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Date:   Thu, 7 Jul 2022 23:18:32 +0200
From:   David Sterba <dsterba@suse.cz>
To:     "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc:     Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
        David Sterba <dsterba@suse.com>,
        Nick Terrell <terrelln@fb.com>,
        Chris Down <chris@chrisdown.name>,
        Filipe Manana <fdmanana@suse.com>, Qu Wenruo <wqu@suse.com>,
        Nikolay Borisov <nborisov@suse.com>,
        Gabriel Niebler <gniebler@suse.com>,
        linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
        Ira Weiny <ira.weiny@intel.com>
Subject: Re: [PATCH] btrfs: Convert zlib_decompress_bio() to use
 kmap_local_page()
Message-ID: <20220707211832.GQ15169@twin.jikos.cz>
Reply-To: dsterba@suse.cz
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        "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
        Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
        David Sterba <dsterba@suse.com>, Nick Terrell <terrelln@fb.com>,
        Chris Down <chris@chrisdown.name>,
        Filipe Manana <fdmanana@suse.com>, Qu Wenruo <wqu@suse.com>,
        Nikolay Borisov <nborisov@suse.com>,
        Gabriel Niebler <gniebler@suse.com>, linux-btrfs@vger.kernel.org,
        linux-kernel@vger.kernel.org, Ira Weiny <ira.weiny@intel.com>
References: <20220618091901.25034-1-fmdefrancesco@gmail.com>
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On Sat, Jun 18, 2022 at 11:19:01AM +0200, Fabio M. De Francesco wrote:
> The use of kmap() is being deprecated in favor of kmap_local_page(). With
> kmap_local_page(), the mapping is per thread, CPU local and not globally
> visible.
> 
> Therefore, use kmap_local_page() / kunmap_local() in zlib_decompress_bio()
> because in this function the mappings are per thread and are not visible
> in other contexts.
> 
> Tested with xfstests on QEMU + KVM 32-bits VM with 4GB of RAM and
> HIGHMEM64G enabled. This patch passes 26/26 tests of group "compress".
> 
> Suggested-by: Ira Weiny <ira.weiny@intel.com>
> Reviewed-by: Qu Wenruo <wqu@suse.com>
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>

Added to the kmap patches, thanks.