[Qemu-devel] [PATCH 2/4] block/dirty-bitmap: add hide/unhide API

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

Add functionality to make bitmap temporary anonymous. It will be used
to implement bitmap remove transaction action. We need hide bitmap
persistence too, as there are should not be unnamed persistent bitmaps.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 include/block/dirty-bitmap.h |  2 ++
 block/dirty-bitmap.c         | 26 ++++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index 8044ace63e..542e437123 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -116,5 +116,7 @@ bool bdrv_dirty_bitmap_next_dirty_area(BdrvDirtyBitmap *bitmap,
 BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap_locked(BlockDriverState *bs,
                                                   BdrvDirtyBitmap *bitmap,
                                                   Error **errp);
+void bdrv_dirty_bitmap_hide(BdrvDirtyBitmap *bitmap);
+void bdrv_dirty_bitmap_unhide(BdrvDirtyBitmap *bitmap);
 
 #endif
diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 49646a30e6..592964635e 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -35,6 +35,10 @@ struct BdrvDirtyBitmap {
     bool busy;                  /* Bitmap is busy, it can't be used via QMP */
     BdrvDirtyBitmap *successor; /* Anonymous child, if any. */
     char *name;                 /* Optional non-empty unique ID */
+    char *hidden_name;          /* Backup of @name for removal transaction
+                                   action. Used for hide/unhide API. */
+    bool hidden_persistent;     /* Backup of @persistent for removal transaction
+                                   action. */
     int64_t size;               /* Size of the bitmap, in bytes */
     bool disabled;              /* Bitmap is disabled. It ignores all writes to
                                    the device */
@@ -849,3 +853,25 @@ out:
         qemu_mutex_unlock(src->mutex);
     }
 }
+
+void bdrv_dirty_bitmap_hide(BdrvDirtyBitmap *bitmap)
+{
+    qemu_mutex_lock(bitmap->mutex);
+    assert(!bitmap->hidden_name);
+    bitmap->hidden_name = bitmap->name;
+    bitmap->hidden_persistent = bitmap->persistent;
+    bitmap->name = NULL;
+    bitmap->persistent = false;
+    qemu_mutex_unlock(bitmap->mutex);
+}
+
+void bdrv_dirty_bitmap_unhide(BdrvDirtyBitmap *bitmap)
+{
+    qemu_mutex_lock(bitmap->mutex);
+    assert(!bitmap->name);
+    bitmap->name = bitmap->hidden_name;
+    bitmap->persistent = bitmap->hidden_persistent;
+    bitmap->hidden_name = NULL;
+    bitmap->hidden_persistent = false;
+    qemu_mutex_unlock(bitmap->mutex);
+}
-- 
2.18.0