Re: [PATCH] proc: register filesystem last

[Al Viro]

On Sat, Mar 10, 2018 at 03:06:34AM +0300, Alexey Dobriyan wrote:
> On Fri, Mar 09, 2018 at 02:49:38PM -0800, Andrew Morton wrote:
> > On Sat, 10 Mar 2018 01:27:09 +0300 Alexey Dobriyan <adobriyan@xxxxxxxxx> wrote:
> > 
> > > As soon as register_filesystem() exits, filesystem can be mounted.
> > > It is better to present fully operational /proc.
> > > 
> > > Of course it doesn't matter because /proc is not modular
> > > but do it anyway.
> > > 
> > > Drop error check, it should be handled by panicking.
> > 
> > So... shouldn't we add a call to panic()?
> 
> via FS_PANIC flag, yes. I have a patch somewhere.
> There are 104 filesystems ATM, some internal, some not.
> Some modular, some not.

You do realize that the only case when register_filesystem() fails is
"another driver has already registered filesystem type with the same
name"?  Is there *ever* a case when
	* you could expect that to happen and
	* panic would be a sane response?