Date:	Fri, 03 Jun 2011 00:06:09 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	"Amir G." <amir73il@...rs.sourceforge.net>
CC:	"Ted Ts'o" <tytso@....edu>, Andreas Dilger <adilger@...ger.ca>,
	Dave Chinner <david@...morbit.com>, xfs@....sgi.com,
	linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	sergey57@...il.com, Amir Goldstein <amir73il@...rs.sf.net>
Subject: Re: [PATCH v2] xfstests: add support for ext4dev FSTYP

On 6/2/11 11:59 PM, Amir G. wrote:
> On Fri, Jun 3, 2011 at 3:36 AM, Ted Ts'o <tytso@....edu> wrote:
>> On Thu, Jun 02, 2011 at 11:22:53AM -0600, Andreas Dilger wrote:
>>> On 2011-06-02, at 8:59 AM, Eric Sandeen wrote:
>>>> I don't really mind adding ext4dev to FSTYP case statements, it
>>>> -is- something which blkid could, in theory, still return, and
>>>> making xfstests cope with that and try to invoke fsck -t ext4dev
>>>> doesn't bother me too much.  It is sadly an fs type embedded into
>>>> a few tools.
>>>
>>> I'm perfectly OK with using ext4dev as a filesystem type that allows testing
>>> changes to ext4 on a system that is already running ext4 as the root fs.
>>
>> My take on this is that way too much time has been spent this subject.
> 
> No doubt.
> 
>> Being able to use ext4dev is useful, and given that we have all of
>> this support in our existing system tools, why not use it to make ext4
>> development more efficient/easy?  As a bonus you can build the ext4dev
>> as a module, and that means you the compile/edit/debug cycle can be
>> much faster since you can avoid doing a reboot, for those
>> circumstances where using KVM is not possible/convenient.  Personally,
>> I normally use KVM these days, but I can imagine situations where
>> using ext4dev would be a better way to go.  For example, I'd probably
>> use KVM on my laptop, but for testing on production servers in a data
>> center, I'd probably use ext4dev, for a variety of local deployment
>> considerations that's not worth going into here.
>>
>> That being said, whether or not we modify xfstests seems to be a moot
>> point.  In order for me to do my bigalloc development, I've been
>> patching common.rc so that "/sbin/mkfs.$FSTYP" --> "mkfs.$FSTYP" and
>> "/sbin/fsck -t $FSTYP" --> "fsck.$FSTYP".  It's a 3 line change.  Not
>> a big deal.  I've been making this change using /bin/ed after
>> installing xfstests.  So if the XFS folks want to veto this change ---
>> who cares?  It's not hard to make the change locally in order to make
>> xfstests.
>>
>> On the other hand, given that xfstests is using "mkfs.$FSTYP", I don't
>> see why it's so important that it clings to "fsck -t $FSTYP" instead
>> of using "fsck.$FSTYP".  There's no real benefit to calling the fsck
>> driver; it's just an extra fork and exec, and xfstests is being
>> inconsistent by insisting on the use of the fsck driver, but not using
>> the mkfs driver.
>>
>> But that being said, hacking xfstests is not hard, and if Dave and/or
>> Eric feels strongly about resisting this change, it's not worth a lot
>> of time, one way or another....
>>
>>                                                - Ted
>>
> 
> I blame only myself for not presenting the case correctly.
> I made it sound like I am trying to push my own private hack upstream.
> Actually, all 10 people involved in snapshot development clone my xfstests
> tree from github, so we have no real need for the upstream change.
> The reason I was pushing upstream is because I found this feature
> so useful, I thought other developers may enjoy it as well.
> 
> Anyone on on this thread not having used ext4dev by next LSF
> can come to me to claim his beer ;-)

mmm I like beer, I'll see you then!  ;)

-Eric (tucking this email away for future reference... ;)

> Amir.

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