Re: [Qemu-devel] [PATCH 18/21] qmp: add x-debug-block-dirty-bitmap-sha256

[John Snow <jsnow@redhat.com>]

On 11/09/2016 01:17 PM, Vladimir Sementsov-Ogievskiy wrote:
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  block/dirty-bitmap.c         |  5 +++++
>  blockdev.c                   | 33 +++++++++++++++++++++++++++++++++
>  include/block/dirty-bitmap.h |  2 ++
>  include/qemu/hbitmap.h       |  8 ++++++++
>  qapi/block-core.json         | 26 ++++++++++++++++++++++++++
>  util/hbitmap.c               | 11 +++++++++++
>  6 files changed, 85 insertions(+)
>
> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
> index fe34d48..775181c 100644
> --- a/block/dirty-bitmap.c
> +++ b/block/dirty-bitmap.c
> @@ -589,3 +589,8 @@ BdrvDirtyBitmap *bdrv_dirty_bitmap_next(BlockDriverState *bs,
>      return bitmap == NULL ? QLIST_FIRST(&bs->dirty_bitmaps) :
>                              QLIST_NEXT(bitmap, list);
>  }
> +
> +char *bdrv_dirty_bitmap_sha256(const BdrvDirtyBitmap *bitmap, Error **errp)
> +{
> +    return hbitmap_sha256(bitmap->bitmap, errp);
> +}
> diff --git a/blockdev.c b/blockdev.c
> index db2bdbb..c028070 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -2811,6 +2811,39 @@ void qmp_block_dirty_bitmap_clear(const char *node, const char *name,
>      aio_context_release(aio_context);
>  }
>
> +/**
> + * Completely clear a bitmap, for the purposes of synchronizing a bitmap
> + * immediately after a full backup operation.
> + */
> +BlockDirtyBitmapSha256 *qmp_x_debug_block_dirty_bitmap_sha256(const char *node,
> +                                                              const char *name,
> +                                                              Error **errp)
> +{
> +    AioContext *aio_context;
> +    BdrvDirtyBitmap *bitmap;
> +    BlockDriverState *bs;
> +    BlockDirtyBitmapSha256 *ret = NULL;
> +    char *sha256;
> +
> +    bitmap = block_dirty_bitmap_lookup(node, name, &bs, &aio_context, errp);
> +    if (!bitmap || !bs) {
> +        return NULL;
> +    }
> +
> +    sha256 = bdrv_dirty_bitmap_sha256(bitmap, errp);
> +    if (sha256 == NULL) {
> +        goto out;
> +    }
> +
> +    ret = g_new(BlockDirtyBitmapSha256, 1);
> +    ret->sha256 = sha256;
> +
> +out:
> +    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/dirty-bitmap.h b/include/block/dirty-bitmap.h
> index d71edc4..b022b34 100644
> --- a/include/block/dirty-bitmap.h
> +++ b/include/block/dirty-bitmap.h
> @@ -86,4 +86,6 @@ BdrvDirtyBitmap *bdrv_dirty_bitmap_next(BlockDriverState *bs,
>
>  bool bdrv_has_persistent_bitmaps(BlockDriverState *bs);
>
> +char *bdrv_dirty_bitmap_sha256(const BdrvDirtyBitmap *bitmap, Error **errp);
> +
>  #endif
> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
> index 5c9dd74..d6f3838 100644
> --- a/include/qemu/hbitmap.h
> +++ b/include/qemu/hbitmap.h
> @@ -240,6 +240,14 @@ void hbitmap_deserialize_ones(HBitmap *hb, uint64_t start, uint64_t count,
>  void hbitmap_deserialize_finish(HBitmap *hb);
>
>  /**
> + * hbitmap_sha256:
> + * @bitmap: HBitmap to operate on.
> + *
> + * Returns SHA256 hash of the last level.
> + */
> +char *hbitmap_sha256(const HBitmap *bitmap, Error **errp);
> +
> +/**
>   * hbitmap_free:
>   * @hb: HBitmap to operate on.
>   *
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 2c33a30..f72cfef 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -1289,6 +1289,32 @@
>    'data': 'BlockDirtyBitmap' }
>
>  ##
> +# @BlockDirtyBitmapSha256:
> +#
> +# SHA256 hash of dirty bitmap data
> +#
> +# @sha256: bitmap SHA256 hash
> +#
> +# Since: 2.8
> +##
> +  { 'struct': 'BlockDirtyBitmapSha256',
> +    'data': {'sha256': 'str'} }
> +
> +##
> +# @x-debug-block-dirty-bitmap-sha256
> +#
> +# Get bitmap SHA256
> +#
> +# Returns: BlockDirtyBitmapSha256 on success
> +#          If @node is not a valid block device, DeviceNotFound
> +#          If @name is not found, GenericError with an explanation
> +#
> +# Since 2.8
> +##
> +  { 'command': 'x-debug-block-dirty-bitmap-sha256',
> +    'data': 'BlockDirtyBitmap', 'returns': 'BlockDirtyBitmapSha256' }
> +
> +##
>  # @blockdev-mirror
>  #
>  # Start mirroring a block device's writes to a new destination.
> diff --git a/util/hbitmap.c b/util/hbitmap.c
> index 72623f4..96af071 100644
> --- a/util/hbitmap.c
> +++ b/util/hbitmap.c
> @@ -13,6 +13,7 @@
>  #include "qemu/hbitmap.h"
>  #include "qemu/host-utils.h"
>  #include "trace.h"
> +#include "crypto/hash.h"
>
>  /* HBitmaps provides an array of bits.  The bits are stored as usual in an
>   * array of unsigned longs, but HBitmap is also optimized to provide fast
> @@ -707,3 +708,13 @@ void hbitmap_free_meta(HBitmap *hb)
>      hbitmap_free(hb->meta);
>      hb->meta = NULL;
>  }
> +
> +char *hbitmap_sha256(const HBitmap *bitmap, Error **errp)
> +{
> +    size_t size = bitmap->sizes[HBITMAP_LEVELS - 1] * sizeof(unsigned long);
> +    char *data = (char *)bitmap->levels[HBITMAP_LEVELS - 1];
> +    char *hash = NULL;
> +    qcrypto_hash_digest(QCRYPTO_HASH_ALG_SHA256, data, size, &hash, errp);

By adding this here, you're adding a linking dependency to 
libqemuutil.a, which causes the test-hbitmap test to fail to link from 
this patch forward.

I'm not sure what the correct approach should be, but at a minimum we 
need to link crypto/hash.o to test/test-hbitmap.o to be able to run that 
test. We get build failures otherwise.

> +
> +    return hash;
> +}
>