shrinking ubifs?

shrinking ubifs?

[Jon Ringle]

On ubi0, I have 3 volumes:
ubi0_0 kernel (static volume)
ubi0_1 squashfs (static volume)
ubi0_2 ubifs (dynamic volume)

When I create the volumes, the static volumes are created first and
then the ubifs volume is created with whatever LEBs are left over. I
am using the squashfs and ubifs in a aufs2 union fs. When I need to
reflash either of the static volumes for an upgrade, and the new
images don't fit the space available in the LEBs reserved in the
corresponding static volume, I remove the ubifs volume to create space
and then recreate the ubifs volume again with what is remaining. This
is sub-optimal as this means that and data on the ubifs is now lost.

Is there a way to shrink a UBIFS if there are unused LEBs in the UBIFS?

Thanks
Jon

Re: shrinking ubifs?

[Artem Bityutskiy]

On Thu, 2010-01-14 at 17:15 -0500, Jon Ringle wrote:
> On ubi0, I have 3 volumes:
> ubi0_0 kernel (static volume)
> ubi0_1 squashfs (static volume)
> ubi0_2 ubifs (dynamic volume)
> 
> When I create the volumes, the static volumes are created first and
> then the ubifs volume is created with whatever LEBs are left over. I
> am using the squashfs and ubifs in a aufs2 union fs. When I need to
> reflash either of the static volumes for an upgrade, and the new
> images don't fit the space available in the LEBs reserved in the
> corresponding static volume, I remove the ubifs volume to create space
> and then recreate the ubifs volume again with what is remaining. This
> is sub-optimal as this means that and data on the ubifs is now lost.

Yes, this is not optimal. However, ubifs shrinking is not implemented.
One could UBIFS ioctl to shring the FS, though, it should not be
extremely difficult. It is about garbage-collecting the last LEBs to
somewhere else, and amending the master block.

> Is there a way to shrink a UBIFS if there are unused LEBs in the UBIFS?

Not at the moment, this would need some development.

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)

Re: shrinking ubifs?

[Jon Ringle]

On Sun, Jan 17, 2010 at 5:40 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
> On Thu, 2010-01-14 at 17:15 -0500, Jon Ringle wrote:
>> On ubi0, I have 3 volumes:
>> ubi0_0 kernel (static volume)
>> ubi0_1 squashfs (static volume)
>> ubi0_2 ubifs (dynamic volume)
>>
>> When I create the volumes, the static volumes are created first and
>> then the ubifs volume is created with whatever LEBs are left over. I
>> am using the squashfs and ubifs in a aufs2 union fs. When I need to
>> reflash either of the static volumes for an upgrade, and the new
>> images don't fit the space available in the LEBs reserved in the
>> corresponding static volume, I remove the ubifs volume to create space
>> and then recreate the ubifs volume again with what is remaining. This
>> is sub-optimal as this means that and data on the ubifs is now lost.
>
> Yes, this is not optimal. However, ubifs shrinking is not implemented.
> One could UBIFS ioctl to shring the FS, though, it should not be
> extremely difficult. It is about garbage-collecting the last LEBs to
> somewhere else, and amending the master block.
>
>> Is there a way to shrink a UBIFS if there are unused LEBs in the UBIFS?
>
> Not at the moment, this would need some development.

How about the opposite. If the static volumes became smaller freeing
up some LEBs. Can the UBIFS be expanded to make use of the freed LEBs?

Jon

Re: shrinking ubifs?

[Artem Bityutskiy]

On Fri, 2010-01-22 at 14:21 -0500, Jon Ringle wrote:
> On Sun, Jan 17, 2010 at 5:40 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
> > On Thu, 2010-01-14 at 17:15 -0500, Jon Ringle wrote:
> >> On ubi0, I have 3 volumes:
> >> ubi0_0 kernel (static volume)
> >> ubi0_1 squashfs (static volume)
> >> ubi0_2 ubifs (dynamic volume)
> >>
> >> When I create the volumes, the static volumes are created first and
> >> then the ubifs volume is created with whatever LEBs are left over. I
> >> am using the squashfs and ubifs in a aufs2 union fs. When I need to
> >> reflash either of the static volumes for an upgrade, and the new
> >> images don't fit the space available in the LEBs reserved in the
> >> corresponding static volume, I remove the ubifs volume to create space
> >> and then recreate the ubifs volume again with what is remaining. This
> >> is sub-optimal as this means that and data on the ubifs is now lost.
> >
> > Yes, this is not optimal. However, ubifs shrinking is not implemented.
> > One could UBIFS ioctl to shring the FS, though, it should not be
> > extremely difficult. It is about garbage-collecting the last LEBs to
> > somewhere else, and amending the master block.
> >
> >> Is there a way to shrink a UBIFS if there are unused LEBs in the UBIFS?
> >
> > Not at the moment, this would need some development.
> 
> How about the opposite. If the static volumes became smaller freeing
> up some LEBs. Can the UBIFS be expanded to make use of the freed LEBs?

