[Qemu-devel] [RFC v2 0/8] qemu-img: add measure sub-command

[Stefan Hajnoczi]

RFCv2:
 * Publishing RFC again to discuss the new user-visible interfaces.  Code has
   changed quite a bit, I have not kept any Reviewed-by tags.
 * Rename qemu-img sub-command "measure" and API bdrv_measure() [Nir]
 * Report both "required bytes" and "fully allocated bytes" to handle the empty
   image file and prealloc use cases [Nir and Dan]
 * Use bdrv_getlength() instead of bdrv_nb_sectors() [Berto]
 * Rename "err" label "out" in qemu-img-cmds.c [Nir]
 * Add basic qcow2 support, doesn't support qemu-img convert from existing 
files yet

RFCv1:
 * Publishing patch series with just raw support, no qcow2 yet.  Please review
   the command-line interface and let me know if you are happy with this
   approach.

Users and management tools sometimes need to know the size required for a new
disk image so that an LVM volume, SAN LUN, etc can be allocated ahead of time.
Image formats like qcow2 have non-trivial metadata that makes it hard to
estimate the exact size without knowledge of file format internals.

This patch series introduces a new qemu-img sub-command that calculates the
required size for both image creation and conversion scenarios.

The conversion scenario is:

  $ qemu-img measure -f raw -O qcow2 input.img
  required bytes: 1327680
  fully allocated bytes: 1074069504

Here an existing image file is taken and the output includes the space required
for data from the input image file.

The creation scenario is:

  $ qemu-img measure -O qcow2 --size 5G
  required bytes: 327680
  fully allocated bytes: 1074069504

Stefan Hajnoczi (8):
  block: add bdrv_measure() API
  raw-format: add bdrv_measure() support
  qcow2: extract preallocation calculation function
  qcow2: extract image creation option parsing
  qcow2: add bdrv_measure() support
  qemu-img: add measure subcommand
  qemu-iotests: support per-format golden output files
  iotests: add test 178 for qemu-img measure

 qapi/block-core.json             |  19 +++
 include/block/block.h            |   4 +
 include/block/block_int.h        |   2 +
 block.c                          |  33 +++++
 block/qcow2.c                    | 296 ++++++++++++++++++++++++++-------------
 block/raw-format.c               |  22 +++
 qemu-img.c                       | 213 ++++++++++++++++++++++++++++
 qemu-img-cmds.hx                 |   9 ++
 tests/qemu-iotests/178           |  75 ++++++++++
 tests/qemu-iotests/178.out.qcow2 |  33 +++++
 tests/qemu-iotests/178.out.raw   |  33 +++++
 tests/qemu-iotests/check         |   5 +
 tests/qemu-iotests/group         |   1 +
 13 files changed, 651 insertions(+), 94 deletions(-)
 create mode 100755 tests/qemu-iotests/178
 create mode 100644 tests/qemu-iotests/178.out.qcow2
 create mode 100644 tests/qemu-iotests/178.out.raw

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2.9.3