On Thu, Aug 02, 2007 at 11:32:55AM -0400, Jeff Layton wrote:
> On Tue, 31 Jul 2007 10:48:24 -0400
> "J. Bruce Fields" <[email protected]> wrote:
> > That's an interesting problem. Thanks for the report!
> >
> > I don't believe that long comma-delimited string actually has any
> > meaning to the kernel--as far as the kernel is concerned, it's just an
> > opaque object that will be passed back to mountd later (along with a
> > path name) to get export options.
> >
> > So I suppose that string could be replaced by a hash, or maybe even just
> > by the ip address of the particular host--the disadvantage to the latter
> > being that it would require the kernel to keep a separate export for
> > each client address.
>
> I started having a look at this today. The original patches that I
> proposed to clean up the rmtab a few months ago also eliminated this
> comma-delimited string. Neil had valid objections to it at the time,
> but if we switched to using the IP address as a cache key like Bruce
> describes then doing that becomes more reasonable.
>
> The only downside I see is the one Bruce points out -- the size of
> the kernel export cache would increase. I don't have a feel for whether
> this is a show stopper, however.
Yeah, there might be some risk of solving that problem at the expense of
people with tons of clients all matching *.example.com. The actual
export objects are actually pretty small--68 bytes, last I checked?
You'd also need two upcalls to mountd per client (for ip address and
export, as opposed to just ip address). I don't know what other costs
there might be.
What about the idea of hashing the comma-delimited list and passing
that? You'd want hash large enough to be collision-free--might as well
use some cryptographic hash, I guess, though it may be mild overkill.
Is there any reason why that wouldn't work?
Could you remind me what problems you were trying to fix with your rmtab
cleanup?
--b.
-
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]
