On 7/24/19 12:47 AM, Markus Armbruster wrote:
> John Snow <jsnow@xxxxxxxxxx> writes:
>
>> From: Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
>>
>> 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@xxxxxxxxxxxxx>
>> [Added deprecation information. --js]
>> Signed-off-by: John Snow <jsnow@xxxxxxxxxx>
>> ---
>> 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.
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