afs: Fix key ref leak in afs_put_operation()

The afs_put_operation() function needs to put the reference to the key
that's authenticating the operation.

Fixes: e49c7b2f ("afs: Build an abstraction around an "operation" concept")
Reported-by: Dave Botsch <botsch@cnf.cornell.edu>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/afs/fs_operation.c

@@ -235,6 +235,7 @@ int afs_put_operation(struct afs_operation *op)
 	afs_end_cursor(&op->ac);
 	afs_put_serverlist(op->net, op->server_list);
 	afs_put_volume(op->net, op->volume, afs_volume_trace_put_put_op);
+	key_put(op->key);
 	kfree(op);
 	return ret;
 }