Re: [PATCH v2 03/33] block: Add BdrvChildRole

[Eric Blake]

On 2/4/20 11:08 AM, Max Reitz wrote:
> This enum will supplement BdrvChildClass when it comes to what role (or
> combination of roles) a child takes for its parent.
>
> Because empty enums are not allowed, let us just start with it filled.
>
> Signed-off-by: Max Reitz <address@hidden>
> ---
>   include/block/block.h | 27 +++++++++++++++++++++++++++
>   1 file changed, 27 insertions(+)
>
> diff --git a/include/block/block.h b/include/block/block.h
> index 38963ef203..0f7e8caa5b 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -279,6 +279,33 @@ enum {
>       DEFAULT_PERM_UNCHANGED      = BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH,
>   };
>   
> +typedef enum BdrvChildRole {
> +    /* Child stores data */
> +    BDRV_CHILD_DATA         = (1 << 0),
> +
> +    /* Child stores metadata */
> +    BDRV_CHILD_METADATA     = (1 << 1),
> +
> +    /* Filtered child */
> +    BDRV_CHILD_FILTERED     = (1 << 2),

I'm not sure this comment does justice for what the flag represents, but 
am not sure of what longer comment to put in its place.

> +
> +    /* Child to COW from (backing child) */
> +    BDRV_CHILD_COW          = (1 << 3),
> +
> +    /*
> +     * The primary child.  For most drivers, this is the child whose
> +     * filename applies best to the parent node.
> +     * Each parent must give this flag to no more than one child at a
> +     * time.
> +     */
> +    BDRV_CHILD_PRIMARY      = (1 << 4),
> +
> +    /* Useful combination of flags */
> +    BDRV_CHILD_IMAGE        = BDRV_CHILD_DATA
> +                              | BDRV_CHILD_METADATA
> +                              | BDRV_CHILD_PRIMARY,
> +} BdrvChildRole;
> +
>   char *bdrv_perm_names(uint64_t perm);
>   uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm);
>   

Whether or not you can improve the comment, the enum makes sense.

Reviewed-by: Eric Blake <address@hidden>

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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