* Peter Xu (pet...@redhat.com) wrote:
> Introducing new migration state "postcopy-recover". If a migration
> procedure is paused and the connection is rebuilt afterward
> successfully, we'll switch the source VM state from "postcopy-paused" to
> the new state "postcopy-recover", then we'll do the resume logic in the
> migration thread (along with the return path thread).
>
> This patch only do the state switch on source side. Another following up
> patch will handle the state switching on destination side using the same
> status bit.
>
> Signed-off-by: Peter Xu <pet...@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
(Although it's a little large, so you may want to split it)
> ---
> migration/migration.c | 76
> ++++++++++++++++++++++++++++++++++++++-------------
> qapi-schema.json | 4 ++-
> 2 files changed, 60 insertions(+), 20 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index deb947b..30dd566 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -495,6 +495,7 @@ static bool migration_is_setup_or_active(int state)
> case MIGRATION_STATUS_ACTIVE:
> case MIGRATION_STATUS_POSTCOPY_ACTIVE:
> case MIGRATION_STATUS_POSTCOPY_PAUSED:
> + case MIGRATION_STATUS_POSTCOPY_RECOVER:
> case MIGRATION_STATUS_SETUP:
> return true;
>
> @@ -571,6 +572,7 @@ MigrationInfo *qmp_query_migrate(Error **errp)
> case MIGRATION_STATUS_CANCELLING:
> case MIGRATION_STATUS_POSTCOPY_ACTIVE:
> case MIGRATION_STATUS_POSTCOPY_PAUSED:
> + case MIGRATION_STATUS_POSTCOPY_RECOVER:
> /* TODO add some postcopy stats */
> info->has_status = true;
> info->has_total_time = true;
> @@ -2035,6 +2037,13 @@ typedef enum MigThrError {
> MIG_THR_ERR_FATAL = 2,
> } MigThrError;
>
> +/* Return zero if success, or <0 for error */
> +static int postcopy_do_resume(MigrationState *s)
> +{
> + /* TODO: do the resume logic */
> + return 0;
> +}
> +
> /*
> * We don't return until we are in a safe state to continue current
> * postcopy migration. Returns MIG_THR_ERR_RECOVERED if recovered, or
> @@ -2043,29 +2052,55 @@ typedef enum MigThrError {
> static MigThrError postcopy_pause(MigrationState *s)
> {
> assert(s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE);
> - migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
> - MIGRATION_STATUS_POSTCOPY_PAUSED);
>
> - /* Current channel is possibly broken. Release it. */
> - assert(s->to_dst_file);
> - qemu_file_shutdown(s->to_dst_file);
> - qemu_fclose(s->to_dst_file);
> - s->to_dst_file = NULL;
> + while (true) {
> + migrate_set_state(&s->state, s->state,
> + MIGRATION_STATUS_POSTCOPY_PAUSED);
>
> - error_report("Detected IO failure for postcopy. "
> - "Migration paused.");
> + /* Current channel is possibly broken. Release it. */
> + assert(s->to_dst_file);
> + qemu_file_shutdown(s->to_dst_file);
> + qemu_fclose(s->to_dst_file);
> + s->to_dst_file = NULL;
>
> - /*
> - * We wait until things fixed up. Then someone will setup the
> - * status back for us.
> - */
> - while (s->state == MIGRATION_STATUS_POSTCOPY_PAUSED) {
> - qemu_sem_wait(&s->postcopy_pause_sem);
> - }
> + error_report("Detected IO failure for postcopy. "
> + "Migration paused.");
> +
> + /*
> + * We wait until things fixed up. Then someone will setup the
> + * status back for us.
> + */
> + while (s->state == MIGRATION_STATUS_POSTCOPY_PAUSED) {
> + qemu_sem_wait(&s->postcopy_pause_sem);
> + }
>
> - trace_postcopy_pause_continued();
> + if (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER) {
> + /* Woken up by a recover procedure. Give it a shot */
> +
> + /*
> + * Firstly, let's wake up the return path now, with a new
> + * return path channel.
> + */
> + qemu_sem_post(&s->postcopy_pause_rp_sem);
>
> - return MIG_THR_ERR_RECOVERED;
> + /* Do the resume logic */
> + if (postcopy_do_resume(s) == 0) {
> + /* Let's continue! */
> + trace_postcopy_pause_continued();
> + return MIG_THR_ERR_RECOVERED;
> + } else {
> + /*
> + * Something wrong happened during the recovery, let's
> + * pause again. Pause is always better than throwing
> + * data away.
> + */
> + continue;
> + }
> + } else {
> + /* This is not right... Time to quit. */
> + return MIG_THR_ERR_FATAL;
> + }
> + }
> }
>
> static MigThrError migration_detect_error(MigrationState *s)
> @@ -2330,7 +2365,10 @@ void migrate_fd_connect(MigrationState *s)
> }
>
> if (resume) {
> - /* TODO: do the resume logic */
> + /* Wakeup the main migration thread to do the recovery */
> + migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_PAUSED,
> + MIGRATION_STATUS_POSTCOPY_RECOVER);
> + qemu_sem_post(&s->postcopy_pause_sem);
> return;
> }
>
> diff --git a/qapi-schema.json b/qapi-schema.json
> index ba41f2c..989f95a 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -669,6 +669,8 @@
> #
> # @postcopy-paused: during postcopy but paused. (since 2.11)
> #
> +# @postcopy-recover: trying to recover from a paused postcopy. (since 2.11)
> +#
> # @completed: migration is finished.
> #
> # @failed: some error occurred during migration process.
> @@ -682,7 +684,7 @@
> { 'enum': 'MigrationStatus',
> 'data': [ 'none', 'setup', 'cancelling', 'cancelled',
> 'active', 'postcopy-active', 'postcopy-paused',
> - 'completed', 'failed', 'colo' ] }
> + 'postcopy-recover', 'completed', 'failed', 'colo' ] }
>
> ##
> # @MigrationInfo:
> --
> 2.7.4
>
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
