linux-kernel - Re: [PATCH v2 2/4] ocfs2: sysfile interfaces for online file check

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Message-Id: <56559BA5020000F90001FC8B@relay2.provo.novell.com>
Date:	Tue, 24 Nov 2015 20:29:41 -0700
From:	"Gang He" <ghe@...e.com>
To:	"Junxiao Bi" <junxiao.bi@...cle.com>,
	"Mark Fasheh" <mfasheh@...e.de>
Cc:	<akpm@...ux-foundation.org>, <ocfs2-devel@....oracle.com>,
	<rgoldwyn@...e.de>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] ocfs2: sysfile interfaces for online file
 check

Hi Mark and Junxiao,


>>> 
> On Tue, Nov 03, 2015 at 04:20:27PM +0800, Junxiao Bi wrote:
>> Hi Gang,
>> 
>> On 11/03/2015 03:54 PM, Gang He wrote:
>> > Hi Junxiao,
>> > 
>> > Thank for your reviewing.
>> > Current design, we use a sysfile as a interface to check/fix a file (via 
> pass a ino number).
>> > But, this operation is manually triggered by user, instead of automatically 
>  fix in the kernel.
>> > Why?
>> > 1) we should let users make this decision, since some users do not want to 
> fix when encountering a file system corruption, maybe they want to keep the 
> file system unchanged for a further investigation.
>> If user don't want this, they should not use error=continue option, let
>> fs go after a corruption is very dangerous.
> 
> Maybe we need another errors=XXX flag (maybe errors=fix)?
> 
> You both make good points, here's what I gather from the conversation:
> 
>  - Some customers would be sad if they have to manually fix corruptions.
>    This takes effort on their part, and if the FS can handle it
>    automatically, it should.
> 
>  - There are valid concerns that automatically fixing things is a change in
>    behavior that might not be welcome, or worse might lead to unforseeable
>    circumstances.
> 
>  - I will add that fixing things automatically implies checking them
>    automatically which could introduce some performance impact depending on
>    how much checking we're doing.
> 
> So if the user wants errors to be fixed automatically, they could mount with
> errros=fix, and everyone else would have no change in behavior unless they
> wanted to make use of the new feature.
That is what I want to say, add a mount option to let users to decide. Here, I want to split "error=fix"
mount option  task out from online file check feature, I think this part should be a independent feature.
We can implement this feature after online file check is done, I want to split the feature into some more 
detailed features, implement them one by one. Do you agree this point?

> 
> 
>> > 2) frankly speaking, this feature will probably bring a second corruption 
> if there is some error in the code, I do not suggest to use automatically fix 
> by default in the first version.
>> I think if this feature could bring more corruption, then this should be
>> fixed first.
> 
> Btw, I am pretty sure that Gang is referring to the feature being new and
> thus more likely to have problems. There is nothing I see in here that is
> file system corrupting.
> 	--Mark
> 
> 
> --
> Mark Fasheh

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