db/commands/collection_to_capped.cpp
index 24439e82b9b..2a4f60cee31 100644
--- a/src/mongo/db/commands/collection_to_capped.cpp
+++ b/src/mongo/db/commands/collection_to_capped.cpp
@@ -161,7 +161,7 @@ namespace mongo {
                 return false;
             }
 
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
             Client::Context ctx(txn, dbname);
 
             Status status = cloneCollectionAsCapped( txn, ctx.db(), from, to, size, temp, true );
diff --git a/src/mongo/db/commands/compact.cpp b/src/mongo/db/commands/compact.cpp
index 8ffac0bff38..5ed0ac16aca 100644
--- a/src/mongo/db/commands/compact.cpp
+++ b/src/mongo/db/commands/compact.cpp
@@ -97,7 +97,7 @@ namespace mongo {
                 return false;
             }
 
-            NamespaceString ns(db, coll);
+            NamespaceString ns(db,coll);
             if ( !ns.isNormal() ) {
                 errmsg = "bad namespace name";
                 return false;
@@ -144,7 +144,7 @@ namespace mongo {
                 compactOptions.validateDocuments = cmdObj["validate"].trueValue();
 
 
-            Lock::DBLock lk(txn->lockState(), db, newlm::MODE_X);
+            Lock::DBWrite lk(txn->lockState(), ns.ns());
             BackgroundOperation::assertNoBgOpInProgForNs(ns.ns());
             Client::Context ctx(txn, ns);
 
diff --git a/src/mongo/db/commands/copydb.cpp b/src/mongo/db/commands/copydb.cpp
index 58f733e02b0..208d792c59e 100644
--- a/src/mongo/db/commands/copydb.cpp
+++ b/src/mongo/db/commands/copydb.cpp
@@ -182,14 +182,15 @@ namespace mongo {
                 cloner.setConnection(conn);
             }
 
-            if (fromSelf) {
-                // SERVER-4328 todo lock just the two db's not everything for the fromself case
-                Lock::GlobalWrite lk(txn->lockState());
-                return cloner.go(txn, todb, fromhost, cloneOptions, NULL, errmsg);
-            }
 
-            Lock::DBLock lk (txn->lockState(), todb, newlm::MODE_X);
-            return cloner.go(txn, todb, fromhost, cloneOptions, NULL, errmsg);
+            // SERVER-4328 todo lock just the two db's not everything for the fromself case
+            scoped_ptr<Lock::ScopedLock> lk( fromSelf ?
+                                             static_cast<Lock::ScopedLock*>(new Lock::GlobalWrite(txn->lockState())) :
+                                             static_cast<Lock::ScopedLock*>(new Lock::DBWrite(txn->lockState(), todb)));
+            if (!cloner.go(txn, todb, fromhost, cloneOptions, NULL, errmsg )) {
+                return false;
+            }
+            return true;
         }
 
     } cmdCopyDB;
diff --git a/src/mongo/db/commands/cpuprofile.cpp b/src/mongo/db/commands/cpuprofile.cpp
index b1c81ca3584..884e43d0c29 100644
--- a/src/mongo/db/commands/cpuprofile.cpp
+++ b/src/mongo/db/commands/cpuprofile.cpp
@@ -133,7 +133,7 @@ namespace mongo {
                                            std::string &errmsg,
                                            BSONObjBuilder &result,
                                            bool fromRepl ) {
-            Lock::DBLock dbXLock(txn->lockState(), db, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), db);
             // The lock here is just to prevent concurrency, nothing will write.
             Client::Context ctx(txn, db);
 
@@ -152,7 +152,7 @@ namespace mongo {
                                           std::string &errmsg,
                                           BSONObjBuilder &result,
                                           bool fromRepl ) {
-            Lock::DBLock dbXLock(txn->lockState(), db, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), db);
             WriteUnitOfWork wunit(txn);
             Client::Context ctx(txn, db);
 
diff --git a/src/mongo/db/commands/create_indexes.cpp b/src/mongo/db/commands/create_indexes.cpp
index 2276c15c67d..58791dea990 100644
--- a/src/mongo/db/commands/create_indexes.cpp
+++ b/src/mongo/db/commands/create_indexes.cpp
@@ -134,7 +134,7 @@ namespace mongo {
 
             // now we know we have to create index(es)
             // Note: createIndexes command does not currently respect shard versioning.
-            Lock::DBLock lk(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite lk(txn->lockState(), ns.ns());
             Client::Context ctx(txn, ns.ns(), false /* doVersion */ );
             Database* db = ctx.db();
 
diff --git a/src/mongo/db/commands/drop_indexes.cpp b/src/mongo/db/commands/drop_indexes.cpp
index 122ed26cc9a..ba93d95bc54 100644
--- a/src/mongo/db/commands/drop_indexes.cpp
+++ b/src/mongo/db/commands/drop_indexes.cpp
@@ -103,7 +103,7 @@ namespace mongo {
 
         CmdDropIndexes() : Command("dropIndexes", false, "deleteIndexes") { }
         bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& anObjBuilder, bool fromRepl) {
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
             WriteUnitOfWork wunit(txn);
             bool ok = wrappedRun(txn, dbname, jsobj, errmsg, anObjBuilder);
             if (!ok) {
@@ -239,7 +239,7 @@ namespace mongo {
 
