From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f51.google.com ([74.125.82.51]:38428 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756997AbbJ2Tgj (ORCPT ); Thu, 29 Oct 2015 15:36:39 -0400 From: Thomas Rohwer Message-ID: <56327543.5070308@gmail.com> Date: Thu, 29 Oct 2015 20:36:35 +0100 MIME-Version: 1.0 To: dsterba@suse.cz, Luke Dashjr , Chris Mason , Josef Bacik , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] btrfs: bugfix: handle FS_IOC32_{GETFLAGS,SETFLAGS,GETVERSION} in btrfs_ioctl References: <201505131715.27483.luke@dashjr.org> <201505141627.56205.luke@dashjr.org> <20150515111922.GB23255@twin.jikos.cz> <201510290822.35540.luke@dashjr.org> <20151029143932.GZ13624@twin.jikos.cz> In-Reply-To: <20151029143932.GZ13624@twin.jikos.cz> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: > I suggest to add an anonymous union and add a u64 member that would > force the type width: > > struct btrfs_ioctl_send_args { > __s64 send_fd; /* in */ > __u64 clone_sources_count; /* in */ > union { > __u64 __user *clone_sources; /* in */ > u64 __pointer_alignment; > }; > __u64 parent_root; /* in */ > __u64 flags; /* in */ > __u64 reserved[4]; /* in */ > }; I am no expert, but would this change alone modify the user space ABI of a 32-bit Linux kernel? I.e. people in the (presumably currently working) btrfs-send situation (32-bit) user space/32-bit kernel would have to upgrade user space tools and kernel at the same time. Otherwise, they will encounter a non-working setup. I think, my suggested patch does not change any working ABI, and no change to the user space tools are necessary. Sincerely, Thomas Rohwer