[[CIFS] Pass truncate open flag through on file open in case setattr fails

on set size to zero.
Signed-off-by: NSebastian Voitzsch <sebastoam/vpotzscj@web.de>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

fs/cifs/file.c

@@ -84,6 +84,8 @@ static inline int cifs_get_disposition(unsigned int flags)
 		return FILE_OVERWRITE_IF;
 	else if ((flags & O_CREAT) == O_CREAT)
 		return FILE_OPEN_IF;
+	else if ((flags & O_TRUNC) == O_TRUNC)
+		return FILE_OVERWRITE;
 	else
 		return FILE_OPEN;
 }