From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D971DC3A589 for ; Tue, 20 Aug 2019 13:31:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B62CB22DBF for ; Tue, 20 Aug 2019 13:31:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729203AbfHTNb0 (ORCPT ); Tue, 20 Aug 2019 09:31:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55762 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729137AbfHTNb0 (ORCPT ); Tue, 20 Aug 2019 09:31:26 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D73C33082A49; Tue, 20 Aug 2019 13:31:25 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-255.rdu2.redhat.com [10.10.120.255]) by smtp.corp.redhat.com (Postfix) with ESMTP id C3B751DA; Tue, 20 Aug 2019 13:31:21 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20190814111535.GC1885@lst.de> References: <20190814111535.GC1885@lst.de> <20190808082744.31405-1-cmaiolino@redhat.com> <20190808082744.31405-3-cmaiolino@redhat.com> To: Christoph Hellwig Cc: dhowells@redhat.com, Carlos Maiolino , linux-fsdevel@vger.kernel.org, adilger@dilger.ca, jaegeuk@kernel.org, darrick.wong@oracle.com, miklos@szeredi.hu, rpeterso@redhat.com, linux-xfs@vger.kernel.org Subject: Re: [PATCH 2/9] cachefiles: drop direct usage of ->bmap method. MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <19938.1566307880.1@warthog.procyon.org.uk> Date: Tue, 20 Aug 2019 14:31:20 +0100 Message-ID: <19939.1566307880@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Tue, 20 Aug 2019 13:31:25 +0000 (UTC) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org Christoph Hellwig wrote: > > + block = page->index; > > + block <<= shift; > > Can't this cause overflows? No, not unless the netfs allows files >16EiB in size and as long as block (type sector_t) is a 64-bit integer. A 16EiB-1 (0xffffffffffffffff) file would have 4P-1 (0xfffffffffffff) pages assuming a 4K page size. At a block size of 1 (and a shift therefore of 12), the maximum block number calculated would be 0xfffffffffffff000. David