[Qemu-devel] [PATCH 1/1] block/dirty-bitmap: Useless bitmaps in image can be removed

[13466399134]

From: Yao Xu <address@hidden>

If qemu-kvm quit without saving bitmaps to image(coredump, host kernel panic,
or host pooweroff), bitmaps in image can not be safely used anymore, and also
can not be removed. Useless bitmaps should be removed.

"block-dirty-bitmap-remove" failed, because block_dirty_bitmap_lookup return 
NULL
"block-dirty-bitmap-add" failed, because qcow2_remove_persistent_dirty_bitmap 
can find the same name bitmap in image. As a result, the bitmap can never be 
used, neither can be removed.

Signed-off-by: Yao Xu <address@hidden>
---
diff --git a/blockdev.c b/blockdev.c
index 58d7570932..d2403f4b7f 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2837,31 +2837,38 @@ void qmp_block_dirty_bitmap_remove(const char *node, 
const char *name,
     Error *local_err = NULL;
 
     bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
-    if (!bitmap || !bs) {
+    if (!bs) {
         return;
     }
 
-    if (bdrv_dirty_bitmap_frozen(bitmap)) {
-        error_setg(errp,
-                   "Bitmap '%s' is currently frozen and cannot be removed",
-                   name);
-        return;
-    } else if (bdrv_dirty_bitmap_qmp_locked(bitmap)) {
-        error_setg(errp,
-                   "Bitmap '%s' is currently locked and cannot be removed",
-                   name);
+    if (bitmap) {
+        if (bdrv_dirty_bitmap_frozen(bitmap)) {
+            error_setg(errp,
+                       "Bitmap '%s' is currently frozen and cannot be removed",
+                       name);
+            return;
+        } else if (bdrv_dirty_bitmap_qmp_locked(bitmap)) {
+            error_setg(errp,
+                       "Bitmap '%s' is currently locked and cannot be removed",
+                       name);
+            return;
+        }
+    }
+
+    bdrv_remove_persistent_dirty_bitmap(bs, name, &local_err);
+    if (local_err != NULL) {
+        error_propagate(errp, local_err);
         return;
     }
 
-    if (bdrv_dirty_bitmap_get_persistance(bitmap)) {
-        bdrv_remove_persistent_dirty_bitmap(bs, name, &local_err);
-        if (local_err != NULL) {
-            error_propagate(errp, local_err);
-            return;
-        }
+    if (bitmap) {
+        bdrv_release_dirty_bitmap(bs, bitmap);
     }
 
-    bdrv_release_dirty_bitmap(bs, bitmap);
+    if (*errp) {
+        error_free(*errp);
+        *errp = NULL;
+    }
 }
 
 /**