[0.4.9] cherry-pick [FASTFAT] Properly queue pending write IRPs.

Addendum to 30b836b

(cherry picked from commit e9e14be)

Author: HeisSpiter

drivers/filesystems/fastfat/rw.c

@@ -1067,6 +1067,7 @@ VfatWrite(
 
         if (!ExAcquireResourceExclusiveLite(&IrpContext->DeviceExt->DirResource, CanWait))
         {
+            Status = STATUS_PENDING;
             goto ByeBye;
         }