Merge tag 'pull-nbd-2025-05-14' of https://repo.or.cz/qemu/ericb into staging

NBD patches for 2025-05-14

- Eric Blake: fix blockdev-mirror to no longer inflate sparse destination
  that already reads as zero

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# gpg: Signature made Wed 14 May 2025 22:28:13 EDT
# gpg:                using RSA key 71C2CC22B1C4602927D2F3AAA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>" [full]
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>" [full]
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* tag 'pull-nbd-2025-05-14' of https://repo.or.cz/qemu/ericb:
  mirror: Reduce I/O when destination is detect-zeroes:unmap
  tests: Add iotest mirror-sparse for recent patches
  iotests/common.rc: add disk_usage function
  mirror: Skip writing zeroes when target is already zero
  mirror: Skip pre-zeroing destination if it is already zero
  mirror: Drop redundant zero_target parameter
  mirror: Allow QMP override to declare target already zero
  mirror: Pass full sync mode rather than bool to internals
  mirror: Minor refactoring
  iotests: Improve iotest 194 to mirror data
  block: Add new bdrv_co_is_all_zeroes() function
  block: Let bdrv_co_is_zero_fast consolidate adjacent extents
  file-posix, gluster: Handle zero block status hint better
  block: Expand block status mode from bool to flags

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>