[PATCH] O_DIRECT memory leak fix

From: Badari Pulavarty <pbadari@us.ibm.com>

I found the problem with O_DIRECT memory leak.

The problem is, when we are doing DIO read and crossed the end of file - we
don't release referencess on all the pages we got from get_user_pages().
(since it is a success case).

The fix is to call dio_cleanup() even for sucess cases.

fs/direct-io.c

@@ -946,6 +946,12 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
 	if (dio->bio)
 		dio_bio_submit(dio);
 
+	/*
+	 * It is possible that, we return short IO due to end of file.
+	 * In that case, we need to release all the pages we got hold on.
+	 */
+	dio_cleanup(dio);
+
 	/*
 	 * OK, all BIOs are submitted, so we can decrement bio_count to truly
 	 * reflect the number of to-be-processed BIOs.