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Date: Fri, 13 Dec 2024 06:11:28 +0100
From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Carlos Maiolino <cem@kernel.org>,
	Hans Holmberg <hans.holmberg@wdc.com>, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 09/43] xfs: generalize the freespace and reserved
 blocks handling
Message-ID: <20241213051128.GF5630@lst.de>
References: <20241211085636.1380516-1-hch@lst.de> <20241211085636.1380516-10-hch@lst.de> <20241212213718.GU6678@frogsfrogsfrogs>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Thu, Dec 12, 2024 at 01:37:18PM -0800, Darrick J. Wong wrote:
> >  		mp->m_sb.sb_frextents =
> > -				percpu_counter_sum_positive(&mp->m_frextents);
> > +			xfs_sum_freecounter(mp, XC_FREE_RTEXTENTS);
> 
> Curious.  xfs_sum_freecounter returns percpu_counter_sum, not its
> _positive variant.  This seems like a bug?  Or at least an omitted
> max(0LL, ...) call?

Good question.  This code is pretty old and it's probably time to do
a full audit of the _positive thingies, including checking if the
existing callers make sense and what the right levels of abstraction
are.

> > @@ -1297,8 +1314,7 @@ xfs_dec_freecounter(
> >  	 * problems (i.e. transaction abort, pagecache discards, etc.) than
> >  	 * slightly premature -ENOSPC.
> >  	 */
> > -	if (has_resv_pool)
> > -		set_aside = xfs_fdblocks_unavailable(mp);
> > +	set_aside = xfs_freecounter_unavailable(mp, ctr);
> 
> Nit: I think you can get rid of the set_aside = 0; above?

Yes.