[2/9] qapi: Add optional field "name" to block dirty bitmap

diff --git a/block-migration.c b/block-migration.c
index 897fdba..e6e016a 100644
--- a/block-migration.c
+++ b/block-migration.c
@@ -315,7 +315,8 @@  static void set_dirty_tracking(void)
     BlkMigDevState *bmds;
 
     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
-        bmds->dirty_bitmap = bdrv_create_dirty_bitmap(bmds->bs, BLOCK_SIZE);
+        bmds->dirty_bitmap = bdrv_create_dirty_bitmap(bmds->bs, BLOCK_SIZE,
+                                                      NULL, NULL);
     }
 }
 
diff --git a/block.c b/block.c
index 6ad0368..16ef61b 100644
--- a/block.c
+++ b/block.c
@@ -52,6 +52,7 @@ 
 struct BdrvDirtyBitmap {
     HBitmap *bitmap;
     int refcnt;
+    char name[1024];
     QLIST_ENTRY(BdrvDirtyBitmap) list;
 };
 
@@ -4532,19 +4533,43 @@  bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov)
     return true;
 }
 
-BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs, int granularity)
+BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs,
+                                        const char *name)
+{
+    BdrvDirtyBitmap *bm;
+    QLIST_FOREACH(bm, &bs->dirty_bitmaps, list) {
+        if (!strcmp(name, bm->name)) {
+            return bm;
+        }
+    }
+    return NULL;
+}
+
+BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
+                                          int granularity,
+                                          const char *name,
+                                          Error **errp)
 {
     int64_t bitmap_size;
     BdrvDirtyBitmap *bitmap;
 
     assert((granularity & (granularity - 1)) == 0);
 
+    if (name && bdrv_find_dirty_bitmap(bs, name)) {
+        if (errp) {
+            error_setg(errp, "Bitmap already exists: %s", name);
+        }
+        return NULL;
+    }
     granularity >>= BDRV_SECTOR_BITS;
     assert(granularity);
     bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS);
     bitmap = g_malloc0(sizeof(BdrvDirtyBitmap));
     bitmap->bitmap = hbitmap_alloc(bitmap_size, ffs(granularity) - 1);
     bitmap->refcnt = 1;
+    if (name) {
+        pstrcpy(bitmap->name, sizeof(bitmap->name), name);
+    }
     QLIST_INSERT_HEAD(&bs->dirty_bitmaps, bitmap, list);
     return bitmap;
 }
@@ -4583,6 +4608,8 @@  BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs)
         info->count = bdrv_get_dirty_count(bs, bm);
         info->granularity =
             ((int64_t) BDRV_SECTOR_SIZE << hbitmap_granularity(bm->bitmap));
+        info->has_name = bm->name[0] != '\0';
+        info->name = g_strdup(bm->name);
         entry->value = info;
         *plist = entry;
         plist = &entry->next;
diff --git a/block/mirror.c b/block/mirror.c
index 2932bab..cc0665b 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -598,7 +598,7 @@  static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,
     s->granularity = granularity;
     s->buf_size = MAX(buf_size, granularity);
 
-    s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity);
+    s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);
     bdrv_set_enable_write_cache(s->target, true);
     bdrv_set_on_error(s->target, on_target_error, on_target_error);
     bdrv_iostatus_enable(s->target);
diff --git a/include/block/block.h b/include/block/block.h
index 0c776e3..8dafa42 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -424,7 +424,12 @@  bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov);
 
 struct HBitmapIter;
 typedef struct BdrvDirtyBitmap BdrvDirtyBitmap;
-BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs, int granularity);
+BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
+                                          int granularity,
+                                          const char *name,
+                                          Error **errp);
+BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs,
+                                        const char *name);
 void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap);
 void bdrv_reference_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap);
 BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs);
diff --git a/qapi-schema.json b/qapi-schema.json
index b9b051c..e91143a 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -920,6 +920,8 @@ 
 #
 # Block dirty bitmap information.
 #
+# @name: the name of dirty bitmap
+#
 # @count: number of dirty bytes according to the dirty bitmap
 #
 # @granularity: granularity of the dirty bitmap in bytes (since 1.4)
@@ -927,7 +929,7 @@ 
 # Since: 1.3
 ##
 { 'type': 'BlockDirtyInfo',
-  'data': {'count': 'int', 'granularity': 'int'} }
+  'data': {'*name': 'str', 'count': 'int', 'granularity': 'int'} }
 
 ##
 # @BlockInfo: