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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, 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 4C171C33CAE for ; Mon, 13 Jan 2020 22:19:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2180920CC7 for ; Mon, 13 Jan 2020 22:19:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="Dvw5S/ZK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728819AbgAMWTe (ORCPT ); Mon, 13 Jan 2020 17:19:34 -0500 Received: from mail-il1-f194.google.com ([209.85.166.194]:41201 "EHLO mail-il1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726530AbgAMWTd (ORCPT ); Mon, 13 Jan 2020 17:19:33 -0500 Received: by mail-il1-f194.google.com with SMTP id f10so9582268ils.8 for ; Mon, 13 Jan 2020 14:19:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:subject:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=1bRlb8icLO9A3T9CUBl/y+fFvzY9LjvdXm5n3OeDKjc=; b=Dvw5S/ZKaOPQshFbiohKBvJWqhiCv2LLZFpqBW5hitEKxLq+JWKJlEphJEmAAsMOpQ pZlK2/LSYRsVrBkb2MhurRPVZxfP+ni2rbtQUGr3sHy1sKdoDmq2wxXtCqvMpxP2K16R q4AuF16H25ZEzKJuzbNWgBrzwlHSqpdcrVGJb6ZLEFX0CKaUawMW6UwPD6VbogPI5p1F Y2DVIzxrCUbRIEtDdDrXLxjN7kZtnuyljM4noA0ClQjmu3GWXIfA8H+e2oil7I3fRGHX /qm22hxKUFF2bxM/1tG0x+7Aez7n5nnBNMkXYfdwe9YFXkI87ET+2WSrdWwhh3DhtmCs Dh3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:subject:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=1bRlb8icLO9A3T9CUBl/y+fFvzY9LjvdXm5n3OeDKjc=; b=sC5f/3m9A3ulQne9wYdlL2BNfE7hGHKjI17PU0qo2VttIhtx11OfFYcJDjfytAw+1z 1U1Yejy5FSJOMwkcjLdxMagSdf/JMkJ5OnUxNgpSMpUr40TEgRQ+aGbrNL7IHwWNvDNx IfCwAOKmmwRiH1O23gJ85akBuFIGdyZNS182yRl6lyuEKjfFvGf+RlU+lfxj81UlARQG ArWSY8iEuveUgvfXKsfWAEPacmltrNRI8j3mTK2IzTkNTNcDlwnmbs7+wmYUkc0Ztu9d X/8Vf8BxRXxQ+Z/ztM3ukMlaP9rORj6Z4X7B3my8GwHd77gxodV21XBBsbG878F4kyZ0 EJsA== X-Gm-Message-State: APjAAAU+4PURQZsTZjTCXEyI66n1zR/b06GiYGeDrVnqTdEnhrgWyjEf oVhBOG2SEBFGwMwgTHEcD4pJrQ== X-Google-Smtp-Source: APXvYqzO0GHbV0w/TmUPEhOW7PoX0tTib7NohzGu9yTqXinG8F1yldxNXPgqeMkVhNSZKFgvHTNGOw== X-Received: by 2002:a92:8655:: with SMTP id g82mr656940ild.2.1578953973226; Mon, 13 Jan 2020 14:19:33 -0800 (PST) Received: from [192.168.1.159] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id f125sm4176309ilh.88.2020.01.13.14.19.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Jan 2020 14:19:32 -0800 (PST) From: Jens Axboe Subject: Re: [RFC 0/8] Replacing the readpages a_op To: Matthew Wilcox Cc: Chris Mason , "linux-xfs@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "jlayton@kernel.org" , "hch@infradead.org" References: <20200113153746.26654-1-willy@infradead.org> <6CA4CD96-0812-4261-8FF9-CD28AA2EC38A@fb.com> <20200113175436.GC332@bombadil.infradead.org> Message-ID: Date: Mon, 13 Jan 2020 15:19:31 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200113175436.GC332@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Jan 13, 2020 at 10:54 AM Matthew Wilcox wrote: > > On Mon, Jan 13, 2020 at 04:42:10PM +0000, Chris Mason wrote: > > Btrfs basically does this now, honestly iomap isn't that far away. > > Given how sensible iomap is for this, I'd rather see us pile into > > that abstraction than try to pass pagevecs for large ranges. > > Otherwise, if > > I completely misread this at first and thought you were proposing we > pass a bio_vec to ->readahead. Initially, this is a layering > violation, completely unnecessary to have all these extra offset/size > fields being allocated and passed around. But ... the bio_vec and the > skb_frag_t are now the same data structure, so both block and network > use it. It may make sense to have this as the common data structure > for 'unit of IO'. The bio supports having the bi_vec allocated > externally to the data structure while the skbuff would need to copy > the array. > > Maybe we need a more neutral name than bio_vec so as to not upset > people. page_frag, perhaps [1]. > > [1] Yes, I know about the one in include/linux/mm_types_task.h Note that bio_vecs support page merging, so page fragment isn't very descriptive. Not sure what a good name would be, but fragment isn't it. But any shared type would imply that others should support that as well if you're passing it around (or by pointer). -- Jens Axboe