Re: [PATCH] 9p: fix WARN_ON when dropping nlink on files with nlink=0

[Breno Leitao]

On Tue, Apr 21, 2026 at 12:59:51AM +0900, Dominique Martinet wrote:
> Breno Leitao wrote on Mon, Apr 20, 2026 at 07:31:14AM -0700:
> >     In cacheless mode the server is authoritative and the inode is on its
> >     way out, so locally adjusting nlink buys nothing. Skip v9fs_dec_count()
> >     entirely when neither CACHE_META nor CACHE_LOOSE is set, which both
> >     avoids the warning and removes a class of nlink races (two concurrent
> >     unlinkers observing nlink > 0 and both calling drop_nlink()) that an
> >     nlink == 0 guard alone would only narrow rather than close.
> 
> I need to check this doesn't actually leak memory or something but this
> sounds better to me, thanks.
> 
> Please send as a proper PATCH mail and I'll tentatively apply for 7.2
> (a bit too late for 7.1)

Ack, 7.2 is more than fine.

Thanks for your help,
--breno