[Qemu-devel] I have some questions in block , can anyone help me, thank you!

[Zhi Hui Li]

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!