From: "Kohada.Tetsuhiro@dc.MitsubishiElectric.co.jp" <Kohada.Tetsuhiro@dc.MitsubishiElectric.co.jp>
To: 'Namjae Jeon' <linkinjeon@kernel.org>
Cc: Namjae Jeon <namjae.jeon@samsung.com>,
"Mori.Takahiro@ab.MitsubishiElectric.co.jp"
<Mori.Takahiro@ab.MitsubishiElectric.co.jp>,
"Motai.Hirotaka@aj.MitsubishiElectric.co.jp"
<Motai.Hirotaka@aj.MitsubishiElectric.co.jp>,
Sungjong Seo <sj1557.seo@samsung.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 3/3] exfat: set EXFAT_SB_DIRTY and VOL_DIRTY at the same timing
Date: Mon, 8 Jun 2020 05:02:19 +0000 [thread overview]
Message-ID: <TY1PR01MB157812F9DFC574527D8AA26E90850@TY1PR01MB1578.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <CAKYAXd8SqaMj6e9urqdKWCdaexgAoN78Pzh0NYQ35iRYA=2tiA@mail.gmail.com>
Thank you for your comment.
> >> Can you split this patch into two? (Don't set VOL_DIRTY on -ENOTEMPTY and
> >> Setting EXFAT_SB_DIRTY is
> >> merged into exfat_set_vol_flag). I need to check the second one more.
> >
> > Can't do that.
> >
> > exfat_set_vol_flag() is called when rmdir processing begins. When Not-empty
> > is detected,
> > VOL_DIRTY has already been written and synced to the media.
> You can move it before calling exfat_remove_entries().
Can be moved, but that doesn't solve the problem.
It causes the similar problem as before.
exfat_remove_entries() calls exfat_get_dentry().
If exfat_get_dentry() fails, update bh and set SB_DIRTY will not be executed.
As a result, SB_DIRTY is not set and sync does not work.
Similar problems occur with other writing functions.
Similar problems occur when pre-write checks are added in the future.
If you don't set VOL_DIRTY at the beginning, you should delay to set VOL_DIRTY until update-bh & set SB_DIRTY.
This avoids unnecessary changes to VOL_DIRTY/VOL_CLEAN.
I think this method is smart, but it is difficult to decide when to set VOL_CLEAN.
(I tried to implement it, but gave up)
> > By doing this, sync is guaranteed if VOL_DIRTY is set by calling
> > exfat_set_vol_flag.
> >
> > This change may still have problems, but it's little better than before, I
> > think.
> I need to check more if it is the best or there is more better way.
I think the sync-problems still exist.
Let's improve little by little. :-)
BR
---
Kohada Tetsuhiro <Kohada.Tetsuhiro@dc.MitsubishiElectric.co.jp>
next prev parent reply other threads:[~2020-06-08 5:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-04 8:44 [PATCH 1/3] exfat: add error check when updating dir-entries Tetsuhiro Kohada
2020-06-04 8:44 ` [PATCH 2/3] exfat: optimize exfat_zeroed_cluster() Tetsuhiro Kohada
2020-06-04 8:44 ` [PATCH 3/3] exfat: set EXFAT_SB_DIRTY and VOL_DIRTY at the same timing Tetsuhiro Kohada
2020-06-05 7:32 ` Namjae Jeon
[not found] ` <229ab132-c5f1-051c-27c4-4f962ceff700@gmail.com>
2020-06-07 0:26 ` Namjae Jeon
2020-06-08 5:02 ` Kohada.Tetsuhiro [this message]
2020-06-09 2:02 ` Namjae Jeon
2020-06-07 0:33 ` [PATCH 1/3] exfat: add error check when updating dir-entries Namjae Jeon
2020-06-09 8:10 ` Tetsuhiro Kohada
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