Re: [PATCH 4/7] proc: Use d_invalidate in proc_prune_siblings_dcache

From: Al Viro
Date: Thu Feb 20 2020 - 18:03:19 EST

On Thu, Feb 20, 2020 at 10:54:20PM +0000, Al Viro wrote:
> On Thu, Feb 20, 2020 at 02:49:53PM -0600, Eric W. Biederman wrote:
> >
> > The function d_prune_aliases has the problem that it will only prune
> > aliases thare are completely unused. It will not remove aliases for
> > the dcache or even think of removing mounts from the dcache. For that
> > behavior d_invalidate is needed.
> >
> > To use d_invalidate replace d_prune_aliases with d_find_alias
> > followed by d_invalidate and dput. This is safe and complete
> > because no inode in proc has any hardlinks or aliases.
> s/no inode.*/it's a fucking directory inode./

Wait... You are using it for sysctls as well? Ho-hum... The thing is,
for sysctls you are likely to run into consequent entries with the
same superblock, making for a big pile of useless playing with
->s_active... And yes, that applied to mainline as well