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Date: Wed, 17 Oct 2012 15:02:14 +0800
From: Wang Sheng-Hui <shhuiw@gmail.com>
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To: linux-btrfs@vger.kernel.org
Subject: Questions about mkfs -A option
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Hi,

I'm reading the mkfs code, and confused by its -A option.
>>From its comments, the value specified by -A should be regarded as
the start of the filesystem. But mkfs will always zero some area
at the beginning of the first dev, regardless -r specified or not.

My question is:
Why mkfs zeros the beginning of the first dev? Is that expected?
And any use case for -A option?


thanks,