From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 86487C2BA83 for ; Wed, 12 Feb 2020 14:59:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5D7742082F for ; Wed, 12 Feb 2020 14:59:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="MuERL3Od" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727698AbgBLO7B (ORCPT ); Wed, 12 Feb 2020 09:59:01 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:43082 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727231AbgBLO7B (ORCPT ); Wed, 12 Feb 2020 09:59:01 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=FgFLJTvBuzlIrLf1DK1nejj+RgbkbMvjMUWGEtVxYBg=; b=MuERL3OdmrQeEWKpBpT5VAehhz E+6+xkiw+s2UiGXu4mgWVmfRQUEEx0E+R2LkMpxjsWrcgNO272pjwNAilmDIs6pRP7LpIOIVSrppB +cJxC/+5C92Ltp45Y44BZREyDIcmQA/0q2W9yM1CVfLzV47+uuvXamcQZiE5X5iMtsaPhzK09IFDp VvG5tlIqNJVKdy+Xia1dyAEdco37dyFinfTUo7ppecnZ2DFYWqzKTUss7QKuBW5Mgh4Vvtdp7ZmPy ZNbfBuZ4qnIKBWqAOucnmyaBhHnqPAohxYyPsvE3dB+LsqqmKfX6vvyHw5tlVMkhsKXS+n/YlJX+r zogXuURQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j1tTg-0004Q9-RN; Wed, 12 Feb 2020 14:59:00 +0000 Date: Wed, 12 Feb 2020 06:59:00 -0800 From: Matthew Wilcox To: Christoph Hellwig Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 09/25] fs: Add a filesystem flag for large pages Message-ID: <20200212145900.GD7778@bombadil.infradead.org> References: <20200212041845.25879-1-willy@infradead.org> <20200212041845.25879-10-willy@infradead.org> <20200212074318.GG7068@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200212074318.GG7068@infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Feb 11, 2020 at 11:43:18PM -0800, Christoph Hellwig wrote: > On Tue, Feb 11, 2020 at 08:18:29PM -0800, Matthew Wilcox wrote: > > From: "Matthew Wilcox (Oracle)" > > > > The page cache needs to know whether the filesystem supports pages > > > PAGE_SIZE. > > Does it make sense to set this flag on the file_system_type, which > is rather broad scope, or a specific superblock or even inode? > > For some file systems we might require on-disk flags that aren't set > for all instances. I don't see why we'd need on-disk flags or need to control this on a per-inode or per-sb basis. My intent for this flag is to represent whether the filesystem understands large pages; how the file is cached should make no difference to the on-disk layout.