Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 25 May 2023 01:07:36 -0400
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
Message-ID: <ZG7tGKYM3zq5MG7v@moria.home.lan>
References: <20230509195847.1745548-1-kent.overstreet@linux.dev>
 <20230509195847.1745548-2-kent.overstreet@linux.dev>
 <20230510130151.GL4253@hirez.programming.kicks-ass.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230510130151.GL4253@hirez.programming.kicks-ass.net>
Precedence: bulk

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...