From: Ivan Shapovalov <intelfx@intelfx.name>
Subject: Re: [patch] reiser4: port for Linux-4.1
Date: Wed, 10 Feb 2016 07:04:07 +0300
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To: Edward Shishkin <edward.shishkin@gmail.com>, Ivan Shapovalov <intelfx100@gmail.com>, =?UTF-8?Q?Du=C5=A1an_=C4=8Coli=C4=87?= <dusanc@gmail.com>
Cc: reiserfs-devel <reiserfs-devel@vger.kernel.org>


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On 2016-02-09 at 18:53 +0100, Edward Shishkin wrote:
> Hi all,
>=20
> There is a pending patch for precise discarsd, which I can not merge
> because it is incomplete. Just want to know, is there any progress on
> this?
>=20
> So we found that calculating discard params by mkfs and storing
> them in superblock is a dirty option, so I suggest to reserve a
> contiguous area (1 MiB?) on disk at "mkfs -d" time (just mark it busy
> in the bitmap). And calculate erase unit size and offset at mount
> time.
> If calculation failed for some reasons, then use non-precise discard.
>=20
> So, I think, we'll need one d32 field in disk superblock, which
> indicates
> number of reserved blocks (0 means no reservation) and a pair of
> definitions in disk_format40.h:
>=20
> #define FORMAT40_FIRST_RESERVED_FOR_PROBING \
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0((REISER4_MASTER_OFFSET / PAGE_=
CACHE_SIZE) + 6)
> #define FORMAT40_MAX_BLOCKS_RESERVED_FOR_PROBING
>=20
> If any questions, or technical stoppers, then let me know.
>=20
> Thanks,
> Edward.
>=20

Hello Edward,

yes, finishing this is on top of my to-do list (but it is being
dequeued at a very slow rate due to the university...).

I was under assumption of that we still want to go by path of probing
parameters at mkfs time + having a special utility for rewriting these
fields. But if you are now ok with probing at mount time, then that's
great. I'll try to do something in nearest week or two.

--=20
Ivan Shapovalov / intelfx /


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