From: Mingming Subject: [PATCH 4/4 v2] Fix direct IO return values over fullfilled fallocate space Date: Thu, 08 Oct 2009 18:13:12 -0700 Message-ID: <1255050792.4931.185.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 e39.co.us.ibm.com ([32.97.110.160]:58760 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932095AbZJIBNy (ORCPT ); Thu, 8 Oct 2009 21:13:54 -0400 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e39.co.us.ibm.com (8.14.3/8.13.1) with ESMTP id n9917W9u019483 for ; Thu, 8 Oct 2009 19:07:32 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id n991DEuU156250 for ; Thu, 8 Oct 2009 19:13:14 -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 n991DDER007067 for ; Thu, 8 Oct 2009 19:13:14 -0600 Sender: linux-ext4-owner@vger.kernel.org List-ID: ext4: Fix direct IO return values over fullfilled fallocate space To prepare direct IO write, we need to split the unwritten extents before submit the IO. In case of no split needs at all, ext4_split_unwritten_extents() was incorrectly returns 0 instead of the size of uninitialized extents. This bug caused wrong return value sent back to VFS code when it gets called from async IO path, leads to falling back to buffered IO. Signed-off-by: Mingming Cao --- fs/ext4/extents.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 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 @@ -2788,6 +2788,8 @@ fix_extent_len: * into three uninitialized extent(at most). After IO complete, the part * being filled will be convert to initialized by the end_io callback function * via ext4_convert_unwritten_extents(). + * + * Returns the size of uninitialized extent to be written, on success. */ static int ext4_split_unwritten_extents(handle_t *handle, struct inode *inode, @@ -2805,7 +2807,6 @@ static int ext4_split_unwritten_extents( unsigned int allocated, ee_len, depth; ext4_fsblk_t newblock; int err = 0; - int ret = 0; ext_debug("ext4_split_unwritten_extents: inode %lu," "iblock %llu, max_blocks %u\n", inode->i_ino, @@ -2827,8 +2828,8 @@ static int ext4_split_unwritten_extents( * the size of extent to write, there is no need to split * uninitialized extent */ - if (allocated <= max_blocks) - return ret; + if (iblock == ee_block && allocated <= max_blocks) + return allocated; err = ext4_ext_get_access(handle, inode, path + depth); if (err)