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

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Message-ID: <87txcfudzu.fsf@devron.myhome.or.jp>
Date:	Tue, 04 Feb 2014 23:52:21 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Amit Sahrawat <a.sahrawat@...sung.com>
Subject: Re: [PATCH v3 1/6] fat: add i_disksize to represent uninitialized size

OGAWA Hirofumi <hirofumi@...l.parknet.co.jp> 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.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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