Re: [Qemu-devel] [PATCH v8 06/10] qmp: Add block-dirty-bitmap-enable and block-dirty-bitmap-disable

[Max Reitz]

On 2014-11-26 at 18:41, John Snow wrote:
> From: Fam Zheng <address@hidden>
>
> This allows to put the dirty bitmap into a disabled state where no more
> writes will be tracked.
>
> It will be used before backup or writing to persistent file.
>
> Signed-off-by: Fam Zheng <address@hidden>
> Signed-off-by: John Snow <address@hidden>
> ---
>   block.c               | 15 +++++++++++++
>   blockdev.c            | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++
>   include/block/block.h |  2 ++
>   qapi/block-core.json  | 28 +++++++++++++++++++++++
>   qmp-commands.hx       | 10 +++++++++
>   5 files changed, 116 insertions(+)
>
> diff --git a/block.c b/block.c
> index 40cb9cf..1aa723b 100644
> --- a/block.c
> +++ b/block.c
> @@ -56,6 +56,7 @@ struct BdrvDirtyBitmap {
>       int64_t size;
>       int64_t granularity;
>       char *name;
> +    bool enabled;
>       QLIST_ENTRY(BdrvDirtyBitmap) list;
>   };
>   
> @@ -5361,6 +5362,7 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
>       bitmap->granularity = granularity;
>       bitmap->bitmap = hbitmap_alloc(bitmap->size, ffs(sector_granularity) - 1);
>       bitmap->name = g_strdup(name);
> +    bitmap->enabled = true;
>       QLIST_INSERT_HEAD(&bs->dirty_bitmaps, bitmap, list);
>       return bitmap;
>   }
> @@ -5379,6 +5381,16 @@ void bdrv_release_dirty_bitmap(BlockDriverState *bs, 
> BdrvDirtyBitmap *bitmap)
>       }
>   }
>   
> +void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
> +{
> +    bitmap->enabled = false;
> +}
> +
> +void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
> +{
> +    bitmap->enabled = true;
> +}
> +
>   BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs)
>   {
>       BdrvDirtyBitmap *bm;
> @@ -5447,6 +5459,9 @@ void bdrv_set_dirty(BlockDriverState *bs, int64_t 
> cur_sector,
>   {
>       BdrvDirtyBitmap *bitmap;
>       QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) {
> +        if (!bitmap->enabled) {
> +            continue;
> +        }
>           hbitmap_set(bitmap->bitmap, cur_sector, nr_sectors);
>       }
>   }
> diff --git a/blockdev.c b/blockdev.c
> index af1152f..276a31b 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1159,6 +1159,41 @@ SnapshotInfo 
> *qmp_blockdev_snapshot_delete_internal_sync(const char *device,
>       return info;

This conflicts with Stefan's AioContext series, so it doesn't apply to 
block-next. The above line should read "return NULL;" instead.

>   }
>   
> +/**
> + * Return a dirty bitmap (if present), after validating
> + * the device and bitmap names. Returns NULL on error,
> + * including when the device and/or bitmap is not found.
> + */
> +static BdrvDirtyBitmap *block_dirty_bitmap_lookup(const char *device,
> +                                                  const char *name,
> +                                                  Error **errp)
> +{
> +    BlockDriverState *bs;
> +    BdrvDirtyBitmap *bitmap;
> +
> +    if (!device) {
> +        error_setg(errp, "Device cannot be NULL");
> +        return NULL;
> +    }
> +    if (!name) {
> +        error_setg(errp, "Bitmap name cannot be NULL");
> +        return NULL;
> +    }
> +
> +    bs = bdrv_lookup_bs(device, NULL, errp);
> +    if (!bs) {
> +        return NULL;
> +    }
> +
> +    bitmap = bdrv_find_dirty_bitmap(bs, name);
> +    if (!bitmap) {
> +        error_setg(errp, "Dirty bitmap not found: %s", name);
> +        return NULL;
> +    }
> +
> +    return bitmap;
> +}
> +
>   /* New and old BlockDriverState structs for group snapshots */

And this line should read "/* New and old BlockDriverState structs for 
atomic group operations */". With those changes it applies.

With that changed (it's not even a change of the code, just a change of 
the patch):

Reviewed-by: Max Reitz <address@hidden>