[Gluster-devel] [RFC] Improved distribution

[Jeff Darcy]

On Tue, 17 Apr 2012 11:14:21 -0400 (EDT)
Kaleb Keithley <kkeithle at redhat.com> wrote:

> ISTR Avati and/or Vijay telling us — when we were in BLR — that the
> hash of the filename is salted with the hash of the pathname up to,
> but not including the filename.
> 
> Am I misremembering that? (Of course I haven't looked at the code.)

I just did, and if there's anything but the name included I'm missing
it.  Here's the DHT function that computes the hash.

  73 int     
  74 dht_hash_compute (int type, const char *name, uint32_t *hash_p)
  75 {                       
  76         char     *rsync_friendly_name = NULL;
  77 
  78         MAKE_RSYNC_FRIENDLY_NAME (rsync_friendly_name, name);
  79         
  80         return dht_hash_compute_internal (type,
  rsync_friendly_name, hash_p);
  81 }

The name comes from dht_subvol_get_hashed (a few levels up), thus.

 380         subvol = dht_layout_search (this, layout, loc->name);

AFAIK loc->name is just the last part of the name, and there's no
provision anywhere in this path for non-textual input like a parent
hash.  It would probably be a good idea for us to do something like
that, but currently we don't.