Re: [Qemu-devel] [sheepdog] [PATCH v2 2/2] sheepdog: support user-defined redundancy option

[MORITA Kazutaka <morita.kazutaka@gmail.com>]

At Tue, 29 Oct 2013 16:25:52 +0800,
Liu Yuan wrote:
> 
> Sheepdog support two kinds of redundancy, full replication and erasure coding.
> 
> # create a fully replicated vdi with x copies
>  -o redundancy=x (1 <= x <= SD_MAX_COPIES)
> 
> # create a erasure coded vdi with x data strips and y parity strips
>  -o redundancy=x:y (x must be one of {2,4,8,16} and 1 <= y < SD_EC_MAX_STRIP)
> 
> E.g, to convert a vdi into sheepdog vdi 'test' with 8:3 erasure coding scheme
> 
> $ qemu-img convert -o redundancy=8:3 linux-0.2.img sheepdog:test
> 
> Cc: Kevin Wolf <kwolf@redhat.com>
> Cc: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Liu Yuan <namei.unix@gmail.com>
> ---
>  block/sheepdog.c          |   78 ++++++++++++++++++++++++++++++++++++++++++++-
>  include/block/block_int.h |    1 +
>  2 files changed, 78 insertions(+), 1 deletion(-)
> 
> diff --git a/block/sheepdog.c b/block/sheepdog.c
> index e66d2f8..bd7cfd6 100644
> --- a/block/sheepdog.c
> +++ b/block/sheepdog.c
> @@ -91,6 +91,14 @@
>  #define SD_NR_VDIS   (1U << 24)
>  #define SD_DATA_OBJ_SIZE (UINT64_C(1) << 22)
>  #define SD_MAX_VDI_SIZE (SD_DATA_OBJ_SIZE * MAX_DATA_OBJS)
> +/*
> + * For erasure coding, we use at most SD_EC_MAX_STRIP for data strips and
> + * (SD_EC_MAX_STRIP - 1) for parity strips
> + *
> + * SD_MAX_COPIES is sum of number of dats trips and parity strips.
> + */
> +#define SD_EC_MAX_STRIP 16
> +#define SD_MAX_COPIES (SD_EC_MAX_STRIP * 2 - 1)
>  
>  #define SD_INODE_SIZE (sizeof(SheepdogInode))
>  #define CURRENT_VDI_ID 0
> @@ -1446,6 +1454,65 @@ out:
>      return ret;
>  }
>  
> +static int64_t is_numeric(const char *s)
> +{
> +    char *end;
> +    return strtosz_suffix(s, &end, STRTOSZ_DEFSUFFIX_B);
> +}

I think the type of the return value should be bool.

Thanks,

Kazutaka