Merge remote-tracking branch 'remotes/stefanha-gitlab/tags/block-pull-request' into staging

Pull request

This dirty bitmap fix solves a crash that can be triggered in the destination
QEMU process during live migration.

# gpg: Signature made Wed 24 Mar 2021 14:51:31 GMT
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha-gitlab/tags/block-pull-request:
  migrate-bitmaps-postcopy-test: check that we can't remove in-flight bitmaps
  migration/block-dirty-bitmap: make incoming disabled bitmaps busy

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 16 insertions, 0 deletions

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 9750936..35f5ef6 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -839,6 +839,8 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)
             error_report_err(local_err);
             return -EINVAL;
         }
+    } else {
+        bdrv_dirty_bitmap_set_busy(s->bitmap, true);
     }
 
     b = g_new(LoadBitmapState, 1);
@@ -914,6 +916,8 @@ static void cancel_incoming_locked(DBMLoadState *s)
         assert(!s->before_vm_start_handled || !b->migrated);
         if (bdrv_dirty_bitmap_has_successor(b->bitmap)) {
             bdrv_reclaim_dirty_bitmap(b->bitmap, &error_abort);
+        } else {
+            bdrv_dirty_bitmap_set_busy(b->bitmap, false);
         }
         bdrv_release_dirty_bitmap(b->bitmap);
     }
@@ -951,6 +955,8 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
 
     if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
         bdrv_reclaim_dirty_bitmap(s->bitmap, &error_abort);
+    } else {
+        bdrv_dirty_bitmap_set_busy(s->bitmap, false);
     }
 
     for (item = s->bitmaps; item; item = g_slist_next(item)) {
diff --git a/tests/qemu-iotests/tests/migrate-bitmaps-postcopy-test b/tests/qemu-iotests/tests/migrate-bitmaps-postcopy-test
index d046ebe..584062b 100755
--- a/tests/qemu-iotests/tests/migrate-bitmaps-postcopy-test
+++ b/tests/qemu-iotests/tests/migrate-bitmaps-postcopy-test
@@ -224,6 +224,16 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         self.start_postcopy()
 
         self.vm_b_events += self.vm_b.get_qmp_events()
+
+        # While being here, let's check that we can't remove in-flight bitmaps.
+        for vm in (self.vm_a, self.vm_b):
+            for i in range(0, nb_bitmaps):
+                result = vm.qmp('block-dirty-bitmap-remove', node='drive0',
+                                name=f'bitmap{i}')
+                self.assert_qmp(result, 'error/desc',
+                                f"Bitmap 'bitmap{i}' is currently in use by "
+                                "another operation and cannot be used")
+
         self.vm_b.shutdown()
         # recreate vm_b, so there is no incoming option, which prevents
         # loading bitmaps from disk