From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752880AbZIQPL3 (ORCPT ); Thu, 17 Sep 2009 11:11:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752710AbZIQPL2 (ORCPT ); Thu, 17 Sep 2009 11:11:28 -0400 Received: from dip-colo-pa.panasas.com ([67.152.220.67]:43333 "EHLO daytona.int.panasas.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752604AbZIQPL1 (ORCPT ); Thu, 17 Sep 2009 11:11:27 -0400 Message-ID: <4AB2519F.8020409@panasas.com> Date: Thu, 17 Sep 2009 18:11:27 +0300 From: Boaz Harrosh User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.1) Gecko/20090722 Remi/fc10 Thunderbird/3.0b3 MIME-Version: 1.0 To: Jan Kara , Nick Piggin CC: linux-fsdevel@vger.kernel.org, LKML , pbadari@us.ibm.com, Andrew Morton Subject: Re: Is nobh code still useful? References: <20090917135627.GB13660@duck.suse.cz> In-Reply-To: <20090917135627.GB13660@duck.suse.cz> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 17 Sep 2009 15:11:31.0026 (UTC) FILETIME=[2308CB20:01CA37A9] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/17/2009 04:56 PM, Jan Kara wrote: > Hi, > > during my page_mkwrite() work, I've looked at who uses nobh_ versions of > various functions in fs/buffer.c. It seems only ext2 and jfs use them. ext3 > uses them only from writepage() (which means we needn't attach buffers to a > page when it was written via mmap in writeback mode) and ext4 tries to use > them but in fact it's nop because it always attaches buffers to the page > earlier. So it's not really widely used, there's quite some code to support > it (including one page flag), and it also slightly complicates my > page_mkwrite() fixes. > So I wanted to ask does somebody actually remember what it is good for? > Buffer heads obviously consume some memory so was that the reason? OTOH we > have to map the page whenever we write to it or send it to disk via > writepage(). > > Honza I'm currently using nobh_truncate_page() in fs/exofs/inode.c::exofs_truncate(). Though, I suspect that once I do the conversion to Nick's: "[patch 00/11] new truncate sequence" and it is submitted, that use will disappear. Thanks Boaz