Re: [PATCH v3 4/7] migration/block-dirty-bitmap: fix bitmaps pre-blockdev migration during mirror job
On 5/19/20 5:51 AM, Vladimir Sementsov-Ogievskiy wrote: 18.05.2020 23:36, Eric Blake wrote: On 5/15/20 7:40 AM, Vladimir Sementsov-Ogievskiy wrote: Important thing for bitmap migration is to select destination block node to obtain the migrated bitmap. + /* Skip filters without bitmaos */ + while (bs && bs->drv && bs->drv->is_filter && + !bdrv_has_named_bitmaps(bs)) + { + bs = bs->backing->bs ?: bs->file->bs; Is this correct, or should it be: bs = bs->backing ? bs->backing->bs : bs->file->bs; Hmm, yes, otherwise it should crash on file-based filter :) Otherwise looks reasonable, but I'm hesitant to include it in today's bitmap pull request in order to give it more review/testing time. It should be ready for a pull request next week, though. Can you post a v4, to make it easier for me to build? -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org
Re: [PATCH v3 4/7] migration/block-dirty-bitmap: fix bitmaps pre-blockdev migration during mirror job
18.05.2020 23:36, Eric Blake wrote: On 5/15/20 7:40 AM, Vladimir Sementsov-Ogievskiy wrote: Important thing for bitmap migration is to select destination block node to obtain the migrated bitmap. Prepatch, on source we use bdrv_get_device_or_node_name() to identify the node, and on target we do bdrv_lookup_bs. bdrv_get_device_or_node_name() returns blk name only for direct children of blk. So, bitmaps of direct children of blks are migrated by blk name and others - by node name. Old libvirt is unprepared to bitmap migration by node-name, node-names are mostly auto-generated. So actually only migration by blk name works for it. Newer libvirt will use new interface (which will be added soon) to specify node-mapping for bitmaps migration explicitly. Still, let's improve the current behavior a bit. Now, consider classic libvirt migrations assisted by mirror block job: mirror block job inserts filter, so our source is not a direct child of blk, and bitmaps are migrated by node-names. And this just don't work either "won't" or "doesn't" with auto-generated node names trailing '.' Let's fix it by allowing use blk-name even if some implicit filters are inserted. s/allowing use/using/ Note2: we, of course, can't skip filters and use blk name to migrate bitmaps in filtered node by blk name for this blk if these filters have named bitmaps which should be migrated. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1652424 Signed-off-by: Vladimir Sementsov-Ogievskiy --- migration/block-dirty-bitmap.c | 39 +- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c index 7e93718086..5d3a7d2b07 100644 --- a/migration/block-dirty-bitmap.c +++ b/migration/block-dirty-bitmap.c @@ -319,14 +319,48 @@ static int init_dirty_bitmap_migration(void) { BlockDriverState *bs; DirtyBitmapMigBitmapState *dbms; + GHashTable *handled_by_blk = g_hash_table_new(NULL, NULL); + BlockBackend *blk; dirty_bitmap_mig_state.bulk_completed = false; dirty_bitmap_mig_state.prev_bs = NULL; dirty_bitmap_mig_state.prev_bitmap = NULL; dirty_bitmap_mig_state.no_bitmaps = false; + /* + * Use blockdevice name for direct (or filtered) children of named block + * backends. + */ + for (blk = blk_next(NULL); blk; blk = blk_next(blk)) { + const char *name = blk_name(blk); + + if (!name || strcmp(name, "") == 0) { + continue; + } + + bs = blk_bs(blk); + + /* Skip filters without bitmaos */ + while (bs && bs->drv && bs->drv->is_filter && + !bdrv_has_named_bitmaps(bs)) + { + bs = bs->backing->bs ?: bs->file->bs; Is this correct, or should it be: bs = bs->backing ? bs->backing->bs : bs->file->bs; Hmm, yes, otherwise it should crash on file-based filter :) Otherwise looks reasonable, but I'm hesitant to include it in today's bitmap pull request in order to give it more review/testing time. It should be ready for a pull request next week, though. -- Best regards, Vladimir
Re: [PATCH v3 4/7] migration/block-dirty-bitmap: fix bitmaps pre-blockdev migration during mirror job
On 5/15/20 7:40 AM, Vladimir Sementsov-Ogievskiy wrote: Important thing for bitmap migration is to select destination block node to obtain the migrated bitmap. Prepatch, on source we use bdrv_get_device_or_node_name() to identify the node, and on target we do bdrv_lookup_bs. bdrv_get_device_or_node_name() returns blk name only for direct children of blk. So, bitmaps of direct children of blks are migrated by blk name and others - by node name. Old libvirt is unprepared to bitmap migration by node-name, node-names are mostly auto-generated. So actually only migration by blk name works for it. Newer libvirt will use new interface (which will be added soon) to specify node-mapping for bitmaps migration explicitly. Still, let's improve the current behavior a bit. Now, consider classic libvirt migrations assisted by mirror block job: mirror block job inserts filter, so our source is not a direct child of blk, and bitmaps are migrated by node-names. And this just don't work either "won't" or "doesn't" with auto-generated node names trailing '.' Let's fix it by allowing use blk-name even if some implicit filters are inserted. s/allowing use/using/ Note2: we, of course, can't skip filters and use blk name to migrate bitmaps in filtered node by blk name for this blk if these filters have named bitmaps which should be migrated. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1652424 Signed-off-by: Vladimir Sementsov-Ogievskiy --- migration/block-dirty-bitmap.c | 39 +- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c index 7e93718086..5d3a7d2b07 100644 --- a/migration/block-dirty-bitmap.c +++ b/migration/block-dirty-bitmap.c @@ -319,14 +319,48 @@ static int init_dirty_bitmap_migration(void) { BlockDriverState *bs; DirtyBitmapMigBitmapState *dbms; +GHashTable *handled_by_blk = g_hash_table_new(NULL, NULL); +BlockBackend *blk; dirty_bitmap_mig_state.bulk_completed = false; dirty_bitmap_mig_state.prev_bs = NULL; dirty_bitmap_mig_state.prev_bitmap = NULL; dirty_bitmap_mig_state.no_bitmaps = false; +/* + * Use blockdevice name for direct (or filtered) children of named block + * backends. + */ +for (blk = blk_next(NULL); blk; blk = blk_next(blk)) { +const char *name = blk_name(blk); + +if (!name || strcmp(name, "") == 0) { +continue; +} + +bs = blk_bs(blk); + +/* Skip filters without bitmaos */ +while (bs && bs->drv && bs->drv->is_filter && + !bdrv_has_named_bitmaps(bs)) +{ +bs = bs->backing->bs ?: bs->file->bs; Is this correct, or should it be: bs = bs->backing ? bs->backing->bs : bs->file->bs; Otherwise looks reasonable, but I'm hesitant to include it in today's bitmap pull request in order to give it more review/testing time. It should be ready for a pull request next week, though. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org