Re: [Qemu-devel] [PATCH 15/25] qcow2: add .bdrv_can_store_new_dirty_bitmap

[John Snow]

On 02/14/2017 11:59 AM, Vladimir Sementsov-Ogievskiy wrote:
> Realize .bdrv_can_store_new_dirty_bitmap interface.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy 
> Reviewed-by: Max Reitz 
> ---
>  block/qcow2-bitmap.c | 40 
>  block/qcow2.c|  1 +
>  block/qcow2.h|  4 
>  3 files changed, 45 insertions(+)
> 
> diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
> index b177a95..419d51e 100644
> --- a/block/qcow2-bitmap.c
> +++ b/block/qcow2-bitmap.c
> @@ -1182,3 +1182,43 @@ fail:
>  
>  bitmap_list_free(bm_list);
>  }
> +
> +bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs,
> +  const char *name,
> +  uint32_t granularity,
> +  Error **errp)
> +{
> +BDRVQcow2State *s = bs->opaque;
> +const char *reason = NULL;
> +bool found;
> +Qcow2BitmapList *bm_list;
> +
> +if (check_constraints_on_bitmap(bs, name, granularity) != 0) {
> +reason = "it doesn't satisfy the constraints";
> +goto common_errp;
> +}

"the constraints" are still entirely opaque to the caller, it may not be
obvious that it's because of the name length.

(But maybe you fix this in patch 25.)

> +
> +if (s->nb_bitmaps == 0) {
> +return true;
> +}
> +
> +bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
> +   s->bitmap_directory_size, errp);
> +if (bm_list == NULL) {
> +return false;
> +}

Another opportunity for caching the bm_list.

> +
> +found = find_bitmap_by_name(bm_list, name);
> +bitmap_list_free(bm_list);
> +if (found) {
> +reason = "bitmap with the same name is already stored";
> +goto common_errp;
> +}
> +
> +return true;
> +
> +common_errp:
> +error_setg(errp, "Can't make bitmap '%s' persistent in '%s', as %s.",
> +   name, bdrv_get_device_or_node_name(bs), reason);
> +return false;
> +}

We don't check total numbers of bitmaps here? (I'll keep reading ahead
in the series.)

> diff --git a/block/qcow2.c b/block/qcow2.c
> index d0e41bf..6e1fe53 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -3541,6 +3541,7 @@ BlockDriver bdrv_qcow2 = {
>  
>  .bdrv_load_autoloading_dirty_bitmaps = 
> qcow2_load_autoloading_dirty_bitmaps,
>  .bdrv_store_persistent_dirty_bitmaps = 
> qcow2_store_persistent_dirty_bitmaps,
> +.bdrv_can_store_new_dirty_bitmap = qcow2_can_store_new_dirty_bitmap,
>  };
>  
>  static void bdrv_qcow2_init(void)
> diff --git a/block/qcow2.h b/block/qcow2.h
> index d9a7643..749710d 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -616,5 +616,9 @@ void qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, 
> void **table);
>  /* qcow2-bitmap.c functions */
>  void qcow2_load_autoloading_dirty_bitmaps(BlockDriverState *bs, Error 
> **errp);
>  void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error 
> **errp);
> +bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs,
> +  const char *name,
> +  uint32_t granularity,
> +  Error **errp);
>  
>  #endif
> 

Benefit of the doubt:

Reviewed-by: John Snow 

[Qemu-devel] [PATCH 15/25] qcow2: add .bdrv_can_store_new_dirty_bitmap

[Vladimir Sementsov-Ogievskiy]

Realize .bdrv_can_store_new_dirty_bitmap interface.

Signed-off-by: Vladimir Sementsov-Ogievskiy 
Reviewed-by: Max Reitz 
---
 block/qcow2-bitmap.c | 40 
 block/qcow2.c|  1 +
 block/qcow2.h|  4 
 3 files changed, 45 insertions(+)

diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index b177a95..419d51e 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -1182,3 +1182,43 @@ fail:
 
 bitmap_list_free(bm_list);
 }
+
+bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs,
+  const char *name,
+  uint32_t granularity,
+  Error **errp)
+{
+BDRVQcow2State *s = bs->opaque;
+const char *reason = NULL;
+bool found;
+Qcow2BitmapList *bm_list;
+
+if (check_constraints_on_bitmap(bs, name, granularity) != 0) {
+reason = "it doesn't satisfy the constraints";
+goto common_errp;
+}
+
+if (s->nb_bitmaps == 0) {
+return true;
+}
+
+bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
+   s->bitmap_directory_size, errp);
+if (bm_list == NULL) {
+return false;
+}
+
+found = find_bitmap_by_name(bm_list, name);
+bitmap_list_free(bm_list);
+if (found) {
+reason = "bitmap with the same name is already stored";
+goto common_errp;
+}
+
+return true;
+
+common_errp:
+error_setg(errp, "Can't make bitmap '%s' persistent in '%s', as %s.",
+   name, bdrv_get_device_or_node_name(bs), reason);
+return false;
+}
diff --git a/block/qcow2.c b/block/qcow2.c
index d0e41bf..6e1fe53 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3541,6 +3541,7 @@ BlockDriver bdrv_qcow2 = {
 
 .bdrv_load_autoloading_dirty_bitmaps = 
qcow2_load_autoloading_dirty_bitmaps,
 .bdrv_store_persistent_dirty_bitmaps = 
qcow2_store_persistent_dirty_bitmaps,
+.bdrv_can_store_new_dirty_bitmap = qcow2_can_store_new_dirty_bitmap,
 };
 
 static void bdrv_qcow2_init(void)
diff --git a/block/qcow2.h b/block/qcow2.h
index d9a7643..749710d 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -616,5 +616,9 @@ void qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, 
void **table);
 /* qcow2-bitmap.c functions */
 void qcow2_load_autoloading_dirty_bitmaps(BlockDriverState *bs, Error **errp);
 void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp);
+bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs,
+  const char *name,
+  uint32_t granularity,
+  Error **errp);
 
 #endif
-- 
1.8.3.1