Merge remote-tracking branch 'mreitz/tags/pull-block-2018-02-13' into queue-block

Block patches for the block queue

# gpg: Signature made Tue Feb 13 17:00:13 2018 CET
# gpg:                using RSA key F407DB0061D5CF40
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>"
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1  1829 F407 DB00 61D5 CF40

* mreitz/tags/pull-block-2018-02-13: (40 commits)
  iotests: Add l2-cache-entry-size to iotest 137
  iotests: Test downgrading an image using a small L2 slice size
  iotests: Test valid values of l2-cache-entry-size
  qcow2: Allow configuring the L2 slice size
  qcow2: Rename l2_table in count_cow_clusters()
  qcow2: Rename l2_table in count_contiguous_clusters_unallocated()
  qcow2: Rename l2_table in count_contiguous_clusters()
  qcow2: Rename l2_table in qcow2_alloc_compressed_cluster_offset()
  qcow2: Update qcow2_truncate() to support L2 slices
  qcow2: Update expand_zero_clusters_in_l1() to support L2 slices
  qcow2: Prepare expand_zero_clusters_in_l1() for adding L2 slice support
  qcow2: Read refcount before L2 table in expand_zero_clusters_in_l1()
  qcow2: Update qcow2_update_snapshot_refcount() to support L2 slices
  qcow2: Prepare qcow2_update_snapshot_refcount() for adding L2 slice support
  qcow2: Update zero_single_l2() to support L2 slices
  qcow2: Update discard_single_l2() to support L2 slices
  qcow2: Update handle_alloc() to support L2 slices
  qcow2: Update handle_copied() to support L2 slices
  qcow2: Update qcow2_alloc_cluster_link_l2() to support L2 slices
  qcow2: Update qcow2_get_cluster_offset() to support L2 slices
  ...

Signed-off-by: Kevin Wolf <kwolf@redhat.com>