Re: [Qemu-devel] [PATCH 6/7] file-posix: Add dynamic-auto-read-only QAPI feature

[Eric Blake <eblake@redhat.com>]

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On 6/6/19 10:38 AM, Markus Armbruster wrote:
> From: Kevin Wolf <kwolf@redhat.com>
> 
> In commit 23dece19da4 ('file-posix: Make auto-read-only dynamic') ,
> auto-read-only=on changed its behaviour in file-posix for the 4.0
> release. This change cannot be detected through the usual mechanisms
> like schema introspection. Add a new feature flag to the schema to
> allow libvirt to detect the presence of the new behaviour.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  qapi/block-core.json | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 1defcde048..f5e1ee91f9 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -2859,6 +2859,15 @@
>  #                         file is large, do not use in production.
>  #                         (default: off) (since: 3.0)
>  #
> +# Features:
> +# @dynamic-auto-read-only: If present, enabled auto-read-only means that the
> +#                          driver will open the image read-only at first,
> +#                          dynamically reopen the image file read-write when
> +#                          the first writer is attached to the node and reopen
> +#                          read-only when the last writer is detached. This
> +#                          allows to give QEMU write permissions only on demand

s/allows to give/allows giving/

> +#                          when an operation actually needs write access.
> +#
>  # Since: 2.9
>  ##
>  { 'struct': 'BlockdevOptionsFile',
> @@ -2868,7 +2877,9 @@
>              '*aio': 'BlockdevAioOptions',
>  	    '*drop-cache': {'type': 'bool',
>  	                    'if': 'defined(CONFIG_LINUX)'},
> -            '*x-check-cache-dropped': 'bool' } }
> +            '*x-check-cache-dropped': 'bool' },
> +  'features': [ { 'name': 'dynamic-auto-read-only',
> +                  'if': 'defined(CONFIG_POSIX)' } ] }
>  
>  ##
>  # @BlockdevOptionsNull:
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


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