[Qemu-devel] [PATCH 00/12] bitmaps: introduce 'bitmap' sync mode

[John Snow]

This series adds a new "BITMAP" sync mode that is meant to replace the
existing "INCREMENTAL" sync mode.

This mode can be changed by issuing any of three bitmap sync modes;
passed as arguments to the job.

The three bitmap sync modes are:
- CONDITIONAL: This is an alias for the old incremental mode. The bitmap is
               conditionally synchronized based on the return code of the job
               upon completion.
- NEVER: This is, effectively, the differential backup mode. It never clears
         the bitmap, as the name suggests.
- ALWAYS: Here is the new, exciting thing. The bitmap is always synchronized,
          even on failure. On success, this is identical to incremental, but
          on failure it clears only the bits that were copied successfully.
          This can be used to "resume" incremental backups from later points
          in times.

I wrote this series by accident on my way to implement incremental mode
for mirror, but this happened first -- the problem is that Mirror mode
uses its existing modes in a very particular way; and this was the best
way to add bitmap support into the mirror job properly.

In this series:
patches 1-2: Adds CONDITIONAL
patch 3: Adds NEVER
Patches 4-7: Adds ALWAYS.
Patches 8-11: Adds iotest 257
Patch 12: Minor permission loosening for RO bitmaps.

Next up:
 - Add these modes to Mirror. (Done*, but need tests.)
 - Allow the use of bitmaps and bitmap sync modes with non-BITMAP modes;
   This will allow for resumable/re-tryable full backups.

John Snow (12):
  qapi: add BitmapSyncMode enum
  block/backup: Add mirror sync mode 'bitmap'
  block/backup: add 'never' policy to bitmap sync mode
  hbitmap: Fix merge when b is empty, and result is not an alias of a
  hbitmap: enable merging across granularities
  block/dirty-bitmap: add bdrv_dirty_bitmap_claim
  block/backup: add 'always' bitmap sync policy
  iotests: add testing shim for script-style python tests
  iotests: teach run_job to cancel pending jobs
  iotests: teach FilePath to produce multiple paths
  iotests: add test 257 for bitmap-mode backups
  block/backup: loosen restriction on readonly bitmaps

 qapi/block-core.json          |   51 +-
 include/block/block_int.h     |    7 +-
 include/qemu/hbitmap.h        |    8 +
 block/backup.c                |   52 +-
 block/dirty-bitmap.c          |   14 +
 block/mirror.c                |    6 +-
 block/replication.c           |    2 +-
 blockdev.c                    |   12 +-
 util/hbitmap.c                |   36 +-
 tests/qemu-iotests/257        |  412 ++++++
 tests/qemu-iotests/257.out    | 2199 +++++++++++++++++++++++++++++++++
 tests/qemu-iotests/group      |    1 +
 tests/qemu-iotests/iotests.py |   83 +-
 13 files changed, 2830 insertions(+), 53 deletions(-)
 create mode 100755 tests/qemu-iotests/257
 create mode 100644 tests/qemu-iotests/257.out

-- 
2.21.0