From mboxrd@z Thu Jan  1 00:00:00 1970
From: Edward Shishkin <edward.shishkin@gmail.com>
Subject: Re: [patch] reiser4: port for Linux-4.1
Date: Wed, 10 Feb 2016 10:01:29 +0100
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To: intelfx@intelfx.name, Ivan Shapovalov <intelfx100@gmail.com>, =?UTF-8?B?RHXFoWFuIMSMb2xpxIc=?= <dusanc@gmail.com>
Cc: reiserfs-devel <reiserfs-devel@vger.kernel.org>

On 02/10/2016 05:04 AM, Ivan Shapovalov wrote:
> On 2016-02-09 at 18:53 +0100, Edward Shishkin wrote:
>> Hi all,
>>
>> 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?
>>
>> 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.
>>
>> 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:
>>
>> #define FORMAT40_FIRST_RESERVED_FOR_PROBING \
>>         ((REISER4_MASTER_OFFSET / PAGE_CACHE_SIZE) + 6)
>> #define FORMAT40_MAX_BLOCKS_RESERVED_FOR_PROBING
>>
>> If any questions, or technical stoppers, then let me know.
>>
>> Thanks,
>> Edward.
>>
> 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...).


Ah, this is of highest priority, ofc.


>
> 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


I am afraid that 99% of users will be unaware of that utility..

Thanks,
Edward.


> 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.
>