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=-5.3 required=3.0 tests=BAYES_00, 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 38F05C433E2 for ; Tue, 15 Sep 2020 08:22:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 10D4C21D80 for ; Tue, 15 Sep 2020 08:22:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726186AbgIOIQr (ORCPT ); Tue, 15 Sep 2020 04:16:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:60030 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726123AbgIOIQD (ORCPT ); Tue, 15 Sep 2020 04:16:03 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 6B1A8AC6E; Tue, 15 Sep 2020 08:16:15 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id B5957DA818; Tue, 15 Sep 2020 10:14:48 +0200 (CEST) Date: Tue, 15 Sep 2020 10:14:48 +0200 From: David Sterba To: Omar Sandoval Cc: dsterba@suse.cz, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 2/9] btrfs: send: avoid copying file data Message-ID: <20200915081448.GG1791@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Omar Sandoval , linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <20200911141339.GR18399@twin.jikos.cz> <20200914220448.GC148663@relinquished.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200914220448.GC148663@relinquished.localdomain> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Mon, Sep 14, 2020 at 03:04:48PM -0700, Omar Sandoval wrote: > On Fri, Sep 11, 2020 at 04:13:39PM +0200, David Sterba wrote: > > On Fri, Aug 21, 2020 at 12:39:52AM -0700, Omar Sandoval wrote: > > > +static int put_data_header(struct send_ctx *sctx, u32 len) > > > +{ > > > + struct btrfs_tlv_header *hdr; > > > + > > > + if (sctx->send_max_size - sctx->send_size < sizeof(*hdr) + len) > > > + return -EOVERFLOW; > > > + hdr = (struct btrfs_tlv_header *)(sctx->send_buf + sctx->send_size); > > > + hdr->tlv_type = cpu_to_le16(BTRFS_SEND_A_DATA); > > > + hdr->tlv_len = cpu_to_le16(len); > > > > I think we need put_unaligned_le16 here, it's mapping a random buffer to > > a pointer, this is not alignment safe in general. > > I think you're right, although tlv_put() seems to have this same > problem. Indeed and there's more: tlv_put, TLV_PUT_DEFINE_INT, begin_cmd, send_cmd. Other direct assignments are in local structs so the alignment is fine.