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Wed, 1 Sep 2021 13:47:54 +0200 (CEST) From: Markus Armbruster To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH v2 18/19] qapi: backup: add immutable-source parameter References: <20210827181808.311670-1-vsementsov@virtuozzo.com> <20210827181808.311670-19-vsementsov@virtuozzo.com> Date: Wed, 01 Sep 2021 13:47:54 +0200 In-Reply-To: <20210827181808.311670-19-vsementsov@virtuozzo.com> (Vladimir Sementsov-Ogievskiy's message of "Fri, 27 Aug 2021 21:18:07 +0300") Message-ID: <8735qobjpx.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Received-SPF: pass client-ip=216.205.24.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.392, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-block@nongnu.org, wencongyang2@huawei.com, xiechanglong.d@gmail.com, qemu-devel@nongnu.org, jsnow@redhat.com, hreitz@redhat.com, eblake@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Vladimir Sementsov-Ogievskiy writes: > We are on the way to implement internal-backup with fleecing scheme, > which includes backup job copying from fleecing block driver node > (which is target of copy-before-write filter) to final target of > backup. This job doesn't need own filter, as fleecing block driver node > is a kind of snapshot, it's immutable from reader point of view. > > Let's add a parameter for backup to not insert filter but instead > unshare writes on source. This way backup job becomes a simple copying > process. > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > qapi/block-core.json | 12 +++++++- > include/block/block_int.h | 1 + > block/backup.c | 61 +++++++++++++++++++++++++++++++++++---- > block/replication.c | 2 +- > blockdev.c | 1 + > 5 files changed, 70 insertions(+), 7 deletions(-) > > diff --git a/qapi/block-core.json b/qapi/block-core.json > index 8a333136f5..995ca16a5e 100644 > --- a/qapi/block-core.json > +++ b/qapi/block-core.json > @@ -1391,6 +1391,15 @@ > # above node specified by @drive. If this option is not given, > # a node name is autogenerated. (Since: 4.2) > # > +# @immutable-source: If true, assume source is immutable and don't insert filter Suggest comma after immutable. > +# as no copy-before-write operations are needed. It will > +# fail if there are existing writers on source node, as well, > +# any attempt to add writer to source node during backup will > +# fail. @filter-node-name must not be set. Suggest to split the sentence like "... fail if there are existing writers on source node. Any attempt ... will also fail." > +# If false, insert copy-before-write filter above source node > +# (see also @filter-node-name parameter). > +# Default is false. (Since 6.2) > +# > # @x-perf: Performance options. (Since 6.0) > # > # Note: @on-source-error and @on-target-error only affect background > @@ -1407,7 +1416,8 @@ > '*on-source-error': 'BlockdevOnError', > '*on-target-error': 'BlockdevOnError', > '*auto-finalize': 'bool', '*auto-dismiss': 'bool', > - '*filter-node-name': 'str', '*x-perf': 'BackupPerf' } } > + '*filter-node-name': 'str', '*immutable-source': 'bool', > + '*x-perf': 'BackupPerf' } } > > ## > # @DriveBackup: [...]