Re: [PATCH 0/6] Extended file stat system call
- From: "Myklebust, Trond" <Trond Myklebust netapp com>
- To: Roland McGrath <roland hack frob com>
- Cc: "linux-cifs vger kernel org" <linux-cifs vger kernel org>, "linux-nfs vger kernel org" <linux-nfs vger kernel org>, "nautilus-list gnome org" <nautilus-list gnome org>, "libc-alpha sourceware org" <libc-alpha sourceware org>, "kfm-devel kde org" <kfm-devel kde org>, "wine-devel winehq org" <wine-devel winehq org>, "samba-technical lists samba org" <samba-technical lists samba org>, David Howells <dhowells redhat com>, Steve French <smfrench gmail com>, "linux-api vger kernel org" <linux-api vger kernel org>, "linux-fsdevel vger kernel org" <linux-fsdevel vger kernel org>, "linux-ext4 vger kernel org" <linux-ext4 vger kernel org>
- Subject: Re: [PATCH 0/6] Extended file stat system call
- Date: Fri, 27 Apr 2012 00:33:06 +0000
On Thu, 2012-04-26 at 15:05 -0700, Roland McGrath wrote:
> > What if the xstat() and struct xstat eventually becomes what userspace
> > uses as stat() (as a wrapper) and struct stat (if such a thing is
> > possible with glibc versioning)?
> It's certainly possible with symbol versioning, though it seems much more
> likely that we'd stick with the existing struct stat and stat* interfaces
> and only have the implementation using statx underneath (e.g. for new
> machines or kernel ABIs where the kernel stops providing any calls except
> for statxat), at least for the foreseeable future.
> > Do older programs that think they're using stat() and don't know about
> > the extra fields available expect to see a useful value in st_ino?
> POSIX requires that st_ino have a useful value for the standard *stat calls.
Yes, but we're talking about non-POSIX filesystems here. If the
filesystem doesn't have a useful value for st_ino, then the usual way of
dealing with those POSIX requirements is to fake up values. The question
then becomes whether or not we care if it is the kernel or userland that
fakes up those values.
Linux NFS client maintainer
Trond Myklebust netapp com
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