diff --git a/block.c b/block.c
index 0e63524556..dffa9dedc0 100644
--- a/block.c
+++ b/block.c
@@ -52,8 +52,17 @@
#include <windows.h>
#endif
+/**
+ * A BdrvDirtyBitmap can be in three possible states:
+ * (1) successor is NULL and disabled is false: full r/w mode
+ * (2) successor is NULL and disabled is true: read only mode ("disabled")
+ * (3) successor is set: frozen mode.
+ * A frozen bitmap cannot be renamed, deleted, anonymized, cleared, set,
+ * or enabled. A frozen bitmap can only abdicate() or reclaim().
+ */
struct BdrvDirtyBitmap {
HBitmap *bitmap;
+ BdrvDirtyBitmap *successor;
char *name;
bool disabled;
QLIST_ENTRY(BdrvDirtyBitmap) list;
@@ -5518,6 +5527,7 @@ BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs, const char *name)
void bdrv_dirty_bitmap_make_anon(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
{
+ assert(!bdrv_dirty_bitmap_frozen(bitmap));
g_free(bitmap->name);
bitmap->name = NULL;
}
@@ -5553,9 +5563,98 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
return bitmap;
}
+bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap)
+{
+ return bitmap->successor;
+}
+
bool bdrv_dirty_bitmap_enabled(BdrvDirtyBitmap *bitmap)
{
- return !bitmap->disabled;
+ return !(bitmap->disabled || bitmap->successor);
+}
+
+/**
+ * Create a successor bitmap destined to replace this bitmap after an operation.
+ * Requires that the bitmap is not frozen and has no successor.
+ */
+int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs,
+ BdrvDirtyBitmap *bitmap, Error **errp)
+{
+ uint64_t granularity;
+ BdrvDirtyBitmap *child;
+
+ if (bdrv_dirty_bitmap_frozen(bitmap)) {
+ error_setg(errp, "Cannot create a successor for a bitmap that is "
+ "currently frozen");
+ return -1;
+ }
+ assert(!bitmap->successor);
+
+ /* Create an anonymous successor */
+ granularity = bdrv_dirty_bitmap_granularity(bitmap);
+ child = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);
+ if (!child) {
+ return -1;
+ }
+
+ /* Successor will be on or off based on our current state. */
+ child->disabled = bitmap->disabled;
+
+ /* Install the successor and freeze the parent */
+ bitmap->successor = child;
+ return 0;
+}
+
+/**
+ * For a bitmap with a successor, yield our name to the successor,
+ * delete the old bitmap, and return a handle to the new bitmap.
+ */
+BdrvDirtyBitmap *bdrv_dirty_bitmap_abdicate(BlockDriverState *bs,
+ BdrvDirtyBitmap *bitmap,
+ Error **errp)
+{
+ char *name;
+ BdrvDirtyBitmap *successor = bitmap->successor;
+
+ if (successor == NULL) {
+ error_setg(errp, "Cannot relinquish control if "
+ "there's no successor present");
+ return NULL;
+ }
+
+ name = bitmap->name;
+ bitmap->name = NULL;
+ successor->name = name;
+ bitmap->successor = NULL;
+ bdrv_release_dirty_bitmap(bs, bitmap);
+
+ return successor;
+}
+
+/**
+ * In cases of failure where we can no longer safely delete the parent,
+ * we may wish to re-join the parent and child/successor.
+ * The merged parent will be un-frozen, but not explicitly re-enabled.
+ */
+BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs,
+ BdrvDirtyBitmap *parent,
+ Error **errp)
+{
+ BdrvDirtyBitmap *successor = parent->successor;
+
+ if (!successor) {
+ error_setg(errp, "Cannot reclaim a successor when none is present");
+ return NULL;
+ }
+
+ if (!hbitmap_merge(parent->bitmap, successor->bitmap)) {
+ error_setg(errp, "Merging of parent and successor bitmap failed");
+ return NULL;
+ }
+ bdrv_release_dirty_bitmap(bs, successor);
+ parent->successor = NULL;
+
+ return parent;
}
void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
@@ -5563,6 +5662,7 @@ void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
BdrvDirtyBitmap *bm, *next;
QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, next) {
if (bm == bitmap) {
+ assert(!bdrv_dirty_bitmap_frozen(bm));
QLIST_REMOVE(bitmap, list);
hbitmap_free(bitmap->bitmap);
g_free(bitmap->name);
@@ -5574,11 +5674,13 @@ void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
{
+ assert(!bdrv_dirty_bitmap_frozen(bitmap));
bitmap->disabled = true;
}
void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
{
+ assert(!bdrv_dirty_bitmap_frozen(bitmap));
bitmap->disabled = false;
}
diff --git a/blockdev.c b/blockdev.c
index 5dde1e86da..e8b712e7e2 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2065,9 +2065,16 @@ void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
return;
}
+ if (bdrv_dirty_bitmap_frozen(bitmap)) {
+ error_setg(errp,
+ "Bitmap '%s' is currently frozen and cannot be removed",
+ name);
+ goto out;
+ }
bdrv_dirty_bitmap_make_anon(bs, bitmap);
bdrv_release_dirty_bitmap(bs, bitmap);
+ out:
aio_context_release(aio_context);
}
diff --git a/include/block/block.h b/include/block/block.h
index 5d131f0372..1635c227f3 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -454,6 +454,15 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
uint32_t granularity,
const char *name,
Error **errp);
+int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs,
+ BdrvDirtyBitmap *bitmap,
+ Error **errp);
+BdrvDirtyBitmap *bdrv_dirty_bitmap_abdicate(BlockDriverState *bs,
+ BdrvDirtyBitmap *bitmap,
+ Error **errp);
+BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs,
+ BdrvDirtyBitmap *bitmap,
+ Error **errp);
BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs,
const char *name);
void bdrv_dirty_bitmap_make_anon(BlockDriverState *bs, BdrvDirtyBitmap *bitmap);
@@ -464,6 +473,7 @@ BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs);
uint32_t bdrv_get_default_bitmap_granularity(BlockDriverState *bs);
uint32_t bdrv_dirty_bitmap_granularity(BdrvDirtyBitmap *bitmap);
bool bdrv_dirty_bitmap_enabled(BdrvDirtyBitmap *bitmap);
+bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap);
int bdrv_get_dirty(BlockDriverState *bs, BdrvDirtyBitmap *bitmap, int64_t sector);
void bdrv_set_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap,
int64_t cur_sector, int nr_sectors);
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 6237f9d437..f3b92d80c9 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1008,6 +1008,7 @@
# Returns: nothing on success
# If @node is not a valid block device or node, DeviceNotFound
# If @name is not found, GenericError with an explanation
+# if @name is frozen by an operation, GenericError
#
# Since 2.4
##