[PATCH 2/4] hbitmap: introduce hbitmap_reverse()

[Andrey Zhadchenko]

and bdrv_dirty_bitmap_reverse() helper

Signed-off-by: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com>
---
 block/dirty-bitmap.c         |  9 +++++++++
 include/block/block_int-io.h |  1 +
 include/qemu/hbitmap.h       |  8 ++++++++
 util/hbitmap.c               | 15 +++++++++++++++
 4 files changed, 33 insertions(+)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 13a1979755..c7f453fdb9 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -888,3 +888,12 @@ void bdrv_dirty_bitmap_merge_internal(BdrvDirtyBitmap 
*dest,
         }
     }
 }
+
+void bdrv_dirty_bitmap_reverse(BdrvDirtyBitmap *bitmap)
+{
+    assert(!bdrv_dirty_bitmap_readonly(bitmap));
+    assert(!bdrv_dirty_bitmap_inconsistent(bitmap));
+    bdrv_dirty_bitmaps_lock(bitmap->bs);
+    hbitmap_reverse(bitmap->bitmap);
+    bdrv_dirty_bitmaps_unlock(bitmap->bs);
+}
diff --git a/include/block/block_int-io.h b/include/block/block_int-io.h
index 4a7cf2b4fd..093613e7d1 100644
--- a/include/block/block_int-io.h
+++ b/include/block/block_int-io.h
@@ -109,6 +109,7 @@ void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, 
HBitmap **out);
 void bdrv_dirty_bitmap_merge_internal(BdrvDirtyBitmap *dest,
                                       const BdrvDirtyBitmap *src,
                                       HBitmap **backup, bool lock);
+void bdrv_dirty_bitmap_reverse(BdrvDirtyBitmap *bitmap);
 
 void bdrv_inc_in_flight(BlockDriverState *bs);
 void bdrv_dec_in_flight(BlockDriverState *bs);
diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index 8136e33674..dbdc9aa2d4 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -350,4 +350,12 @@ bool hbitmap_status(const HBitmap *hb, int64_t start, 
int64_t count,
  */
 int64_t hbitmap_iter_next(HBitmapIter *hbi);
 
+/**
+ * hbitmap_reverse:
+ * @bitmap: The HBitmap to operate on
+ *
+ * Reverse the bits in the bitmap.
+ */
+void hbitmap_reverse(HBitmap *bitmap);
+
 #endif
diff --git a/util/hbitmap.c b/util/hbitmap.c
index 16674f33e4..b99c4b1eec 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -940,3 +940,18 @@ char *hbitmap_sha256(const HBitmap *bitmap, Error **errp)
 
     return hash;
 }
+
+void hbitmap_reverse(HBitmap *bitmap)
+{
+    int64_t pnum, pos = 0;
+    int64_t size = bitmap->orig_size;
+
+    while (pos < size) {
+        if (hbitmap_status(bitmap, pos, size - pos, &pnum)) {
+            hbitmap_reset(bitmap, pos, pnum);
+        } else {
+            hbitmap_set(bitmap, pos, pnum);
+        }
+        pos += pnum;
+    }
+}
-- 
2.43.0