Re: [Jfs-discussion] [RFC PATCH 0/9] Convert JFS to use iomap

[Dave Kleikamp <dave.kleikamp@oracle.com>]

On 5/29/22 6:51PM, Dave Chinner wrote:
> On Sat, May 28, 2022 at 02:59:31PM -0400, Theodore Ts'o wrote:
>> +linux-ext4
>>
>> On Sat, May 28, 2022 at 03:36:39PM +1000, Dave Chinner wrote:
>>> The other filesystem that uses nobh is the standalone ext2
>>> filesystem that nobody uses anymore as the ext4 module provides ext2
>>> functionality for distros these days. Hence there's an argument that
>>> can be made for removing fs/ext2 as well. In which case, the whole
>>> nobh problem goes away by deprecating and removing both the
>>> filesysetms that use that infrastructure in 2 years time....
>>
>> This got brought up at this past week's ext4 video chat, where Willy
>> asked Jan (who has been maintaining ext2) whether he would be open to
>> converting ext2 to use iomap.  The answer was yes.  So once jfs and
>> ext2 are converted, we'll be able to nuke the nobh code.
>>
>>  From Willy's comments on the video chat, my understanding is that jfs
>> was even simpler to convert that ext2, and this allows us to remove
>> the nobh infrastructure without asking the question about whether it's
>> time to remove jfs.
> 
> I disagree there - if we are changing code that has been unchanged
> for a decade or more, there are very few users of that code, and
> there's a good chance that data corruption regressions will result
> from the changes being proposed, then asking the question "why take
> the risk" is very pertinent.
> 
> "Just because we can" isn't a good answer. The best code is code we
> don't have to write and maintain. If it's a burden to maintain and a
> barrier to progress, then we should seriously be considering
> removing it, not trying to maintain the fiction that it's a viable
> supported production quality filesystem that people can rely on....

I'm onboard to sunsetting jfs. I don't know of anyone that is currently 
using it in any serious way. (jfs-discussion group, this is a good time 
to chime in if you feel differently.)

On the other hand, because it is not being used in an any 
mission-critical way, it may be a good filesystem to do an early 
conversion on to see what issues might come up. Unfortunately, I've got 
a really busy two months in front of me and won't be much help.

Thanks,
Shaggy

> 
>>>> We also need to convert more filesystems to use iomap.
>>>
>>> We also need to deprecate and remove more largely unmaintained and
>>> unused filesystems. :)
>>
>> Well, Dave Kleikamp is still around and sends jfs pull requests from
>> time to time, and so it's not as unmaintained as, say, fs/adfs,
>> fs/freevxs, fs/hpfs, fs/minix, and fs/sysv.
> 
> Yes, but the changes that have been made over the past decade are
> all small and minor - there's been no feature work, no cleanup work,
> no attempt to update core infrastructure, etc. There's beeen no
> serious attempts to modernise or update the code for a decade...
> 
>> As regards to minixfs, I'd argue that ext2 is a better reference file
>> system than minixfs.  So..... are we ready to remove minixfs?  I could
>> easily see that some folks might still have sentimental attachment to
>> minixfs.  :-)
> 
> AFAIC, yes, minixfs and and those other ones should have been
> deprecated long ago....
> 
> Cheers,
> 
> Dave.