             LOG(0) << "CMD: reIndex " << toDeleteNs << endl;
 
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
             Client::Context ctx(txn, toDeleteNs);
 
             Collection* collection = ctx.db()->getCollection( txn, toDeleteNs );
diff --git a/src/mongo/db/commands/find_and_modify.cpp b/src/mongo/db/commands/find_and_modify.cpp
index 0e05feb5a71..4477e62bec0 100644
--- a/src/mongo/db/commands/find_and_modify.cpp
+++ b/src/mongo/db/commands/find_and_modify.cpp
@@ -97,7 +97,7 @@ namespace mongo {
                 return false;
             }
 
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
             Client::Context ctx(txn, ns);
             
             return runNoDirectClient( txn, ns , 
@@ -137,7 +137,7 @@ namespace mongo {
                                       BSONObjBuilder& result,
                                       string& errmsg) {
 
-            Lock::DBLock lk(txn->lockState(), nsToDatabaseSubstring(ns), newlm::MODE_X);
+            Lock::DBWrite lk(txn->lockState(), ns);
             WriteUnitOfWork wunit(txn);
             Client::Context cx(txn, ns);
             
@@ -335,7 +335,7 @@ namespace mongo {
                 }
             }
 
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
             WriteUnitOfWork wunit(txn);
             Client::Context ctx(txn, ns);
 
diff --git a/src/mongo/db/commands/mr.cpp b/src/mongo/db/commands/mr.cpp
index 81ed57a285d..e58e001a221 100644
--- a/src/mongo/db/commands/mr.cpp
+++ b/src/mongo/db/commands/mr.cpp
@@ -332,9 +332,7 @@ namespace mongo {
             if (_useIncremental) {
                 // We don't want to log the deletion of incLong as it isn't replicated. While
                 // harmless, this would lead to a scary looking warning on the secondaries.
-                Lock::DBLock lk(_txn->lockState(),
-                                nsToDatabaseSubstring(_config.incLong),
-                                newlm::MODE_X);
+                Lock::DBWrite lk(_txn->lockState(), _config.incLong);
                 if (Database* db = dbHolder().get(_txn, _config.incLong)) {
                     WriteUnitOfWork wunit(_txn);
                     db->dropCollection(_txn, _config.incLong);
@@ -593,11 +591,9 @@ namespace mongo {
                 op->setMessage("m/r: merge post processing",
                                "M/R Merge Post Processing Progress",
                                _safeCount(_db, _config.tempNamespace, BSONObj()));
-                auto_ptr<DBClientCursor> cursor = _db.query(_config.tempNamespace , BSONObj());
-                while (cursor->more()) {
-                    Lock::DBLock lock(_txn->lockState(),
-                                      nsToDatabaseSubstring(_config.outputOptions.finalNamespace),
-                                      newlm::MODE_X);
+                auto_ptr<DBClientCursor> cursor = _db.query( _config.tempNamespace , BSONObj() );
+                while ( cursor->more() ) {
+                    Lock::DBWrite lock(_txn->lockState(), _config.outputOptions.finalNamespace);
                     WriteUnitOfWork wunit(_txn);
                     BSONObj o = cursor->nextSafe();
                     Helpers::upsert( _txn, _config.outputOptions.finalNamespace , o );
@@ -1114,9 +1110,7 @@ namespace mongo {
             if ( ! _onDisk )
                 return;
 
-            Lock::DBLock kl(_txn->lockState(),
-                            nsToDatabaseSubstring(_config.incLong),
-                            newlm::MODE_X);
+            Lock::DBWrite kl(_txn->lockState(), _config.incLong);
             WriteUnitOfWork wunit(_txn);
 
             for ( InMemory::iterator i=_temp->begin(); i!=_temp->end(); i++ ) {
diff --git a/src/mongo/db/commands/test_commands.cpp b/src/mongo/db/commands/test_commands.cpp
index 204be07b75b..316d763babf 100644
--- a/src/mongo/db/commands/test_commands.cpp
+++ b/src/mongo/db/commands/test_commands.cpp
@@ -64,7 +64,7 @@ namespace mongo {
             string ns = dbname + "." + coll;
             BSONObj obj = cmdObj[ "obj" ].embeddedObjectUserCheck();
 
-            Lock::DBLock lk(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite lk(txn->lockState(), ns);
             WriteUnitOfWork wunit(txn);
             Client::Context ctx(txn,  ns );
             Database* db = ctx.db();
diff --git a/src/mongo/db/commands/write_commands/batch_executor.cpp b/src/mongo/db/commands/write_commands/batch_executor.cpp
index f5e372359b0..8b21578ce89 100644
--- a/src/mongo/db/commands/write_commands/batch_executor.cpp
+++ b/src/mongo/db/commands/write_commands/batch_executor.cpp
@@ -696,7 +696,7 @@ namespace mongo {
         /**
          * Gets the lock-holding object.  Only valid if hasLock().
          */
-        Lock::DBLock& getLock() { return *_writeLock; }
+        Lock::DBWrite& getLock() { return *_writeLock; }
 
