What is wrong?

[Brian Norris]

+ others

Hi Leon,

Can you please keep the CC list intact? And please try to reply below
the quotes and trim context, rather than top-posting. Thanks!

On Thu, Feb 27, 2014 at 02:00:25PM +0200, Leon Pollak wrote:
> I am VERY(!) thankful to you for the answer.
> First, I am calm now that there is no any error on my side and the 
> system remains clean despite these messages.
> Second, yes, the workaround worked.

That's nice to hear, but that is (as you note) a workaround. You should
not need an extra sync after remounting read-only. Do you think you can
try the linked patch?

commit 807612db2f9940b9fa6deaef054eb16d51bd3e00
Author: Andrew Ruder <andrew.ruder at elecsyscorp.com>
Date:   Thu Jan 30 09:26:54 2014 -0600

    fs/super.c: sync ro remount after blocking writers

Perhaps Richard or Andrew can comment on whether this patch should help
you. But I think JFFS2 on NAND uses write-buffered support which can be
affected by this bug.

> May thanks to you for your help!!!

You're welcome.

I have a few other questions: are you using NOR or NAND (it looks like
maybe NAND)?

Leaving most context intact for others, below.

> On Wednesday 26 February 2014 17:11:48 you wrote:
> > On Wed, Feb 26, 2014 at 04:07:21PM +0200, Leon Pollak wrote:
> > > The NAND is write protected by HW and the partition is mounted as
> > > RO.
> > > At some moment I need to update a small file.
> > > So I do:
> > > - HW write protect off,
> > > - remount RW,
> > > - update file,
> > > - sync,
> > > - remount RO,
> > > - write protect on.
> > > 
> > > Looking at linux console I see a lot of messages like:
> > > Erase at 0x00400000 failed immediately: errno -5
> > > Erase at 0x003e0000 failed immediately: errno -5
> > > ......
> > > Erase at 0x00340000 failed immediately: errno -5
> > > jffs2_flush_wbuf(): Write failed with -5
> > > Write of 2016 bytes at 0x002578a0 failed. returned -5, retlen 0
> > > Not marking the space at 0x002578a0 as dirty because the flash
> > > driver
> > > returned retlen zero.
> > > 
> > > 
> > > This is repeated for a long time, but everything seems work OK.
> > > The sequential starts and even file updates are also OK, without
> > > error messages.
> > > 
> > > What do I do wrong? Thanks a lot.
> > 
> > It's possible you're seeing symptoms of this:
> > 
> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit
> > /?id=807612db2f9940b9fa6deaef054eb16d51bd3e00
> > 
> > It seems like maybe JFFS2 is still doing some GC and/or write flushing
> > after the remount.
> > 
> > Could try this?
> > 
> >  - HW write protect off,
> >  - remount RW,
> >  - update file,
> >  - sync,
> >  - remount RO,
> >  - sync, <---------- add this, to see if you're experiencing any
> >                      writeback after remount
> >  - write protect on.

Regards,
Brian