On Wed, 2019-08-14 at 15:27 -0400, John Snow wrote:
>
> On 8/14/19 6:07 AM, Vladimir Sementsov-Ogievskiy wrote:
> > To get rid of implicit filters related workarounds in future let's
> > deprecate them now.
> >
> > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
> > ---
> > qemu-deprecated.texi | 7 +++++++
> > qapi/block-core.json | 6 ++++--
> > include/block/block_int.h | 10 +++++++++-
> > blockdev.c | 10 ++++++++++
> > 4 files changed, 30 insertions(+), 3 deletions(-)
> >
> > diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
> > index 2753fafd0b..8222440148 100644
> > --- a/qemu-deprecated.texi
> > +++ b/qemu-deprecated.texi
> > @@ -183,6 +183,13 @@ the 'wait' field, which is only applicable to sockets in server mode
> >
> > Use blockdev-mirror and blockdev-backup instead.
> >
> > +@subsection implicit filters (since 4.2)
> > +
> > +Mirror and commit jobs inserts filters, which becomes implicit if user
> > +omitted filter-node-name parameter. So omitting it is deprecated, set it
> > +always. Note, that drive-mirror don't have this parameter, so it will
> > +create implicit filter anyway, but drive-mirror is deprecated itself too.
> > +
> > @section Human Monitor Protocol (HMP) commands
> >
> > @subsection The hub_id parameter of 'hostfwd_add' / 'hostfwd_remove' (since 3.1)
> > diff --git a/qapi/block-core.json b/qapi/block-core.json
> > index 4e35526634..0505ac9d8b 100644
> > --- a/qapi/block-core.json
> > +++ b/qapi/block-core.json
> > @@ -1596,7 +1596,8 @@
> > # @filter-node-name: the node name that should be assigned to the
> > # filter driver that the commit job inserts into the graph
> > # above @top. If this option is not given, a node name is
> > -# autogenerated. (Since: 2.9)
> > +# autogenerated. Omitting this option is deprecated, it will
> > +# be required in future. (Since: 2.9)
> > #
> > # @auto-finalize: When false, this job will wait in a PENDING state after it has
> > # finished its work, waiting for @block-job-finalize before
> > @@ -2249,7 +2250,8 @@
> > # @filter-node-name: the node name that should be assigned to the
> > # filter driver that the mirror job inserts into the graph
> > # above @device. If this option is not given, a node name is
> > -# autogenerated. (Since: 2.9)
> > +# autogenerated. Omitting this option is deprecated, it will
> > +# be required in future. (Since: 2.9)
> > #
> > # @copy-mode: when to copy data to the destination; defaults to 'background'
> > # (Since: 3.0)
> > diff --git a/include/block/block_int.h b/include/block/block_int.h
> > index 3aa1e832a8..624da0b4a2 100644
> > --- a/include/block/block_int.h
> > +++ b/include/block/block_int.h
> > @@ -762,7 +762,15 @@ struct BlockDriverState {
> > bool sg; /* if true, the device is a /dev/sg* */
> > bool probed; /* if true, format was probed rather than specified */
> > bool force_share; /* if true, always allow all shared permissions */
> > - bool implicit; /* if true, this filter node was automatically inserted */
> > +
> > + /*
> > + * @implicit field is deprecated, don't set it to true for new filters.
> > + * If true, this filter node was automatically inserted and user don't
> > + * know about it and unprepared for any effects of it. So, implicit
> > + * filters are workarounded and skipped in many places of the block
> > + * layer code.
> > + */
> > + bool implicit;
> >
> > BlockDriver *drv; /* NULL means no media */
> > void *opaque;
> > diff --git a/blockdev.c b/blockdev.c
> > index 36e9368e01..b3cfaccce1 100644
> > --- a/blockdev.c
> > +++ b/blockdev.c
> > @@ -3292,6 +3292,11 @@ void qmp_block_commit(bool has_job_id, const char *job_id, const char *device,
> > BlockdevOnError on_error = BLOCKDEV_ON_ERROR_REPORT;
> > int job_flags = JOB_DEFAULT;
> >
> > + if (!has_filter_node_name) {
> > + warn_report("Omitting filter-node-name parameter is deprecated, it "
> > + "will be required in future");
> > + }
> > +
> > if (!has_speed) {
> > speed = 0;
> > }
> > @@ -3990,6 +3995,11 @@ void qmp_blockdev_mirror(bool has_job_id, const char *job_id,
> > Error *local_err = NULL;
> > int ret;
> >
> > + if (!has_filter_node_name) {
> > + warn_report("Omitting filter-node-name parameter is deprecated, it "
> > + "will be required in future");
> > + }
> > +
> > bs = qmp_get_root_bs(device, errp);
> > if (!bs) {
> > return;
> >
>
> This might be OK to do right away, though.
>
> I asked Markus this not too long ago; do we want to amend the QAPI
> schema specification to allow commands to return with "Warning" strings,
> or "Deprecated" stings to allow in-band deprecation notices for cases
> like these?
>
> example:
>
> { "return": {},
> "deprecated": True,
> "warning": "Omitting filter-node-name parameter is deprecated, it will
> be required in the future"
> }
>
> There's no "error" key, so this should be recognized as success by
> compatible clients, but they'll definitely see the extra information.
>
> Part of my motivation is to facilitate a more aggressive deprecation of
> legacy features by ensuring that we are able to rigorously notify users
> through any means that they need to adjust their scripts.
>
> --js
>
This is a very good idea IMHO.
Best regards,
Maxim Levitsky
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