Re: [Qemu-block] [PATCH v2 4/8] nbd: Support auto-read-only option

[Eric Blake]

On 10/12/18 6:55 AM, Kevin Wolf wrote:
> If read-only=off, but auto-read-only=on is given, open a read-write NBD
> connection if the server provides a read-write export, but instead of
> erroring out for read-only exports, just degrade to read-only.
>
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
>   block/nbd-client.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)

Reviewed-by: Eric Blake <address@hidden>

> diff --git a/block/nbd-client.c b/block/nbd-client.c
> index 9686ecbd5e..76e9ca3abe 100644
> --- a/block/nbd-client.c
> +++ b/block/nbd-client.c
> @@ -992,11 +992,11 @@ int nbd_client_init(BlockDriverState *bs,
>           logout("Failed to negotiate with the NBD server\n");
>           return ret;
>       }
> -    if (client->info.flags & NBD_FLAG_READ_ONLY &&
> -        !bdrv_is_read_only(bs)) {
> -        error_setg(errp,
> -                   "request for write access conflicts with read-only export");
> -        return -EACCES;
> +    if (client->info.flags & NBD_FLAG_READ_ONLY) {
> +        ret = bdrv_apply_auto_read_only(bs, "NBD export is read-only", errp);
> +        if (ret < 0) {
> +            return ret;
> +        }
>       }
>       if (client->info.flags & NBD_FLAG_SEND_FUA) {
>           bs->supported_write_flags = BDRV_REQ_FUA;

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org