Re: [Qemu-devel] [2.3 PATCH v7 06/10] qmp: Add block-dirty-bitmap-enable and block-dirty-bitmap-disable

[Max Reitz <mreitz@redhat.com>]

On 2014-11-25 at 20:46, John Snow wrote:
> From: Fam Zheng <famz@redhat.com>
>
> 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 <famz@redhat.com>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>   block.c               | 15 +++++++++++++
>   blockdev.c            | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++
>   include/block/block.h |  2 ++
>   qapi/block-core.json  | 28 +++++++++++++++++++++++
>   qmp-commands.hx       | 10 +++++++++
>   5 files changed, 117 insertions(+)
>
> diff --git a/block.c b/block.c
> index 9582550..7217066 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(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
> +{
> +    bitmap->enabled = false;
> +}
> +
> +void bdrv_enable_dirty_bitmap(BlockDriverState *bs, 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 e2fe687..baaf902 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1873,6 +1873,68 @@ void qmp_block_dirty_bitmap_remove(const char *device, const char *name,
>       bdrv_release_dirty_bitmap(bs, bitmap);
>   }
>   
> +static BdrvDirtyBitmap *block_dirty_bitmap_lookup(const char *device,
> +                                                  const char *name,
> +                                                  Error **errp)
> +{
> +    BlockDriverState *bs;
> +    BdrvDirtyBitmap *bitmap;
> +    Error *local_err = NULL;
> +
> +    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, &local_err);
> +    if (!bs) {
> +        error_propagate(errp, local_err);

Comments from patch 2 apply here as well: I'm still in favor of 
blk_by_name(), and you don't need local_err.

> +        return NULL;
> +    }
> +
> +    bitmap = bdrv_find_dirty_bitmap(bs, name);
> +    if (!bitmap) {
> +        error_setg(errp, "Dirty bitmap not found: %s", name);
> +        return NULL;
> +    }
> +
> +    return bitmap;
> +}
> +
> +void qmp_block_dirty_bitmap_enable(const char *device, const char *name,
> +                                   Error **errp)
> +{
> +    BdrvDirtyBitmap *bitmap;
> +    Error *local_err = NULL;
> +
> +    bitmap = block_dirty_bitmap_lookup(device, name, &local_err);
> +    if (!bitmap) {
> +        error_propagate(errp, local_err);

Again, no need for error_propagate().

> +        return;
> +    }
> +
> +    bdrv_enable_dirty_bitmap(NULL, bitmap);
> +}
> +
> +void qmp_block_dirty_bitmap_disable(const char *device, const char *name,
> +                                    Error **errp)
> +{
> +    BdrvDirtyBitmap *bitmap;
> +    Error *local_err = NULL;
> +
> +    bitmap = block_dirty_bitmap_lookup(device, name, &local_err);
> +    if (!bitmap) {
> +        error_propagate(errp, local_err);

Here, too.

With or without any of the "ret = foo(..., &local_err); if (ret 
indicates error) { error_propagate(errp, local_err);" replaced by "ret = 
foo(..., errp); if (ret indicates error) {":

Reviewed-by: Max Reitz <mreitz@redhat.com>