From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935516AbeBLNee (ORCPT ); Mon, 12 Feb 2018 08:34:34 -0500 Received: from mail-wr0-f177.google.com ([209.85.128.177]:46333 "EHLO mail-wr0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933917AbeBLNec (ORCPT ); Mon, 12 Feb 2018 08:34:32 -0500 X-Google-Smtp-Source: AH8x2249Cblpp0Euc1MNXRjNGk2HFwzQ1kQqvbhzXucvvrDdBeT1ZKMX/Oog8bLEmBsKCq8dmyxcSQ== Subject: Re: ext4 iomap SEEK broken [was: [GIT PULL] ext4 updates for 4.15] From: Jiri Slaby To: "Theodore Ts'o" , linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, Christoph Hellwig References: <20171113031502.f6mctmlmgk5psh77@thunk.org> <7ae851b1-92a8-779a-a066-1c7e34867465@suse.cz> <45062110-e80c-f1e8-3710-743c1ae4d232@suse.cz> Message-ID: <6db646d9-9ec0-ddda-d480-357cf3c70a09@suse.cz> Date: Mon, 12 Feb 2018 14:34:29 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <45062110-e80c-f1e8-3710-743c1ae4d232@suse.cz> Content-Type: text/plain; charset=iso-8859-2 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/12/2018, 01:14 PM, Jiri Slaby wrote: > On 02/12/2018, 11:02 AM, Jiri Slaby wrote: >> Given this happens only on 32bit kernel, I assume some 32bit overflow. >> But I am unable to see it (yet). > > Just to add, a diff of strace in good and bad kernels: > @@ -655,14 +655,4 @@ > _llseek(3, 4275568640, [4286054400], SEEK_DATA) = 0 > _llseek(3, 4286054400, [4288675840], SEEK_HOLE) = 0 > _llseek(3, 4288675840, [4299161600], SEEK_DATA) = 0 > -_llseek(3, 4299161600, [4301783040], SEEK_HOLE) = 0 > +_llseek(3, 4299161600, [4299161600], SEEK_HOLE) = 2621440 > > llseek returns a very invalid value when it comes to 0x100400000. It gets cropped to 0x400000, so: --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3523,7 +3523,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, iomap->flags |= IOMAP_F_DIRTY; iomap->bdev = inode->i_sb->s_bdev; iomap->dax_dev = sbi->s_daxdev; - iomap->offset = first_block << blkbits; + iomap->offset = (u64)first_block << blkbits; iomap->length = (u64)map.m_len << blkbits; if (ret == 0) { sounds about right? > regards, -- js suse labs