         /**
          * Gets the target collection for the batch operation.  Value is undefined
@@ -721,7 +721,7 @@ namespace mongo {
         bool _lockAndCheckImpl(WriteOpResult* result);
 
         // Guard object for the write lock on the target database.
-        scoped_ptr<Lock::DBLock> _writeLock;
+        scoped_ptr<Lock::DBWrite> _writeLock;
 
         // Context object on the target database.  Must appear after writeLock, so that it is
         // destroyed in proper order.
@@ -919,9 +919,7 @@ namespace mongo {
         }
 
         invariant(!_context.get());
-        _writeLock.reset(new Lock::DBLock(txn->lockState(),
-                                          nsToDatabase(request->getNS()),
-                                          newlm::MODE_X));
+        _writeLock.reset(new Lock::DBWrite(txn->lockState(), request->getNS()));
         if (!checkIsMasterForDatabase(request->getNS(), result)) {
             return false;
         }
@@ -1126,7 +1124,7 @@ namespace mongo {
         }
 
         ///////////////////////////////////////////
-        Lock::DBLock writeLock(txn->lockState(), nsString.db(), newlm::MODE_X);
+        Lock::DBWrite writeLock(txn->lockState(), nsString.ns());
         ///////////////////////////////////////////
 
         if (!checkShardVersion(txn, &shardingState, *updateItem.getRequest(), result))
@@ -1181,7 +1179,7 @@ namespace mongo {
         }
 
         ///////////////////////////////////////////
-        Lock::DBLock writeLock(txn->lockState(), nss.db(), newlm::MODE_X);
+        Lock::DBWrite writeLock(txn->lockState(), nss.ns());
         ///////////////////////////////////////////
 
         // Check version once we're locked
diff --git a/src/mongo/db/concurrency/d_concurrency.cpp b/src/mongo/db/concurrency/d_concurrency.cpp
index 6701159a420..15e108a53f2 100644
--- a/src/mongo/db/concurrency/d_concurrency.cpp
+++ b/src/mongo/db/concurrency/d_concurrency.cpp
@@ -313,7 +313,7 @@ namespace {
         if (supportsDocLocking()) {
             _lockState->lock(_id, mode);
         }
-        else {
+        else if (isRead) {
             _lockState->lock(_id, isRead ? newlm::MODE_S : newlm::MODE_X);
         }
     }
@@ -322,6 +322,9 @@ namespace {
         _lockState->unlock(_id);
     }
 
+    Lock::DBWrite::DBWrite(Locker* lockState, const StringData& dbOrNs) :
+        DBLock(lockState, nsToDatabaseSubstring(dbOrNs), newlm::MODE_X) { }
+
     Lock::DBRead::DBRead(Locker* lockState, const StringData& dbOrNs) :
         DBLock(lockState, nsToDatabaseSubstring(dbOrNs), newlm::MODE_S) { }
 
diff --git a/src/mongo/db/concurrency/d_concurrency.h b/src/mongo/db/concurrency/d_concurrency.h
index a55eaa077f3..d4f11bb28d4 100644
--- a/src/mongo/db/concurrency/d_concurrency.h
+++ b/src/mongo/db/concurrency/d_concurrency.h
@@ -196,10 +196,9 @@ namespace mongo {
          *   MODE_S:  shared read access to the collection, blocking any writers
          *   MODE_X:  exclusive access to the collection, blocking all other readers and writers
          *
-         * An appropriate DBLock must already be held before locking a collection: it is an error,
-         * checked with a dassert(), to not have a suitable database lock before locking the
-         * collection. For storage engines that do not support document-level locking, MODE_IS
-         * will be upgraded to MODE_S and MODE_IX will be upgraded to MODE_X.
+         * An appropriate DBLock must already be held before locking a collection.
+         * For storage engines that do not support document-level locking, MODE_IS will be
+         * upgraded to MODE_S and MODE_IX will be upgraded to MODE_X.
          */
         class CollectionLock : boost::noncopyable {
         public:
@@ -211,6 +210,18 @@ namespace mongo {
         };
 
         /**
+         * Exclusive database lock -- DEPRECATED, please transition to DBLock and collection locks
+         *
+         * Allows exclusive write access to the given database, blocking any other access.
+         * Allows further (recursive) acquisition of database locks for this database in any mode.
+         * Also acquires the global lock in intent-exclusive (IX) mode.
+         */
+        class DBWrite : public DBLock {
+        public:
+            DBWrite(Locker* lockState, const StringData& dbOrNs);
+        };
+
+        /**
          * Shared database lock -- DEPRECATED, please transition to DBLock and collection locks
          *
          * Allows concurrent read access to the given database, blocking any writers.
diff --git a/src/mongo/db/concurrency/d_concurrency_test.cpp b/src/mongo/db/concurrency/d_concurrency_test.cpp
index ddc59b17bd7..3391eab52a7 100644
--- a/src/mongo/db/concurrency/d_concurrency_test.cpp
+++ b/src/mongo/db/concurrency/d_concurrency_test.cpp
@@ -133,10 +133,10 @@ namespace mongo {
         ASSERT(ls.getLockMode(resIdDb) == newlm::MODE_S);
     }
 
-    TEST(DConcurrency, DBLockTakesX) {
+    TEST(DConcurrency, DBWriteTakesX) {
         LockState ls;
 
