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* block: rename backup-top to copy-before-writeVladimir Sementsov-Ogievskiy2021-09-011-42/+0Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We are going to convert backup_top to full featured public filter, which can be used in separate of backup job. Start from renaming from "how it used" to "what it does". While updating comments in 283 iotest, drop and rephrase also things about ".active", as this field is now dropped, and filter doesn't have "inactive" mode. Note that this change may be considered as incompatible interface change, as backup-top filter format name was visible through query-block and query-named-block-nodes. Still, consider the following reasoning: 1. backup-top was never documented, so if someone depends on format name (for driver that can't be used other than it is automatically inserted on backup job start), it's a kind of "undocumented feature use". So I think we are free to change it. 2. There is a hope, that there is no such users: it's a lot more native to give a good node-name to backup-top filter if need to operate with it somehow, and don't touch format name. 3. Another "incompatible" change in further commit would be moving copy-before-write filter from using backing child to file child. And this is even more reasonable than renaming: for now all public filters are file-child based. So, it's a risky change, but risk seems small and good interface worth it. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-Id: <20210824083856.17408-6-vsementsov@virtuozzo.com> Signed-off-by: Hanna Reitz <hreitz@redhat.com>
* qapi: backup: add perf.use-copy-range parameterVladimir Sementsov-Ogievskiy2021-01-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Experiments show, that copy_range is not always making things faster. So, to make experimentation simpler, let's add a parameter. Some more perf parameters will be added soon, so here is a new struct. For now, add new backup qmp parameter with x- prefix for the following reasons: - We are going to add more performance parameters, some will be related to the whole block-copy process, some only to background copying in backup (ignored for copy-before-write operations). - On the other hand, we are going to use block-copy interface in other block jobs, which will need performance options as well.. And it should be the same structure or at least somehow related. So, there are too much unclean things about how the interface and now we need the new options mostly for testing. Let's keep them experimental for a while. In do_backup_common() new x-perf parameter handled in a way to make further options addition simpler. We add use-copy-range with default=true, and we'll change the default in further patch, after moving backup to use block-copy. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-Id: <20210116214705.822267-2-vsementsov@virtuozzo.com> [mreitz: s/5\.2/6.0/] Signed-off-by: Max Reitz <mreitz@redhat.com>
* block: introduce backup-top filter driverVladimir Sementsov-Ogievskiy2019-10-101-0/+41
Backup-top filter caches write operations and does copy-before-write operations. The driver will be used in backup instead of write-notifiers. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-id: 20191001131409.14202-5-vsementsov@virtuozzo.com Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>