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envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.104, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Jun 02, 2025 at 10:37:54PM -0300, Fabiano Rosas wrote: > The QAPI converts an empty list on the block-bitmap-mapping input into > a NULL BitmapMigrationNodeAliasList. The empty list is a valid input > for the block-bitmap-mapping option, so commit 3cba22c9ad ("migration: > Fix block_bitmap_mapping migration") started using the > s->parameters.has_block_bitmap_mapping field to tell when the user has > passed in an empty list vs. when no list has been passed at all. > > However, using the has_block_bitmap_mapping field of s->parameters is > only possible because MigrationParameters has had its members made > optional due to historical reasons. > > In order to make improvements to the way configuration options are set > for a migration, we'd like to reduce the usage of the has_* fields of > the global configuration object (s->parameters). > > Add a separate boolean to track the status of the block_bitmap_mapping > option. > > (this was verified to not regress iotest 300, which is the test that > 3cba22c9ad refers to) > > Signed-off-by: Fabiano Rosas > --- > migration/migration.h | 7 +++++++ > migration/options.c | 6 +++--- > 2 files changed, 10 insertions(+), 3 deletions(-) > > diff --git a/migration/migration.h b/migration/migration.h > index d53f7cad84..ab797540b0 100644 > --- a/migration/migration.h > +++ b/migration/migration.h > @@ -510,6 +510,13 @@ struct MigrationState { > bool rdma_migration; > > GSource *hup_source; > + > + /* > + * The block-bitmap-mapping option is allowed to be an emtpy list, > + * therefore we need a way to know wheter the user has given > + * anything as input. > + */ > + bool has_block_bitmap_mapping; > }; > > void migrate_set_state(MigrationStatus *state, MigrationStatus old_state, > diff --git a/migration/options.c b/migration/options.c > index f64e141394..cf77826204 100644 > --- a/migration/options.c > +++ b/migration/options.c > @@ -685,7 +685,7 @@ bool migrate_has_block_bitmap_mapping(void) > { > MigrationState *s = migrate_get_current(); > > - return s->parameters.has_block_bitmap_mapping; > + return s->has_block_bitmap_mapping; > } > > uint32_t migrate_checkpoint_delay(void) > @@ -989,7 +989,7 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp) > params->has_announce_step = true; > params->announce_step = s->parameters.announce_step; > > - if (s->parameters.has_block_bitmap_mapping) { > + if (s->has_block_bitmap_mapping) { > params->has_block_bitmap_mapping = true; > params->block_bitmap_mapping = > QAPI_CLONE(BitmapMigrationNodeAliasList, > @@ -1469,7 +1469,7 @@ static void migrate_params_apply(MigrationParameters *params) > qapi_free_BitmapMigrationNodeAliasList( > s->parameters.block_bitmap_mapping); > > - s->parameters.has_block_bitmap_mapping = true; > + s->has_block_bitmap_mapping = true; > s->parameters.block_bitmap_mapping = > QAPI_CLONE(BitmapMigrationNodeAliasList, > params->block_bitmap_mapping); > -- > 2.35.3 > This is definitely unfortunate, and I'm still scratching my head on understanding why it's necessary. E.g. I tried to revert this patch manually and iotest 300 passed, with: ===8<=== >From a952479805d8bdfe532ad4e0c0092f758991af08 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Fri, 6 Jun 2025 10:44:37 -0400 Subject: [PATCH] Revert "migration: Add a flag to track block-bitmap-mapping input" This reverts commit fd755a53c0e4ce9739d20d7cdd69400b2a37102c. Signed-off-by: Peter Xu --- migration/migration.h | 7 ------- migration/options.c | 4 ++-- 2 files changed, 2 insertions(+), 9 deletions(-) diff --git a/migration/migration.h b/migration/migration.h index 49761f4699..e710c421f8 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -510,13 +510,6 @@ struct MigrationState { bool rdma_migration; GSource *hup_source; - - /* - * The block-bitmap-mapping option is allowed to be an emtpy list, - * therefore we need a way to know wheter the user has given - * anything as input. - */ - bool has_block_bitmap_mapping; }; void migrate_set_state(MigrationStatus *state, MigrationStatus old_state, diff --git a/migration/options.c b/migration/options.c index dd2288187d..e71a57764d 100644 --- a/migration/options.c +++ b/migration/options.c @@ -765,7 +765,7 @@ bool migrate_has_block_bitmap_mapping(void) { MigrationState *s = migrate_get_current(); - return s->has_block_bitmap_mapping; + return s->parameters.has_block_bitmap_mapping; } uint32_t migrate_checkpoint_delay(void) @@ -1376,7 +1376,7 @@ void qmp_migrate_set_parameters(MigrationParameters *params, Error **errp) * params structure with the user input around. */ if (params->has_block_bitmap_mapping) { - migrate_get_current()->has_block_bitmap_mapping = true; + migrate_get_current()->parameters.has_block_bitmap_mapping = true; } if (migrate_params_check(tmp, errp)) { -- 2.49.0 ===8<=== I'm staring at commit 3cba22c9ad now, looks like what it wants to do is making sure construct_alias_map() will be invoked even if the block bitmap mapping is NULL itself. But then right below the code, it has: static int init_dirty_bitmap_migration(DBMSaveState *s, Error **errp) { ... if (migrate_has_block_bitmap_mapping()) { alias_map = construct_alias_map(migrate_block_bitmap_mapping(), true, &error_abort); } ... if (!alias_map) { ... } } Looks like it's also ready for !alias_map anyway. I'm definitely puzzled by this code. Even if so, IIUC the question can still be asked on whether we can always assume has_block_bitmap_mapping to be always true, then here instead of: if (migrate_has_block_bitmap_mapping()) { alias_map = construct_alias_map(migrate_block_bitmap_mapping(), true, &error_abort); } We do: alias_map = construct_alias_map(migrate_block_bitmap_mapping(), true, &error_abort); After all it looks like construct_alias_map() takes NULL too.. -- Peter Xu