Re: [PATCH v3 0/5] scsi: persistent reservation live migration

[Kevin Wolf <kwolf@redhat.com>]

Am 29.01.2026 um 22:20 hat Stefan Hajnoczi geschrieben:
> v3:
> - Use warn_report_err() instead of suppressing errors [Daniel Berrangé]
> - Wrap lines exceeding 80 characters
> 
> v2:
> - Add user documentation [Paolo]
> - Send PREEMPT on the source if migration fails. This rollback operation
>   ensures the source regains access to the LUN even if migration fails after
>   the destination issues its own PREEMPT.
> 
> Live migration does not work for SCSI Persistent Reservations acquired on
> scsi-block devices. This patch series migrates the reservation key and
> reservation type so that the destination QEMU can take over the persistent
> reservation with the PREEMPT service action upon live migration.
> 
> The approach involves snooping PERSISTENT RESERVE OUT replies and tracking the
> scsi-block device's current reservation key and reservation type. In most cases
> this involves no additional SCSI commands. This approach isn't perfect: if
> another machine modifies the reservation on the physical LUN, then QEMU's state
> becomes stale. Persistent reservations are inherently cooperative, so this is
> acceptable as long as real applications don't run into problems.
> 
> I am also working on a test suite called pr-tests that runs sg_persist(8)
> commands across multiple machines in order to exercise various scenarios:
> https://gitlab.com/stefanha/pr-tests

On top of this, should we do something to catch cases where migrate-pr
is off, but the user still tries to migrate while PRs are in use? Maybe
have a migration blocker as long as pr_state->key is set?

Kevin