Index: drivers/filesystems/fastfat/dir.c
===================================================================
--- drivers/filesystems/fastfat/dir.c	(revision 72609)
+++ drivers/filesystems/fastfat/dir.c	(working copy)
@@ -421,6 +421,12 @@
 #endif
     Buffer = VfatGetUserBuffer(IrpContext->Irp, FALSE);
 
+    if (!ExAcquireResourceExclusiveLite(&IrpContext->DeviceExt->DirResource,
+        BooleanFlagOn(IrpContext->Flags, IRPCONTEXT_CANWAIT)))
+    {        
+        return STATUS_PENDING;
+    }
+
     if (!ExAcquireResourceSharedLite(&pFcb->MainResource,
                                      BooleanFlagOn(IrpContext->Flags, IRPCONTEXT_CANWAIT)))
     {
@@ -428,6 +434,7 @@
         if (NT_SUCCESS(Status))
             Status = STATUS_PENDING;
 
+        ExReleaseResourceLite(&IrpContext->DeviceExt->DirResource);
         return Status;
     }
 
@@ -461,6 +468,7 @@
             if (!pCcb->SearchPattern.Buffer)
             {
                 ExReleaseResourceLite(&pFcb->MainResource);
+                ExReleaseResourceLite(&IrpContext->DeviceExt->DirResource);
                 return STATUS_INSUFFICIENT_RESOURCES;
             }
             RtlCopyUnicodeString(&pCcb->SearchPattern, pSearchPattern);
@@ -477,6 +485,7 @@
         if (!pCcb->SearchPattern.Buffer)
         {
             ExReleaseResourceLite(&pFcb->MainResource);
+            ExReleaseResourceLite(&IrpContext->DeviceExt->DirResource);
             return STATUS_INSUFFICIENT_RESOURCES;
         }
         pCcb->SearchPattern.Buffer[0] = L'*';
@@ -504,13 +513,6 @@
     DirContext.ShortNameU.Buffer = ShortNameBuffer;
     DirContext.ShortNameU.MaximumLength = sizeof(ShortNameBuffer);
 
-    if (!ExAcquireResourceExclusiveLite(&IrpContext->DeviceExt->DirResource,
-                                        BooleanFlagOn(IrpContext->Flags, IRPCONTEXT_CANWAIT)))
-    {
-        ExReleaseResourceLite(&pFcb->MainResource);
-        return STATUS_PENDING;
-    }
-
     while ((Status == STATUS_SUCCESS) && (BufferLength > 0))
     {
         Status = FindFile(IrpContext->DeviceExt,
@@ -586,8 +588,8 @@
         IrpContext->Irp->IoStatus.Information = Stack->Parameters.QueryDirectory.Length - BufferLength;
     }
 
+    ExReleaseResourceLite(&pFcb->MainResource);
     ExReleaseResourceLite(&IrpContext->DeviceExt->DirResource);
-    ExReleaseResourceLite(&pFcb->MainResource);
 
     return Status;
 }
Index: ntoskrnl/io/iomgr/file.c
===================================================================
--- ntoskrnl/io/iomgr/file.c	(revision 72609)
+++ ntoskrnl/io/iomgr/file.c	(working copy)
@@ -1978,8 +1978,14 @@
 
     /* Allocate an IRP */
     Irp = IoAllocateIrp(DeviceObject->StackSize, FALSE);
-    if (!Irp) return;
 
+    if (!Irp)
+    {
+        /* Release the lock if we were holding it */
+        if (FileObject->Flags & FO_SYNCHRONOUS_IO) IopUnlockFileObject(FileObject);
+        return;
+    }
+
     /* Set it up */
     Irp->UserEvent = &Event;
     Irp->UserIosb = &Irp->IoStatus;