fix(cleanup): ensure VDI is active before relink

[Wescoeur]

A VDI can have the JRN_RELINK tag which triggers a parent change, but this can fail with LVM driver if a host has been rebooted, in this situation the parent is not active. Before this fix:

Jan  2 16:01:16 xcp-host-1 SMGC: [3802739] Coalescing *85ff84a8[VHD](65.000G///33.836G|n) -> *cf4a78da[VHD](65.000G///52.555G|n)
Jan  2 16:01:16 xcp-host-1 SMGC: [3802739] ==> Coalesce apparently already done: skipping
Jan  2 16:01:16 xcp-host-1 SM: [3802739] lock: tried lock /var/lock/sm/1f74d512-a410-be6f-c816-8a1e43ea1801/sr, acquired: True (exists: True)
Jan  2 16:01:16 xcp-host-1 SMGC: [3802739] Got sm-config for 568e74bb[VHD](65.000G///65.133G|n): {'relinking': 'True', 'import_task': 'OpaqueRef:28d03111-0fee-0a21-e659-a1e90a1f3a91', 'vdi_type': 'vhd', 'vhd-parent': '85ff84a8-153a-4fff-9c59-0fbab710d373'}
Jan  2 16:01:16 xcp-host-1 SMGC: [3802739] Set relinking = True for 568e74bb[VHD](65.000G///65.133G|n)
Jan  2 16:01:16 xcp-host-1 SMGC: [3802739] Got sm-config for 568e74bb[VHD](65.000G///65.133G|n): {'relinking': 'True', 'import_task': 'OpaqueRef:28d03111-0fee-0a21-e659-a1e90a1f3a91', 'vdi_type': 'vhd', 'vhd-parent': '85ff84a8-153a-4fff-9c59-0fbab710d373'}
Jan  2 16:01:16 xcp-host-1 SMGC: [3802739] Got sm-config for dd9c344a[VHD](65.000G///8.000M|n): {'relinking': 'True', 'import_task': 'OpaqueRef:28d03111-0fee-0a21-e659-a1e90a1f3a91', 'vdi_type': 'vhd', 'vhd-parent': '85ff84a8-153a-4fff-9c59-0fbab710d373'}
Jan  2 16:01:16 xcp-host-1 SMGC: [3802739] Set relinking = True for dd9c344a[VHD](65.000G///8.000M|n)
Jan  2 16:01:16 xcp-host-1 SMGC: [3802739] Got sm-config for dd9c344a[VHD](65.000G///8.000M|n): {'relinking': 'True', 'import_task': 'OpaqueRef:28d03111-0fee-0a21-e659-a1e90a1f3a91', 'vdi_type': 'vhd', 'vhd-parent': '85ff84a8-153a-4fff-9c59-0fbab710d373'}
Jan  2 16:01:16 xcp-host-1 SM: [3802739] LVMCache: refreshing
Jan  2 16:01:16 xcp-host-1 fairlock[3906]: /run/fairlock/devicemapper acquired
Jan  2 16:01:16 xcp-host-1 fairlock[3906]: /run/fairlock/devicemapper sent '3802739 - 20917096.949649855-'
Jan  2 16:01:16 xcp-host-1 SM: [3802739] ['/sbin/lvs', '--noheadings', '--units', 'b', '-o', '+lv_tags', '/dev/VG_XenStorage-1f74d512-a410-be6f-c816-8a1e43ea1801']
Jan  2 16:01:16 xcp-host-1 SM: [3802739]   pread SUCCESS
Jan  2 16:01:16 xcp-host-1 fairlock[3906]: /run/fairlock/devicemapper released
Jan  2 16:01:16 xcp-host-1 SM: [3802739] ['/usr/bin/vhd-util', 'scan', '-f', '-m', 'VHD-*', '-l', 'VG_XenStorage-1f74d512-a410-be6f-c816-8a1e43ea1801']
Jan  2 16:01:18 xcp-host-1 SM: [3802739]   pread SUCCESS
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739] SR 1f74 ('sr001-clu001-tdeaz-az07-svc-data23') (538 VDIs in 68 VHD trees): no changes
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]   Relinking 568e74bb[VHD](65.000G///65.133G|n) from *85ff84a8[VHD](65.000G///33.836G|n) to *cf4a78da[VHD](65.000G///52.555G|n)
Jan  2 16:01:18 xcp-host-1 SM: [3802739] lock: opening lock file /var/lock/sm/lvm-1f74d512-a410-be6f-c816-8a1e43ea1801/568e74bb-3eab-4e15-974a-a34a4bf7d779
Jan  2 16:01:18 xcp-host-1 SM: [3802739] lock: acquired /var/lock/sm/lvm-1f74d512-a410-be6f-c816-8a1e43ea1801/568e74bb-3eab-4e15-974a-a34a4bf7d779
Jan  2 16:01:18 xcp-host-1 SM: [3802739] Refcount for lvm-1f74d512-a410-be6f-c816-8a1e43ea1801:568e74bb-3eab-4e15-974a-a34a4bf7d779 (0, 0) + (1, 0) => (1, 0)
Jan  2 16:01:18 xcp-host-1 SM: [3802739] Refcount for lvm-1f74d512-a410-be6f-c816-8a1e43ea1801:568e74bb-3eab-4e15-974a-a34a4bf7d779 set => (1, 0b)
Jan  2 16:01:18 xcp-host-1 fairlock[3906]: /run/fairlock/devicemapper acquired
Jan  2 16:01:18 xcp-host-1 SM: [3802739] ['/sbin/lvchange', '-ay', '/dev/VG_XenStorage-1f74d512-a410-be6f-c816-8a1e43ea1801/VHD-568e74bb-3eab-4e15-974a-a34a4bf7d779']
