Re: [Qemu-block] [PATCH 06/21] backup: rewrite top mode cluster skipping

[Stefan Hajnoczi]

On Fri, Dec 23, 2016 at 05:28:49PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> @@ -374,6 +379,101 @@ static bool coroutine_fn yield_and_check(BackupBlockJob 
> *job)
>      return false;
>  }
>  
> +static void backup_skip_clusters(BackupBlockJob *job,
> +                                 int64_t start, int64_t end)

Missing coroutine_fn to document that this function must be called from
coroutine context.

> +{
> +    CowRequest cow_request;
> +
> +    wait_for_overlapping_requests(job, start, end);
> +    cow_request_begin(&cow_request, job, start, end);
> +
> +    if (end * job->cluster_size > job->common.len) {
> +        int64_t n;
> +        end--;
> +        n = job->common.len - end * job->cluster_size;
> +        assert(n > 0);
> +
> +        if (hbitmap_get(job->copy_bitmap, end)) {
> +            hbitmap_reset(job->copy_bitmap, end, 1);
> +            job->common.offset += n;
> +        }
> +    }
> +
> +    for ( ; start < end; start++) {
> +        if (!hbitmap_get(job->copy_bitmap, start)) {
> +            continue;
> +        }
> +
> +        hbitmap_reset(job->copy_bitmap, start, 1);
> +        job->common.offset += job->cluster_size;
> +    }
> +
> +    cow_request_end(&cow_request);
> +}
> +
> +static int backup_skip_unallocated_clusters(BackupBlockJob *job,
> +                                            BlockDriverState *base,
> +                                            int64_t start, int *n)

Missing coroutine_fn.

> +{
> +    int ret;
> +    int64_t sectors_per_cluster = cluster_size_sectors(job);
> +    BlockDriverState *bs = blk_bs(job->common.blk);
> +    int64_t sector_end = job->common.len >> BDRV_SECTOR_BITS;
> +    int64_t sector = start * sectors_per_cluster;
> +    int max_sectors = MIN(max_query_sectors(job), sector_end - sector);
> +    int n_sectors = 0;
> +
> +    ret = bdrv_is_allocated_above(bs, base, sector, max_sectors, &n_sectors);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +
> +    if (sector + n_sectors == sector_end || ret == 1) {
> +        *n = DIV_ROUND_UP(n_sectors, sectors_per_cluster);
> +    } else if (n_sectors < sectors_per_cluster) {
> +        *n = 1;
> +        ret = 1;
> +    } else {
> +        *n = n_sectors / sectors_per_cluster;
> +    }
> +
> +    if (ret == 0) {
> +        backup_skip_clusters(job, start, start + *n);
> +    }
> +
> +    return 0;
> +}
> +
> +static void backup_skip_loop(BackupBlockJob *job, BlockDriverState *base)

Missing coroutine_fn.

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