From patchwork Thu Jul 22 19:29:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Sterba X-Patchwork-Id: 12394561 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 EAFE7C4338F for ; Thu, 22 Jul 2021 19:32:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CC79B60EB5 for ; Thu, 22 Jul 2021 19:32:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229977AbhGVSwE (ORCPT ); Thu, 22 Jul 2021 14:52:04 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:37822 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229556AbhGVSwE (ORCPT ); Thu, 22 Jul 2021 14:52:04 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 6B1C71FF0C; Thu, 22 Jul 2021 19:32:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1626982358; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=xvIZzOywIgeyxIvE2uxZ9qTLVGuKeoUKADxQx8DgUx4=; b=TUx3L1COHL6FbAXEF1voZ5fBX4RwaEyvTBj21Ujn/YPSq+s5KKyYBLN1/YZzXk0yJA35z4 WlYP52u6tL+13o0Vk/87lgPb0l5c9R4nyoy977ggMQMnYJHF1XnFA9+THwng2LgV/6c5Up W20IdDRR31Jce6lVQsAz2gyXaL01+xI= Received: from ds.suse.cz (ds.suse.cz [10.100.12.205]) by relay2.suse.de (Postfix) with ESMTP id 63214A3B87; Thu, 22 Jul 2021 19:32:38 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 9F6A7DAF95; Thu, 22 Jul 2021 21:29:56 +0200 (CEST) From: David Sterba To: linux-btrfs@vger.kernel.org Cc: David Sterba Subject: [PATCH] btrfs: allow degenerate raid0/raid10 Date: Thu, 22 Jul 2021 21:29:55 +0200 Message-Id: <20210722192955.18709-1-dsterba@suse.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org The data on raid0 and raid10 are supposed to be spread over multiple devices, so the minimum constraints are set to 2 and 4 respectively. This is an artificial limit and there's some interest to remove it. Change this to allow raid0 on one device and raid10 on two devices. This works as expected eg. when converting or removing devices. The only difference is when raid0 on two devices gets one device removed. Unpatched would silently create a single profile, while newly it would be raid0. The motivation is to allow to preserve the profile type as long as it possible for some intermediate state (device removal, conversion). Unpatched kernel will mount and use the degenerate profiles just fine but won't allow any operation that would not satisfy the stricter device number constraints, eg. not allowing to go from 3 to 2 devices for raid10 or various profile conversions. Example output: # btrfs fi us -T . Overall: Device size: 10.00GiB Device allocated: 1.01GiB Device unallocated: 8.99GiB Device missing: 0.00B Used: 200.61MiB Free (estimated): 9.79GiB (min: 9.79GiB) Free (statfs, df): 9.79GiB Data ratio: 1.00 Metadata ratio: 1.00 Global reserve: 3.25MiB (used: 0.00B) Multiple profiles: no Data Metadata System Id Path RAID0 single single Unallocated -- ---------- --------- --------- -------- ----------- 1 /dev/sda10 1.00GiB 8.00MiB 1.00MiB 8.99GiB -- ---------- --------- --------- -------- ----------- Total 1.00GiB 8.00MiB 1.00MiB 8.99GiB Used 200.25MiB 352.00KiB 16.00KiB # btrfs dev us . /dev/sda10, ID: 1 Device size: 10.00GiB Device slack: 0.00B Data,RAID0/1: 1.00GiB Metadata,single: 8.00MiB System,single: 1.00MiB Unallocated: 8.99GiB Note "Data,RAID0/1", with btrfs-progs 5.13+ the number of devices per profile is printed. Signed-off-by: David Sterba Reviewed-by: Qu Wenruo --- fs/btrfs/volumes.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 86846d6e58d0..ad943357072b 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -38,7 +38,7 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = { .sub_stripes = 2, .dev_stripes = 1, .devs_max = 0, /* 0 == as many as possible */ - .devs_min = 4, + .devs_min = 2, .tolerated_failures = 1, .devs_increment = 2, .ncopies = 2, @@ -103,7 +103,7 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = { .sub_stripes = 1, .dev_stripes = 1, .devs_max = 0, - .devs_min = 2, + .devs_min = 1, .tolerated_failures = 0, .devs_increment = 1, .ncopies = 1,