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_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 20E3EC433E9 for ; Thu, 21 Jan 2021 07:39:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C0FBB238EE for ; Thu, 21 Jan 2021 07:39:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727495AbhAUHjG (ORCPT ); Thu, 21 Jan 2021 02:39:06 -0500 Received: from mx2.suse.de ([195.135.220.15]:36732 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727468AbhAUHix (ORCPT ); Thu, 21 Jan 2021 02:38:53 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611214687; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=ZyekRtuwcL6rmFXShlpi80pfIVx/0q3gXt2cqy36h+g=; b=lK1jJrx9dNPPn4jwdrIlFIR5t/K4D/9ryfgd3KLrhK+ceKmWs6VzDd5tsnV509vusXqKk4 /9dJFZLqKXKbKxGISH9w5/XhS7JkFD5Y2s0P3eOCg6BmsjZBXmLTCmkaiNHWlCUcyUsBig P+lf0jF+zqfmmjoUyeEI2hmpVlF8ITU= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 45D96AAAE; Thu, 21 Jan 2021 07:38:07 +0000 (UTC) Subject: Re: [PATCH] btrfs: rework the order of btrfs_ordered_extent::flags To: Qu Wenruo , linux-btrfs@vger.kernel.org References: <20210121061354.61271-1-wqu@suse.com> From: Nikolay Borisov Autocrypt: addr=nborisov@suse.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210121061354.61271-1-wqu@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 21.01.21 г. 8:13 ч., Qu Wenruo wrote: > [BUG] > There is a long existing bug in the last parameter of > btrfs_add_ordered_extent(), in commit 771ed689d2cd ("Btrfs: Optimize > compressed writeback and reads") back to 2008. > > In that ancient commit btrfs_add_ordered_extent() expects the @type > parameter to be one of the following: > - BTRFS_ORDERED_REGULAR > - BTRFS_ORDERED_NOCOW > - BTRFS_ORDERED_PREALLOC > - BTRFS_ORDERED_COMPRESSED > > But we pass 0 in cow_file_range(), which means BTRFS_ORDERED_IO_DONE. > > Ironically extra check in __btrfs_add_ordered_extent() won't set the bit > if we're seeing (type == IO_DONE || type == IO_COMPLETE), and avoid any > obvious bug. > > But this still leads to regular COW ordered extent having no bit to > indicate its type in various trace events, rendering REGULAR bit > useless. > > [FIX] > This patch will change the following aspects to avoid such problem: > - Reorder btrfs_ordered_extent::flags > Now the type bits go first (REGULAR/NOCOW/PREALLCO/COMPRESSED), then > DIRECT bit, finally extra status bits like IO_DONE/COMPLETE/IOERR. > > - Add extra ASSERT() for btrfs_add_ordered_extent_*() > > - Remove @type parameter for btrfs_add_ordered_extent_compress() > As the only valid @type here is BTRFS_ORDERED_COMPRESSED. > > - Remove the unnecessary special check for IO_DONE/COMPLETE in > __btrfs_add_ordered_extent() > This is just to make the code work, with extra ASSERT(), there are > limited values can be passed in. > > Signed-off-by: Qu Wenruo Reviewed-by: Nikolay Borisov