cifs: add pid field to cifs_writedata

We'll need this to handle rwpidforward option correctly when we use
async writes in the aio_write op.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Pavel Shilovsky <piastry@etersoft.ru>
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 159fcc5..5fedf6c 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1802,6 +1802,7 @@
 				rc = -EBADF;
 				break;
 			}
+			wdata->pid = wdata->cfile->pid;
 			rc = cifs_async_writev(wdata);
 		} while (wbc->sync_mode == WB_SYNC_ALL && rc == -EAGAIN);