[Qemu-devel] [PATCH] util/hbitmap: Add an API to reset all set bits in hbitmap

[Wen Congyang <wency@cn.fujitsu.com>]

The function bdrv_clear_dirty_bitmap() is updated to use
faster hbitmap_reset_all() call.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block.c                |  2 +-
 include/qemu/hbitmap.h |  8 ++++++++
 tests/test-hbitmap.c   | 38 ++++++++++++++++++++++++++++++++++++++
 util/hbitmap.c         | 13 +++++++++++++
 4 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/block.c b/block.c
index 7904098..49d472f 100644
--- a/block.c
+++ b/block.c
@@ -3309,7 +3309,7 @@ void bdrv_reset_dirty_bitmap(BdrvDirtyBitmap *bitmap,
 void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap)
 {
     assert(bdrv_dirty_bitmap_enabled(bitmap));
-    hbitmap_reset(bitmap->bitmap, 0, bitmap->size);
+    hbitmap_reset_all(bitmap->bitmap);
 }
 
 void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index f0a85f8..bb94a00 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -132,6 +132,14 @@ void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t count);
 void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count);
 
 /**
+ * hbitmap_reset_all:
+ * @hb: HBitmap to operate on.
+ *
+ * Reset all bits in an HBitmap.
+ */
+void hbitmap_reset_all(HBitmap *hb);
+
+/**
  * hbitmap_get:
  * @hb: HBitmap to operate on.
  * @item: Bit to query (0-based).
diff --git a/tests/test-hbitmap.c b/tests/test-hbitmap.c
index 9f41b5f..161eeb4 100644
--- a/tests/test-hbitmap.c
+++ b/tests/test-hbitmap.c
@@ -184,6 +184,23 @@ static void hbitmap_test_reset(TestHBitmapData *data,
     }
 }
 
+static void hbitmap_test_reset_all(TestHBitmapData *data)
+{
+    size_t n;
+
+    hbitmap_reset_all(data->hb);
+
+    n = (data->size + BITS_PER_LONG - 1) / BITS_PER_LONG;
+    if (n == 0) {
+        n = 1;
+    }
+    memset(data->bits, 0, n * sizeof(unsigned long));
+
+    if (data->granularity == 0) {
+        hbitmap_test_check(data, 0);
+    }
+}
+
 static void hbitmap_test_check_get(TestHBitmapData *data)
 {
     uint64_t count = 0;
@@ -364,6 +381,26 @@ static void test_hbitmap_reset(TestHBitmapData *data,
     hbitmap_test_set(data, L3 / 2, L3);
 }
 
+static void test_hbitmap_reset_all(TestHBitmapData *data,
+                                   const void *unused)
+{
+    hbitmap_test_init(data, L3 * 2, 0);
+    hbitmap_test_set(data, L1 - 1, L1 + 2);
+    hbitmap_test_reset_all(data);
+    hbitmap_test_set(data, 0, L1 * 3);
+    hbitmap_test_reset_all(data);
+    hbitmap_test_set(data, L2, L1);
+    hbitmap_test_reset_all(data);
+    hbitmap_test_set(data, L2, L3 - L2 + 1);
+    hbitmap_test_reset_all(data);
+    hbitmap_test_set(data, L3 - 1, 3);
+    hbitmap_test_reset_all(data);
+    hbitmap_test_set(data, 0, L3 * 2);
+    hbitmap_test_reset_all(data);
+    hbitmap_test_set(data, L3 / 2, L3);
+    hbitmap_test_reset_all(data);
+}
+
 static void test_hbitmap_granularity(TestHBitmapData *data,
                                      const void *unused)
 {
@@ -627,6 +664,7 @@ int main(int argc, char **argv)
     hbitmap_test_add("/hbitmap/set/overlap", test_hbitmap_set_overlap);
     hbitmap_test_add("/hbitmap/reset/empty", test_hbitmap_reset_empty);
     hbitmap_test_add("/hbitmap/reset/general", test_hbitmap_reset);
+    hbitmap_test_add("/hbitmap/reset/all", test_hbitmap_reset_all);
     hbitmap_test_add("/hbitmap/granularity", test_hbitmap_granularity);
 
     hbitmap_test_add("/hbitmap/truncate/nop", test_hbitmap_truncate_nop);
diff --git a/util/hbitmap.c b/util/hbitmap.c
index a10c7ae..25d3cdb 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -356,6 +356,19 @@ void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count)
     hb_reset_between(hb, HBITMAP_LEVELS - 1, start, last);
 }
 
+void hbitmap_reset_all(HBitmap *hb)
+{
+    unsigned int i;
+
+    /* Same as hbitmap_alloc() except memset() */
+    for (i = HBITMAP_LEVELS; --i >= 1; ) {
+        memset(hb->levels[i], 0, hb->sizes[i] * sizeof(unsigned long));
+    }
+
+    hb->levels[0][0] = 1UL << (BITS_PER_LONG - 1);
+    hb->count = 0;
+}
+
 bool hbitmap_get(const HBitmap *hb, uint64_t item)
 {
     /* Compute position and bit in the last layer.  */
-- 
2.1.0