On 20/01/2016 08:12, Denis V. Lunev wrote:
There is a possibility to hit assert qcow2_get_specific_info that
s->qcow_version is undefined. This happens when VM in starting from
suspended state, i.e. it processes incoming migration, and in the same
time 'info block' is called.
The problem is that in the qcow2_invalidate_cache closes and the image
and memsets BDRVQcowState in the middle.
The patch moves processing of qcow2_get_specific_info into coroutine
context and ensures that qcow2_invalidate_cache and qcow2_get_specific_info
can not run simultaneosly.
I'm sitting next to Kevin :) and this is not a qcow2 bug.
The problem is that qcow2_invalidate_cache is being called in coroutine
context. The process_incoming_migration_co code starting with
bdrv_invalidate_cache_all should be moved out of the coroutine and into
the main loop. You can use a bottom half to get out of coroutine context.
The result should be a much simpler patch, too.
Thanks, and sorry for the delay. I saw qcow2 in the title and assumed
it was something I knew nothing about. :)
Paolo