From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fout-b3-smtp.messagingengine.com (fout-b3-smtp.messagingengine.com [202.12.124.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E09335208DE for ; Wed, 30 Sep 2026 18:23:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.12.124.146 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790792623; cv=none; b=JzA/DGO9ZHabXm51E8pP9+WWftFWQyLbQ3OD3I+7F/5jAn3/M5l+3tVp1W/VXgumZ1gtdAjTmFfNzPVWxopBcZR96Aj6h9a47d/m2fCPUPKEgW3s+dezgbpMtP3i8bZ62MbIt5HAZeVYKBBDvBIRvklrj4+1uERJNrZpoIXXfu8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790792623; c=relaxed/simple; bh=Gqa2Hzn1vbJaug9IYttLXJEbVr4ZX10Xx4CeqyP0PZs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=I7o9FejnnfDBAC13dsPv+R5W/83DhbtdR2O/3PugWQFeUHI6PANctPYwK7mkXhGd/SScQqrr2+1temhLi/2FUK0I8XOtzSElTeIXsnp3i0cFaw3jk8W8sMBHx/rQORbkAaDmLU/Bx/6XCW7K2ndydMbP/LIOlCpG0ZhA/UKvlHk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=bur.io; spf=pass smtp.mailfrom=bur.io; dkim=pass (2048-bit key) header.d=bur.io header.i=@bur.io header.b=umydw8jq; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=jYrzGWH1; arc=none smtp.client-ip=202.12.124.146 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=bur.io Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bur.io Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bur.io header.i=@bur.io header.b="umydw8jq"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="jYrzGWH1" Received: from phl-compute-11.internal (phl-compute-11.internal [10.202.2.51]) by mailfout.stl.internal (Postfix) with ESMTP id BDE321D00009; Wed, 30 Sep 2026 14:23:39 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-11.internal (MEProxy); Wed, 30 Sep 2026 14:23:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bur.io; h=cc:cc :content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:subject :subject:to:to; s=fm2; t=1790792619; x=1790879019; bh=wjF98rn73H FDRXAxlG5Nt/9P+YCQo5ijKfFMLlXBthk=; b=umydw8jqqPm23CEhYUjYeTfheX SBrvoJvCoYiGhZ8yNywssRTkh6j/Mf/SVsP5kovwSceIy0gfmzvIOlHtxzw0//PH ZcZ11Gtp/IhjDXSROzVvgOwAabOvJ+YFzToud3sb2iqVW+OGN5BXrONijfFXUcXR vLVHpwKNzs8KkQjzriyiQfH0nnxQIQCGfzk7qS2MXxH8+vFmMw2k3mhw7FOzT4xn qsAm0B7oFM7qSPUDqWGrDl2xOFDjhYhGkAxoOVRE8egEUxyUrahgO2xBuAiBo644 Rk8IC6hQw0KMHESrBOM3BtymVRUpBaL2hmdNLiEjlYsTwqT9GSxJRQaER5Jw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:subject:subject:to :to:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm1; t= 1790792619; x=1790879019; bh=wjF98rn73HFDRXAxlG5Nt/9P+YCQo5ijKfF MLlXBthk=; b=jYrzGWH1C33CHm5Frx2Ot7/L5LsTJfYPh7MgQwCva5tsUUHwORp tPTO8HMAlqufD8LGqbome0ZOZLy9G/kdL4Z4niMhEJW3e0umDwCn5P47MSYok3Wi 4bt2LYdd9xGTb/psx4Fe0+Mm8y1LOkwgjk5NYCBRC9Mo1P+4e5Qs34wpFKn4HyXL +Hrs8FYZhpKIcoo3jRQuWM4kM0mlEyKjBX0riYOm/Ih57F8SFtTSY6GHFSv+KYf9 81yWvmf8ZkoxvNRD08WR4zWxg422kcA2FTXAARDqoYsRZkztis0qVp6YoPikmMQT /602jxOFV2ayMSIUzGf4LeVH4+FjZfMs3ZA== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTGQ0xzT3N0tenB4a1ef4oR2emIIMddpLAVUtVH3dl/L3a96zgYmHR2KjuRbHliPS+ IWCGjYuFVmyb0fMT9pYuOHCKaTLg/3QGpQISs0xkfkufa2m3bRN5kOg7KB5kEYwBVDoJ23 pOHbW8Vijc5ldhVvJMxDDOGuz8CiXcyxNlin/9R+Nw7aH42bL6Dx4hPCx/un0EQoTO/LI3 Dd/gJi0x/gaE95ylVpuwcVoOOCfcamCdUgsAWaRVWlSrwNV4VXgXk28+l3akFqZqvsIRTT ZzbmiTQMUya3YClknGdQdRoPcswSY9jJJI+0ZPWSyxdOCkFLq/KlXeWt+JaaMxZb/L80e8 JKXYDWNdGBXQRAgsX9E73/wQbziViAFqB6gM9ruKuqqWvVByJ7oxH6KajXWHLT149Bo/xE h45KJewCtRSKqK/wvS4krQHZwJZM3G0tXvBCLsjx5U4lwNWiQP2bWtvybDDjlnuOdAz91v X2mpvEvKj/FPMRCnjhY28TPb8QVk509xyeeiccISlB2dI3hUug/EGTHqo+RulM3J8hgAIy XiAgSRpkZitpeihk8aZz4iFrpwKb1ZFTez8g37pkr0bLy4bkABg7SRWLMlMFvepsUmC5tc 4pKrWJSAq8m/PmFSkF6khgZxcn4uIc5GZE04goK3O4h2fanK4t4MIVuytiLA X-ME-Proxy: Feedback-ID: i083147f8:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 30 Sep 2026 14:23:39 -0400 (EDT) Date: Wed, 30 Sep 2026 11:23:25 -0700 From: Boris Burkov To: Qu Wenruo Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH v2 2/2] btrfs: introduce more accurate usebackuproot options Message-ID: <20260930182325.GA3186434@zen.localdomain> References: <9c907c139ede11a4b3026bd15b310de034690bc6.1788678078.git.wqu@suse.com> Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9c907c139ede11a4b3026bd15b310de034690bc6.1788678078.git.wqu@suse.com> On Sun, Sep 06, 2026 at 04:33:38PM +0930, Qu Wenruo wrote: > Previously we had no way to tell btrfs to use which backup slot, but > always use the newest backup, and retry until all backup roots are > exhausted. > > This doesn't give any control to the end user, even if the end user > wants to use a specific backup slot. > > To address this problem, allow more fine-control on usebackuproot rescue > option by introducing the following 4 rescue mount options: > > - rescue=usebackuproot_0 > - rescue=usebackuproot_1 > - rescue=usebackuproot_2 > - rescue=usebackuproot_3 What do you think about mirroring the compression levels and having the option parse as rescue=usebackuproot[:N] rather than 4 options? > > The number 0 means the newest slot, which should be the same as the one > recorded in the super block and no need to load any backup root. > > 1/2/3 means the second/third/fourth(oldest) backup slot to use. > > The existing "rescue=usebackuproot" is just an alias of > "rescue=usebackuproot_1". > > This will allow users to choose which backup root to use, thus can have > a better control than blindly choose any slot that can pass the very > basic root node checks. > > Signed-off-by: Qu Wenruo