Re: [NFS] What's slated for inclusion in 2.6.24-rc1 from the NFS client git tree...

[David Chinner <dgc@sgi.com>]

On Fri, Oct 05, 2007 at 02:12:22PM -0400, Jeff Layton wrote:
> On Fri, 05 Oct 2007 13:30:10 -0400
> Valdis.Kletnieks@vt.edu wrote:
> 
> > On Thu, 04 Oct 2007 10:00:50 EDT, Trond Myklebust said:
> > 
> > > How about a boot/module parameter to turn it on or off?
> > > 
> > > I don't see any point in having a sysctl for something like this: either
> > > you have legacy applications or you don't. It is not something that you
> > > switch off as you go off to lunch.
> > 
> > How does Joe Sysadmin tell if he has an affected legacy app or not?
> > 
> > (The obvious "try it and see what breaks" is a non-starter for many places,
> > because you too easily end up in a loop of "enable it, find 4-5 show stoppers,
> > turn it off, fix them, lather rinse repease".  Been there, done that, got
> > the tshirt - a project I got dragged into involves a large storage array that
> > appears to insist on exporting 64-bit stuff, and a large farm of clients that
> > are very 64-bit unclean....)
> > 
> 
> Note that "try it and see what breaks" isn't reliable either. If glibc
> gets back a 64 bit inode number that just happens to fit in the 32-bit
> field, then everything will work. You don't actually get an EOVERFLOW
> until st_ino overflows the field, and that may not happen often enough
> for testing this way to detect it...

There's a damn easy way of testing this.

Use XFS on a 64 bit Linux NFS server, mount is '-o inode64,ino64'
and then export it to you client that is going to have problems.
the "ino64" mount option guarantees that the userspace visible
inode number is always > 32 bits in length....

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group