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 6AA18C54FCB for ; Wed, 22 Apr 2020 20:26:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 349F52082E for ; Wed, 22 Apr 2020 20:26:50 +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="RtfjmJhY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726173AbgDVU0t (ORCPT ); Wed, 22 Apr 2020 16:26:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725779AbgDVU0t (ORCPT ); Wed, 22 Apr 2020 16:26:49 -0400 Received: from mail-wm1-x341.google.com (mail-wm1-x341.google.com [IPv6:2a00:1450:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA6CFC03C1A9 for ; Wed, 22 Apr 2020 13:26:48 -0700 (PDT) Received: by mail-wm1-x341.google.com with SMTP id u16so4052372wmc.5 for ; Wed, 22 Apr 2020 13:26:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=colorremedies-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=qSdCKYPVhngCOHBuKy0lP/JtuGIHCEvOeoiLIHG7PnU=; b=RtfjmJhYUGEp1iKRXs0FnqkAR97ajkn9ptcWprvSH0NpEgOZ34g3RfCopuUmw0I8ic 79jKhSDrpzWJNqWOJDmA/MOjJA8hg76cEWz2BOOv4PnlAzzgJZjbPBU4G5g4twzlVpKM fBAHcxymhB2MsFV0WKcizytKFr9mchT5ZTX8iC8f3vQ9roOmL5UyVTDiMuTHqfyC31tm i8FbKs1jpV9oaW7IxV6JaaSaAat/p497UsEsVTQ2z0+XNu5xNJnIMY+D+a63kXg4mckK yA/XeGpbyXLhBkevjCHieIVZGpXOhEk74xNcbZdWlPW52TWmAHf1Hs6uwX6XNhBhErsX d9iQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=qSdCKYPVhngCOHBuKy0lP/JtuGIHCEvOeoiLIHG7PnU=; b=LcOKji3TMltGSBFibBD/PQjV1yJCfMdDpCSofe7wMi0KIIpH3BoKd5BL+7zNXzMZRl 5PN9Fec3O4HDlqSGskXnxYBESBrwnR9sLTl7n2VD8cCSFgkM8Y7nf+VGTRFUgHh4UF+G jEegDbbd1RlLBfBJfVm971ugVExut0daHNbAWcZq8meFqh38laWw+ZRsagISpavyndnL MdSJErZR2+AjEMhEDBAu8fWYEv7abW6x5LwYcBRGDNjnghsWREYfqHYUr48YbeLWkeX8 HXPlr32MSCzI/WC+BCKc/GpI2ggsW53o/ZqTvirFFa78rjDUnF9rA9PdtyCEd7rkrQL1 mbxw== X-Gm-Message-State: AGi0PuZb/n3PHUzNYKha+zSqK5ZquhTo6UiqWWbZn75KoRMieM0Yw6gj iOGLArwRbUjBS/5EqGx6XVFc5daxAn4PnDXWBwGikHkiJco= X-Google-Smtp-Source: APiQypLUnXrAR8eBDBjw8XLcfbUvv3RHvpAKURDbULdl79VDVnfXMdAs7JP05iWTc85iS+k12E4X27v82XUnH3UuKwg= X-Received: by 2002:a1c:1b0b:: with SMTP id b11mr264730wmb.182.1587587207463; Wed, 22 Apr 2020 13:26:47 -0700 (PDT) MIME-Version: 1.0 References: <20200422205209.0e2efd53@nic.cz> In-Reply-To: <20200422205209.0e2efd53@nic.cz> From: Chris Murphy Date: Wed, 22 Apr 2020 14:26:31 -0600 Message-ID: Subject: Re: when does btrfs create sparse extents? To: Marek Behun Cc: 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 On Wed, Apr 22, 2020 at 12:52 PM Marek Behun wrote: > > Hello, > > there was a bug fixed recently in U-Boot's btrfs driver - the driver > failed to read files with sparse extents. This causes that sometimes > device failes to boot Linux, since the kernel fails to load from > storage. > > So when does kernel's btrfs driver write sparse extents? Is it always > when it finds a PAGE_SIZEd and aligned all-zeros block? Or is it more > complicated? I'm not a btrfs developer, so with respect to kernel code behavior I can't answer directly. But I wonder if other sources of this sparseness has been considered? Maybe the build system is creating or preserving sparseness? e.g. `tar --hole-detection` or `--sparse` is used. Another possibility is Btrfs supports two kinds of holes in the on-disk format for sparse files. Maybe uboot only supported the original (current default) type, and the bug really fixed the newer 'no-holes' feature version? -- Chris Murphy