From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 EAA754409; Tue, 15 Oct 2024 05:05:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728968715; cv=none; b=HehRw+5265yuiiHz4TrFLDBKTbhBnvgS7yMM8LKrNyFDIM4LnfRN4IPUJ7CER3SHIHynQ0NwE09gDHbCzVAkK0YbpIV+dN6jgMkSQUYVmj8MWdFjMgNx4UVYK5dOJvIfCVczxmwfyQPVkyVQpxbn2+bXWZaegVF1G+6tQRVQXqA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728968715; c=relaxed/simple; bh=RbAhWTuItMFAIA6NkLv3EHzhAomLVnEWgdUI6fHnAPU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Nj6wEMZ78TaCocs6YSyASegmA1PotN2OpK9VVb5+Zi5QnTz561tcKSClLUZI8ytLFCcz29mdDy7oS1T0mSNkjx/xwAelp6g1ys5hW9lrN9KFJ6qQ+H0LYgLRI7T9vNpzjWVKUDlboRAtO6VOdbh8xH2boeqBLF2GCMb2umGdtGk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=XF9TDcO6; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="XF9TDcO6" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=DqxxBECG3Qf88WApnQ1vcQdv3I7w3KQjljwDOi/y3Xs=; b=XF9TDcO6Za8S1oiBOylCVyR5V5 nHW+XZdzQdT7KB9UgNT5KET1gb9E7iQsbIXNCrjn49afBnB0BBshKoQ8JhGzffvuULJVxcljKU/RF Gvc8YnLkvG+wv4pyV5W9/NO0CbwGP7diZi3uRppbWYHAI46HMFbekx3bKFbakfbBWx2Cu2rKAtrj7 z9BMulMkudBQnqDx5eOXp18jgKAy7cwW5LPN+avqj7cjiZfizZ6XdI5plCKZvG2hhZR26PWISFZOn 9ZBGE1kP7wjfQu7LtS6BUafyJ544RPFVnIjL5068yRdndEjJ8NiNOHK4PZL9S3o3MWaASi7mHaVDz nvBCH+rw==; Received: from hch by bombadil.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1t0Zk8-0000000752W-3q98; Tue, 15 Oct 2024 05:05:12 +0000 Date: Mon, 14 Oct 2024 22:05:12 -0700 From: Christoph Hellwig To: Jaegeuk Kim Cc: Daeho Jeong , Christoph Hellwig , Daeho Jeong , kernel-team@android.com, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org Subject: Re: [f2fs-dev] [PATCH v5] f2fs: introduce device aliasing file Message-ID: References: <20241010192626.1597226-1-daeho43@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@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: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Mon, Oct 14, 2024 at 04:42:07PM +0000, Jaegeuk Kim wrote: > > > > Plz, refer to this patch and the description there. > > > > https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs-tools.git/commit/?h=dev-test&id=8cc4e257ec20bee207bb034d5ac406e1ab31eaea > > Also, I added this in the description. > > --- > For example, > "mkfs.f2fs -c /dev/block/test@test_alias /dev/block/main" gives > a file $root/test_alias which carves out /dev/block/test partition. What partition? So mkfs.f2fs adds additional devices based on the man page. So the above creates a file system with two devices, but the second device is not added to the general space pool, but mapped to a specific file? How does this file work. I guess it can't be unlinked and renamed. It probably also can't be truncated and hole punched, or use insert/collapse range. How does the user find out about this magic file? What is the use case? Are the exact semantics documented somewhere?