That works automatically. UBIFS expands automatically, but up to the
size which you specified with the '-c' mkfs.ubifs option.

http://www.linux-mtd.infradead.org/faq/ubifs.html#L_max_leb_cnt

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)

Re: shrinking ubifs?

[Jon Ringle]

On Wed, Jan 27, 2010 at 11:25 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
> On Fri, 2010-01-22 at 14:21 -0500, Jon Ringle wrote:
>> How about the opposite. If the static volumes became smaller freeing
>> up some LEBs. Can the UBIFS be expanded to make use of the freed LEBs?
>
> That works automatically. UBIFS expands automatically, but up to the
> size which you specified with the '-c' mkfs.ubifs option.

Can the same thing be done using ubimkvol?
ubimkvol -m -N ubifs /dev/ubi0

Re: shrinking ubifs?

[Artem Bityutskiy]

On Wed, 2010-01-27 at 11:34 -0500, Jon Ringle wrote:
> On Wed, Jan 27, 2010 at 11:25 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
> > On Fri, 2010-01-22 at 14:21 -0500, Jon Ringle wrote:
> >> How about the opposite. If the static volumes became smaller freeing
> >> up some LEBs. Can the UBIFS be expanded to make use of the freed LEBs?
> >
> > That works automatically. UBIFS expands automatically, but up to the
> > size which you specified with the '-c' mkfs.ubifs option.
> 
> Can the same thing be done using ubimkvol?
> ubimkvol -m -N ubifs /dev/ubi0

Sorry, I don't understand the question...

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)

Re: shrinking ubifs?

[Jon Ringle]

On Wed, Jan 27, 2010 at 11:35 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
> On Wed, 2010-01-27 at 11:34 -0500, Jon Ringle wrote:
>> On Wed, Jan 27, 2010 at 11:25 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
>> > On Fri, 2010-01-22 at 14:21 -0500, Jon Ringle wrote:
>> >> How about the opposite. If the static volumes became smaller freeing
>> >> up some LEBs. Can the UBIFS be expanded to make use of the freed LEBs?
>> >
>> > That works automatically. UBIFS expands automatically, but up to the
>> > size which you specified with the '-c' mkfs.ubifs option.
>>
>> Can the same thing be done using ubimkvol?
>> ubimkvol -m -N ubifs /dev/ubi0
>
> Sorry, I don't understand the question...

I create my ubi volumes from an initramfs environment that is compiled
against klibc. So far, I haven't been able to build mkfs.ubifs against
klibc, so I create my ubifs volume by using ubimkvol and then mounting
it as ubifs.

Jon

Re: shrinking ubifs?

[Artem Bityutskiy]

On Sun, 2010-01-31 at 23:01 -0500, Jon Ringle wrote:
> On Wed, Jan 27, 2010 at 11:35 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
> > On Wed, 2010-01-27 at 11:34 -0500, Jon Ringle wrote:
> >> On Wed, Jan 27, 2010 at 11:25 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
> >> > On Fri, 2010-01-22 at 14:21 -0500, Jon Ringle wrote:
> >> >> How about the opposite. If the static volumes became smaller freeing
> >> >> up some LEBs. Can the UBIFS be expanded to make use of the freed LEBs?
> >> >
> >> > That works automatically. UBIFS expands automatically, but up to the
> >> > size which you specified with the '-c' mkfs.ubifs option.
> >>
> >> Can the same thing be done using ubimkvol?
> >> ubimkvol -m -N ubifs /dev/ubi0
> >
> > Sorry, I don't understand the question...
> 
> I create my ubi volumes from an initramfs environment that is compiled
> against klibc. So far, I haven't been able to build mkfs.ubifs against
> klibc, so I create my ubifs volume by using ubimkvol and then mounting
> it as ubifs.

I see. Well, that is about UBIFS, about the default formatting code,
when UBIFS formats empty volume. That code should be hacked and the
maximum FS size should be increased to the value you need.
-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)