Re: [PATCH] ubi: account the fastmap data blocks when checking found_pebs

[Hou Tao <houtao1@xxxxxxxxxx>]

Hi,

On 2019/1/16 16:00, Richard Weinberger wrote:
> Am Mittwoch, 16. Januar 2019, 01:59:35 CET schrieb Hou Tao:
>> Now the data blocks used by current fastmap are not tracked by
>> wear-leveling subsystem. So taking these blocks into account
>> when checking found_pebs in ubi_wl_init(), else there will
>> be ubi assertion as shown below when fastmap is enabled on
>> a large NAND Flash (e.g. 2GB):
>>
>> [  335.877389] UBI assert failed in ubi_wl_init at 1705 (pid 2349)
>> [  335.878315] CPU: 7 PID: 2349 Comm: ubiattach Not tainted 4.20.0-10912-gd5d655675196-dirty #1
>> [  335.879436] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
>> [  335.881012] Call Trace:
>> [  335.881402]  dump_stack+0x5b/0x8b
>> [  335.881869]  ubi_wl_init+0xf8b/0x1500
>> [  335.882960]  ubi_attach+0x63b/0xaa0
>> [  335.883889]  ubi_attach_mtd_dev+0x107f/0x2e50
>> [  335.887300]  ctrl_cdev_ioctl+0x13e/0x1d0
>> [  335.888910]  do_vfs_ioctl+0x197/0xe60
>> [  335.893337]  ksys_ioctl+0x66/0x70
>> [  335.893788]  __x64_sys_ioctl+0x6f/0xb0
>> [  335.894309]  do_syscall_64+0x91/0x270
>> [  335.895337]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
>> ---
>>  drivers/mtd/ubi/ubi.h | 13 +++++++++++++
>>  drivers/mtd/ubi/wl.c  |  3 ++-
>>  2 files changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
>> index d47b9e436e67..90c28522aa07 100644
>> --- a/drivers/mtd/ubi/ubi.h
>> +++ b/drivers/mtd/ubi/ubi.h
>> @@ -1235,4 +1235,17 @@ static inline struct ubi_wl_entry *ubi_find_fm_block(const struct ubi_device *ub
>>  	return NULL;
>>  }
>>  
>> +/**
>> + * ubi_fm_data_blocks - return the number of data blocks used by fastmap
>> + * @ubi: UBI device description object
>> + *
>> + * This function returns zero if fastmap is not available.
>> + */
>> +static inline int ubi_fm_data_blocks(struct ubi_device *ubi)
>> +{
>> +	/* the first block is the super block of fastmap */
>> +	if (ubi->fm)
>> +		return ubi->fm->used_blocks - 1;
>> +	return 0;
>> +}
>>  #endif /* !__UBI_UBI_H__ */
>> diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
>> index 6f2ac865ff05..1b8f37ed8063 100644
>> --- a/drivers/mtd/ubi/wl.c
>> +++ b/drivers/mtd/ubi/wl.c
>> @@ -1702,7 +1702,8 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
>>  
>>  	dbg_wl("found %i PEBs", found_pebs);
>>  
>> -	ubi_assert(ubi->good_peb_count == found_pebs);
>> +	ubi_assert(ubi->good_peb_count ==
>> +		   found_pebs + ubi_fm_data_blocks(ubi));
>>  
>>  	reserved_pebs = WL_RESERVED_PEBS;
>>  	ubi_fastmap_init(ubi, &reserved_pebs);
> 
> This should get accounted in the loop above.
>          list_for_each_entry(aeb, &ai->fastmap, u.list) {
> 
I have considered to add these data blocks into the fastmap list in ubi_scan_fastmap(), but
it seems nobody will try to find the data block in fastmap list, so I choose a quick fix for
the assertion.

> I agree that this logic needs a redesign.
> Please see this patch series I sent last year but had no time to further work
> on it:
> https://lkml.org/lkml/2018/6/13/755
> 
> I'd highly appreciate if you could revive it. :-)
> 
Do you mean the whole patch set ? And we are planning to enable fast-map in our products,
so I could try to do it.

Regards,
Tao

> Thanks,
> //richard
> 
> 
> 
> 
> .
> 


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