Re: [Qemu-devel] [PATCH] qmp: add query-block-dirty-bitmap

["Denis V. Lunev" <den@virtuozzo.com>]

On 01/22/2016 08:07 PM, Vladimir Sementsov-Ogievskiy wrote:
> Add qmp command to query dirty bitmap. This is needed for external
> backup.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>   block.c               | 41 ++++++++++++++++++++++++++++++++++++++++
>   blockdev.c            | 21 +++++++++++++++++++++
>   include/block/block.h |  2 ++
>   qapi/block-core.json  | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++
>   qmp-commands.hx       | 22 ++++++++++++++++++++++
>   5 files changed, 138 insertions(+)
>
> diff --git a/block.c b/block.c
> index 5709d3d..9a28589 100644
> --- a/block.c
> +++ b/block.c
> @@ -3717,6 +3717,47 @@ void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
>       }
>   }
>   
> +BlockDirtyBitmapInfo *bdrv_query_dirty_bitmap(BlockDriverState *bs,
> +                                              BdrvDirtyBitmap *bitmap)
> +{
> +    BlockDirtyBitmapInfo *info = g_new0(BlockDirtyBitmapInfo, 1);
> +    BlockDirtyRegionList **plist = &info->dirty_regions;
> +    uint64_t begin = 0, end = 0, size = bitmap->size;
> +    HBitmap *hb = bitmap->bitmap;
> +
> +    info->dirty_count = bdrv_get_dirty_count(bitmap);
> +    info->granularity = bdrv_dirty_bitmap_granularity(bitmap);
> +    info->size = bitmap->size;
> +    info->name = g_strdup(bitmap->name);
> +    info->disabled = bitmap->disabled;
> +    info->dirty_regions = NULL;
> +
> +    for (; begin < size; ++begin) {
> +        BlockDirtyRegion *region;
> +        BlockDirtyRegionList *entry;
> +
> +        if (!hbitmap_get(hb, begin)) {
> +            continue;
> +        }
> +
> +        for (end = begin + 1; end < size && hbitmap_get(hb, end); ++end) {
> +            ;
> +        }
let us implemented faster finder. This would be useful in other places. 
It could be
100 times faster!

