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 A4608178375 for ; Mon, 12 Aug 2024 12:08:13 +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=1723464494; cv=none; b=U4JPJf3FSvisCLQkG9IHtdZXC3uq7tI8ZMEvgIQjsq2b1MXPl0i6veyyEiKDz+KIb7JJpB2eBuieEFOUpUD7ePiMDezh8+PQVc6UQwmV1RCr7ZcpNMK2d4ExkP7boAM/fDL0rKddsIi0tJP/wniZqFrv1/ZSfWVi8aSGCZ5mwuk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723464494; c=relaxed/simple; bh=3xehZGWOpTHjqenbVPZ/01V9UzEM6YxjlopDzRp0pSU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LEL/kHI9Of0WqG0r2qHVSZ2R+M/F6gmwrAdt54ZIcBG6ZfrQeQWJX1tkK/0MnsWCNZ9z/uDeZwtcIvZuwj89P7F+YMJc3W/2fsm/ZMTfXAuNi1GJxvrADtsKs8i3I1IPNLvnJ1ZBmMuG7BUAUP7D64CTgI3C1oZAUFQvN6Ue1NE= 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=TNBNMX1Y; 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="TNBNMX1Y" 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=7Ja3MRqMKX9YNlwVLnaKWoZvlZ4zw/CZ6sjwXtiE1dQ=; b=TNBNMX1YkcI05SSX6Vn5eK3ZXs X8J9I90ogABgQJd67U3P2eFdGhvsuehxtHk/X2hoUIUeVhn5lBXQGbDE626DczjR80VI851w3pwUF UKFqBQfIooTl2z+mqs2pjWP1ClTumWHaapU0PIv2gbKwDOl/j8Ozx66F053mmCCbQd/klCJiZGjMZ 4Z0YyYzvXoGbNnXNU4hT3g2HSk/lZBGW2F0Ue/0mcqMLU7bBsN6qSS0sjSK4I6l4SJc8yk1i2PZEN IrvVL+oqg5YOSiMIw/4lCZSyaGvALE79I6E6YCG62eGVt2jt2y6x2iCosilLnRJOkDNWoI/P28OsW 65Sbfq1g==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sdTqO-00000000D7v-3fDP; Mon, 12 Aug 2024 12:08:12 +0000 Date: Mon, 12 Aug 2024 05:08:12 -0700 From: Christoph Hellwig To: Dave Chinner Cc: Johannes Bauer , linux-ext4@vger.kernel.org Subject: Re: Modification of block device by R/O mount Message-ID: References: <39c23608-8e20-40ad-84a3-4d4c0f9468c0@spornkuller.de> <1cd11635-4015-43e6-8c8c-db5e2f029536@spornkuller.de> Precedence: bulk X-Mailing-List: linux-ext4@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 Fri, Aug 09, 2024 at 11:50:30AM +1000, Dave Chinner wrote: > You'll need someone who actually knows what metadata ext4 needs to > modify directly on read-only mounts to tell you exactly what the > mount is modifying and whether or not it should actually be doing > that or not. However, I personally wouldn't consider this behaviour > a bug if it necessary to allow read-only mounts on read-only block > devices to work reliably... Modifying page cache without dirtying is in general a bug. On a block device we'll mostly get away with it, but it still is asking for trouble later. So this probably still warrants fixing, but as Dave said it isn't exactly a grave bug.