cifs: fix leaked reference on requeued write

Failed async writes that are requeued may not clean up a refcount
on the file, which can result in a leaked open. This scenario arises
very reliably when using persistent handles and a reconnect occurs
while writing.

cifs_writev_requeue only releases the reference if the write fails
(rc != 0). The server->ops->async_writev operation will take its own
reference, so the initial reference can always be released.

Signed-off-by: Adam McCoy <[email protected]>
Signed-off-by: Steve French <[email protected]>
CC: Stable <[email protected]>
Reviewed-by: Pavel Shilovsky <[email protected]>

Author: adam-mccoy

fs/cifs/cifssmb.c

@@ -2152,8 +2152,8 @@ cifs_writev_requeue(struct cifs_writedata *wdata)
 			}
 		}
 
+		kref_put(&wdata2->refcount, cifs_writedata_release);
 		if (rc) {
-			kref_put(&wdata2->refcount, cifs_writedata_release);
 			if (is_retryable_error(rc))
 				continue;
 			i += nr_pages;