-        Lock::DBLock dbWrite(&ls, "db", newlm::MODE_X);
+        Lock::DBWrite dbWrite(&ls, "db");
 
         const newlm::ResourceId resIdDb(newlm::RESOURCE_DATABASE, string("db"));
         ASSERT(ls.getLockMode(resIdDb) == newlm::MODE_X);
diff --git a/src/mongo/db/dbcommands.cpp b/src/mongo/db/dbcommands.cpp
index 793cb492604..4b7e698f1ed 100644
--- a/src/mongo/db/dbcommands.cpp
+++ b/src/mongo/db/dbcommands.cpp
@@ -349,7 +349,7 @@ namespace mongo {
             // Needs to be locked exclusively, because creates the system.profile collection
             // in the local database.
             //
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
             WriteUnitOfWork wunit(txn);
             Client::Context ctx(txn, dbname);
 
@@ -405,7 +405,7 @@ namespace mongo {
             // This doesn't look like it requires exclusive DB lock, because it uses its own diag
             // locking, but originally the lock was set to be WRITE, so preserving the behaviour.
             //
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
             Client::Context ctx(txn, dbname);
 
             int was = _diaglog.setLevel( cmdObj.firstElement().numberInt() );
@@ -461,7 +461,7 @@ namespace mongo {
                 return false;
             }
 
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
             WriteUnitOfWork wunit(txn);
             Client::Context ctx(txn, nsToDrop);
             Database* db = ctx.db();
@@ -561,7 +561,7 @@ namespace mongo {
                     !options["capped"].trueValue() || options["size"].isNumber() ||
                         options.hasField("$nExtents"));
 
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
             WriteUnitOfWork wunit(txn);
             Client::Context ctx(txn, ns);
 
@@ -987,7 +987,7 @@ namespace mongo {
         bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             const string ns = dbname + "." + jsobj.firstElement().valuestr();
 
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
             WriteUnitOfWork wunit(txn);
             Client::Context ctx(txn,  ns );
 
diff --git a/src/mongo/db/exec/stagedebug_cmd.cpp b/src/mongo/db/exec/stagedebug_cmd.cpp
index 9a86fe82da8..0f804e890ee 100644
--- a/src/mongo/db/exec/stagedebug_cmd.cpp
+++ b/src/mongo/db/exec/stagedebug_cmd.cpp
@@ -121,7 +121,7 @@ namespace mongo {
             // TODO A write lock is currently taken here to accommodate stages that perform writes
             //      (e.g. DeleteStage).  This should be changed to use a read lock for read-only
             //      execution trees.
-            Lock::DBLock lk(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite lk(txn->lockState(), dbname);
             Client::Context ctx(txn, dbname);
 
             // Make sure the collection is valid.
diff --git a/src/mongo/db/index_rebuilder.cpp b/src/mongo/db/index_rebuilder.cpp
index 8dd345de946..cbde00dbf04 100644
--- a/src/mongo/db/index_rebuilder.cpp
+++ b/src/mongo/db/index_rebuilder.cpp
@@ -64,7 +64,7 @@ namespace {
 
             // This write lock is held throughout the index building process
             // for this namespace.
-            Lock::DBLock lk(txn->lockState(), nsToDatabaseSubstring(ns), newlm::MODE_X);
+            Lock::DBWrite lk(txn->lockState(), ns);
             Client::Context ctx(txn, ns);
 
             Collection* collection = ctx.db()->getCollection(txn, ns);
diff --git a/src/mongo/db/instance.cpp b/src/mongo/db/instance.cpp
index 2d8b189edc3..dd37aaf5b1e 100644
--- a/src/mongo/db/instance.cpp
+++ b/src/mongo/db/instance.cpp
@@ -621,7 +621,7 @@ namespace mongo {
         UpdateExecutor executor(&request, &op.debug());
         uassertStatusOK(executor.prepare());
 
-        Lock::DBLock lk(txn->lockState(), ns.db(), newlm::MODE_X);
+        Lock::DBWrite lk(txn->lockState(), ns.ns());
         Client::Context ctx(txn,  ns );
 
         UpdateResult res = executor.execute(ctx.db());
@@ -655,7 +655,7 @@ namespace mongo {
         DeleteExecutor executor(&request);
         uassertStatusOK(executor.prepare());
 
-        Lock::DBLock lk(txn->lockState(), ns.db(), newlm::MODE_X);
+        Lock::DBWrite lk(txn->lockState(), ns.ns());
         Client::Context ctx(txn, ns);
 
         long long n = executor.execute(ctx.db());
@@ -914,7 +914,7 @@ namespace mongo {
             uassertStatusOK(status);
         }
 
-        Lock::DBLock lk(txn->lockState(), nsString.db(), newlm::MODE_X);
+        Lock::DBWrite lk(txn->lockState(), ns);
 
