disk: align LVM2 volumes to the extent size #3137
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thozza
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Extract a `CreateLogicalVolume` method from `CreateMountpoint` and implement the latter via the former. This makes it possible to create a Logical Volume for an existing payload.
When the size of a logical volume is not aligned to the extent size of the volume group, LVM2 will automatically align it by rounding up[1]: Rounding up size to full physical extent 29.80 GiB Rounding up size to full physical extent <3.82 GiB Since we don't take that into account when we create a new volume or set the size of an existing one, the size for the whole volume group will be short by that amount and thus the creation of the last volume will fail: Volume group <uuid> has insufficient free space (975 extents): 977 required. To fix this a new `AlignUp` method is added to the `MountpointCreator` creator interface. It will align a given size to the requirements of the implementing container, like e.g. `LVMVolumeGroup`. It is then used by a new `alignEntityBranch` which takes a size and walks the entity path, calling `AlignUp` for all entities that implement said `MountpointCreator` interface; thus the resulting size should fullfil the alignment requirement for all elements in the path. NB: `PartitionTable` already had an `AlignUp` method. Add a corresponding test. [1]: https://github.com/lvmteam/lvm2/blob/868665766491d9d42b8acedaf07cafc7118d165c/lib/metadata/metadata.c#L1072 Co-authored-by: Achilleas Koutsou <achilleas@koutsou.net>
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When the size of a logical volume is not aligned to the extent size of the volume group, LVM2 will automatically align it by rounding up (see metadata.c):
Since we don't take that into account when we create a new volume or set the size of an existing one, the size for the whole volume group will be short by that amount and thus the creation of the last volume
will fail:
To fix this a new
AlignUpmethod is added to theMountpointCreatorcreator interface. It will align a given size to the requirements of the implementing container, like e.g.LVMVolumeGroup. It is then used by a newalignEntityBranchwhich takes a size and walks the entity path, callingAlignUpfor all entities that implement saidMountpointCreatorinterface; thus the resulting size should fullfil the alignment requirement for all elements in the path. NB:PartitionTablealready had anAlignUpmethod.Add a corresponding test.