Merge remote-tracking branch 'remotes/hreitz/tags/pull-block-2021-09-15' into staging

Merge remote-tracking branch 'remotes/hreitz/tags/pull-block-2021-09-15' into staging

Block patches:
- Block-status cache for data regions
- qcow2 optimization (when using subclusters)
- iotests delinting, and let 297 (lint checker) cover named iotests
- qcow2 check improvements
- Added -F (target backing file format) option to qemu-img convert
- Mirror job fix
- Fix for when a migration is initiated while a backup job runs
- Fix for uncached qemu-img convert to a volume with 4k sectors (for an
  unaligned image)
- Minor gluster driver fix

# gpg: Signature made Wed 15 Sep 2021 18:39:11 BST
# gpg:                using RSA key CB62D7A0EE3829E45F004D34A1FA40D098019CDF
# gpg:                issuer "hreitz@redhat.com"
# gpg: Good signature from "Hanna Reitz <hreitz@redhat.com>" [marginal]
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: CB62 D7A0 EE38 29E4 5F00  4D34 A1FA 40D0 9801 9CDF

* remotes/hreitz/tags/pull-block-2021-09-15: (32 commits)
  qemu-img: Add -F shorthand to convert
  qcow2-refcount: check_refblocks(): add separate message for reserved
  qcow2-refcount: check_refcounts_l1(): check reserved bits
  qcow2-refcount: improve style of check_refcounts_l1()
  qcow2-refcount: check_refcounts_l2(): check reserved bits
  qcow2-refcount: check_refcounts_l2(): check l2_bitmap
  qcow2-refcount: fix_l2_entry_by_zero(): also zero L2 entry bitmap
  qcow2-refcount: introduce fix_l2_entry_by_zero()
  qcow2: introduce qcow2_parse_compressed_l2_entry() helper
  qcow2: compressed read: simplify cluster descriptor passing
  qcow2-refcount: improve style of check_refcounts_l2()
  qemu-img: Allow target be aligned to sector size
  qcow2: handle_dependencies(): relax conflict detection
  qcow2: refactor handle_dependencies() loop body
  simplebench: add img_bench_templater.py
  block: bdrv_inactivate_recurse(): check for permissions and fix crash
  tests: add migrate-during-backup
  block/mirror: fix NULL pointer dereference in mirror_wait_on_conflicts()
  iotests/297: Cover tests/
  mirror-top-perms: Fix AbnormalShutdown path
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>