To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 7/6] fat: Support a truncate() for expanding size
References: <87hdaotlci.fsf@devron.myhome.or.jp>
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	<87r79ss658.fsf_-_@devron.myhome.or.jp>
	<20051107170626.4d08e8d6.akpm@osdl.org>
From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Date: Tue, 08 Nov 2005 12:19:56 +0900
In-Reply-To: <20051107170626.4d08e8d6.akpm@osdl.org> (Andrew Morton's message of "Mon, 7 Nov 2005 17:06:26 -0800")
Message-ID: <87ek5rx1ur.fsf@devron.myhome.or.jp>
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Andrew Morton <akpm@osdl.org> writes:

> OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> wrote:
>>
>> +static int fat_cont_expand(struct inode *inode, loff_t size)
>
> Is it not possible to extend generic_cont_expand() so that fatfs can use it?

The generic_cont_expand() is too generic.

If "size" is block boundary, generic_cont_expand() expands the
->i_size to "size + 1", after it, the caller of it will truncate to
"size" by vmtruncate().

This sequence is not need if ->prepare_write() is cont_prepare_write().
The cont_prepare_write() will just fill the blocks with zero until
"size" if blocks is not allocated yet.

FAT is using cont_parepare_write(), so for avoiding the above extra
work, is using own version.

Probably, this version is generic only for cont_parepare_write().

Thanks.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
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