         // CONCURRENCY TODO: is being read locked in big log sufficient here?
         // writelock is used to synchronize stepdowns w/ writes
diff --git a/src/mongo/db/introspect.cpp b/src/mongo/db/introspect.cpp
index c84a1caafa0..c2f11b34e6d 100644
--- a/src/mongo/db/introspect.cpp
+++ b/src/mongo/db/introspect.cpp
@@ -135,11 +135,10 @@ namespace {
         BufBuilder profileBufBuilder(1024);
 
         try {
-            // NOTE: It's kind of weird that we lock the op's namespace, but have to for now
-            // since we're sometimes inside the lock already
-            const string dbname(nsToDatabase(currentOp.getNS()));
-            Lock::DBLock lk(txn->lockState(), dbname, newlm::MODE_X);
-            if (dbHolder().get(txn, dbname) != NULL) {
+            // NOTE: It's kind of weird that we lock the op's namespace, but have to for now since
+            // we're sometimes inside the lock already
+            Lock::DBWrite lk(txn->lockState(), currentOp.getNS() );
+            if (dbHolder().get(txn, nsToDatabase(currentOp.getNS())) != NULL) {
                 // We are ok with the profiling happening in a different WUOW from the actual op.
                 WriteUnitOfWork wunit(txn);
                 Client::Context cx(txn, currentOp.getNS(), false);
diff --git a/src/mongo/db/repl/minvalid.cpp b/src/mongo/db/repl/minvalid.cpp
index 30f1d17c18d..f2b0f4c189e 100644
--- a/src/mongo/db/repl/minvalid.cpp
+++ b/src/mongo/db/repl/minvalid.cpp
@@ -49,14 +49,14 @@ namespace {
 } // namespace
 
     void clearInitialSyncFlag(OperationContext* txn) {
-        Lock::DBLock lk(txn->lockState(), "local", newlm::MODE_X);
+        Lock::DBWrite lk(txn->lockState(), "local");
         WriteUnitOfWork wunit(txn);
         Helpers::putSingleton(txn, minvalidNS, BSON("$unset" << initialSyncFlag));
         wunit.commit();
     }
 
     void setInitialSyncFlag(OperationContext* txn) {
-        Lock::DBLock lk(txn->lockState(), "local", newlm::MODE_X);
+        Lock::DBWrite lk(txn->lockState(), "local");
         WriteUnitOfWork wunit(txn);
         Helpers::putSingleton(txn, minvalidNS, BSON("$set" << initialSyncFlag));
         wunit.commit();
@@ -73,7 +73,7 @@ namespace {
     }
 
     void setMinValid(OperationContext* ctx, OpTime ts) {
-        Lock::DBLock lk(ctx->lockState(), "local", newlm::MODE_X);
+        Lock::DBWrite lk(ctx->lockState(), "local");
         WriteUnitOfWork wunit(ctx);
         Helpers::putSingleton(ctx, minvalidNS, BSON("$set" << BSON("ts" << ts)));
         wunit.commit();
diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index bcc372ca86f..e13ede3039c 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -119,7 +119,7 @@ namespace repl {
         todo : make _logOpRS() call this so we don't repeat ourself?
         */
     OpTime _logOpObjRS(OperationContext* txn, const BSONObj& op) {
-        Lock::DBLock lk(txn->lockState(), "local", newlm::MODE_X);
+        Lock::DBWrite lk(txn->lockState(), "local");
         // XXX soon this needs to be part of an outer WUOW not its own.
         // We can't do this yet due to locking limitations.
         WriteUnitOfWork wunit(txn);
@@ -236,7 +236,7 @@ namespace repl {
                          BSONObj *o2,
                          bool *bb,
                          bool fromMigrate ) {
-        Lock::DBLock lk1(txn->lockState(), "local", newlm::MODE_X);
+        Lock::DBWrite lk1(txn->lockState(), "local");
         WriteUnitOfWork wunit(txn);
 
         if ( strncmp(ns, "local.", 6) == 0 ) {
@@ -320,7 +320,7 @@ namespace repl {
                           BSONObj *o2,
                           bool *bb,
                           bool fromMigrate ) {
-        Lock::DBLock lk(txn->lockState(), "local", newlm::MODE_X);
+        Lock::DBWrite lk(txn->lockState(), "local");
         WriteUnitOfWork wunit(txn);
         static BufBuilder bufbuilder(8*1024); // todo there is likely a mutex on this constructor
 
diff --git a/src/mongo/db/repl/repl_coordinator_external_state_impl.cpp b/src/mongo/db/repl/repl_coordinator_external_state_impl.cpp
index 9ec360369ab..69edf78b57f 100644
--- a/src/mongo/db/repl/repl_coordinator_external_state_impl.cpp
+++ b/src/mongo/db/repl/repl_coordinator_external_state_impl.cpp
@@ -56,9 +56,7 @@ namespace repl {
 namespace {
     // TODO: Change this to local.system.replset when we remove disable the hybrid coordinator.
     const char configCollectionName[] = "local.new.replset";
-    const char configDatabaseName[] = "local";
     const char meCollectionName[] = "local.me";
-    const char meDatabaseName[] = "local";
     const char tsFieldName[] = "ts";
 }  // namespace
 
@@ -90,7 +88,7 @@ namespace {
         std::string myname = getHostName();
         OID myRID;
         {
-            Lock::DBLock lock(txn->lockState(), meDatabaseName, newlm::MODE_X);
+            Lock::DBWrite lock(txn->lockState(), meCollectionName);
 
