Return-Path: Received: from albireo.enyo.de ([5.158.152.32]:55164 "EHLO albireo.enyo.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725889AbeL1MBr (ORCPT ); Fri, 28 Dec 2018 07:01:47 -0500 From: Florian Weimer To: Adhemerval Zanella Cc: linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, libc-alpha@sourceware.org, qemu-devel@nongnu.org, ericvh@gmail.com, lucho@ionkov.net, hpa@zytor.com, arnd@arndb.de Subject: Re: d_off field in struct dirent and 32-on-64 emulation References: <87bm56vqg4.fsf@mid.deneb.enyo.de> <957967d7-5717-8ada-fb30-dfdf19898b6b@linaro.org> <87pntmu9iw.fsf@mid.deneb.enyo.de> <87k1jtvp8u.fsf@mid.deneb.enyo.de> Date: Fri, 28 Dec 2018 13:01:43 +0100 In-Reply-To: <87k1jtvp8u.fsf@mid.deneb.enyo.de> (Florian Weimer's message of "Fri, 28 Dec 2018 12:56:33 +0100") Message-ID: <87ftuhvp08.fsf@mid.deneb.enyo.de> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-ext4-owner@vger.kernel.org List-ID: * Florian Weimer: > * Adhemerval Zanella: > >> On 27/12/2018 16:09, Florian Weimer wrote: >>> * Adhemerval Zanella: >>> >>>> Also for glibc standpoint, although reverting it back to use getdents >>>> syscall for non-LFS mode might fix this issue for architectures that >>>> provides non-LFS getdents syscall it won't be a fix for architectures >>>> that still provides off_t different than off64_t *and* only provides >>>> getdents64 syscall. >>>> >>>> Currently we only have nios2 and csky (unfortunately). But since generic >>>> definition for off_t and off64_t still assumes non-LFS support, all new >>>> 32-bits ports potentially might carry the issue. >>> >>> For csky, we could still change the type of the non-standard d_off >>> field to long long int. This way, only telldir would have to fail >>> when truncation is necessary, as mentioned below: >> >> I think it makes no sense to continue making non-LFS as default for >> newer 32 bits ports, the support will be emulated with LFS syscalls. > > Sorry, I don't see how this matters. seekdir and telldir are NOT > affected by LFS. Ah, right. If struct dirent is 64-bit only, then the d_off member will be 64 bits as well. But it is unclear whether you can use that with lseek (probably yes, in its 64-bit variant), and it's unlikely it's going to work with seekdir because of the POSIX-required long int type.