Re: [PATCH v3 1/6] fat: add i_disksize to represent uninitialized size

From: Namjae Jeon
Date: Thu Feb 06 2014 - 01:41:45 EST

2014-02-04, OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>:
> OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> writes:
>>>> Don't we need to update ->i_disksize after cont_write_begin()?
>>> We don't need to update i_disksize after cont_write_begin.
>>> It is taken care by the fat_get_block after the allocation.
>>> For all write paths we align the mmu_private and i_disksize from
>>> fat_fill_inode and fat_get_block.
>> fat_fill_inode() just set i_disksize to i_size. So, it is not aligned by
>> cluster size or block size.
>> E.g. ->mmu_private = 500. Then, cont_write_begin() can set ->mmu_private
>> to 512 on some case. In this case, fat_get_block() will not be called,
>> because no new allocation.
>> If this is true, it would be possible to have ->mmu_private == 512 and
>> ->i_disksize == 500.
>> I'm missing something?
> BTW, even if above was right, I'm not checking whether updating
> ->i_disksize after cont_write_begin() is right fix or not.
I understand your concern. these can be mismatched.
But, when checking your doubt, I can not find any side effect.
I think that there is no issue regardless of alignment of two value,
in the cont_write_begin.
Could you please share any point I am missing ?
If you suggest checking point or test method, I can check more and
share the result.

Thanks OGAWA.
> --
> OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
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