Messages in this thread |  | | | Date | Thu, 6 Nov 2008 20:28:22 -0800 | | From | Andrew Morton <> | | Subject | Re: [PATCH 2/7] proc: Implement support for automounts in task directories |
| |
On Thu, 06 Nov 2008 19:51:23 -0800 ebiederm@xmission.com (Eric W. Biederman) wrote:
> If we could do all of this with reference counting so that the > mount would persist exactly until the last user of it has gone > away without a periodic poll I would love it. But the infrastructure > doesn't support that today,
Well that sucks. The free-on-last-put idiom occurs in so many places and serves us so well. I wonder what went wrong here?
I guess it has interactions with dentry and inode cache aging which could get tricky.
> and where this is at least partially > a bug fix I would rather not have the change depend on enhancing > the VFS. > > The algorithm is actually very aggressive and in practice you don't > see any /proc/<pid>/net showing up as a mount point.
Do you think it has failure modes? Most particularly: obscure usage patterns which can cause memory exhaustion?
> > Obviously, that becomes clearer as one spends more time with the code, > > but I wonder whether this has all been made as maintainble as it > > possibly could be. > > Good question. > > In the sense of will we have to go through and futz with the code all > of the time. The abstraction seems good. You put a mount on > the proc_automounts list with do_add_mounts and it goes away eventually > with all of the vfs rules maintained. > > In the sense of can the code be read? Perhaps it could be better. > I expect it helps to have run the code and see /proc/net as a filesystem. > that is magically mounted.
'twould be a useful contribution if you were to enshrine your discoveries in /*these things*/. You knew I was working up to that :)
|  |