Kernel with MTD_UBI_FASTMAP=y, fm_autoconvert=0 fails to attach and resize UBI image

[Richard Weinberger]

Philipp,

Am 04.12.2012 08:54, schrieb Philipp Zabel:
> Hi Richard,
>
> Am Montag, den 03.12.2012, 21:01 +0100 schrieb Richard Weinberger:
>> Philipp,
>>
>> Am Mon, 03 Dec 2012 15:06:54 +0100
>> schrieb Philipp Zabel <p.zabel at pengutronix.de>:
>>
>>> Hi,
>>>
>>> on v3.7-rc7 with CONFIG_MTD_UBI_FASTMAP=y, I see the following error
>>> when trying to attach an UBI image without fastmap information that
>>> has to be resized because it is smaller than the mtd partition size:
>>>
>>>      $ cat /sys/module/ubi/parameters/fm_autoconvert
>>>      N
>>>
>>>      $ ubiattach -p /dev/mtd3
>>>      ubiattach: error!: cannot attach "/dev/mtd3"
>>>                 error 28 (No space left on device)
>>>
>>> If I either disable MTD_UBI_FASTMAP in the kernel config or enable the
>>> fm_autoconvert module parameter, attaching works just fine.
>>>
>>> Without fm_autoconvert, ubi_resize_volume fails with -ENOSPC, caused
>>> by ubi_wl_get_peb due to pool->size == 0.
>>> It gets to this point on an otherwise empty flash because ubi_scan_all
>>> puts all PEBs into the erase list. erase_work doesn't seem to be
>>> scheduled before ubi_wl_init returns with ubi->free.rb_node == NULL
>>> and ubi->free_count == 0. Because of this, refill_wl_user_pool breaks
>>> out of its loop immediately and never increases the pool->size
>>> counter.
>>>
>>> If I force synchronous erase in ubi_wl_init, the ubiattach succeeds
>>> the next time I try it as now all PEBs go in the free list:
>>>
>>> @@ -1899,7 +1907,7 @@ int ubi_wl_init(struct ubi_device *ubi, struct
>>> ubi_attach_info *ai) e->ec = aeb->ec;
>>>                  ubi_assert(!ubi_is_fm_block(ubi, e->pnum));
>>>                  ubi->lookuptbl[e->pnum] = e;
>>> -               if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum,
>>> 0)) {
>>> +               if (do_sync_erase(ubi, e, aeb->vol_id, aeb->lnum, 0))
>>> { kmem_cache_free(ubi_wl_entry_slab, e);
>>>                          goto out_free;
>>>                  }
>>>
>>
>> Thanks a lot for identifying this issue!
>> But I'm not sure whether do_sync_erase() is the perfect solution
>> for the issue. Tomorrow I'll try to reproduce it.
>
> Thank you, I'm sure it is not. Enabling fm_autoconvert works for me, so
> I just wanted to put all information I've got out there before wasting
> too much time trying to wrap my head around the issue myself.

Sorry, for the (very) late reply. I completely forgot to take care of this.

I've tried to reproduce the issue, but ubiattach didn't fail.
Most likely because I've used nandsim and you have seen the issue on a real (slow)
NAND device. Is this correct?

Are you sure that ubi_resize_volume() failed because of ubi_wl_get_peb()?
To me it looks more like it failed because ubi->avail_pebs is too low.

Is my assumption correct that you've created an UBI image with ubinize where vol_size
is smaller than your MTD partition?
And, of course, where autoresize is set.

Thanks,
//richard