reiser4: newbie help needed?

reiser4: newbie help needed?

[Johannes Buchner]

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Hi!

I am possibly interested in helping out. Who is currently working on
reiser4? I took a look at the TODO lists, are there any simple tasks to
do for newbies?
Also, where is the latest code development going on?

I also believe that on 'sync', reiser4 currently does absolutely
nothing. The comment in reiser4_sync_inodes says reiser4 does its own
flush elsewhere. Should this be different?

Cheers,
Johannes

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Re: reiser4: newbie help needed?

[Edward Shishkin]

Johannes Buchner wrote:
> Hi!
>
> I am possibly interested in helping out. Who is currently working on
> reiser4?

Nobody.
Because there is no bugreports.

>  I took a look at the TODO lists, are there any simple tasks to
> do for newbies?
>   

If you mean the "todo for inclusion", then no.

Reiser4 has only one technical issue. It can
be resolved only by very experienced people.

> Also, where is the latest code development going on?
>   

in -mm

> I also believe that on 'sync', reiser4 currently does absolutely
> nothing.

this is not good: a file system should respond on sync (1).

>  The comment in reiser4_sync_inodes says reiser4 does its own
> flush elsewhere. Should this be different?
>   

you might want to ask such question _before_ sending patches to akpm. 

BTW excellent comment, what is not clear?

/**
 * reiser4_sync_inodes - sync_inodes of super operations
 * @super:
 * @wbc:
 *
 * This method is called by background and non-backgound writeback. 
Reiser4's
 * implementation uses generic_sync_sb_inodes to call reiser4_writepages for
 * each of dirty inodes. Reiser4_writepages handles pages dirtied via shared
 * mapping - dirty pages get into atoms. Writeout is called to flush some
 * atoms.
 */
 
Edward.

Re: reiser4: newbie help needed?

[Johannes Buchner]

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On Wed, 02 Dec 2009 10:21:18 +0100
Edward Shishkin <edward.shishkin@gmail.com> wrote:

> Johannes Buchner wrote:
> >  I took a look at the TODO lists, are there any simple tasks to
> > do for newbies?
> 
> If you mean the "todo for inclusion", then no.
> 
> Reiser4 has only one technical issue. It can
> be resolved only by very experienced people.

Thanks for replying. I did not have to the inclusion of
reiser4 in mind specifically.

> > I also believe that on 'sync', reiser4 currently does absolutely
> > nothing.
> 
> this is not good: a file system should respond on sync (1).
> 
> >  The comment in reiser4_sync_inodes says reiser4 does its own
> > flush elsewhere. Should this be different?
> >   
> 
> you might want to ask such question _before_ sending patches to akpm. 

I was under the believe that I did not change the behaviour. I see my
mistake now, I was looking at the wrong if-branch. 

I tried now to come up with a correct version for some hours, but I keep
having NULL problems. Maybe a writeback_control object has to be
created, possibly even in fs/fs-writeback.c:sync_inodes_sb, as
write_inode_now does below. I tried that too, but it gave me a
recursion. I'm not sure what the rationale was for introducing a call
with NULL here. Sorry I can't correct this.

Looking forward to your review.

Best wishes,
Johannes

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Re: reiser4: newbie help needed?

[Edward Shishkin]

Johannes Buchner wrote:
> On Wed, 02 Dec 2009 10:21:18 +0100
> Edward Shishkin <edward.shishkin@gmail.com> wrote:
>
>   
>> Johannes Buchner wrote:
>>     

Hello.

>>>  I took a look at the TODO lists, are there any simple tasks to
>>> do for newbies?
>>>       
>> If you mean the "todo for inclusion", then no.
>>
>> Reiser4 has only one technical issue. It can
>> be resolved only by very experienced people.
>>     
>
> Thanks for replying. I did not have to the inclusion of
> reiser4 in mind specifically.
>
>   
>>> I also believe that on 'sync', reiser4 currently does absolutely
>>> nothing.
>>>       
>> this is not good: a file system should respond on sync (1).
>>
>>     
>>>  The comment in reiser4_sync_inodes says reiser4 does its own
>>> flush elsewhere. Should this be different?
>>>   
>>>       
>> you might want to ask such question _before_ sending patches to akpm. 
>>     
>
> I was under the believe that I did not change the behaviour. I see my
> mistake now, I was looking at the wrong if-branch. 
>   

Nop. You've lost the whole point of using of ->sync_inodes(), which is
responsible for reiser4 background (and non-background) writeback,
and now it is not involved by any path.

Here is a good explanation why we need this additional super operation:
http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.21-rc3/2.6.21-rc3-mm1/broken-out/reiser4-sb_sync_inodes.patch

> I tried now to come up with a correct version for some hours, but I keep
> having NULL problems. Maybe a writeback_control object has to be
> created, possibly even in fs/fs-writeback.c:sync_inodes_sb, as
> write_inode_now does below. I tried that too, but it gave me a
> recursion.

It may happens because of missed checks that a process is of pdflush-style.
Perhaps, we need to rename the current_is_pdflush() and get it back.

Thanks,
Edward.

>  I'm not sure what the rationale was for introducing a call
> with NULL here. Sorry I can't correct this.
>
> Looking forward to your review.
>
> Best wishes,
> Johannes
>
>