direct-io: always call ->end_io if non-NULL

This way we can pass back errors to the file system, and allow for
cleanup required for all direct I/O invocations.

Also allow the ->end_io handlers to return errors on their own, so that
I/O completion errors can be passed on to the callers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>


diff --git a/fs/direct-io.c b/fs/direct-io.c
index 1b2f7ff..9c6f885 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -253,8 +253,13 @@
 	if (ret == 0)
 		ret = transferred;
 
-	if (dio->end_io && dio->result)
-		dio->end_io(dio->iocb, offset, transferred, dio->private);
+	if (dio->end_io) {
+		int err;
+
+		err = dio->end_io(dio->iocb, offset, ret, dio->private);
+		if (err)
+			ret = err;
+	}
 
 	if (!(dio->flags & DIO_SKIP_DIO_COUNT))
 		inode_dio_end(dio->inode);