On 7/24/19 12:47 AM, Markus Armbruster wrote:
John Snow <jsnow(a)redhat.com> writes:
> From: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
>
> Let's add a possibility to query dirty-bitmaps not only on root nodes.
> It is useful when dealing both with snapshots and incremental backups.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
> [Added deprecation information. --js]
> Signed-off-by: John Snow <jsnow(a)redhat.com>
> ---
> block/qapi.c | 5 +++++
> qapi/block-core.json | 6 +++++-
> qemu-deprecated.texi | 12 ++++++++++++
> 3 files changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/block/qapi.c b/block/qapi.c
> index 917435f022..15f1030264 100644
> --- a/block/qapi.c
> +++ b/block/qapi.c
> @@ -79,6 +79,11 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
> info->backing_file = g_strdup(bs->backing_file);
> }
>
> + if (!QLIST_EMPTY(&bs->dirty_bitmaps)) {
> + info->has_dirty_bitmaps = true;
> + info->dirty_bitmaps = bdrv_query_dirty_bitmaps(bs);
> + }
> +
> info->detect_zeroes = bs->detect_zeroes;
>
> if (blk && blk_get_public(blk)->throttle_group_member.throttle_state)
{
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 0d43d4f37c..9210ae233d 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -360,6 +360,9 @@
> # @write_threshold: configured write threshold for the device.
> # 0 if disabled. (Since 2.3)
> #
> +# @dirty-bitmaps: dirty bitmaps information (only present if node
> +# has one or more dirty bitmaps) (Since 4.2)
> +#
> # Since: 0.14.0
> #
> ##
> @@ -378,7 +381,7 @@
> '*bps_wr_max_length': 'int', '*iops_max_length':
'int',
> '*iops_rd_max_length': 'int',
'*iops_wr_max_length': 'int',
> '*iops_size': 'int', '*group': 'str',
'cache': 'BlockdevCacheInfo',
> - 'write_threshold': 'int' } }
> + 'write_threshold': 'int', '*dirty-bitmaps':
['BlockDirtyInfo'] } }
>
> ##
> # @BlockDeviceIoStatus:
> @@ -656,6 +659,7 @@
> #
> # @dirty-bitmaps: dirty bitmaps information (only present if the
> # driver has one or more dirty bitmaps) (Since 2.0)
> +# Deprecated in 4.2; see BlockDirtyInfo instead.
> #
> # @io-status: @BlockDeviceIoStatus. Only present if the device
> # supports it and the VM is configured to stop on errors
> diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
> index c90b08d553..6374b66546 100644
> --- a/qemu-deprecated.texi
> +++ b/qemu-deprecated.texi
> @@ -134,6 +134,18 @@ The ``status'' field of the ``BlockDirtyInfo''
structure, returned by
> the query-block command is deprecated. Two new boolean fields,
> ``recording'' and ``busy'' effectively replace it.
>
> +@subsection query-block result field dirty-bitmaps (Since 4.2)
> +
> +The ``dirty-bitmaps`` field of the ``BlockInfo`` structure, returned by
> +the query-block command is itself now deprecated. The ``dirty-bitmaps``
> +field of the ``BlockDeviceInfo`` struct should be used instead, which is the
> +type of the ``inserted`` field in query-block replies, as well as the
> +type of array items in query-named-block-nodes.
Would the text be clearer if it talked only about commands, not about
types?
Here's my (laconic) try:
@subsection query-block result field dirty-bitmaps (Since 4.2)
In the result of query-block, member ``dirty-bitmaps'' has been moved
into member ``inserted''.
Yeah, that's probably better in terms of strictly what the deprecation
is. I was trying to imply that the output will also now be visible in
other commands as well, but that's not the deprecation -- that's the new
feature.
ACK
Aside: same for existing @subsection query-block result field
dirty-bitmaps[i].status (since 4.0).
(Probably not worth editing deprecation text that was already published.)
> +Since the ``dirty-bitmaps`` field is optionally present in both
the old and
> +new locations, clients must use introspection to learn where to anticipate
> +the field if/when it does appear in command output.
> +
I find this hint a bit confusing. Do we need it?
I think so, yes: it's nice to inform readers of how to cope with the
deprecation.
If yes, laconic me again:
Clients should use introspection to learn whether ``dirty-bitmaps'' is
in the new location.
Too terse. I want my documentation to greet me in the morning by reading
me the local newspaper while I brush my teeth.
Yours says the "how", but I think a hint should have the "why":
"Since the ``dirty-bitmaps`` field is not always present in command
output, Clients should use introspection to learn the location of this
field."
But I'm only willing to give you a self-deprecating joke and a final
nudge to keep a more informative hint, and then I'll capitulate and take
your suggestion if you give me a stern look.
--js
> @subsection query-cpus (since 2.12.0)
>
> The ``query-cpus'' command is replaced by the ``query-cpus-fast''
command.