Re: [Qemu-devel] [PATCH v4 08/11] block: Accept node-name for drive-backup

[Max Reitz <mreitz@redhat.com>]

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On 14.07.2016 15:28, Kevin Wolf wrote:
> In order to remove the necessity to use BlockBackend names in the
> external API, we want to allow node-names everywhere. This converts
> drive-backup and the corresponding transaction action to accept a
> node-name without lifting the restriction that we're operating at a root
> node.
> 
> In case of an invalid device name, the command returns the GenericError
> error class now instead of DeviceNotFound, because this is what
> qmp_get_root_bs() returns.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  blockdev.c             | 36 +++++++++---------------------------
>  qapi/block-core.json   |  4 ++--
>  qmp-commands.hx        |  2 +-
>  tests/qemu-iotests/055 |  7 ++-----
>  4 files changed, 14 insertions(+), 35 deletions(-)
> 
> diff --git a/blockdev.c b/blockdev.c
> index 6b1f2f0..b89b5f8 100644
> --- a/blockdev.c
> +++ b/blockdev.c

[...]

> @@ -3203,24 +3195,14 @@ static void do_drive_backup(const char *job_id, const char *device,
>          mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
>      }
>  
> -    blk = blk_by_name(device);
> -    if (!blk) {
> -        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
> -                  "Device '%s' not found", device);
> +    bs = qmp_get_root_bs(device, errp);
> +    if (!bs) {
>          return;
>      }
>  
> -    aio_context = blk_get_aio_context(blk);
> +    aio_context = bdrv_get_aio_context(bs);
>      aio_context_acquire(aio_context);
>  
> -    /* Although backup_run has this check too, we need to use bs->drv below, so
> -     * do an early check redundantly. */

This comment makes a good point, bs->drv may be NULL. I think you should
either call bdrv_is_inserted() or check bs->drv directly.

Max

> -    if (!blk_is_available(blk)) {
> -        error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
> -        goto out;
> -    }
> -    bs = blk_bs(blk);
> -
>      if (!has_format) {
>          format = mode == NEW_IMAGE_MODE_EXISTING ? NULL : bs->drv->format_name;
>      }


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