Re: [libvirt] [Qemu-devel] [PATCH 2/2] qapi: deprecate implicit filters

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(a)virtuozzo.com&gt; > --- > 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.