linux-kernel - Re: [PATCH v3] exfat: remove EXFAT_SB

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Message-ID: <aac9d6c7-1d62-a85d-9bcb-d3c0ddc8fcd6@gmail.com>
Date:   Thu, 18 Jun 2020 17:36:34 +0900
From:   Tetsuhiro Kohada <kohada.t2@...il.com>
To:     Sungjong Seo <sj1557.seo@...sung.com>
Cc:     kohada.tetsuhiro@...mitsubishielectric.co.jp,
        mori.takahiro@...mitsubishielectric.co.jp,
        motai.hirotaka@...mitsubishielectric.co.jp,
        'Namjae Jeon' <namjae.jeon@...sung.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] exfat: remove EXFAT_SB_DIRTY flag

Thank you for your comment.

On 2020/06/17 16:20, Sungjong Seo wrote:
>> remove EXFAT_SB_DIRTY flag and related codes.
>>
>> This flag is set/reset in exfat_put_super()/exfat_sync_fs() to avoid
>> sync_blockdev().
>> However ...
>> - exfat_put_super():
>> Before calling this, the VFS has already called sync_filesystem(), so sync
>> is never performed here.
>> - exfat_sync_fs():
>> After calling this, the VFS calls sync_blockdev(), so, it is meaningless
>> to check EXFAT_SB_DIRTY or to bypass sync_blockdev() here.
>> Not only that, but in some cases can't clear VOL_DIRTY.
>> ex:
>> VOL_DIRTY is set when rmdir starts, but when non-empty-dir is detected,
>> return error without setting EXFAT_SB_DIRTY.
>> If performe 'sync' in this state, VOL_DIRTY will not be cleared.
>>
> 
> Since this patch does not resolve 'VOL_DIRTY in ENOTEMPTY' problem you
> mentioned,
> it would be better to remove the description above for that and to make new
> patch.

I mentioned rmdir as an example.
However, this problem is not only with rmdirs.
VOL_DIRTY remains when some functions abort with an error.
In original, VOL_DIRTY is not cleared even if performe 'sync'.
With this patch, it ensures that VOL_DIRTY will be cleared by 'sync'.

Is my description insufficient?


BTW
Even with this patch applied,  VOL_DIRTY remains until synced in the above case.
It's not  easy to reproduce as rmdir, but I'll try to fix it in the future.


BR
---
Tetsuhiro Kohada <kohada.t2@...il.com>