             BSONObj me;
             // local.me is an identifier for a server for getLastError w:2+
@@ -137,7 +135,7 @@ namespace {
             OperationContext* txn,
             const BSONObj& config) {
         try {
-            Lock::DBLock dbWriteLock(txn->lockState(), configDatabaseName, newlm::MODE_X);
+            Lock::DBWrite dbWriteLock(txn->lockState(), configCollectionName);
             Helpers::putSingleton(txn, configCollectionName, config);
             return Status::OK();
         }
diff --git a/src/mongo/db/repl/rs_initialsync.cpp b/src/mongo/db/repl/rs_initialsync.cpp
index 75b0bc6ecf9..74273a40ba2 100644
--- a/src/mongo/db/repl/rs_initialsync.cpp
+++ b/src/mongo/db/repl/rs_initialsync.cpp
@@ -84,7 +84,7 @@ namespace {
             options.syncIndexes = ! dataPass;
 
             // Make database stable
-            Lock::DBLock dbWrite(txn->lockState(), db, newlm::MODE_X);
+            Lock::DBWrite dbWrite(txn->lockState(), db);
 
             if (!cloner.go(txn, db, host, options, NULL, err, &errCode)) {
                 log() << "initial sync: error while "
diff --git a/src/mongo/db/repl/sync_tail.cpp b/src/mongo/db/repl/sync_tail.cpp
index 9cd57ae030c..20c99e289d9 100644
--- a/src/mongo/db/repl/sync_tail.cpp
+++ b/src/mongo/db/repl/sync_tail.cpp
@@ -123,7 +123,7 @@ namespace repl {
             lk.reset(new Lock::GlobalWrite(txn->lockState()));
         } else {
             // DB level lock for this operation
-            lk.reset(new Lock::DBLock(txn->lockState(), nsToDatabaseSubstring(ns), newlm::MODE_X));
+            lk.reset(new Lock::DBWrite(txn->lockState(), ns)); 
         }
 
         Client::Context ctx(txn, ns);
@@ -328,7 +328,7 @@ namespace {
                     BackgroundSync* bgsync = BackgroundSync::get();
                     if (bgsync->getInitialSyncRequestedFlag()) {
                         // got a resync command
-                        Lock::DBLock lk(txn.lockState(), "local", newlm::MODE_X);
+                        Lock::DBWrite lk(txn.lockState(), "local");
                         WriteUnitOfWork wunit(&txn);
                         Client::Context ctx(&txn, "local");
 
@@ -481,7 +481,7 @@ namespace {
         OpTime lastOpTime;
         {
             OperationContextImpl txn; // XXX?
-            Lock::DBLock lk(txn.lockState(), "local", newlm::MODE_X);
+            Lock::DBWrite lk(txn.lockState(), "local");
             WriteUnitOfWork wunit(&txn);
 
             while (!ops->empty()) {
diff --git a/src/mongo/dbtests/counttests.cpp b/src/mongo/dbtests/counttests.cpp
index fff985c5666..71cb99539d0 100644
--- a/src/mongo/dbtests/counttests.cpp
+++ b/src/mongo/dbtests/counttests.cpp
@@ -43,8 +43,7 @@ namespace CountTests {
 
     class Base {
     public:
-        Base() : lk(_txn.lockState(), nsToDatabaseSubstring(ns()), newlm::MODE_X),
-                 _wunit(&_txn), _context(&_txn, ns()) {
+        Base() : lk(_txn.lockState(), ns()), _wunit(&_txn), _context(&_txn, ns()) {
             _database = _context.db();
             _collection = _database->getCollection( &_txn, ns() );
             if ( _collection ) {
@@ -97,7 +96,7 @@ namespace CountTests {
         OperationContextImpl _txn;
 
     private:
-        Lock::DBLock lk;
+        Lock::DBWrite lk;
         WriteUnitOfWork _wunit;
 
         Client::Context _context;
diff --git a/src/mongo/dbtests/dbhelper_tests.cpp b/src/mongo/dbtests/dbhelper_tests.cpp
index 70ab52c878c..4801b711a1c 100644
--- a/src/mongo/dbtests/dbhelper_tests.cpp
+++ b/src/mongo/dbtests/dbhelper_tests.cpp
@@ -62,7 +62,7 @@ namespace mongo {
 
             {
                 // Remove _id range [_min, _max).
-                Lock::DBLock lk(txn.lockState(), nsToDatabaseSubstring(ns), newlm::MODE_X);
+                Lock::DBWrite lk(txn.lockState(), ns);
                 WriteUnitOfWork wunit(&txn);
                 Client::Context ctx(&txn,  ns );
 
diff --git a/src/mongo/dbtests/namespacetests.cpp b/src/mongo/dbtests/namespacetests.cpp
index aa6d7828629..72a27859efa 100644
--- a/src/mongo/dbtests/namespacetests.cpp
+++ b/src/mongo/dbtests/namespacetests.cpp
@@ -524,7 +524,7 @@ namespace NamespaceTests {
 
                 OperationContextImpl txn;
 
-                Lock::DBLock lk(txn.lockState(), dbName, newlm::MODE_X);
+                Lock::DBWrite lk(txn.lockState(), dbName);
 
                 bool justCreated;
                 Database* db = dbHolder().getOrCreate(&txn, dbName, justCreated);
@@ -567,7 +567,7 @@ namespace NamespaceTests {
 
