Re: [RFC] a possible way of reducing the PITA of ->d_name audits

[Al Viro <viro@zeniv.linux.org.uk>]

On Wed, Sep 10, 2025 at 12:45:41PM +1000, NeilBrown wrote:

>    - dentry is negative and a shared lock is held on parent inode.
>      This is guaranteed for dentries passed to ->atomic_open when create
>      is NOT set.

Umm...  The same goes for tmpfile dentry while it's still negative (nobody
else could make it positive - it's only reachable via the parent's list
of children and those who traverse such will ignore anything negative unhashed
they find there.

> One thing I don't like is the name "unwrap_dentry()".  It says what is
> done rather than what it means or what the purpose is.
> Maybe "access_dentry()" (a bit like rcu_access_pointer()).
> Maybe "dentry_of()" - then we would want to call stable dentries
> "stable_foo" or similar.  So:
> 
>  static int afs_symlink(struct mnt_idmap *idmap, struct inode *dir,
>                       struct stable_dentry stable_child, const char *content)

That has too much of over-the-top hungarian notation feel for my taste, TBH...

Note that these unwrap_dentry() are very likely to move into helpers - if some
function is always called with unwrapped_dentry(something) as an argument,
great, that's probably a candidate for struct stable_dentry.

I'll hold onto the current variant for now...