Merge branch 'for-anthony' of git://repo.or.cz/qemu/kevin

Merge branch 'for-anthony' of git://repo.or.cz/qemu/kevin

* 'for-anthony' of git://repo.or.cz/qemu/kevin:
  Fix -snapshot deleting images on disk change
  block: Use error codes from lower levels for error message
  block: default to 0 minimal / optiomal I/O size
  move 'unsafe' to end of caching modes in help
  virtio-blk: Create exit function to unregister savevm
  block migration: propagate return value when bdrv_write() returns < 0
  ide/atapi: add support for GET EVENT STATUS NOTIFICATION