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=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1240DC47088 for ; Wed, 26 May 2021 17:01:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EABCE613D7 for ; Wed, 26 May 2021 17:01:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233792AbhEZRCy (ORCPT ); Wed, 26 May 2021 13:02:54 -0400 Received: from mx2.suse.de ([195.135.220.15]:33252 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233676AbhEZRCy (ORCPT ); Wed, 26 May 2021 13:02:54 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1622048481; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=IqUFJiR1BUxfxyHwAR4l2oZd55nyMn5ow/XJZiWvM1U=; b=OR2WIrNmO09FqgXt4g03FhUUxpxaqWrRo9qPw0HqiRg6Gkb/cXAjTet+yZK5XxxVgqk6qh rq3aeVMcRSANtORHprOdJJ8pWJdJxILGzW/agfAwAnLW6NIfd985Ul57JmqGFDtRFvnWuT O6eUBWoytbKUVLVG2sEi+BHeQee2JGU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1622048481; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=IqUFJiR1BUxfxyHwAR4l2oZd55nyMn5ow/XJZiWvM1U=; b=sg1CfayORbLqaJ76nHlLSOWC1ROoHZR/qV9G3vhJ7PXCDTluYF9bZUoAsNENIidIE3tE19 sX/vux0sqikFaiBA== Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C0F6BAB71; Wed, 26 May 2021 17:01:21 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id D1A48DA70B; Wed, 26 May 2021 18:58:44 +0200 (CEST) Date: Wed, 26 May 2021 18:58:44 +0200 From: David Sterba To: dsterba@suse.cz, Qu Wenruo , David Sterba , linux-btrfs@vger.kernel.org Subject: Re: [PATCH 8/9] btrfs: simplify eb checksum verification in btrfs_validate_metadata_buffer Message-ID: <20210526165844.GI7604@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Qu Wenruo , David Sterba , linux-btrfs@vger.kernel.org References: <6828072ccda5d55b9d130f48b750455ea728781b.1621961965.git.dsterba@suse.com> <0b51e0c9-896a-4ee2-f965-eec7b57cbd39@gmx.com> <20210526163139.GG7604@twin.jikos.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210526163139.GG7604@twin.jikos.cz> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Wed, May 26, 2021 at 06:31:39PM +0200, David Sterba wrote: > > > + header = page_address(eb->pages[0]) + > > > + get_eb_offset_in_page(eb, offsetof(struct btrfs_leaf, header)); > > > > It takes me near a minute to figure why it's not just > > "get_eb_offset_in_page(eb, 0)". > > > > I'm not sure if we really need that explicit way to just get 0, > > especially most of us (and even some advanced users) know that csum > > comes at the very beginning of a tree block. > > > > And the mention of btrfs_leave can sometimes be confusing, especially > > when we could have tree nodes passed in. > > Ah right, I wanted to use the offsetof for clarity but that it could be > used with nodes makes it confusing again. What if it's replaced by > > get_eb_offset_in_page(eb, offsetof(struct btrfs_header, csum)); > > This makes it clear that it's the checksum and from the experience we > know it's at offset 0. I'd rather avoid magic constants and offsets but > you're right that everybody knows that the checksum is at the beginning > of btree block. --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -584,7 +584,7 @@ static int validate_extent_buffer(struct extent_buffer *eb) const u32 csum_size = fs_info->csum_size; u8 found_level; u8 result[BTRFS_CSUM_SIZE]; - const struct btrfs_header *header; + const u8 *header_csum; int ret = 0; found_start = btrfs_header_bytenr(eb); @@ -609,14 +609,14 @@ static int validate_extent_buffer(struct extent_buffer *eb) } csum_tree_block(eb, result); - header = page_address(eb->pages[0]) + - get_eb_offset_in_page(eb, offsetof(struct btrfs_leaf, header)); + header_csum = page_address(eb->pages[0]) + + get_eb_offset_in_page(eb, offsetof(struct btrfs_header, csum)); - if (memcmp(result, header->csum, csum_size) != 0) { + if (memcmp(result, header_csum, csum_size) != 0) { btrfs_warn_rl(fs_info, "checksum verify failed on %llu wanted " CSUM_FMT " found " CSUM_FMT " level %d", eb->start, - CSUM_FMT_VALUE(csum_size, header->csum), + CSUM_FMT_VALUE(csum_size, header_csum), CSUM_FMT_VALUE(csum_size, result), btrfs_header_level(eb)); ret = -EUCLEAN;