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 97E4F22E41D; Mon, 7 Apr 2025 09:08:54 +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=1744016935; cv=none; b=B2XxcXxYXixCHobIZiihqHBEwi4t2zDsqlOPFUzxc85F8wzvOj/lyUKGeWnYnhx4V001eAzJgI6QE9QmB0wCGJk+V/wfrdELeNJ48UbxluEPkOjn/ZxWIvX2ZpqY9JiGSbFTX8BbKvuFlqNo+iSi+pltY5hzwjVpbj2Ew0LYySI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744016935; c=relaxed/simple; bh=NA23vhUttLHVenuptP8n3w38fIMwxrbF/awe8gtEvbM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fyqfEQbpP8icNp84P80vkZaU/NhDRgw4adr64T/wXC17UpilsS9tudH2jGIchOW31E2dmOJGHkSXSq1JKU9PSLQGF1C6/LmPirP5ZSUFyH3qijFYHbk2CFbeWgAiUlcitxE5+j373QISxKFZz6hHIO4uFiBiXYS4Vo6cErlsX9k= 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=FimAJhvK; 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="FimAJhvK" 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=M61jlF/ve4QmSmhTeUmdNVmwIGJ2BP/aOzBU5BP/5nE=; b=FimAJhvKRx7qL+2muuG5DRbZyl izD4CHwBq92yCQeCaqH8U0gIeKnEdzYt7owvrgWPiypVqnBGhpho6CyKqbJbwqcF3fzLkojeW+7Ij aa/VYQIFkY0DNRE3XYhituaUpcu3f2cpV+XYp/Xa8NTYTAVjFTdJlCDXwRPDvwah31/b/2CMArhbj 641Uvb/UkK+sxZFuNAIcOqI3IkTb+qJIDXlaJJF9Cibd69LWVNCaDVaVhIpedG88fqbeZo2zM+Zd1 +mKnlrZVTDchjTWboKtktw2Fg0q2rSIifkubQYsek2YT/U1q8pfT7bIcSYPXZzhLhR/FcpaQHv3Kj +sbwkh3w==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.1 #2 (Red Hat Linux)) id 1u1iTO-0000000H8D8-1I3x; Mon, 07 Apr 2025 09:08:54 +0000 Date: Mon, 7 Apr 2025 02:08:54 -0700 From: Christoph Hellwig To: Christian Brauner Cc: Jan Kara , linux-fsdevel@vger.kernel.org, Ard Biesheuvel , linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, James Bottomley , mcgrof@kernel.org, hch@infradead.org, david@fromorbit.com, rafael@kernel.org, djwong@kernel.org, pavel@kernel.org, peterz@infradead.org, mingo@redhat.com, will@kernel.org, boqun.feng@gmail.com Subject: Re: [PATCH] fs: allow nesting with FREEZE_EXCL Message-ID: References: <20250404-work-freeze-v1-1-31f9a26f7bc9@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@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: <20250404-work-freeze-v1-1-31f9a26f7bc9@kernel.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Fri, Apr 04, 2025 at 12:24:09PM +0200, Christian Brauner wrote: > If hibernation races with filesystem freezing (e.g. DM reconfiguration), > then hibernation need not freeze a filesystem because it's already > frozen but userspace may thaw the filesystem before hibernation actually > happens. > > If the race happens the other way around, DM reconfiguration may > unexpectedly fail with EBUSY. > > So allow FREEZE_EXCL to nest with other holders. An exclusive freezer > cannot be undone by any of the other concurrent freezers. What is FREEZE_EXCL? I can't find it anywhere including in linux-next.