                 OperationContextImpl txn;
 
-                Lock::DBLock lk(txn.lockState(), dbName, newlm::MODE_X);
+                Lock::DBWrite lk(txn.lockState(), dbName);
 
                 bool justCreated;
                 Database* db = dbHolder().getOrCreate(&txn, dbName, justCreated);
diff --git a/src/mongo/dbtests/querytests.cpp b/src/mongo/dbtests/querytests.cpp
index 598dad993d1..aaeaf6c6817 100644
--- a/src/mongo/dbtests/querytests.cpp
+++ b/src/mongo/dbtests/querytests.cpp
@@ -239,7 +239,7 @@ namespace QueryTests {
 
             {
                 // Check internal server handoff to getmore.
-                Lock::DBLock lk(_txn.lockState(), "unittests", newlm::MODE_X);
+                Lock::DBWrite lk(_txn.lockState(), ns);
                 WriteUnitOfWork wunit(&_txn);
                 Client::Context ctx(&_txn,  ns );
                 ClientCursorPin clientCursor( ctx.db()->getCollection(&_txn, ns), cursorId );
@@ -585,7 +585,7 @@ namespace QueryTests {
         }
         void run() {
             const char *ns = "unittests.querytests.OplogReplaySlaveReadTill";
-            Lock::DBLock lk(_txn.lockState(), "unittests", newlm::MODE_X);
+            Lock::DBWrite lk(_txn.lockState(), ns);
             WriteUnitOfWork wunit(&_txn);
             Client::Context ctx(&_txn,  ns );
 
@@ -1401,7 +1401,7 @@ namespace QueryTests {
     public:
         CollectionInternalBase( const char *nsLeaf ) :
           CollectionBase( nsLeaf ),
-          _lk(_txn.lockState(), "unittests", newlm::MODE_X),
+          _lk(_txn.lockState(), ns() ),
           _wunit( &_txn ),
           _ctx(&_txn, ns()) {
         }
@@ -1410,7 +1410,7 @@ namespace QueryTests {
         }
 
     private:
-        Lock::DBLock _lk;
+        Lock::DBWrite _lk;
         WriteUnitOfWork _wunit;
         Client::Context _ctx;
     };
diff --git a/src/mongo/dbtests/threadedtests.cpp b/src/mongo/dbtests/threadedtests.cpp
index 420c38f3d7f..797d1d72f6d 100644
--- a/src/mongo/dbtests/threadedtests.cpp
+++ b/src/mongo/dbtests/threadedtests.cpp
@@ -199,7 +199,7 @@ namespace ThreadedTests {
                                 Lock::DBRead x(&lockState, "local");
                             }
                             {
-                                Lock::DBLock x(&lockState, "local", newlm::MODE_X);
+                                Lock::DBWrite x(&lockState, "local");
                                 //  No actual writing here, so no WriteUnitOfWork
                                 if( sometimes ) {
                                     Lock::TempRelease t(&lockState);
@@ -211,11 +211,11 @@ namespace ThreadedTests {
                             }
 
                             { 
-                                Lock::DBLock x(&lockState, "admin", newlm::MODE_X);
+                                Lock::DBWrite x(&lockState, "admin"); 
                             }
                         }
                         else if( q == 3 ) {
-                            Lock::DBLock x(&lockState, "foo", newlm::MODE_X);
+                            Lock::DBWrite x(&lockState, "foo");
                             Lock::DBRead y(&lockState, "admin");
                         }
                         else if( q == 4 ) { 
@@ -223,7 +223,7 @@ namespace ThreadedTests {
                             Lock::DBRead y(&lockState, "admin");
                         }
                         else { 
-                            Lock::DBLock w(&lockState, "foo", newlm::MODE_X);
+                            Lock::DBWrite w(&lockState, "foo");
 
                             {
                                 Lock::TempRelease t(&lockState);
diff --git a/src/mongo/s/d_merge.cpp b/src/mongo/s/d_merge.cpp
index 9d1e728ac4f..a314f2161c7 100644
--- a/src/mongo/s/d_merge.cpp
+++ b/src/mongo/s/d_merge.cpp
@@ -293,7 +293,7 @@ namespace mongo {
         //
 
         {
-            Lock::DBLock writeLk(txn->lockState(), nss.db(), newlm::MODE_X);
+            Lock::DBWrite writeLk(txn->lockState(), nss.ns());
             shardingState.mergeChunks(txn, nss.ns(), minKey, maxKey, mergeVersion);
         }
 
diff --git a/src/mongo/s/d_migrate.cpp b/src/mongo/s/d_migrate.cpp
index 87b56cd89ca..7a22feb0a2a 100644
--- a/src/mongo/s/d_migrate.cpp
+++ b/src/mongo/s/d_migrate.cpp
@@ -1244,7 +1244,7 @@ namespace mongo {
                 myVersion.incMajor();
 
                 {
-                    Lock::DBLock lk(txn->lockState(), dbname, newlm::MODE_X);
+                    Lock::DBWrite lk(txn->lockState(), ns );
                     verify( myVersion > shardingState.getVersion( ns ) );
 
