Re: [Qemu-block] [PATCH 16/19] block/nbd: Implement bdrv_dirname()

[Kevin Wolf]

Am 26.04.2016 um 23:32 hat Max Reitz geschrieben:
> The idea behind this implementation is that the export name might be
> interpreted as a path (which is the only apparent interpretation of
> relative filenames for NBD paths).
> 
> The default implementation of bdrv_dirname() would handle that just fine
> for nbd+tcp, but not for nbd+unix, because in that case, the last
> element of the path is the Unix socket path and not the export name.
> Therefore, we need to implement an own bdrv_dirname() which uses the
> legacy NBD URL which has the export name at the end.
> 
> Signed-off-by: Max Reitz <address@hidden>
> ---
>  block/nbd.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/block/nbd.c b/block/nbd.c
> index f7ea3b3..64534bb 100644
> --- a/block/nbd.c
> +++ b/block/nbd.c
> @@ -469,6 +469,32 @@ static void nbd_refresh_filename(BlockDriverState *bs, 
> QDict *options)
>      bs->full_open_options = opts;
>  }
>  
> +static char *nbd_dirname(BlockDriverState *bs, Error **errp)
> +{
> +    const char *path   = qdict_get_try_str(bs->options, "path");
> +    const char *host   = qdict_get_try_str(bs->options, "host");
> +    const char *port   = qdict_get_try_str(bs->options, "port");
> +    const char *export = qdict_get_try_str(bs->options, "export");
> +
> +    if (path && export) {
> +        return g_strdup_printf("nbd:unix:%s:exportname=%s/", path, export);
> +    } else if (path && !export) {
> +        return g_strdup_printf("nbd:unix:%s:exportname=", path);
> +    } else if (!path && export && port) {
> +        return g_strdup_printf("nbd://%s:%s/%s/", host, port, export);
> +    } else if (!path && export && !port) {
> +        return g_strdup_printf("nbd://%s/%s/", host, export);
> +    } else if (!path && !export && port) {
> +        return g_strdup_printf("nbd://%s:%s/", host, port);
> +    } else if (!path && !export && !port) {
> +        return g_strdup_printf("nbd://%s/", host);
> +    }

Many different cases already, and it's only going to get worse. Wouldn't
it be better to store saddr in BDRVNBDState (so that we don't have to
parse the options a second time here) and to go for the full version
here always? Then it's one case for tcp and one for unix and that's it.

Kevin