migration/multifd: put IOV initialization into compression method
Different compression methods may require different numbers of IOVs.
Based on streaming compression of zlib and zstd, all pages will be
compressed to a data block, so two IOVs are needed for packet header
and compressed data block.
Signed-off-by: Yuan Liu <yuan1.liu@intel.com>
Reviewed-by: Nanhai Zou <nanhai.zou@intel.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>