Re: per-mount maxvnodes

[Matthew Mondor <mm_lists%pulsar-zone.net@localhost>]

On Thu, 7 Jun 2012 17:50:58 +0200
Manuel Bouyer <bouyer%antioche.eu.org@localhost> wrote:

> On Thu, Jun 07, 2012 at 11:09:26AM -0400, Mouse wrote:
> > > Therefore comes the idea to have a per-mount maxvnodes.
> > 
> > > I tried implementing it, the biggest problem is how to set the value.
> > 
> > sysctl kern./usr/local.maxvnodes?
> > 
> > It's a little ambiguous, in that it's possible - or at least it was
> > last time I tried it - to have multiple mounts with the same mounted-on
> > string.  But that's definitely an unusual case, and I see nothing wrong
> > with accessing the topmost mount in that case; that's what normal
> > filesystem accesses will do, after all.
> 
> No, I think this should be a mount option. Maybe it's time to revisit the
> mount(2) interface (proplist anyone ? :)

If mounts had an ID (like processes), then it'd be easier to use sysctl
for them (commands such as mount and df might want to also export such
IDs, so possibly also statvfs(2))... There are device ID, but I'm not
sure this could serve this purpose properly.

This also reminds me of the thread about possibly allowing to
temporarily enable noatime for a particular operation such as a backup
or find... Perhaps that such options should eventually be dynamically
scoped such that a particular process or lwp could temporarily bind
another value for its own use (if it has the necessary privileges, of
course)?  I'm not sure how far fetched this can be relatively to the
code, I'm not very familiar with the FS code.
-- 
Matt