fix: skip in-use loop devices during vgcreate/vgextend

[leelavg]

• filter out loop devices based on Major number from lsblk
• check whether the back-file is being used by k8s for mounting block
  devices and skip using that loop device in volume groups ops

Fixes: #97

Signed-off-by: Leela Venkaiah G [email protected]

[leelavg]

• well, the fix itself is working, just felt that FilterMap got kinda ugly and want to test some more cases, so made PR as draft
• however PR is re-viewable, below is the log showing how devices are skipped if they are mounted by k8s

{"level":"info","ts":1645098272.500616,"logger":"controller.lvmvolumegroup.vg-manager","msg":"does not match filter","reconciler group":"lvm.topolvm.io","reconciler kind":"LVMVolumeGroup","name":"test","namespace":"lvm-operator-system","Device.Name":"loop1","filter.Name":"usableLoopDevice"}
{"level":"info","ts":1645098272.5372882,"logger":"controller.lvmvolumegroup.vg-manager","msg":"does not match filter","reconciler group":"lvm.topolvm.io","reconciler kind":"LVMVolumeGroup","name":"test","namespace":"lvm-operator-system","Device.Name":"loop2","filter.Name":"usableLoopDevice"}
{"level":"info","ts":1645098272.5835214,"logger":"controller.lvmvolumegroup.vg-manager","msg":"does not match filter","reconciler group":"lvm.topolvm.io","reconciler kind":"LVMVolumeGroup","name":"test","namespace":"lvm-operator-system","Device.Name":"loop3","filter.Name":"usableLoopDevice"}

[leelavg]

• tested locally

# before restart of vg-manager
sh-4.4# vgs
  VG   #PV #LV #SN Attr   VSize  VFree 
  test   3  10   0 wz--n- <4.37t <3.39t
sh-4.4# pvs
  PV           VG   Fmt  Attr PSize  PFree  
  /dev/nvme0n1 test lvm2 a--  <1.46t 490.41g
  /dev/nvme1n1 test lvm2 a--  <1.46t  <1.46t
  /dev/nvme2n1 test lvm2 a--  <1.46t  <1.46t

# after restart of vg-manager with 5 in-use loop devices and 1 usable loop devices and so vg is extended correctly
sh-4.4# pvs  
  PV           VG   Fmt  Attr PSize  PFree  
  /dev/loop5   test lvm2 a--  <5.00g  <5.00g
  /dev/nvme0n1 test lvm2 a--  <1.46t 490.41g
  /dev/nvme1n1 test lvm2 a--  <1.46t  <1.46t
  /dev/nvme2n1 test lvm2 a--  <1.46t  <1.46t
sh-4.4# vgs
  VG   #PV #LV #SN Attr   VSize VFree
  test   4  10   0 wz--n- 4.37t 3.39t

sh-4.4# lsblk
NAME                                            MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
loop0                                             7:0    0   100G  0 loop 
loop1                                             7:1    0   100G  0 loop 
loop2                                             7:2    0   100G  0 loop 
loop3                                             7:3    0   100G  0 loop 
loop4                                             7:4    0   100G  0 loop 
loop5                                             7:5    0     5G  0 loop 
sdb                                               8:16   0 893.8G  0 disk 
|-sdb1                                            8:17   0     1M  0 part 
|-sdb2                                            8:18   0   127M  0 part 
|-sdb3                                            8:19   0   384M  0 part /boot
`-sdb4                                            8:20   0 893.3G  0 part /sysroot
sr0                                              11:0    1   987M  0 rom  
nvme0n1                                         259:0    0   1.5T  0 disk 
|-test-6777f3ec--40de--4e8d--ac55--d32b71f7819a 253:0    0   100G  0 lvm  
|-test-ca957a21--0ae2--4b05--9e14--2896b38a0fd7 253:1    0   100G  0 lvm  
|-test-7901dd21--4942--4f1c--945c--7e5d23e49d01 253:2    0   100G  0 lvm  
|-test-32d72da7--580f--4c59--a9ef--5eed39ff139e 253:3    0   100G  0 lvm  
|-test-3e617cc8--c26f--40ac--9460--214421330e7a 253:4    0   100G  0 lvm  
|-test-6251c743--7326--4c96--9724--3eb34a667087 253:5    0   100G  0 lvm  
|-test-0681a68f--94bb--484d--add5--2f72e2859978 253:6    0   100G  0 lvm  
|-test-cfd826d7--cc8f--4ea8--9dbe--3b27904671c5 253:7    0   100G  0 lvm  
|-test-9d4aa183--72fc--441a--a577--59e4ff4c0f94 253:8    0   100G  0 lvm  
`-test-9cd06305--96a3--4b90--8080--01f45b0fa4e0 253:9    0   100G  0 lvm  
nvme1n1                                         259:1    0   1.5T  0 disk 
nvme2n1                                         259:2    0   1.5T  0 disk 

[sp98]

nit

[leelavg]

• Tested again below scenarios

1. An usable loop devices exists before vg-manager comes up and reboot vg-manager without creating block PVCs
2. An usable and unusable loop devices exist after vg-manager reboot
3. General, no loop devices before vg-manager comes up

[leelavg]

• btw, losetup already exists in the operator due to installation of util-linux

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: leelavg, nbalacha, sp98

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[leelavg]

/cherry-pick release-4.10

[openshift-cherrypick-robot]

@leelavg: new pull request created: #122

In response to this:

/cherry-pick release-4.10

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