linux-kernel - Re: [RFC PATCH 2/9] mm: zswap: refactor storing to the tree out of zswap

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Date: Wed, 27 Mar 2024 15:29:13 -0700
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Chengming Zhou <chengming.zhou@...ux.dev>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Johannes Weiner <hannes@...xchg.org>, 
	Nhat Pham <nphamcs@...il.com>, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/9] mm: zswap: refactor storing to the tree out of zswap_store()

On Tue, Mar 26, 2024 at 7:25 PM Chengming Zhou <chengming.zhou@...ux.dev> wrote:
>
> On 2024/3/26 07:50, Yosry Ahmed wrote:
> > Refactor the code that attempts storing to the xarray, handling erros,
> > and freeing stale entries into a helper. This will be reused in a
> > following patch to free other types of tree elements as well.
> >
> > Signed-off-by: Yosry Ahmed <yosryahmed@...gle.com>
> > ---
> >  mm/zswap.c | 42 ++++++++++++++++++++++++++----------------
> >  1 file changed, 26 insertions(+), 16 deletions(-)
> >
> > diff --git a/mm/zswap.c b/mm/zswap.c
> > index 1cf3ab4b22e64..ff1975afb7e3d 100644
> > --- a/mm/zswap.c
> > +++ b/mm/zswap.c
> > @@ -827,6 +827,30 @@ static void zswap_entry_free(struct zswap_entry *entry)
> >       atomic_dec(&zswap_stored_pages);
> >  }
> >
> > +/*********************************
> > +* zswap tree functions
> > +**********************************/
> > +static int zswap_tree_store(struct xarray *tree, pgoff_t offset, void *new)
> > +{
> > +     void *old;
> > +     int err;
> > +
> > +     old = xa_store(tree, offset, new, GFP_KERNEL);
> > +     err = xa_is_err(old);
>
> Seems to use xa_err() to return errno, xa_is_err() just return a bool.

Good catch. It happens to work out because returning 1 would have the
same effect as returning the errno. Will fix it in the next version.

Thanks!