Added initial support for SPDK v19.07

[tbykowsk]

This pull request introduces to Linstor a possibility to create a storage pool from SPDK lvol store, construct SPDK lvol bdev and expose it as SPDK nvmf subsystem.

How to start using it:

1. Download and compile SPDK v19.07
2. Setup SPDK
   spdk-19.07/scripts/setup.sh
3. Start SPDK nvmf_tgt
   spdk-19.07/app/nvmf_tgt/nvmf_tgt
4. Create SPDK nvme bdev from a drive
   spdk-19.07/scripts/rpc.py construct_nvme_bdev -b NVMe1 -t PCIe -a 0000:3e:00.0
5. Create SPDK lvol store on the nvme bdev
   spdk-19.07/scripts/rpc.py construct_lvol_store NVMe1n1 sample-lvol-store
6. Create a symlink to SPDK rpc.py script
   ln -s spdk-19.07/scripts/rpc.py /usr/bin/rpc.py
7. Start Linstor and create a SPDK storage pool and a resource from it

linstor node create sample-node 10.1.0.1 --node-type Combined
linstor storage-pool-definition create spdk-pool
linstor storage-pool create spdk sample-node spdk-pool sample-lvol-store
linstor resource-definition create sample-resource
linstor volume-definition create sample-resource 10G
linstor resource create --layer-list nvme,storage --storage-pool spdk-pool sample-node sample-resource

[ghernadi]

Thank you for the PR!

Here are some things that I discovered while quickly reviewing the code (not tested yet)

Major:
satellite/src/main/java/com/linbit/linstor/storage/layer/adapter/nvme/NvmeLayer.java: 133-140
getSingleChild() might return LuksRscData or other *Data from layers between nvme and storage
(in this case it might be a bit confusing that VlmLayerObject is extending VlmProviderObject).
To solve this issue you might want to use LayerRscUtils.getRscDataByProvider(rscLayerObject, DeviceLayerKind.STORAGE). However, usually it makes sense to at least briefly think about cases where one NVME-volume is composed of multiple STORAGE-volumes (things like these will come in future). It is OK if you say this layer only works if ALL NVME-volumes are SPDK (if not, fall back to normal NVMe logic). I dont think there is right now a "correct" solution - just keep things like this in mind.

Major:
/satellite/src/main/java/com/linbit/linstor/storage/layer/adapter/nvme/NvmeUtils.java: 56-57
Agreed, but we still cannot simply change that prefix that easily as that would break compatibility with already deployed nvme devices after upgrading linstor-satellite and restarting the satellite where the nvme devices still having the old names.

Minor:
/satellite/src/main/java/com/linbit/linstor/storage/layer/adapter/nvme/NvmeSpdkUtils.java: 160
error message states "Failed to create subsystem!", whereas the method just tried to delete the subsystem

[tbykowsk]

Thank you very much for the review!
Please verify if the issues have been resolved as you requested

[ghernadi]

This PR has been rebased on top of our master - the merge conflicts above can therefore be ignored.
SPDK support is included in v1.3.0