On Wed, Oct 18, 2017 at 06:40:07PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
>
> When 'pause-before-switchover' is enabled, the outgoing migration
> will pause before invalidating the block devices and serializing
> the device state.
> At this point the management layer gets the chance to clean up any
> device jobs or other device users before the migration completes.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> ---
> migration/migration.c | 10 ++++++++++
> migration/migration.h | 1 +
> qapi/migration.json | 5 ++++-
> 3 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 98429dc843..fba3342368 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1521,6 +1521,16 @@ bool migrate_use_multifd(void)
> return s->enabled_capabilities[MIGRATION_CAPABILITY_X_MULTIFD];
> }
>
> +bool migrate_pause_before_switchover(void)
> +{
> + MigrationState *s;
> +
> + s = migrate_get_current();
> +
> + return s->enabled_capabilities[
> + MIGRATION_CAPABILITY_PAUSE_BEFORE_SWITCHOVER];
> +}
> +
> int migrate_multifd_channels(void)
> {
> MigrationState *s;
> diff --git a/migration/migration.h b/migration/migration.h
> index b83cceadc4..969866303e 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -177,6 +177,7 @@ bool migrate_zero_blocks(void);
>
> bool migrate_auto_converge(void);
> bool migrate_use_multifd(void);
> +bool migrate_pause_before_switchover(void);
> int migrate_multifd_channels(void);
> int migrate_multifd_page_count(void);
>
> diff --git a/qapi/migration.json b/qapi/migration.json
> index f8b365e3f5..4960231ba2 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -341,6 +341,9 @@
> # @return-path: If enabled, migration will use the return path even
> # for precopy. (since 2.10)
> #
> +# @pause-before-switchover: Pause outgoing migration before serialising
> device
> +# state and before disabling block IO (since 2.11)
Nit: Not sure whether it's good to avoid naming "disabling block IO",
since after all this pre-switch state can be used to do other things
as well in the future.
Reviewed-by: Peter Xu <pet...@redhat.com>
> +#
> # @x-multifd: Use more than one fd for migration (since 2.11)
> #
> # Since: 1.2
> @@ -348,7 +351,7 @@
> { 'enum': 'MigrationCapability',
> 'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
> 'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
> - 'block', 'return-path', 'x-multifd' ] }
> + 'block', 'return-path', 'pause-before-switchover', 'x-multifd' ] }
>
> ##
> # @MigrationCapabilityStatus:
> --
> 2.13.6
>
--
Peter Xu
