[Qemu-devel] [PATCH 1/2] drity-bitmap: refactor merge: separte can_merge

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Separate can_merge, to reuse it for transaction support for merge
command.

Also, switch some asserts to errors.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 include/block/dirty-bitmap.h |  3 +++
 include/qemu/hbitmap.h       |  8 ++++++++
 block/dirty-bitmap.c         | 32 +++++++++++++++++++++++++++-----
 blockdev.c                   | 10 ----------
 util/hbitmap.c               |  6 +++++-
 5 files changed, 43 insertions(+), 16 deletions(-)

diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index 288dc6adb6..412a333c02 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -71,6 +71,9 @@ void bdrv_dirty_bitmap_set_persistance(BdrvDirtyBitmap *bitmap,
 void bdrv_dirty_bitmap_set_qmp_locked(BdrvDirtyBitmap *bitmap, bool qmp_locked);
 void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src,
                              Error **errp);
+bool bdrv_can_merge_dirty_bitmap(BdrvDirtyBitmap *dst,
+                                 const BdrvDirtyBitmap *src,
+                                 Error **errp);
 
 /* Functions that require manual locking.  */
 void bdrv_dirty_bitmap_lock(BdrvDirtyBitmap *bitmap);
diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index ddca52c48e..d08bc20ea3 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -85,6 +85,14 @@ void hbitmap_truncate(HBitmap *hb, uint64_t size);
 bool hbitmap_merge(HBitmap *a, const HBitmap *b);
 
 /**
+ * hbitmap_can_merge:
+ *
+ * Returns same value as hbitmap_merge, but do not do actual merge.
+ *
+ */
+bool hbitmap_can_merge(HBitmap *a, const HBitmap *b);
+
+/**
  * hbitmap_empty:
  * @hb: HBitmap to operate on.
  *
diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index db1782ec1f..1137224aaa 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -784,6 +784,30 @@ int64_t bdrv_dirty_bitmap_next_zero(BdrvDirtyBitmap *bitmap, uint64_t offset)
     return hbitmap_next_zero(bitmap->bitmap, offset);
 }
 
+bool bdrv_can_merge_dirty_bitmap(BdrvDirtyBitmap *dst,
+                                 const BdrvDirtyBitmap *src,
+                                 Error **errp)
+{
+    if (bdrv_dirty_bitmap_frozen(dst)) {
+        error_setg(errp, "Bitmap '%s' is frozen and cannot be modified",
+                   dst->name);
+        return false;
+    }
+
+    if (bdrv_dirty_bitmap_readonly(dst)) {
+        error_setg(errp, "Bitmap '%s' is readonly and cannot be modified",
+                   dst->name);
+        return false;
+    }
+
+    if (!hbitmap_can_merge(dst->bitmap, src->bitmap)) {
+        error_setg(errp, "Bitmaps are incompatible and can't be merged");
+        return false;
+    }
+
+    return true;
+}
+
 void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src,
                              Error **errp)
 {
@@ -792,11 +816,9 @@ void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src,
 
     qemu_mutex_lock(dest->mutex);
 
-    assert(bdrv_dirty_bitmap_enabled(dest));
-    assert(!bdrv_dirty_bitmap_readonly(dest));
-
-    if (!hbitmap_merge(dest->bitmap, src->bitmap)) {
-        error_setg(errp, "Bitmaps are incompatible and can't be merged");
+    if (bdrv_can_merge_dirty_bitmap(dest, src, errp)) {
+        bool ret = hbitmap_merge(dest->bitmap, src->bitmap);
+        assert(ret);
     }
 
     qemu_mutex_unlock(dest->mutex);
diff --git a/blockdev.c b/blockdev.c
index 58d7570932..63c4d33124 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2955,16 +2955,6 @@ void qmp_x_block_dirty_bitmap_merge(const char *node, const char *dst_name,
         return;
     }
 
-    if (bdrv_dirty_bitmap_frozen(dst)) {
-        error_setg(errp, "Bitmap '%s' is frozen and cannot be modified",
-                   dst_name);
-        return;
-    } else if (bdrv_dirty_bitmap_readonly(dst)) {
-        error_setg(errp, "Bitmap '%s' is readonly and cannot be modified",
-                   dst_name);
-        return;
-    }
-
     src = bdrv_find_dirty_bitmap(bs, src_name);
     if (!src) {
         error_setg(errp, "Dirty bitmap '%s' not found", src_name);
diff --git a/util/hbitmap.c b/util/hbitmap.c
index bcd304041a..b56377b043 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -723,6 +723,10 @@ void hbitmap_truncate(HBitmap *hb, uint64_t size)
     }
 }
 
+bool hbitmap_can_merge(HBitmap *a, const HBitmap *b)
+{
+    return (a->size == b->size) && (a->granularity == b->granularity);
+}
 
 /**
  * Given HBitmaps A and B, let A := A (BITOR) B.
@@ -736,7 +740,7 @@ bool hbitmap_merge(HBitmap *a, const HBitmap *b)
     int i;
     uint64_t j;
 
-    if ((a->size != b->size) || (a->granularity != b->granularity)) {
+    if (!hbitmap_can_merge(a, b)) {
         return false;
     }
 
-- 
2.11.1