linux-ext4 - Re: [PATCH,RFC] Adding quotacheck functionality to e2fsck

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Message-ID: <87tys3hwvd.fsf@openvz.org>
Date:	Fri, 26 Mar 2010 19:27:02 +0300
From:	Dmitry Monakhov <dmonakhov@...nvz.org>
To:	Jan Kara <jack@...e.cz>
Cc:	Andreas Dilger <andreas.dilger@...cle.com>, tytso@....edu,
	linux-ext4@...r.kernel.org
Subject: Re: [PATCH,RFC] Adding quotacheck functionality to e2fsck

Dmitry Monakhov <dmonakhov@...nvz.org> writes:

> Jan Kara <jack@...e.cz> writes:
>
>> On Fri 26-03-10 11:18:28, Dmitry Monakhov wrote:
>>> > If there isn't a reason to continue using unjournaled quota (i.e. it
>>> > doesn't break to just move to journaled quota everywhere), then these
>>> > could just become aliases for the journaled quota implementation.  The
>>> > other alternative is to deprecate these options in the next kernel and
>>> > have it print out a warning on the console to tell the user to switch
>>> > over to the journaled version.
>>> The only reason to not use journalled quota by default is the currently
>>> it is a bit slower than unjournalled variant.
>>> This is because each quota change result in synchronous quotafile 
>>> update in per-sb-page-cache. And this update is protected by i_mutex.
>>> and dqio_mutex. It may be fixed easily. I've sent a RFC patch two
>>> month ago. I'll update it and will submit it this weekend. 
>>   Well, there is also some overhead caused by more IO we have to do for
>> quota journaling and that is essentially unavoidable. But still I believe
>> we should transition people to journaled quotas...
> Agree. IO overhead due to journalled quota is almost invisible.
> And it must be enabled by default after most annoying lock contention
> will be resolved.
>
> BTW. i've had bad news. Seems what journalled was broken recently.
> Right after i've wrote the first letter. i've started to update the
> quota-speedup patch. And during testing phase i've found that
> journalled quota is inconsistent after power-failure(w/o my patches).
> I've tested ext4.git/for-next branch
> Currently i'm investing the issue.
Ok, i've found the root of issue. dquot_transfer() wasn't called for
symlinks on chown due to lack of ->setattr operation.
Before 'dquot: cleanup dquot transfer routine' patch quota_transfer()
was performed by notify_transfer() itself.
Now it must be handled by in corresponding ->setattr

BTW i'm wondering, even if we don't care about quota. Inode's attributes
are metadata and must goes trough journal(i.e via extXXX_setattr).
so every inode type must has corresponding ->setattr.
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