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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 62A8FCA9EA0 for ; Fri, 25 Oct 2019 09:47:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2A60121D7B for ; Fri, 25 Oct 2019 09:47:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=colorremedies-com.20150623.gappssmtp.com header.i=@colorremedies-com.20150623.gappssmtp.com header.b="vytd8p1W" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2438998AbfJYJrm (ORCPT ); Fri, 25 Oct 2019 05:47:42 -0400 Received: from mail-wr1-f44.google.com ([209.85.221.44]:35258 "EHLO mail-wr1-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2438883AbfJYJrm (ORCPT ); Fri, 25 Oct 2019 05:47:42 -0400 Received: by mail-wr1-f44.google.com with SMTP id l10so1563010wrb.2 for ; Fri, 25 Oct 2019 02:47:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=colorremedies-com.20150623.gappssmtp.com; s=20150623; h=mime-version:from:date:message-id:subject:to; bh=RX3dlZUKSdD/mblhXscvsoUL1t0ggHrf1RzAkd1EaeI=; b=vytd8p1W5tD99tivoTe2JD7o5UbHqEsG1bOc77sHGJdJHV+mlxjj76m7btOFJcW013 fXryF6KqkDI3lJv/9WFfaDv3Tfbnz0eExOgmBa0mBhXLErfyld+FUEqaU0ZgnwPY/uMu nXailAjR44ZTTFQO4J5SCmTMYpB9YEFkFOu++e8vatfWtUbrKTHlyMFqKTMS/PwBDXNu yn/zGZbP3rchqQuyjtnIJfaQHOywTENgwc789Fw9fP5O+RZAP/a9gzieXd8ATP03vwfl 69n4AJ6yZZI59kQZKcV+9sF7VB8WQhfpA6HCLHYnHs8SsIjc0yfaEQjuUCaTVEiMU3d+ 0rpA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=RX3dlZUKSdD/mblhXscvsoUL1t0ggHrf1RzAkd1EaeI=; b=b0vkrN/FLK3wMm8JTHBmDWBVVWPvkrBHhgLeU5lEUWAR0V/CKBIzIIm0IV4jqRamGC Gq4cqmY5EZpW1AMloqwkT/5TjiLFab8GKEVAKH3XDTw2NtmfarsXR4UfZsXQ/ey+/6xf DeT4epPlfKytw/E6xxXDFFUmUL0isEGNFPkx4OEqY9wxGnYFyaWl7EiEx0khV1lYrYue f/SC9RrMrreumymxUz131QHoNvblSOdHLxrVAxJif+66Wn1BmD5c4TKZXdtzudm3FM7Z 8LptQvSpvTpTWR8MXPUWn48XhABg+agdV28MTDtSJPJmgR/hn+A6xUOyy9xNAC+7N/Cu Y/jA== X-Gm-Message-State: APjAAAVU8XEZUDv36egh/3cMS576OFojTAHpGiDa7VwRKntBjb7XBtWJ S3jT0qGZmnzKgYUOmjtn0/2sr62SZzzw6FB5KNr6aJ8RRFqMlw== X-Google-Smtp-Source: APXvYqz/xUrtoXDCG319onE6P2qOb03E4nGBuflVC6lBQHLrdlj0nCtW1G7hrm5CMWNQEuEeBrSDTiKP6S4jr7mPLwA= X-Received: by 2002:adf:9799:: with SMTP id s25mr2134560wrb.390.1571996859792; Fri, 25 Oct 2019 02:47:39 -0700 (PDT) MIME-Version: 1.0 From: Chris Murphy Date: Fri, 25 Oct 2019 11:47:19 +0200 Message-ID: Subject: Does GRUB btrfs support log tree? To: Btrfs BTRFS Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org I see references to root and chunk trees, but not the log tree. If boot related files: kernel, initramfs, bootloader configuration files, are stored on Btrfs; and if they are changed in such a way as to rely on the log tree; and then there's a crash; what's the worse case scenario effect? At first glance, if the bootloader doesn't support log tree, it would have a stale view of the file system. Since log tree writes means a full file system update hasn't happened, the old file system state hasn't been dereferenced, so even in an SSD + discard case, the system should still be bootable. And at that point Btrfs kernel code does log replay, and catches the system up, and the next update will boot the new state. Correct? -- Chris Murphy