[PATCH] AIO/DIO oops fix

The problem here is, finished_one_bio() shouldn't call aio_complete() since
no work has been done.  I have a fix for this - can you verify this ?  I am
not really comfortable with this "tweaking".  (I am not really sure about
IO errors like EIO etc.  - if they can lead to calling aio_complete()
twice)

Fix is to call aio_complete() ONLY if there is something to report.  Note
the we don't update dio->result with any error codes from get_user_pages(),
they just passed as "ret" value from do_direct_IO().
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/direct-io.c

@@ -235,7 +235,8 @@ static void finished_one_bio(struct dio *dio)
 			dio_complete(dio, dio->block_in_file << dio->blkbits,
 					dio->result);
 			/* Complete AIO later if falling back to buffered i/o */
-			if (dio->result == dio->size || dio->rw == READ) {
+			if (dio->result == dio->size ||
+				((dio->rw == READ) && dio->result)) {
 				aio_complete(dio->iocb, dio->result, 0);
 				kfree(dio);
 				return;