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Date: Tue, 14 Jan 2020 17:19:31 +0100
From: David Sterba <dsterba@suse.cz>
Subject: Re: [PATCH v4] btrfs: Use larger zlib buffer for s390 hardware
 compression
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References: <20200107143058.GU3929@twin.jikos.cz>
 <20200108105103.29028-1-zaslonko@linux.ibm.com>
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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

On Mon, Jan 13, 2020 at 11:03:29AM +0100, Zaslonko Mikhail wrote:
> Hello David,
>=20
> On 09.01.2020 02:10, David Sterba wrote:
> > On Wed, Jan 08, 2020 at 07:48:31PM +0100, Zaslonko Mikhail wrote:
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD } e=
lse if (workspace->strm.avail_out =3D=3D 0) {
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD /* get another page for the stream end */
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD kunmap(out_page);
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD if (nr_pages =3D=3D nr_dest_pages) {
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD out_p=
age =3D NULL;
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD ret =
=3D -E2BIG;
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD goto =
out;
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD }
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD out_page =3D alloc_page(GFP_NOFS | __GFP_=
HIGHMEM);
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD if (out_page =3D=3D NULL) {
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD ret =
=3D -ENOMEM;
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD goto =
out;
> >>>> +=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD=EF=
=BF=BD=EF=BF=BD=EF=BF=BD=EF=BF=BD }
> >>>
> >>> Do we need zlib_deflateEnd() for the above error cases?=EF=BF=BD Than=
ks,
> >>
> >> 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 allocat=
ed=20
> >> memory, in the kernel it doesn't do much apart from setting the return=
=20
> >> code (since all the memory allocations for kernel zlib are performed i=
n advance).
> >=20
> > Agreed, deflateEnd is not necessary in the error cases.
>=20
> Can I consider this as 'Acked-by' from your side?

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