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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 50A2DC3A5A5 for ; Tue, 3 Sep 2019 06:58:28 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8706C206B8 for ; Tue, 3 Sep 2019 06:58:27 +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="rpXp0SPn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8706C206B8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 46MyTX6RgdzDqjN for ; Tue, 3 Sep 2019 16:58:24 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=bombadil.srs.infradead.org (client-ip=2607:7c80:54:e::133; helo=bombadil.infradead.org; envelope-from=batv+680e2818d6643897e706+5854+infradead.org+hch@bombadil.srs.infradead.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=infradead.org header.i=@infradead.org header.b="rpXp0SPn"; dkim-atps=neutral Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 46MyTJ5BtSzDqR5 for ; Tue, 3 Sep 2019 16:58:11 +1000 (AEST) 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=4hSYkiCPCpSgRGHZSvIjoW5chKDDuf7TDPZ/KesWimM=; b=rpXp0SPnAU2Bqz1hm0nm2/Yhf UNxaHXOTptV/vZxgW3l45UkXmbSzFCF6jpcGgR4N3NWzh00kL4gHglfJtSMHQvR60R6+PNJDDrW0d nlQ6UmPC6dG+rbeDzAOVh+DAfSlcO467RK/ptDPHANCLGc0TquzUn/UuPyqUQQAs9e/x7qVnC0pN5 oGhHbdcJW7UypcG0tDscA3Rv00tKuFzAz15Ot23KmxGbbcv4gjTz0zF3F72iLahRGtWWNR3c8raTD m0dAbbkkgkLz1z+7Yy5HZ8Y5BF/zMkUDMO5uyeI7JxTtiMS8hPeSYqePPLoHLc+WsBf4OrHTAsIfJ W14CT7M+A==; Received: from hch by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1i52lP-0003At-I5; Tue, 03 Sep 2019 06:58:03 +0000 Date: Mon, 2 Sep 2019 23:58:03 -0700 From: Christoph Hellwig To: Gao Xiang Subject: Re: [PATCH 00/21] erofs: patchset addressing Christoph's comments Message-ID: <20190903065803.GA11205@infradead.org> References: <20190802125347.166018-1-gaoxiang25@huawei.com> <20190901055130.30572-1-hsiangkao@aol.com> <20190902124645.GA8369@infradead.org> <20190902142452.GE2664@architecture4> <20190902152323.GB14009@infradead.org> <20190902155037.GD179615@architecture4> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190902155037.GD179615@architecture4> User-Agent: Mutt/1.11.4 (2019-03-13) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devel@driverdev.osuosl.org, Greg Kroah-Hartman , Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-erofs@lists.ozlabs.org Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" On Mon, Sep 02, 2019 at 11:50:38PM +0800, Gao Xiang wrote: > > > You means killing erofs_get_meta_page or avoid erofs_read_raw_page? > > > > > > - For killing erofs_get_meta_page, here is the current erofs_get_meta_page: > > > > > I think it is simple enough. read_cache_page need write a similar > > > filler, or read_cache_page_gfp will call .readpage, and then > > > introduce buffer_heads, that is what I'd like to avoid now (no need these > > > bd_inode buffer_heads in memory...) > > > > If using read_cache_page_gfp and ->readpage works, please do. The > > fact that the block device inode uses buffer heads is an implementation > > detail that might not last very long and should be invisible to you. > > It also means you can get rid of a lot of code that you don't have > > to maintain and others don't have to update for global API changes. > > I care about those useless buffer_heads in memory for our products... > > Since we are nobh filesystem (a little request, could I use it > after buffer_heads are fully avoided, I have no idea why I need > those buffer_heads in memory.... But I think bd_inode is good > for caching metadata...) Then please use read_cache_page with iomap_readpage(s), and write comment explaining why your are not using read_cache_page_gfp. 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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 95D73C3A5A5 for ; Tue, 3 Sep 2019 06:58:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 67A10206B8 for ; Tue, 3 Sep 2019 06:58:09 +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="rpXp0SPn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726980AbfICG6J (ORCPT ); Tue, 3 Sep 2019 02:58:09 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:33686 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725919AbfICG6I (ORCPT ); Tue, 3 Sep 2019 02:58:08 -0400 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=4hSYkiCPCpSgRGHZSvIjoW5chKDDuf7TDPZ/KesWimM=; b=rpXp0SPnAU2Bqz1hm0nm2/Yhf UNxaHXOTptV/vZxgW3l45UkXmbSzFCF6jpcGgR4N3NWzh00kL4gHglfJtSMHQvR60R6+PNJDDrW0d nlQ6UmPC6dG+rbeDzAOVh+DAfSlcO467RK/ptDPHANCLGc0TquzUn/UuPyqUQQAs9e/x7qVnC0pN5 oGhHbdcJW7UypcG0tDscA3Rv00tKuFzAz15Ot23KmxGbbcv4gjTz0zF3F72iLahRGtWWNR3c8raTD m0dAbbkkgkLz1z+7Yy5HZ8Y5BF/zMkUDMO5uyeI7JxTtiMS8hPeSYqePPLoHLc+WsBf4OrHTAsIfJ W14CT7M+A==; Received: from hch by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1i52lP-0003At-I5; Tue, 03 Sep 2019 06:58:03 +0000 Date: Mon, 2 Sep 2019 23:58:03 -0700 From: Christoph Hellwig To: Gao Xiang Cc: Christoph Hellwig , Gao Xiang , Chao Yu , Greg Kroah-Hartman , linux-fsdevel@vger.kernel.org, devel@driverdev.osuosl.org, linux-erofs@lists.ozlabs.org, Chao Yu Subject: Re: [PATCH 00/21] erofs: patchset addressing Christoph's comments Message-ID: <20190903065803.GA11205@infradead.org> References: <20190802125347.166018-1-gaoxiang25@huawei.com> <20190901055130.30572-1-hsiangkao@aol.com> <20190902124645.GA8369@infradead.org> <20190902142452.GE2664@architecture4> <20190902152323.GB14009@infradead.org> <20190902155037.GD179615@architecture4> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190902155037.GD179615@architecture4> User-Agent: Mutt/1.11.4 (2019-03-13) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Sep 02, 2019 at 11:50:38PM +0800, Gao Xiang wrote: > > > You means killing erofs_get_meta_page or avoid erofs_read_raw_page? > > > > > > - For killing erofs_get_meta_page, here is the current erofs_get_meta_page: > > > > > I think it is simple enough. read_cache_page need write a similar > > > filler, or read_cache_page_gfp will call .readpage, and then > > > introduce buffer_heads, that is what I'd like to avoid now (no need these > > > bd_inode buffer_heads in memory...) > > > > If using read_cache_page_gfp and ->readpage works, please do. The > > fact that the block device inode uses buffer heads is an implementation > > detail that might not last very long and should be invisible to you. > > It also means you can get rid of a lot of code that you don't have > > to maintain and others don't have to update for global API changes. > > I care about those useless buffer_heads in memory for our products... > > Since we are nobh filesystem (a little request, could I use it > after buffer_heads are fully avoided, I have no idea why I need > those buffer_heads in memory.... But I think bd_inode is good > for caching metadata...) Then please use read_cache_page with iomap_readpage(s), and write comment explaining why your are not using read_cache_page_gfp.