From: Mingming Subject: [PATCH 1/2] direct IO returns value fix for holes/fallocate Date: Mon, 05 Oct 2009 14:59:06 -0700 Message-ID: <1254779946.4236.217.camel@mingming-laptop> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: ext4 development , Curt Wohlgemuth To: tytso@mit.edu Return-path: Received: from e36.co.us.ibm.com ([32.97.110.154]:56088 "EHLO e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754735AbZJEV7q (ORCPT ); Mon, 5 Oct 2009 17:59:46 -0400 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e36.co.us.ibm.com (8.14.3/8.13.1) with ESMTP id n95Lv9jE023728 for ; Mon, 5 Oct 2009 15:57:09 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id n95Lx8PO244016 for ; Mon, 5 Oct 2009 15:59:08 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n95Lx7nK022852 for ; Mon, 5 Oct 2009 15:59:07 -0600 Sender: linux-ext4-owner@vger.kernel.org List-ID: ext4: Direct IO return value fix for holes/fallocate When direct IO complete, ext4 will convert unwritten extents to written, for writes over preallocated space, or holes. ext4_direct_IO should returns the number of bytes read/write on success. However there is a bug that cause ext4_direct_IO returns the number of bytes converted to written extents, which is 0 on success. This bug causes direct IO falls back to buffered IO even on sucessful rewrites or preallocated space. Bug is reported by Curt Wohlgemuth , and verified the following patch fixed it the issue. Signed-off-by: Mingming Cao --- fs/ext4/extents.c | 1 + fs/ext4/inode.c | 8 ++++++-- 2 files changed, 7 insertions(+), 2 deletions(-) Index: linux-2.6.31-rc4/fs/ext4/extents.c =================================================================== --- linux-2.6.31-rc4.orig/fs/ext4/extents.c +++ linux-2.6.31-rc4/fs/ext4/extents.c @@ -3500,6 +3500,7 @@ retry: * * This function is called from the direct IO end io call back * function, to convert the fallocated extents after IO is completed. + * Returns 0 on success. */ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset, loff_t len) Index: linux-2.6.31-rc4/fs/ext4/inode.c =================================================================== --- linux-2.6.31-rc4.orig/fs/ext4/inode.c +++ linux-2.6.31-rc4/fs/ext4/inode.c @@ -3693,13 +3693,17 @@ static ssize_t ext4_ext_direct_IO(int rw if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) { ext4_free_io_end(iocb->private); iocb->private = NULL; - } else if (ret > 0) + } else if (ret > 0){ + int err; /* * for non AIO case, since the IO is already * completed, we could do the convertion right here */ - ret = ext4_convert_unwritten_extents(inode, + err = ext4_convert_unwritten_extents(inode, offset, ret); + if (err < 0) + ret = err; + } return ret; }