external journal an data= option

external journal an data= option

[Wolfgang Walter]

Hello,

while testing ext4 with an external journal I found the following problem with 
longterm kernel 4.4.30:

I could mount the filesystem without specifying the option data=....

It seems that it is then mounted with data=ordered and indeed this is what

	cat /proc/mounts

shows.

But I could not change any option afterwards with -o remount. It always said 
that data=ordered is not valid with an external journal.

If I mount with explicitly stating data=writeback or data=journal remount 
works fine.

So It seems that ext4 does forbid (at least in 4.4.30) data=ordered as an 
option but uses it implicitly as default mode even with an external journal.

Regards,
-- 
Wolfgang Walter
Studentenwerk München
Anstalt des öffentlichen Rechts

Re: external journal an data= option

[Jan Kara]

Hi,

On Mon 21-11-16 16:39:53, Wolfgang Walter wrote:
> while testing ext4 with an external journal I found the following problem with 
> longterm kernel 4.4.30:
> 
> I could mount the filesystem without specifying the option data=....
> 
> It seems that it is then mounted with data=ordered and indeed this is what
> 
> 	cat /proc/mounts
> 
> shows.

Yes, that is correct.

> But I could not change any option afterwards with -o remount. It always said 
> that data=ordered is not valid with an external journal.
> 
> If I mount with explicitly stating data=writeback or data=journal remount 
> works fine.
> 
> So It seems that ext4 does forbid (at least in 4.4.30) data=ordered as an 
> option but uses it implicitly as default mode even with an external journal.

Can you show the exact error message and the set of mount options you use?
I'm not aware we would refuse data=ordered mode due to external journal...

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR