linux-ext4 - Re: [Regression] ext4: changes to mb_optimize

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Date:   Mon, 15 Aug 2022 13:03:37 +0200
From:   Stefan Wahren <stefan.wahren@...e.com>
To:     Jan Kara <jack@...e.cz>
Cc:     linux-ext4@...r.kernel.org, Ojaswin Mujoo <ojaswin@...ux.ibm.com>,
        Harshad Shirwadkar <harshadshirwadkar@...il.com>,
        Theodore Ts'o <tytso@....edu>,
        Ritesh Harjani <riteshh@...ux.ibm.com>,
        linux-fsdevel@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Geetika.Moolchandani1@....com, regressions@...ts.linux.dev,
        Florian Fainelli <f.fainelli@...il.com>
Subject: Re: [Regression] ext4: changes to mb_optimize_scan cause issues on
 Raspberry Pi

Hi Jan,

Am 15.08.22 um 12:34 schrieb Jan Kara:
> Hi Stefan,
>
> Back from vacation...
>
> On Sun 31-07-22 22:42:56, Stefan Wahren wrote:
>> Hi Jan,
>>
>> Am 28.07.22 um 12:00 schrieb Jan Kara:
>>> Also can get filesystem metadata image of your card like:
>>>     e2image -r <fs-device> - | gzip >/tmp/ext4-image.gz
>>>
>>> and put it somewhere for download? The image will contain only fs metadata,
>>> not data so it should be relatively small and we won't have access to your
>>> secrets ;). With the image we'd be able to see how the free space looks
>>> like and whether it perhaps does not trigger some pathological behavior.
>> i've problems with this. If i try store uncompressed the metadata of the
>> second SD card partition (/dev/sdb2 = rootfs) the generated image file is
>> nearly big as the whole partition. In compressed state it's 25 MB. Is this
>> expected?
> Yes, that is expected. The resulting file is a sparse file that contains
> only metadata blocks that is the reason why it compresses so well but looks
> big.

i've added here:

https://github.com/lategoodbye/mb_optimize_scan_regress/blob/main/Kingston_SDCIT_rootfs_metadata.gz

>
> 								Honza
>