> +
> +        region = g_new0(BlockDirtyRegion, 1);
> +        entry = g_new0(BlockDirtyRegionList, 1);
> +        region->start = begin;
> +        region->count = end - begin;
> +        entry->value = region;
> +        *plist = entry;
> +        plist = &entry->next;
> +
> +        begin = end;
> +    }
> +
> +    return info;
> +}
> +
>   /**
>    * Advance an HBitmapIter to an arbitrary offset.
>    */
> diff --git a/blockdev.c b/blockdev.c
> index 07cfe25..d2bc453 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -2734,6 +2734,27 @@ void qmp_block_dirty_bitmap_clear(const char *node, const char *name,
>       aio_context_release(aio_context);
>   }
>   
> +BlockDirtyBitmapInfo *qmp_query_block_dirty_bitmap(const char *node,
> +                                                   const char *name,
> +                                                   Error **errp)
> +{
> +    AioContext *aio_context;
> +    BdrvDirtyBitmap *bitmap;
> +    BlockDriverState *bs;
> +    BlockDirtyBitmapInfo *ret = NULL;
> +
> +    bitmap = block_dirty_bitmap_lookup(node, name, &bs, &aio_context, errp);
> +    if (!bitmap) {
> +        return NULL;
> +    }
> +
> +    ret = bdrv_query_dirty_bitmap(bs, bitmap);
> +
> +    aio_context_release(aio_context);
> +
> +    return ret;
> +}
> +
>   void hmp_drive_del(Monitor *mon, const QDict *qdict)
>   {
>       const char *id = qdict_get_str(qdict, "id");
> diff --git a/include/block/block.h b/include/block/block.h
> index 25f36dc..9d6bd33 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -505,6 +505,8 @@ void bdrv_set_dirty_bitmap(BdrvDirtyBitmap *bitmap,
>                              int64_t cur_sector, int nr_sectors);
>   void bdrv_reset_dirty_bitmap(BdrvDirtyBitmap *bitmap,
>                                int64_t cur_sector, int nr_sectors);
> +BlockDirtyBitmapInfo *bdrv_query_dirty_bitmap(BlockDriverState *bs,
> +                                              BdrvDirtyBitmap *bitmap);
>   void bdrv_dirty_iter_init(BdrvDirtyBitmap *bitmap, struct HBitmapIter *hbi);
>   void bdrv_set_dirty_iter(struct HBitmapIter *hbi, int64_t offset);
>   int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap);
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 0a915ed..12ed759 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -414,6 +414,58 @@
>   ##
>   { 'command': 'query-block', 'returns': ['BlockInfo'] }
>   
> +##
> +# @BlockDirtyRegion:
> +#
> +# Region in bytes.
> +#
> +# @start: first byte
> +#
> +# @count: number of bytes in the region
> +#
> +# Since: 2.3
> +##
> +{ 'struct': 'BlockDirtyRegion',
> +  'data': { 'start': 'int', 'count': 'int' } }
> +
> +##
> +# @BlockDirtyBitmapInfo
> +#
> +# @name: the name of the dirty bitmap
> +#
> +# @size: size of the dirty bitmap in sectors
> +#
> +# @granularity: granularity of the dirty bitmap in bytes
> +#
> +# @disabled: whether the dirty bitmap is disabled
> +#
> +# @dirty-count: number of dirty bytes according to the dirty bitmap
> +#
> +# @dirty-regions: dirty regions of the bitmap
> +#
> +# Since 2.3
> +##
> +{ 'struct': 'BlockDirtyBitmapInfo',
> +  'data': { 'name': 'str',
> +            'size': 'int',
> +            'granularity': 'int',
> +            'disabled': 'bool',
> +            'dirty-count': 'int',
> +            'dirty-regions': ['BlockDirtyRegion'] } }
> +
> +##
> +# @query-block-dirty-bitmap
> +#
> +# Get a description for specified dirty bitmap including it's dirty regions.
> +# This command is in general for testing purposes.
> +#
> +# Returns: @BlockDirtyBitmapInfo
> +#
> +# Since: 2.3
> +##
> +{ 'command': 'query-block-dirty-bitmap',
> +  'data': 'BlockDirtyBitmap',
> +  'returns': 'BlockDirtyBitmapInfo' }
1) should we consider part-by-part retrieval? This could be useful for 
large discs.
2) Change to since 2.6
3) Do you think that content should be retrieved separately than data?


>   
>   ##
>   # @BlockDeviceTimedStats:
> diff --git a/qmp-commands.hx b/qmp-commands.hx
> index db072a6..75d9345 100644
> --- a/qmp-commands.hx
> +++ b/qmp-commands.hx
> @@ -1457,6 +1457,28 @@ Example:
>   EQMP
>   
>       {
> +        .name       = "query-block-dirty-bitmap",
> +        .args_type  = "node:B,name:s",
> +        .mhandler.cmd_new = qmp_marshal_query_block_dirty_bitmap,
> +    },
> +
> +SQMP
> +
> +query-block-dirty-bitmap
> +------------------------
> +Since 2.6
> +
> +Get dirty bitmap info, including contents. Bitmap data are returned as array of
> +dirty regions
> +
> +Arguments:
> +
> +- "node": device/node on which to remove dirty bitmap (json-string)
> +- "name": name of the dirty bitmap to remove (json-string)
> +
> +EQMP
> +
> +    {
>           .name       = "blockdev-snapshot-sync",
>           .args_type  = "device:s?,node-name:s?,snapshot-file:s,snapshot-node-name:s?,format:s?,mode:s?",
>           .mhandler.cmd_new = qmp_marshal_blockdev_snapshot_sync,
can you pls use den@openvz.org addr sending patches to me?