Re: [Qemu-devel] [PATCH v2 08/11] block: extend block-commit to accept a string for the backing file

[Eric Blake]

On 05/27/2014 08:28 AM, Jeff Cody wrote:
> On some image chains, QEMU may not always be able to resolve the
> filenames properly, when updating the backing file of an image
> after a block commit.
> 
> For instance, certain relative pathnames may fail, or drives may
> have been specified originally by file descriptor (e.g. /dev/fd/???),
> or a relative protocol pathname may have been used.
> 
> In these instances, QEMU may lack the information to be able to make
> the correct choice, but the user or management layer most likely does
> have that knowledge.
> 
> With this extension to the block-commit api, the user is able to change
> the backing file of the overlay image as part of the block-commit
> operation.
> 
> This allows the change to be 'safe', in the sense that if the attempt
> to write the overlay image metadata fails, then the block-commit
> operation returns failure, without disrupting the guest.
> 
> If the commit top is the active layer, then specifying the backing
> file string will be treated as an error (there is no overlay image
> to modify in that case).
> 
> If a backing file string is not specified in the command, the backing
> file string to use is determined in the same manner as it was
> previously.
> 
> Signed-off-by: Jeff Cody <address@hidden>
> ---
>  block.c                   |  8 ++++++--
>  block/commit.c            |  9 ++++++---
>  blockdev.c                |  8 +++++++-
>  include/block/block.h     |  3 ++-
>  include/block/block_int.h |  3 ++-
>  qapi-schema.json          | 23 +++++++++++++++++++++--
>  qmp-commands.hx           | 19 ++++++++++++++++++-
>  7 files changed, 62 insertions(+), 11 deletions(-)
> 


> +# @backing-file: #optional The backing file string to write into the overlay
> +#                          image of 'top'.  If 'top' is the active layer,
> +#                          specifying a backing file string is an error. This
> +#                          filename is not validated.
> +#
> +#                          If a pathname string is such that it cannot be
> +#                          resolved be QEMU, that means that subsequent QMP 
> or

s/be/by/

> +++ b/qmp-commands.hx

> +                    If a pathname string is such that it cannot be
> +                    resolved be QEMU, that means that subsequent QMP or

and again

If those two typo fixes are the only change,

Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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