Re: [PATCH] migration: Attempt disk reactivation in more failure scenarios

[Juan Quintela <quintela@redhat.com>]

Eric Blake <eblake@redhat.com> wrote:
> Commit fe904ea824 added a fail_inactivate label, which tries to
> reactivate disks on the source after a failure while s->state ==
> MIGRATION_STATUS_ACTIVE, but didn't actually use the label if
> qemu_savevm_state_complete_precopy() failed.  This failure to
> reactivate is also present in commit 6039dd5b1c (also covering the new
> s->state == MIGRATION_STATUS_DEVICE state) and 403d18ae (ensuring
> s->block_inactive is set more reliably).
>
> Consolidate the two labels back into one - no matter HOW migration is
> failed, if there is any chance we can reach vm_start() after having
> attempted inactivation, it is essential that we have tried to restart
> disks before then.  This also makes the cleanup more like
> migrate_fd_cancel().
>
> Suggested-by: Kevin Wolf <kwolf@redhat.com>
> Signed-off-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

I still can't believe that power down disks and decide if restart (or
not) the vm is such a complicated bussiness.  Sniff.