[ovirt-devel] Why we don't call "blockPull" to merge snapshot(base to top) in vdsm?

[pengyixiang]

hello, everyone!
      We create a snapshot chain as follows map [1], if we delete "Snapshot1", it will call [2] in vdsm, in last, "virsh blockcommit' will be called,
but if we delete "Snapshot2", it will call [3] in vdsm, what the "sdm.api.merge.Job" means?  And I can find"blockCommit" used in vdsm by [4],
rather than "blockPull" is not used as [5], why we don't use it to merge snapshot to topVolume?








[1]


[2] https://github.com/oVirt/vdsm/blob/2b98daffb2c2dec1bbbd3427d3d32861d77f01a7/lib/vdsm/virt/vm.py#L5744


[3] https://github.com/oVirt/vdsm/blob/98e6a5d1ad1b097b9c993dca33372f970a3adce4/lib/vdsm/API.py#L1655
[4]
$ grep -nR "blockCommit"
lib/vdsm/api/vdsm-api.yml:287:            commit: A blockCommit operation (backward
lib/vdsm/api/vdsm-api.html:2413:<tr><td class="attrlist">commit</td><td class="attrlist"></td><td class="attrlist">A blockCommit operation (backward merge)</td></tr>
vdsm/virt/vm.py:4909:                ret = self._dom.blockCommit(drive.path, base, top, bandwidth,
vdsm/virt/vm.py:4912:                    raise RuntimeError("blockCommit failed rc:%i", ret)
vdsm/virt/vm.py:4918:        # blockCommit will cause data to be written into the base volume.
vdsm/virt/vm.py:5238:        # volume automatically as part of the blockCommit operation.  Update


[5]
$ grep -nR "blockPull"
lib/vdsm/api/vdsm-api.yml:290:            pull: A blockPull operation (forward merge)
lib/vdsm/api/vdsm-api.html:2412:<tr><td class="attrlist">pull</td><td class="attrlist"></td><td class="attrlist">A blockPull operation (forward merge)</td></tr>








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