From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265268AbUEZAKl (ORCPT ); Tue, 25 May 2004 20:10:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265269AbUEZAKl (ORCPT ); Tue, 25 May 2004 20:10:41 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:428 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S265268AbUEZAKg (ORCPT ); Tue, 25 May 2004 20:10:36 -0400 Date: Wed, 26 May 2004 01:10:33 +0100 From: viro@parcelfarce.linux.theplanet.co.uk To: Linus Torvalds Cc: Andrew Morton , olh@suse.de, linux-kernel@vger.kernel.org Subject: Re: very low performance on SCSI disks if device node is in tmpfs Message-ID: <20040526001033.GA12308@parcelfarce.linux.theplanet.co.uk> References: <20040525184732.GB26661@suse.de> <20040525144836.1af59a96.akpm@osdl.org> <20040525145923.68af0ad8.akpm@osdl.org> <20040525154107.053b9ef6.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 25, 2004 at 05:05:46PM -0700, Linus Torvalds wrote: > > > On Tue, 25 May 2004, Andrew Morton wrote: > > > > We need to set file->f_ra _after_ calling blkdev_open(), when inode->i_mapping > > points at the right thing. And we need to get it from > > inode->i_mapping->host->i_mapping too, which represents the underlying device. > > Hmm.. Is f_mapping is guaranteed to be non-NULL? At least for the O_DIRECT > case, we explicitly test for f_mapping being non-NULL, although that test > is quite possibly bogus. Maybe we should fix that too? ->f_mapping should never be NULL after successive open().