From: Joel Becker Subject: Re: [PATCH 3/3] Add a pair of system calls to make extended file stats available Date: Tue, 29 Jun 2010 15:48:44 -0700 Message-ID: <20100629224844.GF4150@mail.oracle.com> References: <20100629200259.23196.81509.stgit@warthog.procyon.org.uk> <20100629200315.23196.68742.stgit@warthog.procyon.org.uk> <26026.1277851016@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ulrich Drepper , viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org, smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, mcao-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org, aneesh.kumar-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, linux-cifs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, samba-technical-w/Ol4Ecudpl8XjKLYN78aQ@public.gmane.org, sjayaraman-l3A5Bk7waGM@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: David Howells Return-path: Content-Disposition: inline In-Reply-To: <26026.1277851016-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-cifs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org On Tue, Jun 29, 2010 at 11:36:56PM +0100, David Howells wrote: > Ulrich Drepper wrote: > > And while you're at it, maybe some spare fields at the end are nice. > > I made it so that the syscall can return variable length data: the main xstat > struct, plus extra records yet to be defined. They could even be variable > length and assembled/disassembled with something like the control message > macros for recvmsg(). The less variable length stuff the better, I think. At least, for the stuff stat(2) already returns, you should have a fixed-size structure. Even if I only pass the GIVE_ME_UIDS flag, I don't want to have to deal with the variable size stuff until I've actually asked for esoteric things. I'll know that the non-UIDS fields are garbage by the fact that I didn't ask for them. Joel -- "Time is an illusion, lunchtime doubly so." -Douglas Adams Joel Becker Consulting Software Developer Oracle E-mail: joel.becker-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org Phone: (650) 506-8127