Jan  2 16:01:18 xcp-host-1 fairlock[3906]: /run/fairlock/devicemapper sent '3802739 - 20917099.141269115-'
Jan  2 16:01:18 xcp-host-1 SM: [3802739]   pread SUCCESS
Jan  2 16:01:18 xcp-host-1 fairlock[3906]: /run/fairlock/devicemapper released
Jan  2 16:01:18 xcp-host-1 SM: [3802739] lock: released /var/lock/sm/lvm-1f74d512-a410-be6f-c816-8a1e43ea1801/568e74bb-3eab-4e15-974a-a34a4bf7d779
Jan  2 16:01:18 xcp-host-1 SM: [3802739] ['/usr/bin/vhd-util', 'modify', '--debug', '-p', '/dev/VG_XenStorage-1f74d512-a410-be6f-c816-8a1e43ea1801/VHD-cf4a78da-316f-4fd9-a82d-07a47c142a39', '-n', '/dev/VG_XenStorage-1f74d512-a410-be6f-c816-8a1e43ea1801/VHD-568e74bb-3eab-4e15-974a-a34a4bf7d779']
Jan  2 16:01:18 xcp-host-1 SM: [3802739] FAILED in util.pread: (rc 2) stdout: 'failed to set parent to '/dev/VG_XenStorage-1f74d512-a410-be6f-c816-8a1e43ea1801/VHD-cf4a78da-316f-4fd9-a82d-07a47c142a39': -2
Jan  2 16:01:18 xcp-host-1 SM: [3802739] ', stderr: ''
Jan  2 16:01:18 xcp-host-1 SM: [3802739] lock: released /var/lock/sm/1f74d512-a410-be6f-c816-8a1e43ea1801/sr
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739] *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]          ***********************
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]          *  E X C E P T I O N  *
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]          ***********************
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739] coalesce: EXCEPTION <class 'util.CommandException'>, No such file or directory
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]   File "/opt/xensource/sm/cleanup.py", line 2024, in coalesce
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]     self._coalesce(vdi)
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]   File "/opt/xensource/sm/cleanup.py", line 2228, in _coalesce
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]     vdi._relinkSkip()
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]   File "/opt/xensource/sm/cleanup.py", line 963, in _relinkSkip
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]     child._setParent(self.parent)
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]   File "/opt/xensource/sm/cleanup.py", line 1396, in _setParent
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]     vhdutil.setParent(self.path, parent.path, parent.raw)
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]   File "/opt/xensource/sm/vhdutil.py", line 215, in setParent
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]     ioretry(cmd)
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]   File "/opt/xensource/sm/vhdutil.py", line 94, in ioretry
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]     errlist=[errno.EIO, errno.EAGAIN])
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]   File "/opt/xensource/sm/util.py", line 347, in ioretry
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]     return f()
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]   File "/opt/xensource/sm/vhdutil.py", line 93, in <lambda>
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]     return util.ioretry(lambda: util.pread2(cmd, text=text),
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]   File "/opt/xensource/sm/util.py", line 255, in pread2
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]     return pread(cmdlist, quiet=quiet, text=text)
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]   File "/opt/xensource/sm/util.py", line 217, in pread
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]     raise CommandException(rc, str(cmdlist), stderr.strip())
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739]
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739] *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jan  2 16:01:18 xcp-host-1 SMGC: [3802739] Coalesce failed, skipping