Message ID | 20180416170930.35504-1-dgilbert@redhat.com |
---|---|
State | New |
Headers | show |
Series | [v2,for,2.13] migration: Don't activate block devices if using -S | expand |
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote: > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > Activating the block devices causes the locks to be taken on > the backing file. If we're running with -S and the destination libvirt > hasn't started the destination with 'cont', it's expecting the locks are > still untaken. I will try to change the naming, because we have: - don't activate block device - and we stop calling bdrv_invalidate_cache_all i.e. behind the scenes bdrv_invalidate_cache activates a block device, not bad O:-) > Don't activate the block devices if we're not going to autostart the VM; > 'cont' already will do that anyway. This change is tied to the new > migration capability 'late-block-activate' that defaults to off, keeping > the old behaviour by default. I have read the old discussion, and we have: - current patch (not call bdrv_invalidate_cache() at bottom_handler) - kevin approach: create two commands activate_devices/deactivate_devices and make libvirt use them correctly I am not really sure which one is better, but as the patch author is Dave .... > bz: https://bugzilla.redhat.com/show_bug.cgi?id=1560854 > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > migration/migration.c | 34 +++++++++++++++++++++++++++------- > qapi/migration.json | 6 +++++- > 2 files changed, 32 insertions(+), 8 deletions(-) Reviewed-by: Juan Quintela <quintela@redhat.com> > +# @late-block-activate: If enabled, the destination will not activate block > +# devices (and thus take locks) immediately at the end of migration. > +# (since 2.13) > +# > # Since: 1.2 > ## > { 'enum': 'MigrationCapability', > 'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks', > 'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram', > 'block', 'return-path', 'pause-before-switchover', 'x-multifd', > - 'dirty-bitmaps' ] } > + 'dirty-bitmaps', 'late-block-activate' ] } > > ## > # @MigrationCapabilityStatus: Just wondering, is there a way to enable a capability for 2.13 and newer, and not activate it for older versions? I *think* that this feature should be on in new releases, and off by default with old machine types. But I haven't through long enough to know what needs to be changed. Later, Juan.
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote: > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > Activating the block devices causes the locks to be taken on > the backing file. If we're running with -S and the destination libvirt > hasn't started the destination with 'cont', it's expecting the locks are > still untaken. > > Don't activate the block devices if we're not going to autostart the VM; > 'cont' already will do that anyway. This change is tied to the new > migration capability 'late-block-activate' that defaults to off, keeping > the old behaviour by default. > > bz: https://bugzilla.redhat.com/show_bug.cgi?id=1560854 > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com>
diff --git a/migration/migration.c b/migration/migration.c index 52a5092add..a05c6c893b 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -197,6 +197,16 @@ static void migrate_generate_event(int new_state) } } +static bool migrate_late_block_activate(void) +{ + MigrationState *s; + + s = migrate_get_current(); + + return s->enabled_capabilities[ + MIGRATION_CAPABILITY_LATE_BLOCK_ACTIVATE]; +} + /* * Called on -incoming with a defer: uri. * The migration can be started later after any parameters have been @@ -306,13 +316,23 @@ static void process_incoming_migration_bh(void *opaque) Error *local_err = NULL; MigrationIncomingState *mis = opaque; - /* Make sure all file formats flush their mutable metadata. - * If we get an error here, just don't restart the VM yet. */ - bdrv_invalidate_cache_all(&local_err); - if (local_err) { - error_report_err(local_err); - local_err = NULL; - autostart = false; + /* If capability late_block_activate is set: + * Only fire up the block code now if we're going to restart the + * VM, else 'cont' will do it. + * This causes file locking to happen; so we don't want it to happen + * unless we really are starting the VM. + */ + if (!migrate_late_block_activate() || + (autostart && (!global_state_received() || + global_state_get_runstate() == RUN_STATE_RUNNING))) { + /* Make sure all file formats flush their mutable metadata. + * If we get an error here, just don't restart the VM yet. */ + bdrv_invalidate_cache_all(&local_err); + if (local_err) { + error_report_err(local_err); + local_err = NULL; + autostart = false; + } } /* diff --git a/qapi/migration.json b/qapi/migration.json index 9d0bf82cf4..757302762d 100644 --- a/qapi/migration.json +++ b/qapi/migration.json @@ -357,13 +357,17 @@ # @dirty-bitmaps: If enabled, QEMU will migrate named dirty bitmaps. # (since 2.12) # +# @late-block-activate: If enabled, the destination will not activate block +# devices (and thus take locks) immediately at the end of migration. +# (since 2.13) +# # Since: 1.2 ## { 'enum': 'MigrationCapability', 'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks', 'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram', 'block', 'return-path', 'pause-before-switchover', 'x-multifd', - 'dirty-bitmaps' ] } + 'dirty-bitmaps', 'late-block-activate' ] } ## # @MigrationCapabilityStatus: