linux-ext4 - One question about ext4

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Date:	Thu, 19 Jul 2012 22:51:40 +0800
From:	Wang Sheng-Hui <shhuiw@...il.com>
To:	Allison Henderson <achender@...ux.vnet.ibm.com>,
	Lukas Czerner <lczerner@...hat.com>,
	Theodore Ts'o <tytso@....edu>, linux-ext4@...r.kernel.org
Subject: One question about ext4_fallocate

Dear all,

I have one question about ext4_fallocate:
	For its parameters, offset & len, it will preallocate
	one space with length >= len, right?

>From the code:
	map.m_lblk = offset >> blkbits;
	/*
	 * We can't just convert len to max_blocks because
	 * If blocksize = 4096 offset = 3072 and len = 2048
	 */
	max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
		- map.m_lblk;

We can see that the target space is enlarged to the (floor, ceiling) of 
(offset, offset+len). Right?

If I'm wrong, please correct me.


Regards,
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