[pve-devel] [RFC qemu 04/13] block/copy-before-write: create block_copy bitmap in filter node

[Fiona Ebner <f.ebner@proxmox.com>]

From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

Currently block_copy creates copy_bitmap in source node. But that is in
bad relation with .independent_close=true of copy-before-write filter:
source node may be detached and removed before .bdrv_close() handler
called, which should call block_copy_state_free(), which in turn should
remove copy_bitmap.

That's all not ideal: it would be better if internal bitmap of
block-copy object is not attached to any node. But that is not possible
now.

The simplest solution is just create copy_bitmap in filter node, where
anyway two other bitmaps are created.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
 block/block-copy.c         | 3 ++-
 block/copy-before-write.c  | 2 +-
 include/block/block-copy.h | 1 +
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/block/block-copy.c b/block/block-copy.c
index e13d7bc6b6..b61685f1a2 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -346,6 +346,7 @@ static int64_t block_copy_calculate_cluster_size(BlockDriverState *target,
 }
 
 BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
+                                     BlockDriverState *copy_bitmap_bs,
                                      const BdrvDirtyBitmap *bitmap,
                                      Error **errp)
 {
@@ -360,7 +361,7 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
         return NULL;
     }
 
-    copy_bitmap = bdrv_create_dirty_bitmap(source->bs, cluster_size, NULL,
+    copy_bitmap = bdrv_create_dirty_bitmap(copy_bitmap_bs, cluster_size, NULL,
                                            errp);
     if (!copy_bitmap) {
         return NULL;
diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index b866e42271..41cb0955c9 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -456,7 +456,7 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
             ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
              bs->file->bs->supported_zero_flags);
 
-    s->bcs = block_copy_state_new(bs->file, s->target, bitmap, errp);
+    s->bcs = block_copy_state_new(bs->file, s->target, bs, bitmap, errp);
     if (!s->bcs) {
         error_prepend(errp, "Cannot create block-copy-state: ");
         ret = -EINVAL;
diff --git a/include/block/block-copy.h b/include/block/block-copy.h
index 0700953ab8..8b41643bfa 100644
--- a/include/block/block-copy.h
+++ b/include/block/block-copy.h
@@ -25,6 +25,7 @@ typedef struct BlockCopyState BlockCopyState;
 typedef struct BlockCopyCallState BlockCopyCallState;
 
 BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
+                                     BlockDriverState *copy_bitmap_bs,
                                      const BdrvDirtyBitmap *bitmap,
                                      Error **errp);
 
-- 
2.39.2