Block patches

# gpg: Signature made Fri Oct  6 16:30:57 2017 CEST
# 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-2017-10-06:
  block/mirror: check backing in bdrv_mirror_top_flush
  qcow2: truncate the tail of the image file after shrinking the image
  qcow2: fix return error code in qcow2_truncate()
  iotests: Fix 195 if IMGFMT is part of TEST_DIR
  block/mirror: check backing in bdrv_mirror_top_refresh_filename
  block: support passthrough of BDRV_REQ_FUA in crypto driver
  block: convert qcrypto_block_encrypt|decrypt to take bytes offset
  block: convert crypto driver to bdrv_co_preadv|pwritev
  block: fix data type casting for crypto payload offset
  crypto: expose encryption sector size in APIs
  block: use 1 MB bounce buffers for crypto instead of 16KB

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