Re: [PATCH v2 00/16] nfsd/sunrpc: add support for a workqueue-based nfsd

[Al Viro]

On Thu, Dec 11, 2014 at 06:29:37PM -0800, Linus Torvalds wrote:
> On Thu, Dec 11, 2014 at 6:12 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
> >
> > Linus, do you see any problems with the following patch (against the mainline)?
> 
> Not concpetually, but create_kthread() uses CLONE_FS, and I don't
> think it's just umask that things like nfsd want to avoid sharing.
> What about all the *other* fields?
> 
> Just as an example: even if all the threads actually end up all having
> the same global root, what about contention on 'fs->lock'?
> 
> I have *not* looked at the details, and maybe there's some reason I'm
> completely off, but it worries me.

Umm...  I would be very surprised if it turned out to be a problem.
nfsd really doesn't give a fuck about its cwd and root - not in the
thread side of things.  And (un)exporting is (a) not on a hot path
and (b) not done from a kernel thread anyway.  fh_to_dentry and friends
doesn't care about root/cwd, etc.

I don't see anything that could cause that kind of issues.
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