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From:   Kent Overstreet <kent.overstreet@linux.dev>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     linux-kernel@vger.kernel.org, Coly Li <colyli@suse.de>
Subject: Re: [PATCH 2/2] bcache: Convert to lock_cmp_fn
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On Wed, May 10, 2023 at 03:01:51PM +0200, Peter Zijlstra wrote:
> >  static struct btree *mca_bucket_alloc(struct cache_set *c,
> >  				      struct bkey *k, gfp_t gfp)
> >  {
> > @@ -572,7 +593,7 @@ static struct btree *mca_bucket_alloc(struct cache_set *c,
> >  		return NULL;
> >  
> >  	init_rwsem(&b->lock);
> > -	lockdep_set_novalidate_class(&b->lock);
> > +	lock_set_cmp_fn(&b->lock, btree_lock_cmp_fn, btree_lock_print_fn);
> >  	mutex_init(&b->write_lock);
> >  	lockdep_set_novalidate_class(&b->write_lock);
> 
> I can't help but notice you've got yet another novalidate_class usage
> here. What does it take to get rid of that?

A locking rework, probably switching bcache to six locks.

I'd rather prioritize getting bcachefs merged and then working on an
upgrade path from bcache -> bcahcefs so we can depracate bcache,
though...