On Tue, Feb 04, 2025 at 10:13:51PM +0100, Kevin Wolf wrote:
> 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.
>
> v3:
> - Moved bdrv_is_inactive() to patch 1 to fix the build [Fabiano]
> - Patch 5 ('block: Allow inactivating already inactive nodes') has
> become patch 2 to fix the logical ordering [Eric]
> - Patch 8: Fixed typo in the documentation [Eric]
> - Patch 10: Fixed typo in the commit message [Stefan]
> - Added Patch 11: Drain nodes for setting inactive flag [Stefan]
> - Patch 14: Test reading inactive images from both sides [Eric]
> - Patch 16: Fix typo in a comment [Eric]
>
> 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 (16):
> block: Add 'active' field to BlockDeviceInfo
> block: Allow inactivating already inactive nodes
> block: Inactivate external snapshot overlays when necessary
> migration/block-active: Remove global active flag
> block: Don't attach inactive child to active node
> 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: Drain nodes before inactivating them
> 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 | 64 +++-
> 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 | 140 ++++++++
> tests/qemu-iotests/tests/qsd-migrate.out | 59 ++++
> 27 files changed, 1004 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
>
> --
> 2.48.1
> Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
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