[PATCH 00/21] block: publish backup-top filter

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Hi all!

We have image fleecing scheme to export point-in-time state of active
disk (iotest 222):


                                      backup(sync=none)
                     ┌───────────────────────────────────────┐
                     ▼                                       │
┌────────────┐     ┌────────────────┐  backing             ┌─────────────┐
│ NBD export │ ─── │ temp qcow2 img │ ───────────────────▶ │ active disk │
└────────────┘     └────────────────┘                      └─────────────┘
                                                             ▲
┌────────────┐                                               │
│ guest blk  │ ──────────────────────────────────────────────┘
└────────────┘                        


Actually, backup job inserts a backup-top filter, so in detail it looks
like:

                                      backup(sync=none)
                     ┌───────────────────────────────────────┐
                     ▼                                       │
┌────────────┐     ┌────────────────┐  backing             ┌─────────────┐
│ NBD export │ ─── │ temp qcow2 img │ ───────────────────▶ │ active disk │
└────────────┘     └────────────────┘                      └─────────────┘
                     ▲                                       ▲
                     │ target                                │
                     │                                       │
┌────────────┐     ┌────────────────┐  backing               │
│ guest blk  │ ──▶ │   backup-top   │ ───────────────────────┘
└────────────┘     └────────────────┘

And job does nothing here. In a new blockdev world user is intended to
operate on node level, and insert/remove filters by hand. Let's get rid
of job in the scheme:

┌────────────┐     ┌────────────────┐  backing             ┌─────────────┐
│ NBD export │ ─── │ temp qcow2 img │ ───────────────────▶ │ active disk │
└────────────┘     └────────────────┘                      └─────────────┘
                     ▲                                       ▲
                     │ target                                │
                     │                                       │
┌────────────┐     ┌────────────────┐  backing               │
│ guest blk  │ ──▶ │   backup-top   │ ───────────────────────┘
└────────────┘     └────────────────┘


The series prepares qom-set to make possible inserting filters above
root node (patches 01-04), rename backup-top to copy-before-write, do
other preparations for publishing the filter, and finally publish it,
add qapi interface and test new fleecing scheme in 222.

Vladimir Sementsov-Ogievskiy (21):
  block: introduce bdrv_replace_child_bs()
  block: introduce blk_replace_bs
  qdev-properties: PropertyInfo: add realized_set_allowed field
  qdev: allow setting drive property for realized device
  block: rename backup-top to copy-before-write
  block/backup: drop support for copy_range
  block-copy: always set BDRV_REQ_SERIALISING flag
  block/backup: stricter backup_calculate_cluster_size()
  block/backup: move cluster size calculation to block-copy
  block/copy-before-write: relax permission requirements when no parents
  block/copy-before-write: use file child instead of backing
  block/copy-before-write: bdrv_cbw_append(): replace child at last
  block/copy-before-write: introduce cbw_init()
  block/copy-before-write: cbw_init(): rename variables
  block/copy-before-write: cbw_init(): use file child after attaching
  block/copy-before-write: cbw_init(): use options
  block/block-copy: switch to fully set bitmap by default
  block/block-copy: make setting progress optional
  block/copy-before-write: make public block driver
  qapi: publish copy-before-write filter
  itotests/222: add test-case for copy-before-write filter

 qapi/block-core.json                        |  22 +-
 block/{backup-top.h => copy-before-write.h} |  26 +-
 include/block/block-copy.h                  |   4 +-
 include/block/block.h                       |   2 +
 include/hw/qdev-properties.h                |   1 +
 include/sysemu/block-backend.h              |   1 +
 block.c                                     |  36 +++
 block/backup-top.c                          | 253 -------------------
 block/backup.c                              | 115 ++-------
 block/block-backend.c                       |   8 +
 block/block-copy.c                          |  95 +++++++-
 block/copy-before-write.c                   | 257 ++++++++++++++++++++
 hw/core/qdev-properties-system.c            |  30 ++-
 hw/core/qdev-properties.c                   |   6 +-
 MAINTAINERS                                 |   4 +-
 block/meson.build                           |   2 +-
 tests/qemu-iotests/222                      |  56 ++++-
 tests/qemu-iotests/222.out                  |  72 ++++++
 tests/qemu-iotests/283                      |  35 ++-
 tests/qemu-iotests/283.out                  |   4 +-
 20 files changed, 606 insertions(+), 423 deletions(-)
 rename block/{backup-top.h => copy-before-write.h} (56%)
 delete mode 100644 block/backup-top.c
 create mode 100644 block/copy-before-write.c

-- 
2.29.2