Re: [PATCH] fs: inode: Reduce volatile inode wraparound risk when ino_t is 64 bit

[Matthew Wilcox]

On Fri, Dec 20, 2019 at 07:35:38PM +0200, Amir Goldstein wrote:
> On Fri, Dec 20, 2019 at 6:46 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> >
> > On Fri, Dec 20, 2019 at 03:41:11PM +0200, Amir Goldstein wrote:
> > > Suggestion:
> > > 1. Extend the kmem_cache API to let the ctor() know if it is
> > > initializing an object
> > >     for the first time (new page) or recycling an object.
> >
> > Uh, what?  The ctor is _only_ called when new pages are allocated.
> > Part of the contract with the slab user is that objects are returned to
> > the slab in an initialised state.
> 
> Right. I mixed up the ctor() with alloc_inode().
> So is there anything stopping us from reusing an existing non-zero
> value of  i_ino in shmem_get_inode()? for recycling shmem ino
> numbers?

I think that would be an excellent solution to the problem!  At least,
I can't think of any problems with it.