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Date: Mon, 14 Nov 2011 13:47:41 +0800
From: Zhi Hui Li <zhihuili@linux.vnet.ibm.com>
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Subject: [Qemu-devel] I have some questions in block , can anyone help me,
	thank you!
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To: QEMU-devel <qemu-devel@nongnu.org>
Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, Markus Armbruster <armbru@redhat.com>


questions:

1) In qcow2.c, in function: qcow2_co_readv
    In qcow2.h, in struct BDRVQcowState
I want to know the relations between sector_num in function 
qcow2_co_readv and cluster_sectors in struct BDRVQcowState ?



2) In qcow2.c, in function; qcow2_co_writev
at line 547:

index_in_cluster = sector_num & (s->cluster_sectors - 1);
How to understand it ?


3) In qcow2.c,  in the function  : qcow2_co_readv and qcow2_co_writev
I want to know the least unit that it was read by the function.
for example:
BDRVQcowState s;
Is s->cluster_size or 512 ?



Thank you very much !

Best regards!