From: Steve French Subject: Re: [PATCH 3/3] Add a pair of system calls to make extended file stats available Date: Tue, 29 Jun 2010 17:33:56 -0500 Message-ID: References: <20100629200259.23196.81509.stgit@warthog.procyon.org.uk> <20100629200315.23196.68742.stgit@warthog.procyon.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: David Howells , viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@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: Ulrich Drepper Return-path: In-Reply-To: Sender: linux-cifs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org On Tue, Jun 29, 2010 at 5:13 PM, Ulrich Drepper wro= te: > On Tue, Jun 29, 2010 at 13:03, David Howells wr= ote: >> Add a pair of system calls to make extended file stats available, in= cluding >> file creation time, inode version and data version where available t= hrough the >> underlying filesystem: > > If you add something like this you might want to integrate another > extension. =A0This has been discussed a long time ago. =A0In almost n= o > situation all the information is needed. =A0Some of the pieces of > information returned by the syscall might be harder to collect than > other. =A0It makes sense in such a situation to allow the caller to > specify what she is interested in. =A0A bitmask of some sort. =A0This= was > brought up by the HPC people with gigantic filesystems. > > For this the syscall interface should have a parameter to specify wha= t > is requested and the stat-like structure should have a field > specifying what is actually present. =A0The latter bitmask must be a > superset of the former. > > Previous discussions centered around reusing the stat data structure > and somehow make it work. =A0But no clean solution was found. =A0If a= new > structure is added anyway this could solve the issue. That makes sense, especially for network file systems. NFSv4 protocol spec anticipates that: "With the NFS version 4 protocol, the client is able query what attribu= tes the server supports and construct requests with only those supported attributes (or a subset thereof)." and we were talking about something similar for SMB2 Unix Extensions (posix extensions) at the last plugfest (for SMB2 kernel client to Samba) and testing events. --=20 Thanks, Steve