dirty_bitmap_load_start() creates an incoming migrated bitmap with bdrv_create_dirty_bitmap() and, if the source marked it persistent, calls bdrv_dirty_bitmap_set_persistence() without checking whether the destination node can be written to. Same gap as qmp_block_dirty_bitmap_add(), reached via incoming migration: a persistent bitmap for a read-only destination (e.g. a migrated CD-ROM-class attachment with dirty-bitmaps migration enabled) ends up writable in memory on a node that can never store it.
Reject it the same way, with one difference from the QMP path: every destination node is BDRV_O_INACTIVE until migration completes, so bdrv_is_writable() would reject every incoming persistent bitmap, not just read-only ones. Check bdrv_is_read_only() alone. Signed-off-by: Denis V. Lunev <[email protected]> CC: Eric Blake <[email protected]> CC: Vladimir Sementsov-Ogievskiy <[email protected]> CC: John Snow <[email protected]> CC: Andrey Drobyshev <[email protected]> --- migration/block-dirty-bitmap.c | 22 +++++++++---- tests/qemu-iotests/tests/migrate-bitmaps-test | 33 +++++++++++++++++++ .../tests/migrate-bitmaps-test.out | 4 +-- 3 files changed, 50 insertions(+), 9 deletions(-) diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c index cba54e25cd..1b8f39c12b 100644 --- a/migration/block-dirty-bitmap.c +++ b/migration/block-dirty-bitmap.c @@ -812,13 +812,6 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s) error_report("Bitmap with the same name ('%s') already exists on " "destination", bdrv_dirty_bitmap_name(s->bitmap)); return -EINVAL; - } else { - s->bitmap = bdrv_create_dirty_bitmap(s->bs, granularity, - s->bitmap_name, &local_err); - if (!s->bitmap) { - error_report_err(local_err); - return -EINVAL; - } } if (flags & DIRTY_BITMAP_MIG_START_FLAG_RESERVED_MASK) { @@ -835,6 +828,21 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s) persistent = flags & DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT; } + /* Not bdrv_is_writable(): nodes stay inactive until migration ends. */ + if (persistent && bdrv_is_read_only(s->bs)) { + error_report("Cannot make migrated bitmap '%s' persistent " + "on read-only node '%s'", s->bitmap_name, + bdrv_get_node_name(s->bs)); + return -EINVAL; + } + + s->bitmap = bdrv_create_dirty_bitmap(s->bs, granularity, + s->bitmap_name, &local_err); + if (!s->bitmap) { + error_report_err(local_err); + return -EINVAL; + } + if (persistent) { bdrv_dirty_bitmap_set_persistence(s->bitmap, true); } diff --git a/tests/qemu-iotests/tests/migrate-bitmaps-test b/tests/qemu-iotests/tests/migrate-bitmaps-test index 8fb4099201..cb9154ca8d 100755 --- a/tests/qemu-iotests/tests/migrate-bitmaps-test +++ b/tests/qemu-iotests/tests/migrate-bitmaps-test @@ -206,6 +206,39 @@ class TestDirtyBitmapMigration(iotests.QMPTestCase): self.vm_b.launch() self.check_bitmap(self.vm_b, sha256 if persistent else False) + def test_migration_to_readonly_destination(self): + granularity = 512 + mig_caps = [{'capability': 'events', 'state': True}, + {'capability': 'dirty-bitmaps', 'state': True}] + + self.vm_b.add_incoming("defer") + self.vm_b.add_drive(disk_b, 'read-only=on') + + self.add_bitmap(self.vm_a, granularity, True) + self.vm_a.hmp_qemu_io('drive0', 'write 0 4096') + + self.vm_a.cmd('migrate-set-capabilities', capabilities=mig_caps) + self.vm_a.cmd('migrate', uri=mig_cmd) + while True: + event = self.vm_a.event_wait('MIGRATION') + if event['data']['status'] == 'completed': + break + self.vm_a.shutdown() + + self.vm_b.launch() + self.vm_b.cmd('migrate-set-capabilities', capabilities=mig_caps) + self.vm_b.cmd('migrate-incoming', uri=incoming_cmd) + while True: + event = self.vm_b.event_wait('MIGRATION') + if event['data']['status'] in ('completed', 'failed'): + break + + self.assert_qmp(event, 'data/status', 'failed') + + # A failed incoming load makes the destination process exit on + # its own; reap it so tearDown()'s shutdown() is a clean no-op. + self.vm_b.wait() + def inject_test_case(klass, suffix, method, *args, **kwargs): mc = operator.methodcaller(method, *args, **kwargs) diff --git a/tests/qemu-iotests/tests/migrate-bitmaps-test.out b/tests/qemu-iotests/tests/migrate-bitmaps-test.out index cafb8161f7..73e375a9d7 100644 --- a/tests/qemu-iotests/tests/migrate-bitmaps-test.out +++ b/tests/qemu-iotests/tests/migrate-bitmaps-test.out @@ -1,5 +1,5 @@ -..................................... +...................................... ---------------------------------------------------------------------- -Ran 37 tests +Ran 38 tests OK -- 2.53.0
