[BUG] JFFS2 power loss recovery issues in 2.6.25, 2.6.26-rc

[BUG] JFFS2 power loss recovery issues in 2.6.25, 2.6.26-rc

[Alexey Korolev]

Hi, 

One of recent patches broke JFFS2 power loss recoverability.
We faced the issue in Linux 2.6.25 and 2.6.26-rc but not in 2.6.24,
2.6.23.

If to reboot platform during file write. And try to read it again rest
of file will contain trash. 
Issue is well reproducible on NAND, especially if to delete large file
before write and reboot.

We made some investigations for this issue and found commit number which
breaks JFFS2 power loss recoverability.
It is:  [JFFS2] Improve getdents vs. f_pos handling on NOR flash.
        http://git.infradead.org/mtd-2.6.git?a=commitdiff;h=15953580e79b58caefb107e77f218e009b9992e6

Currently we don't know why it breaks JFFS2 and how it could be fixed
except roll back. 
So I would much appreciate any ideas on how it could be fixed. 


Thanks

Re: [BUG] JFFS2 power loss recovery issues in 2.6.25, 2.6.26-rc

[Jared Hulbert]

> We made some investigations for this issue and found commit number which
> breaks JFFS2 power loss recoverability.
> It is:  [JFFS2] Improve getdents vs. f_pos handling on NOR flash.
>        http://git.infradead.org/mtd-2.6.git?a=commitdiff;h=15953580e79b58caefb107e77f218e009b9992e6
>
> Currently we don't know why it breaks JFFS2 and how it could be fixed
> except roll back.

Does everything work when you unmerge this one commit?

Re: [BUG] JFFS2 power loss recovery issues in 2.6.25, 2.6.26-rc

[Alexey Korolev]

Hi,
> > We made some investigations for this issue and found commit number which
> > breaks JFFS2 power loss recoverability.
> > It is:  [JFFS2] Improve getdents vs. f_pos handling on NOR flash.
> >        http://git.infradead.org/mtd-2.6.git?a=commitdiff;h=15953580e79b58caefb107e77f218e009b9992e6
> >
> > Currently we don't know why it breaks JFFS2 and how it could be fixed
> > except roll back.
> 
> Does everything work when you unmerge this one commit?
> 
Correct, commit roll back fixes the problem. 

Thanks
Alexey

Re: [BUG] JFFS2 power loss recovery issues in 2.6.25, 2.6.26-rc

[David Woodhouse]

On Mon, 2008-06-02 at 12:41 +0100, Alexey Korolev wrote:
> Hi,
> > > We made some investigations for this issue and found commit number which
> > > breaks JFFS2 power loss recoverability.
> > > It is:  [JFFS2] Improve getdents vs. f_pos handling on NOR flash.
> > >        http://git.infradead.org/mtd-2.6.git?a=commitdiff;h=15953580e79b58caefb107e77f218e009b9992e6
> > >
> > > Currently we don't know why it breaks JFFS2 and how it could be fixed
> > > except roll back.
> > 
> > Does everything work when you unmerge this one commit?
> > 
> Correct, commit roll back fixes the problem. 

But leaves another one. I was away last week, and I'm home now -- I'll
try to reproduce and understand what's going on.

-- 
dwmw2

Re: [BUG] JFFS2 power loss recovery issues in 2.6.25, 2.6.26-rc

[Alexey Korolev]

Hi David,
> On Mon, 2008-06-02 at 12:41 +0100, Alexey Korolev wrote:
> > Hi,
> > > > We made some investigations for this issue and found commit number which
> > > > breaks JFFS2 power loss recoverability.
> > > > It is:  [JFFS2] Improve getdents vs. f_pos handling on NOR flash.
> > > >        http://git.infradead.org/mtd-2.6.git?a=commitdiff;h=15953580e79b58caefb107e77f218e009b9992e6
> > > >
> > > > Currently we don't know why it breaks JFFS2 and how it could be fixed
> > > > except roll back.
> > > 
> > > Does everything work when you unmerge this one commit?
> > > 
> > Correct, commit roll back fixes the problem. 
> 
> But leaves another one. I was away last week, and I'm home now -- I'll
> try to reproduce and understand what's going on.
> 
> 
We made more investigations of this problem. Joakim has assisted us to understan the patch. This patch can't break PLR feature on NAND. The only way it affects on tests is timing. So commit roll back will not fix the problem, but hides. 

Now we are collecting more information about the problem. We will let you know as
soon as we find something interesting about it. 

Thanks,
Alexey