[U-Boot] [PATCH] JFFS2: accelerate scanning.

[Detlev Zundel <dzu@denx.de>]

Hi Baidu,

>>> diff --git a/fs/jffs2/jffs2_1pass.c b/fs/jffs2/jffs2_1pass.c
>>> index dfb1745..f38f755 100644
>>> --- a/fs/jffs2/jffs2_1pass.c
>>> +++ b/fs/jffs2/jffs2_1pass.c
>>> @@ -1441,7 +1441,7 @@ dump_dirents(struct b_lists *pL)
>>>  }
>>>  #endif
>>>
>>> -#define DEFAULT_EMPTY_SCAN_SIZE      4096
>>> +#define DEFAULT_EMPTY_SCAN_SIZE      1024
>>
>> Hm, this is not mentioned in the commit log.  So is this detection
>> already there and you simply decrease the amount of empty space you are
>> looking for?
>>
>
> 1KB FF is enough to get the conclusion that the erase block is empty.
> I refer kenel to do this change

Ah, so this is in the kernel, right?  If I look into 'fs/jffs2/scan.c' I
see that this constant even changed to 256 in 2.6.37.  We should adapt
accordingly.

You should also include a statement in the commit message that this
change "syncs up with jffs2 in the linux kernel".  This is important
information.

[...]

>>>               while (ofs < EMPTY_SCAN_SIZE(part->sector_size) &&
>>>                               *(uint32_t *)(&buf[ofs]) == 0xFFFFFFFF)
>>>                       ofs += 4;
>>>
>>> -             if (ofs == EMPTY_SCAN_SIZE(part->sector_size))
>>> +             if (ofs == EMPTY_SCAN_SIZE(part->sector_size)) {
>>> +                     printf("Block at 0x%08x is empty (erased)\n", sector_ofs);
>>
>> Hm, you add this output so lets consider what it says - wouldn't it be
>> better to say "is considered to be empty"?  After all, we only infer the
>> emptiness in the code.
>>
> Yes, thanks. You description is better.

The kernel does it even better :)

 D1(printk(KERN_DEBUG "%d bytes at start of block seems clean... assuming all clean\n", EMPTY_SCAN_SIZE(c->sector_size)));

Use that please.

Cheers
  Detlev

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