                     // bump the metadata's version up and "forget" about the chunk being moved
@@ -1658,7 +1658,7 @@ namespace mongo {
 
             if ( getState() != DONE ) {
                 // Unprotect the range if needed/possible on unsuccessful TO migration
-                Lock::DBLock lk(txn->lockState(), nsToDatabaseSubstring(ns), newlm::MODE_X);
+                Lock::DBWrite lk(txn->lockState(), ns);
                 string errMsg;
                 if (!shardingState.forgetPending(txn, ns, min, max, epoch, &errMsg)) {
                     warning() << errMsg << endl;
@@ -1716,7 +1716,7 @@ namespace mongo {
                     indexSpecs.insert(indexSpecs.begin(), indexes.begin(), indexes.end());
                 }
 
-                Lock::DBLock lk(txn->lockState(),  nsToDatabaseSubstring(ns), newlm::MODE_X);
+                Lock::DBWrite lk(txn->lockState(),  ns);
                 Client::Context ctx(txn,  ns);
                 Database* db = ctx.db();
                 Collection* collection = db->getCollection( txn, ns );
@@ -1801,7 +1801,7 @@ namespace mongo {
 
                 {
                     // Protect the range by noting that we're now starting a migration to it
-                    Lock::DBLock lk(txn->lockState(), nsToDatabaseSubstring(ns), newlm::MODE_X);
+                    Lock::DBWrite lk(txn->lockState(), ns);
                     if (!shardingState.notePending(txn, ns, min, max, epoch, &errmsg)) {
                         warning() << errmsg << endl;
                         setState(FAIL);
@@ -2101,7 +2101,7 @@ namespace mongo {
                         }
                     }
 
-                    Lock::DBLock lk(txn->lockState(), nsToDatabaseSubstring(ns), newlm::MODE_X);
+                    Lock::DBWrite lk(txn->lockState(), ns);
                     Client::Context ctx(txn, ns);
 
                     if (serverGlobalParams.moveParanoia) {
diff --git a/src/mongo/s/d_split.cpp b/src/mongo/s/d_split.cpp
index e718bf9db19..c5f6fe331a3 100644
--- a/src/mongo/s/d_split.cpp
+++ b/src/mongo/s/d_split.cpp
@@ -787,14 +787,14 @@ namespace mongo {
             //
             
             {
-                Lock::DBLock writeLk(txn->lockState(), dbname, newlm::MODE_X);
+                Lock::DBWrite writeLk(txn->lockState(), ns);
 
-                // NOTE: The newShardVersion resulting from this split is higher than any
-                // other chunk version, so it's also implicitly the newCollVersion
+                // NOTE: The newShardVersion resulting from this split is higher than any other
+                // chunk version, so it's also implicitly the newCollVersion
                 ChunkVersion newShardVersion = collVersion;
 
-                // Increment the minor version once, shardingState.splitChunk increments once
-                // per split point (resulting in the correct final shard/collection version)
+                // Increment the minor version once, shardingState.splitChunk increments once per
+                // split point (resulting in the correct final shard/collection version)
                 // TODO: Revisit this interface, it's a bit clunky
                 newShardVersion.incMinor();
 
diff --git a/src/mongo/s/d_state.cpp b/src/mongo/s/d_state.cpp
index 71340b94288..24928c69400 100644
--- a/src/mongo/s/d_state.cpp
+++ b/src/mongo/s/d_state.cpp
@@ -595,7 +595,7 @@ namespace mongo {
         {
             // DBLock needed since we're now potentially changing the metadata, and don't want
             // reads/writes to be ongoing.
-            Lock::DBLock writeLk(txn->lockState(), nsToDatabaseSubstring(ns), newlm::MODE_X);
+            Lock::DBWrite writeLk(txn->lockState(), ns );
 
             //
             // Get the metadata now that the load has completed
@@ -1298,7 +1298,7 @@ namespace mongo {
         }
 
         bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
-            Lock::DBLock dbXLock(txn->lockState(), dbname, newlm::MODE_X);
+            Lock::DBWrite dbXLock(txn->lockState(), dbname);
             Client::Context ctx(txn, dbname);
 
             shardingState.appendInfo( result );
diff --git a/src/mongo/s/metadata_loader.h b/src/mongo/s/metadata_loader.h
index a058a1e5cfa..744a0d0c25a 100644
--- a/src/mongo/s/metadata_loader.h
+++ b/src/mongo/s/metadata_loader.h
@@ -48,12 +48,12 @@ namespace mongo {
      * CollectionMetadata has both persisted and volatile state (for now) - the persisted 
      * config server chunk state and the volatile pending state which is only tracked locally
      * while a server is the primary.  This requires a two-step loading process - the persisted
-     * chunk state *cannot* be loaded in a DBLock lock while the pending chunk state *must* be.
+     * chunk state *cannot* be loaded in a DBWrite lock while the pending chunk state *must* be.
      * 
      * Example usage: 
      * beforeMetadata = <get latest local metadata>;
      * remoteMetadata = makeCollectionMetadata( beforeMetadata, remoteMetadata );
-     * DBLock lock(txn, dbname, newlm::MODE_X);
+     * DBWrite lock( ns );
      * afterMetadata = <get latest local metadata>;
      * promotePendingChunks( afterMetadata, remoteMetadata );
      *