Re: [Qemu-devel] [PATCH V9 09/11] quorum: Add quorum_co_get_block_status.

[Max Reitz <mreitz@redhat.com>]

On 2013-10-02 14:39, Benoît Canet wrote:
> Signed-off-by: Benoit Canet <benoit@irqsave.net>
> ---
>   block/quorum.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 67 insertions(+)
>
> diff --git a/block/quorum.c b/block/quorum.c
> index 223ad22..084d030 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -171,6 +171,22 @@ static int quorum_sha256_compare(QuorumVoteValue *a, QuorumVoteValue *b)
>       return memcmp(a->h, b->h, HASH_LENGTH);
>   }
>   
> +static int quorum_64bits_compare(QuorumVoteValue *a, QuorumVoteValue *b)
> +{
> +    int64_t i = a->l;
> +    int64_t j = b->l;
> +
> +    if (i < j) {
> +        return -1;
> +    }
> +
> +    if (i > j) {
> +        return 1;
> +    }
> +
> +    return 0;
> +}
> +
>   static QuorumAIOCB *quorum_aio_get(BDRVQuorumState *s,
>                                      BlockDriverState *bs,
>                                      QEMUIOVector *qiov,
> @@ -575,6 +591,56 @@ static void quorum_invalidate_cache(BlockDriverState *bs)
>       }
>   }
>   
> +static int64_t coroutine_fn quorum_co_get_block_status(BlockDriverState *bs,
> +                                                       int64_t sector_num,
> +                                                       int nb_sectors,
> +                                                       int *pnum)
> +{
> +    BDRVQuorumState *s = bs->opaque;
> +    QuorumVoteVersion *winner = NULL;
> +    QuorumVotes result_votes, num_votes;
> +    QuorumVoteValue result_value, num_value;
> +    int i, num;
> +    int64_t result = 0;
> +
> +    QLIST_INIT(&result_votes.vote_list);
> +    QLIST_INIT(&num_votes.vote_list);
> +    result_votes.compare = quorum_64bits_compare;
> +    num_votes.compare = quorum_64bits_compare;
> +
> +    for (i = 0; i < s->total; i++) {
> +        result = bdrv_get_block_status(&s->bs[i], sector_num, nb_sectors, &num);
> +        /* skip failed requests */
> +        if (result < 0) {
> +            continue;
> +        }
> +        result_value.l = result & BDRV_BLOCK_DATA;
> +        num_value.l = num;
> +        quorum_count_vote(&result_votes, &result_value, i);
> +        quorum_count_vote(&num_votes, &num_value, i);
> +    }
> +
> +    winner = quorum_get_vote_winner(&result_votes);
> +    result = winner->value.l;
> +    if (winner->vote_count < s->threshold) {
> +        result = -ERANGE;
> +        goto free_exit;
> +    }
> +
> +    winner = quorum_get_vote_winner(&num_votes);
> +    if (winner->vote_count < s->threshold) {
> +        result = -ERANGE;
> +        goto free_exit;
> +    }
> +    *pnum = winner->value.l;
I wouldn't vote here. I think it would be better to take the minimum 
value for pnum (the minimum of num_votes) and consider the sector 
unallocated if it's unallocated for any child. But voting seems okay, too.

Max

> +
> +free_exit:
> +    quorum_free_vote_list(&result_votes);
> +    quorum_free_vote_list(&num_votes);
> +
> +    return result;
> +}
> +
>   static BlockDriver bdrv_quorum = {
>       .format_name        = "quorum",
>       .protocol_name      = "quorum",
> @@ -586,6 +652,7 @@ static BlockDriver bdrv_quorum = {
>       .bdrv_aio_readv     = quorum_aio_readv,
>       .bdrv_aio_writev    = quorum_aio_writev,
>       .bdrv_invalidate_cache = quorum_invalidate_cache,
> +    .bdrv_co_get_block_status = quorum_co_get_block_status,
>   };
>   
>   static void bdrv_quorum_init(void)