+ dirty_bitmap_truncate(bitmap, size);
+ }
+}
+
void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap
*bitmap)
{
BdrvDirtyBitmap *bm, *next;
diff --git a/include/block/block.h b/include/block/block.h
index a8c6369..3a85690 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -454,6 +454,7 @@ BdrvDirtyBitmap
*bdrv_create_dirty_bitmap(BlockDriverState *bs,
uint32_t granularity,
const char *name,
Error **errp);
+void bdrv_dirty_bitmap_truncate(BlockDriverState *bs);
int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs,
BdrvDirtyBitmap *bitmap,
Error **errp);
diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index c19c1cb..a75157e 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -65,6 +65,16 @@ struct HBitmapIter {
HBitmap *hbitmap_alloc(uint64_t size, int granularity);
/**
+ * hbitmap_truncate:
+ * @hb: The bitmap to change the size of.
+ * @size: The number of elements to change the bitmap to accommodate.
+ *
+ * truncate or grow an existing bitmap to accommodate a new number of
elements.
+ * This may invalidate existing HBitmapIterators.
+ */
+void hbitmap_truncate(HBitmap *hb, uint64_t size);
+
+/**
* hbitmap_merge:
* @a: The bitmap to store the result in.
* @b: The bitmap to merge into @a.
diff --git a/util/hbitmap.c b/util/hbitmap.c
index 962ff29..dd8c2f3 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -90,6 +90,9 @@ struct HBitmap {
* bitmap will still allocate HBITMAP_LEVELS arrays.
*/
unsigned long *levels[HBITMAP_LEVELS];
+
+ /* The length of each levels[] array. */
+ uint64_t sizes[HBITMAP_LEVELS];
};
/* Advance hbi to the next nonzero word and return it. hbi->pos
@@ -384,6 +387,7 @@ HBitmap *hbitmap_alloc(uint64_t size, int
granularity)
hb->granularity = granularity;
for (i = HBITMAP_LEVELS; i-- > 0; ) {
size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
+ hb->sizes[i] = size;
hb->levels[i] = g_new0(unsigned long, size);
}
@@ -396,6 +400,57 @@ HBitmap *hbitmap_alloc(uint64_t size, int
granularity)
return hb;
}
+void hbitmap_truncate(HBitmap *hb, uint64_t size)
+{
+ bool truncate;
+ unsigned i;
+ uint64_t num_elements = size;
+ uint64_t old;
+
+ /* Size comes in as logical elements, adjust for granularity. */
+ size = (size + (1ULL << hb->granularity) - 1) >> hb->granularity;
+ assert(size <= ((uint64_t)1 << HBITMAP_LOG_MAX_SIZE));
+ truncate = size < hb->size;
+
+ if (size == hb->size) {
+ /* A hard day's work */
+ return;
+ }
+
+ hb->size = size;
+ for (i = HBITMAP_LEVELS; i-- > 0; ) {
+ size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
+ if (hb->sizes[i] == size) {
+ continue;
+ }
+ old = hb->sizes[i];
+ hb->sizes[i] = size;
+ hb->levels[i] = g_realloc_n(hb->levels[i], size,
sizeof(unsigned long));
+ if (!truncate) {
+ memset(&hb->levels[i][old], 0x00,
+ (size - old) * sizeof(*hb->levels[i]));
+ }
+ }
+ assert(size == 1);
+
+ /* Clear out any "extra space" we may have that the user didn't
request:
+ * It may have garbage data in it, now. */
+ if (truncate) {
+ /* Due to granularity fuzziness, we may accidentally reset
some of
+ * the last bits that are actually valid. So, record the
current value,
+ * reset the "dead range," then re-set the one element we
care about. */
+ uint64_t fix_count = (hb->size << hb->granularity) -
num_elements;
+ if (fix_count) {
+ bool set = hbitmap_get(hb, num_elements - 1);
+ hbitmap_reset(hb, num_elements, fix_count);
+ if (set) {
+ hbitmap_set(hb, num_elements - 1, 1);
+ }
+ }
+ }
+}
+
+
/**
* Given HBitmaps A and B, let A := A (BITOR) B.
* Bitmap B will not be modified.