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Subject: Re: [PATCH 1/2] ext4: reduce computation of overhead during resize
Thread-Topic: [PATCH 1/2] ext4: reduce computation of overhead during resize
From:   "Kiselev, Oleg" <okiselev@amazon.com>
To:     Jan Kara <jack@suse.cz>
CC:     "linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>,
        Theodore Ts'o <tytso@mit.edu>
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Date:   Fri, 15 Jul 2022 23:52:32 +0000
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> On Jul 15, 2022, at 2:27 AM, Jan Kara <jack@suse.cz> wrote:
>=20
> CAUTION: This email originated from outside of the organization. Do not c=
lick links or open attachments unless you can confirm the sender and know t=
he content is safe.
>=20
>=20
>=20
> On Thu 14-07-22 19:53:38, Kiselev, Oleg wrote:
>>>=20
>>>> +       sbi->s_overhead +=3D overhead;
>>>> +       es->s_overhead_clusters =3D cpu_to_le32((unsigned long) sbi->s=
_overhead);
>>>                                               ^^^ the typecast looks
>>> bogus here...
>>=20
>> This cast is the reverse of le32_to_cpu() cast done in fs/ext4/super.c:_=
_ext4_fill_super():
>>        sbi->s_overhead =3D le32_to_cpu(es->s_overhead_clusters);
>> And follows the logic of casting done in fs/ext4/ioctl.c:set_overhead() =
and fs/ext4/ioctl.c:ext4_update_overhead().
>=20
> I didn't mean the cpu_to_le32() call but rather the (unsigned long) part.
> That is pointless because sbi->s_overhead is already 'unsigned long' and
> even if it was not, I have hard time seeing a reason why would casting to
> unsigned long make any difference here.

Got it.  You are right.  The indent of your comment got mangled by mail, so=
 it looked like it was directed to cpu_to_ie32()! =20

>=20
>                                                                        Ho=
nza
> --
> Jan Kara <jack@suse.com>
> SUSE Labs, CR