On Monday April 9, [email protected] wrote:
> On Mon, Apr 09, 2007 at 08:31:37AM -0400, Trond Myklebust wrote:
> > That is a protocol limitation, not a client limitation.
>
> <Groan>
>
> And after quickly checking RFC 3010, I see this limitation hasn't been
> lifted in NFSv4.
>
> Speaking of which, right now ext3 doesn't know whether it's talking to
> an NFSv2 or NFS v3/v4 server, so it's always passing a 32-bit cookie.
> If NFSv3/v4 could use an explicit interface to request a 64-bit
> cookie, instead of just relying on the f_pos field in the file handle,
> we can reduce the chance of hash collisions when reading an ext3
> directory significantly.
>
We don't use f_pos (any more), we call llseek.
I think it would make a lot of sense - as Trond suggests - to not pass
O_LARGEFILE to dentry_open for an NFSv2 request. Then ext3 could
trigger off that and return 64bits of cookie ... and I think nfsd will
actually pass them all back to the client now. There is a
truncate-to-32bits bug that has only just been fixed.
But if a separate call is wanted, we have the export_operations struct
to put it in. All we need is a good case an useful specification.
> If there are 2 or 3 directory entries that have a hash collision,
> would the NFS protocol allow the server to juggle things so that those
> 2-3 directory entries with the hash collision are sent back in a
> single readdir RPC reply? Is it aceptable/legal to have multiple
> entries in the same READDIR reply packet have the same cookie value?
I think Trond has answered this, but I think it is also worth noting
that every entry returned in a READDIR reply includes a cookie, the
NFS client may use any of those cookies in a subsequent READDIR. One
might hope the client will only ever use the last, but one can never
be sure....
NeilBrown
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
