Re: [PATCH v2 00/15] block: Managing inactive nodes (QSD migration)

[Fabiano Rosas <farosas@suse.de>]

Kevin Wolf <kwolf@redhat.com> writes:

> This series adds a mechanism that allows the user or management tool to
> manually activate and inactivate block nodes instead of fully relying on
> the automatic management in the migration code.
>
> One case where this is needed is for migration with shared storage and
> devices backed by qemu-storage-daemon, which as an external process is
> not involved in the VM migration. Management tools can manually
> orchestrate the handover in this scenario. The new qemu-iotests case
> qsd-migrate demonstrates this.
>
> There are other cases without qemu-storage-daemon where manual
> management is necessary. For example, after migration, the destination
> VM only activates images on 'cont', but after migrating a paused VM, the
> user may want to perform operations on a block node while the VM is
> still paused.
>
> This series adds support for block exports on an inactive node (needed
> for shared storage migration with qemu-storage-daemon) only to NBD.
> Adding it to other export types will be done in a future series.
>
> v2:
> - Added a comprehensive test case that tests how inactive nodes
>   interoperate with many operations
> - Added a couple of fixes for bugs uncovered by the tests (that would
>   usually lead to crashes when an unsupported operation is performed on
>   inactive nodes)
> - Added 'active' status to query-block information
>
> Kevin Wolf (15):
>   block: Add 'active' field to BlockDeviceInfo
>   block: Inactivate external snapshot overlays when necessary
>   migration/block-active: Remove global active flag
>   block: Don't attach inactive child to active node
>   block: Allow inactivating already inactive nodes
>   block: Fix crash on block_resize on inactive node
>   block: Add option to create inactive nodes
>   block: Add blockdev-set-active QMP command
>   block: Support inactive nodes in blk_insert_bs()
>   block/export: Don't ignore image activation error in blk_exp_add()
>   block/export: Add option to allow export of inactive nodes
>   nbd/server: Support inactive nodes
>   iotests: Add filter_qtest()
>   iotests: Add qsd-migrate case
>   iotests: Add (NBD-based) tests for inactive nodes
>
>  qapi/block-core.json                          |  44 ++-
>  qapi/block-export.json                        |  10 +-
>  include/block/block-common.h                  |   1 +
>  include/block/block-global-state.h            |   6 +
>  include/block/export.h                        |   3 +
>  migration/migration.h                         |   3 -
>  block.c                                       |  62 +++-
>  block/block-backend.c                         |  16 +-
>  block/export/export.c                         |  29 +-
>  block/monitor/block-hmp-cmds.c                |   5 +-
>  block/qapi.c                                  |   1 +
>  blockdev.c                                    |  48 +++
>  migration/block-active.c                      |  46 ---
>  migration/migration.c                         |   8 -
>  nbd/server.c                                  |  17 +
>  tests/qemu-iotests/iotests.py                 |   8 +
>  tests/qemu-iotests/041                        |   4 +-
>  tests/qemu-iotests/165                        |   4 +-
>  tests/qemu-iotests/184.out                    |   2 +
>  tests/qemu-iotests/191.out                    |  16 +
>  tests/qemu-iotests/273.out                    |   5 +
>  tests/qemu-iotests/tests/copy-before-write    |   3 +-
>  tests/qemu-iotests/tests/inactive-node-nbd    | 303 ++++++++++++++++++
>  .../qemu-iotests/tests/inactive-node-nbd.out  | 239 ++++++++++++++
>  tests/qemu-iotests/tests/migrate-bitmaps-test |   7 +-
>  tests/qemu-iotests/tests/qsd-migrate          | 132 ++++++++
>  tests/qemu-iotests/tests/qsd-migrate.out      |  51 +++
>  27 files changed, 986 insertions(+), 87 deletions(-)
>  create mode 100755 tests/qemu-iotests/tests/inactive-node-nbd
>  create mode 100644 tests/qemu-iotests/tests/inactive-node-nbd.out
>  create mode 100755 tests/qemu-iotests/tests/qsd-migrate
>  create mode 100644 tests/qemu-iotests/tests/qsd-migrate.out

Series:

Acked-by: Fabiano Rosas <farosas@suse.de>

I checked that this series doesn't regress the original double
inactivate issue fixed by Peter Xu [1]. I also ported the tests[2] on
top of this and everything looks good. Thanks!

1- 8597af7615 (migration/block: Rewrite disk activation, 2024-12-06)
2- https://lore.kernel.org/r/20241125144612.16194-6-farosas@suse.de