[Qemu-devel] [PATCH v14 00/14] qemu-img: Implement commit like QMP

[Max Reitz]

qemu-img should use QMP commands whenever possible in order to ensure
feature completeness of both online and offline image operations. For
the "commit" command, this is relatively easy, so implement it first
(in the hope that indeed others will follow).

As qemu-img does not have access to QMP (due to QMP being intertwined
with basically everything in qemu), we cannot directly use QMP, but at
least use the functions the corresponding QMP commands are using (which
would be "block-commit", in this case).


v14:
- Patch 3:
  - Pull the optimized code out into an own function [Kevin]
  - Only run the optimized code if the image header, the reftable, a
    single refblock and the L1 table can be described by that single
    refblock [Kevin]
  - Zero out the L1 table before modifying anything else [Kevin]
  - Always set bs->drv to NULL if an error occured which broke the
    in-memory refcount information and thus rendered the BDS unusable
    (because all of the qcow2 code assumes that the in-memory
    information is correct, obviously) [Kevin]
  - Do truncation last, because while it is the eventual goal, it is
    also the structurally least invasive and therefore least important
    operation (we don't want it to fail and leave the BDS unusable)
    [Kevin]
- Patch 6: In the meantime, two more places which test data/len have
  crept in, remove them [Kevin]
- Patch 8:
  - Drop the block_job_resume() call [Kevin, although he'd probably
    prefer not to be mentioned for this]
  - Improve error message when there is no backing file [Kevin]
- Patch 10: Rebase onto patch 8 (dropped block_job_resume())
- Patch 11:
  - Rebase onto patch 8 (different error message if the base image has
    not been explicitly specified)
  - Explanation about what "For reasons of consistency" means (or at
    least an example of inconsistency) [Kevin]
- Patch 14:
  - Write some data to the top image so it can be leaked
  - Swap order of l1_update and empty_image_prepare (l1_update now
    occurs before empty_image_prepare; the second l1_update occurs at
    the same time as the reftable_update, so it's safe to omit that one)
  - Output changed accordingly


git-backport-diff against v13:

Key:
[----] : patches are identical
[####] : number of functional differences between upstream/downstream patch
[down] : patch is downstream-only
The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively

001/14:[----] [--] 'qcow2: Allow "full" discard'
002/14:[----] [--] 'qcow2: Implement bdrv_make_empty()'
003/14:[0306] [FC] 'qcow2: Optimize bdrv_make_empty()'
004/14:[----] [--] 'blockjob: Introduce block_job_complete_sync()'
005/14:[----] [--] 'blockjob: Add "ready" field'
006/14:[0002] [FC] 'iotests: Omit length/offset test in 040 and 041'
007/14:[----] [--] 'block/mirror: Improve progress report'
008/14:[0009] [FC] 'qemu-img: Implement commit like QMP'
009/14:[----] [--] 'qemu-img: Empty image after commit'
010/14:[0001] [FC] 'qemu-img: Enable progress output for commit'
011/14:[0019] [FC] 'qemu-img: Specify backing file for commit'
012/14:[----] [--] 'iotests: Add _filter_qemu_img_map'
013/14:[----] [--] 'iotests: Add test for backing-chain commits'
014/14:[0026] [FC] 'iotests: Add test for qcow2's bdrv_make_empty'


Max Reitz (14):
  qcow2: Allow "full" discard
  qcow2: Implement bdrv_make_empty()
  qcow2: Optimize bdrv_make_empty()
  blockjob: Introduce block_job_complete_sync()
  blockjob: Add "ready" field
  iotests: Omit length/offset test in 040 and 041
  block/mirror: Improve progress report
  qemu-img: Implement commit like QMP
  qemu-img: Empty image after commit
  qemu-img: Enable progress output for commit
  qemu-img: Specify backing file for commit
  iotests: Add _filter_qemu_img_map
  iotests: Add test for backing-chain commits
  iotests: Add test for qcow2's bdrv_make_empty

 block/Makefile.objs              |   3 +-
 block/blkdebug.c                 |   2 +
 block/mirror.c                   |  34 ++++---
 block/qcow2-cluster.c            |  27 ++++--
 block/qcow2-snapshot.c           |   2 +-
 block/qcow2.c                    | 192 ++++++++++++++++++++++++++++++++++++++-
 block/qcow2.h                    |   2 +-
 blockjob.c                       |  42 +++++++--
 include/block/block.h            |   2 +
 include/block/blockjob.h         |  20 ++++
 qapi/block-core.json             |   4 +-
 qemu-img-cmds.hx                 |   4 +-
 qemu-img.c                       | 147 +++++++++++++++++++++++++-----
 qemu-img.texi                    |  16 +++-
 tests/qemu-iotests/040           |   4 +-
 tests/qemu-iotests/041           |   5 +-
 tests/qemu-iotests/097           | 122 +++++++++++++++++++++++++
 tests/qemu-iotests/097.out       | 119 ++++++++++++++++++++++++
 tests/qemu-iotests/098           |  82 +++++++++++++++++
 tests/qemu-iotests/098.out       |  52 +++++++++++
 tests/qemu-iotests/common.filter |   7 ++
 tests/qemu-iotests/group         |   2 +
 tests/qemu-iotests/iotests.py    |   3 +-
 23 files changed, 823 insertions(+), 70 deletions(-)
 create mode 100755 tests/qemu-iotests/097
 create mode 100644 tests/qemu-iotests/097.out
 create mode 100755 tests/qemu-iotests/098
 create mode 100644 tests/qemu-iotests/098.out

-- 
1.9.3