From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from shin.romanrm.net (shin.romanrm.net [146.185.199.61]) (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 25826215026 for ; Fri, 11 Oct 2024 12:27:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=146.185.199.61 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728649673; cv=none; b=ddPRftaDc+rl+WMSQWJ0skUJGx8J/uLHP8kOyFsz/J+xKlhLAkqUjT7R9bl8hXsVKC4tI0p/ObWoNMnpTd2Ye6JvcNUN9sMc0Fp92NLU1Ma1Q58hDtdim4JaIpIpv3Ccj72d479FsB8ZyBG3EoZTY05UB5uABB9Db7OIOeu2wl8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728649673; c=relaxed/simple; bh=UXpI3OBBKlVamf43XiZRYp5Psl72oNmEkccN4Z9bqlQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=FAgROof+DTEqz5CCm0Agq2vPpfZmZOaBFsCLYD6WDte47Gme6Bqpzp5Fb/z+PSjoRyH9au+o7gYHjUS4XRh9sZb7uLXa/u3nyR10nX0NUnebJfme1YVCLsoF5SpvLfRyENfTwzKS0QiYu94yLlSD0gJET+vpvKA2eFRsSWoHuhw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=romanrm.net; spf=pass smtp.mailfrom=romanrm.net; arc=none smtp.client-ip=146.185.199.61 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=romanrm.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=romanrm.net Received: from nvm (umi.39.romanrm.net [IPv6:fd39:a9b3:4fb1:1ccb:7900:fcd:12a3:6181]) by shin.romanrm.net (Postfix) with SMTP id 15C813F1D8; Fri, 11 Oct 2024 12:20:45 +0000 (UTC) Date: Fri, 11 Oct 2024 17:20:43 +0500 From: Roman Mamedov To: Yuwei Han Cc: dsterba@suse.cz, linux-btrfs@vger.kernel.org Subject: Re: [RFC] New ioctl to query deleted subvolumes Message-ID: <20241011172043.122e81ff@nvm> In-Reply-To: References: <20241009180300.GN1609@twin.jikos.cz> <308CF1DDC38EE68A+91e40dff-783f-43f4-9e49-a5cd4fa0b7a8@bupt.moe> <20241010170841.GR1609@twin.jikos.cz> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) 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-Transfer-Encoding: 7bit On Fri, 11 Oct 2024 20:06:00 +0800 Yuwei Han wrote: > There is a misunderstanding. What I mean is that why users need to > "confirm" subvol is deleted? I can't come up with actual usage. Hope you > can help me with that. A backup system may delete outdated subvolumes first, then wait until the space has actually freed up, before copying new data; otherwise it could run out of disk space. Especially considering that IO from starting to copy without such a wait would interfere with the cleaner process IO, resulting in it taking a longer time to finish. Or in my case I also wait until deleted subvolumes have been freed up *after* a backup, to then record how much remaining space a backup disk actually has, before unmounting it and putting into storage. -- With respect, Roman