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[142.68.57.212]) by smtp.gmail.com with ESMTPSA id 73sm320171qtg.40.2020.02.05.10.45.12 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 05 Feb 2020 10:45:12 -0800 (PST) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1izPfk-0003uX-6R; Wed, 05 Feb 2020 14:45:12 -0400 Date: Wed, 5 Feb 2020 14:45:12 -0400 From: Jason Gunthorpe To: Jan Kara Cc: Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 3/8] xarray: Explicitely set XA_FREE_MARK in __xa_cmpxchg() Message-ID: <20200205184512.GC28298@ziepe.ca> References: <20200204142514.15826-1-jack@suse.cz> <20200204142514.15826-4-jack@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200204142514.15826-4-jack@suse.cz> User-Agent: Mutt/1.9.4 (2018-02-28) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Feb 04, 2020 at 03:25:09PM +0100, Jan Kara wrote: > __xa_cmpxchg() relies on xas_store() to set XA_FREE_MARK when storing > NULL into xarray that has free tracking enabled. Make the setting of > XA_FREE_MARK explicit similarly as its clearing currently it. > > Signed-off-by: Jan Kara > lib/xarray.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/lib/xarray.c b/lib/xarray.c > index ae8b7070e82c..4e32497c51bd 100644 > +++ b/lib/xarray.c > @@ -1477,8 +1477,12 @@ void *__xa_cmpxchg(struct xarray *xa, unsigned long index, > curr = xas_load(&xas); > if (curr == old) { > xas_store(&xas, entry); > - if (xa_track_free(xa) && entry && !curr) > - xas_clear_mark(&xas, XA_FREE_MARK); > + if (xa_track_free(xa)) { > + if (entry && !curr) > + xas_clear_mark(&xas, XA_FREE_MARK); > + else if (!entry && curr) > + xas_set_mark(&xas, XA_FREE_MARK); > + } This feels like an optimization that should also happen for __xa_store, which has very similar code: curr = xas_store(&xas, entry); if (xa_track_free(xa)) xas_clear_mark(&xas, XA_FREE_MARK); Something like if (xa_track_free(xa) && entry && !curr) xas_clear_mark(&xas, XA_FREE_MARK); ? Regards, Jason