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=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 F1C01C4360C for ; Thu, 10 Oct 2019 17:11:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC2332067B for ; Thu, 10 Oct 2019 17:11:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=toxicpanda-com.20150623.gappssmtp.com header.i=@toxicpanda-com.20150623.gappssmtp.com header.b="axdpcj74" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726550AbfJJRLn (ORCPT ); Thu, 10 Oct 2019 13:11:43 -0400 Received: from mail-qt1-f194.google.com ([209.85.160.194]:42021 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726007AbfJJRLm (ORCPT ); Thu, 10 Oct 2019 13:11:42 -0400 Received: by mail-qt1-f194.google.com with SMTP id w14so9740903qto.9 for ; Thu, 10 Oct 2019 10:11:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=toxicpanda-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=FzU0MmF047RefOw0G9S9hSUSkdozDNkJ8vE2RPLcoeg=; b=axdpcj74j1XKbxqdf+5azTorCNEwoExjxibUZZ+JMMyszzkG5f0VloUDg32RRp8v7i u7z8+4OzQ8ZcT3lOw/aba65ZX+Qg5al37rFFXwKYE68ntk/N8Gate7Y7qP/ogS4e0rdo DOu4V+4hdAXhgKzFyyCHMXymn/9ZMJAKnxxUzP40jtrMdvIyndeQ7Fk0XWF1e3+ziruB kpkooPby+RYqvUXgqCZ/365IVcrmjfmQ3MygvctPN+S8XJq+93nBCDv8aMvODwgc+cO8 70XKwJoefwg7mt1m4BVlFUB2eq9nyHSeCVM071foySv7yAGHRnpyRKOpBvzIDuf22xTE 0UGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=FzU0MmF047RefOw0G9S9hSUSkdozDNkJ8vE2RPLcoeg=; b=aVasjxYwPsi0aYHwWybbQX9pBHtaMZGQmStlMXsHE8qmP3WIYROnOyXli4R5DL+c7S pdJrKZm6X3SfBaAu++lS7HhkYC+4xUjYPSeKHIN6X+YQlU9/tg4ds8Vm23AuKlazvEYg 90mrBdfRScF/jhZSLi1r0I5WwqtxW+zLKvvXJ1QQo1G8VNSBoXkLEr9EAZPzeJZKzQV2 4UXNP/yOlwX8pQkgw4CPxnIIK5eVqg+GJz0/+hw7tlltl5LuAEoic6QGNw4FBG+LaQ7M +1iX2aYj6uIK3F7aqQKVaVdvaPVrRVDMJJBu3DK3gu2KaQxAr0j/2AEmkavJ+CbFOhRA EVHg== X-Gm-Message-State: APjAAAVd5SRXVzaNC5mXzoQ7qVC53KRrv6ah2ycmT/olhPIbeMvfylbS +npIbJpFzdnym2UnD++cs5TmNg== X-Google-Smtp-Source: APXvYqzPnbmHg9fWXEwYSqXdnQCHNtYZiKQvxvO1Kk3W8bYcXR9SHHGYmTp9+3URqpDEmE4aEO6ivA== X-Received: by 2002:a0c:f8c2:: with SMTP id h2mr11358530qvo.234.1570727500217; Thu, 10 Oct 2019 10:11:40 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::18ce]) by smtp.gmail.com with ESMTPSA id k17sm3976197qtk.7.2019.10.10.10.11.39 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 10 Oct 2019 10:11:39 -0700 (PDT) Date: Thu, 10 Oct 2019 13:11:38 -0400 From: Josef Bacik To: Dennis Zhou Cc: David Sterba , Chris Mason , Josef Bacik , Omar Sandoval , kernel-team@fb.com, linux-btrfs@vger.kernel.org Subject: Re: [PATCH 15/19] btrfs: load block_groups into discard_list on mount Message-ID: <20191010171137.xxuhjvmqzgifuixd@macbook-pro-91.dhcp.thefacebook.com> References: <31ce602fac88f25567a0b3e89037693ec962c1c7.1570479299.git.dennis@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <31ce602fac88f25567a0b3e89037693ec962c1c7.1570479299.git.dennis@kernel.org> User-Agent: NeoMutt/20180716 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Mon, Oct 07, 2019 at 04:17:46PM -0400, Dennis Zhou wrote: > Async discard doesn't remember the discard state of a block_group when > unmounting or when we crash. So, any block_group that is not fully used > may have undiscarded regions. However, free space caches are read in on > demand. Let the discard worker read in the free space cache so we can > proceed with discarding rather than wait for the block_group to be used. > This prevents us from indefinitely deferring discards until that > particular block_group is reused. > > Signed-off-by: Dennis Zhou What if we did completely discard the last time, now we're going back and discarding again? I think by default we just assume we discarded everything. If we didn't then the user can always initiate a fitrim later. Drop this one. Thanks, Josef