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Date:   Tue, 14 Jan 2020 17:19:31 +0100
From:   David Sterba <dsterba@suse.cz>
To:     Zaslonko Mikhail <zaslonko@linux.ibm.com>
Cc:     Josef Bacik <josef@toxicpanda.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Chris Mason <clm@fb.com>, David Sterba <dsterba@suse.com>,
        Richard Purdie <rpurdie@rpsys.net>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Eduard Shishkin <edward6@linux.ibm.com>,
        Ilya Leoshkevich <iii@linux.ibm.com>,
        linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] btrfs: Use larger zlib buffer for s390 hardware
 compression
Message-ID: <20200114161931.GE3929@suse.cz>
Reply-To: dsterba@suse.cz
Mail-Followup-To: dsterba@suse.cz,
        Zaslonko Mikhail <zaslonko@linux.ibm.com>,
        Josef Bacik <josef@toxicpanda.com>,
        Andrew Morton <akpm@linux-foundation.org>, Chris Mason <clm@fb.com>,
        David Sterba <dsterba@suse.com>, Richard Purdie <rpurdie@rpsys.net>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Eduard Shishkin <edward6@linux.ibm.com>,
        Ilya Leoshkevich <iii@linux.ibm.com>, linux-s390@vger.kernel.org,
        linux-kernel@vger.kernel.org
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 <75a2d45c-fd7b-9542-403d-caea7d977add@toxicpanda.com>
 <94e06859-6174-c80d-3eb6-065f67fbe95d@linux.ibm.com>
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 <62a53ff3-a515-8801-d58b-b518dbe0c55c@linux.ibm.com>
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On Mon, Jan 13, 2020 at 11:03:29AM +0100, Zaslonko Mikhail wrote:
> Hello David,
> 
> On 09.01.2020 02:10, David Sterba wrote:
> > On Wed, Jan 08, 2020 at 07:48:31PM +0100, Zaslonko Mikhail wrote:
> >>>> +??????? } else if (workspace->strm.avail_out == 0) {
> >>>> +??????????? /* get another page for the stream end */
> >>>> +??????????? kunmap(out_page);
> >>>> +??????????? if (nr_pages == nr_dest_pages) {
> >>>> +??????????????? out_page = NULL;
> >>>> +??????????????? ret = -E2BIG;
> >>>> +??????????????? goto out;
> >>>> +??????????? }
> >>>> +??????????? out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
> >>>> +??????????? if (out_page == NULL) {
> >>>> +??????????????? ret = -ENOMEM;
> >>>> +??????????????? goto out;
> >>>> +??????????? }
> >>>
> >>> Do we need zlib_deflateEnd() for the above error cases?? Thanks,
> >>
> >> The original btrfs code did not call zlib_deflateEnd() for -E2BIG and 
> >> -ENOMEM cases, so I stick to the same logic.
> >> Unlike userspace zlib where deflateEnd() frees all dynamically allocated 
> >> memory, in the kernel it doesn't do much apart from setting the return 
> >> code (since all the memory allocations for kernel zlib are performed in advance).
> > 
> > Agreed, deflateEnd is not necessary in the error cases.
> 
> Can I consider this as 'Acked-by' from your side?

Yes, I also sent rev-by to the patch.