SERVER-15888: WriteContext will switch from MODE_IX to MODE_X if collection doesn't exist

4 files changed, 27 insertions, 1 deletions

diff --git a/src/mongo/db/client.cpp b/src/mongo/db/client.cpp
index 9773f982c7f..7601acc5d42 100644
--- a/src/mongo/db/client.cpp
+++ b/src/mongo/db/client.cpp
@@ -279,7 +279,14 @@ namespace mongo {
           _autodb(opCtx, _nss.db(), MODE_IX),
           _collk(opCtx->lockState(), ns, MODE_IX),
           _c(opCtx, ns, _autodb.getDb(), _autodb.justCreated()) {
-          }
+        _collection = _c.db()->getCollection( _txn, ns );
+        if ( !_collection && !_autodb.justCreated() ) {
+            // relock in MODE_X
+            _collk.relockWithMode( MODE_X, _autodb.lock() );
+            Database* db = dbHolder().get(_txn, ns );
+            invariant( db == _c.db() );
+        }
+    }
 
     void Client::Context::checkNotStale() const { 
         switch ( _client->_curOp->getOp() ) {
diff --git a/src/mongo/db/client.h b/src/mongo/db/client.h
index ce2d50717de..86cc28f8c39 100644
--- a/src/mongo/db/client.h
+++ b/src/mongo/db/client.h
@@ -106,6 +106,9 @@ namespace mongo {
         bool justCreated() {
             return _justCreated;
         }
+
+        Lock::DBLock& lock() { return _dbLock; }
+
     private:
         Lock::DBLock _dbLock; // not const, as we may need to relock for implicit create
         Database* _db;
@@ -309,6 +312,7 @@ namespace mongo {
             AutoGetOrCreateDb _autodb;
             Lock::CollectionLock _collk;
             Context _c;
+            Collection* _collection;
         };
     }; // class Client
 
diff --git a/src/mongo/db/concurrency/d_concurrency.cpp b/src/mongo/db/concurrency/d_concurrency.cpp
index f133466d9d7..4615b6ceb79 100644
--- a/src/mongo/db/concurrency/d_concurrency.cpp
+++ b/src/mongo/db/concurrency/d_concurrency.cpp
@@ -287,6 +287,19 @@ namespace mongo {
         }
     }
 
+    void Lock::CollectionLock::relockWithMode(LockMode mode, Lock::DBLock& dbLock ) {
+        if (supportsDocLocking() || enableCollectionLocking) {
+            _lockState->unlock(_id);
+        }
+
+        dbLock.relockWithMode( mode );
+
+        if (supportsDocLocking() || enableCollectionLocking) {
+            _lockState->lock(_id, mode);
+        }
+
+    }
+
     Lock::ResourceLock::ResourceLock(Locker* lockState, ResourceId rid, LockMode mode)
             : _rid(rid),
               _lockState(lockState) {
diff --git a/src/mongo/db/concurrency/d_concurrency.h b/src/mongo/db/concurrency/d_concurrency.h
index bc2454469d1..9ae00cf2db4 100644
--- a/src/mongo/db/concurrency/d_concurrency.h
+++ b/src/mongo/db/concurrency/d_concurrency.h
@@ -211,6 +211,8 @@ namespace mongo {
         public:
             CollectionLock(Locker* lockState, const StringData& ns, const LockMode);
             virtual ~CollectionLock();
+
+            void relockWithMode( const LockMode mode, Lock::DBLock& dblock );
         private:
             const ResourceId _id;
             Locker* _lockState;