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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham 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 B7520C04EB8 for ; Thu, 6 Dec 2018 11:46:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 833A620661 for ; Thu, 6 Dec 2018 11:46:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 833A620661 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-btrfs-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729324AbeLFLqF (ORCPT ); Thu, 6 Dec 2018 06:46:05 -0500 Received: from mx2.suse.de ([195.135.220.15]:56710 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727832AbeLFLqF (ORCPT ); Thu, 6 Dec 2018 06:46:05 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 861A2AFA6; Thu, 6 Dec 2018 11:46:03 +0000 (UTC) Date: Thu, 6 Dec 2018 05:46:01 -0600 From: Goldwyn Rodrigues To: Christoph Hellwig Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH 07/10] dax: export functions for use with btrfs Message-ID: <20181206114601.bzh3356jtyvhxc6m@merlin> References: <20181205122835.19290-1-rgoldwyn@suse.de> <20181205122835.19290-8-rgoldwyn@suse.de> <20181205145227.GA12361@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181205145227.GA12361@infradead.org> User-Agent: NeoMutt/20180323 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 6:52 05/12, Christoph Hellwig wrote: > If you want to export these at all they have to be EXPORT_SYMBOL_GPL. > Understood. > But I'd really like to avoid seeing another duplicate DAX I/O path. > Please try to adopt the existing iomap-based infrastructure for your > needs first. This is not worth with btrfs. With non-page aligned I/O on btrfs, we need to copy the first/last page of the extents for CoW. So, we would end up using the exported functions anyways. Believe me, I have spent some time getting btrfs iomap compatible before giving up. The problems are btrfs needs to carry a lot of information across iomap_begin and iomap_end. While the added private variable helps in this, it also needs hooks in bio_submit() functions for crc calculations during direct writes. -- Goldwyn