On Fri, Apr 24, 2009 at 10:28:18PM +0530, Krishna Kumar2 wrote:
> Hi Bruce,
>
> "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote on 04/24/2009 09:53:21 PM:
>
> > > {
> > > __u32 a = auth[0], b = auth[1], c = auth[2], d = auth[3];
> > > hash = jhash_3words(a, b, jhash_2words(c, d, 0), 0xfeedbeef) &
> > > FHPARM_HASH_MASK;
> > > ...
> > > /*
> > > * Matching check uses something like:
> > > * if (fh->p_auth1 == a && fh->p_auth2 == b && fh->p_auth3 == c
> &&
> > > fh->p_auth4 == d)
> > > */
> > > }
> > >
> > > Is what you had in mind? I am testing some more with this, so far I get
> > > different values for different files and filesystems.
> > >
> > > I am not sure if there is an easier way to do a hash and get the unique
> > > file
> > > associated with the filehandle, this part of the code is very
> complicated.
> >
> > Why not just do a hash on the entire filehandle, however long it may be?
>
> I am not sure how many numbers to hash on, usually the first 4 numbers are
> the
> ino, inode generation, parent inode, parent inode generation, etc, and is a
> unique match. Or filesystems can have their own encode handlers but store
> similar stuff in these indices. I guess a memcmp could also be done if I
> know
> the length of the auth being used.
Why not use the whole thing?:
fh1->fh_size == fh2->fh_size
&& memcmp(fh1->fh_base, fh2->fh_base, fh1->fh_size) == 0
--b.
>
> > (Cc'ing Greg since he says he had some patches which did something
> > similar, and perhaps he could offer a suggestion.)
>
> OK, will wait for response from Greg.
>
> thanks,
>
> - KK
>
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