Merge remote-tracking branch 'kwolf/for-anthony' into staging

# By Paolo Bonzini (14) and others
# Via Kevin Wolf
* kwolf/for-anthony: (24 commits)
  ide: Add fall through annotations
  block: Create proper size file for disk mirror
  ahci: Add migration support
  ahci: Change data types in preparation for migration
  ahci: Remove unused AHCIDevice fields
  hbitmap: add assertion on hbitmap_iter_init
  mirror: do nothing on zero-sized disk
  block/vdi: Check for bad signature
  block/vdi: Improved return values from vdi_open
  block/vdi: Improve debug output for signature
  block: Use error code EMEDIUMTYPE for wrong format in some block drivers
  block: Add special error code for wrong format
  mirror: support arbitrarily-sized iterations
  mirror: support more than one in-flight AIO operation
  mirror: add buf-size argument to drive-mirror
  mirror: switch mirror_iteration to AIO
  mirror: allow customizing the granularity
  block: allow customizing the granularity of the dirty bitmap
  block: return count of dirty sectors, not chunks
  mirror: perform COW if the cluster size is bigger than the granularity
  ...