[Qemu-devel] questions about the bdrv_co_do_readv()

[Yaodong Yang]

In the block-migration period, each chunk of data is read by bdrv_aio_readv(), 
then bdrv_co_aio_rw_vector() , then bdrv_co_do_rw(). 

Inside the bdrv_co_do_rw() function, the bdrv_co_do_readv() function is called 
twice. and exit without finish the execution of the bdrv_co_do_readv() 
function. All these calls are inside the migration thread. Later, the iothread 
will finish the bottom half of the bdrv_co_do_readv() function. I do not why it 
is executed in this way.

In sum, the bdrv_co_do_readv() seems to be executed inside two thread, the 
migration thread and native iothread. Both of them executed the function twice 
for a single request. Could someone explain it for me ? I appreciate it very 
much!

Thanks!
Yaodong