Exclude tapdev and xvd block devices from SR disk selection

The lsblk-based SR disk discovery now filters by device major number,
excluding tapdev (254) and xvd (202) device types.

tapdev devices are used internally by the host storage stack and should
never be selected for SR creation — they are not physical disks.
xvd devices are Xen virtual block devices that appear when a VM or the
dom0 itself has attached virtual disks; they are not suitable as SR
backing storage either.

Without this filter, a host running as a VM (nested virtualization
scenario) or a host with active tapdisk mappings could report xvd
or tapdev devices as candidate disks, causing SR creation on an
inappropriate backing device.

Signed-off-by: Gaëtan Lehmann <gaetan.lehmann@vates.tech>

Author: glehmann

lib/host.py

@@ -701,10 +701,33 @@ def rescan_block_devices_info(self) -> None:
         RAID_TYPES = {'raid0', 'raid1', 'raid4', 'raid5', 'raid6', 'raid10', 'linear'}
         USED_TYPES = RAID_TYPES | {'lvm', 'mpath', 'crypt'}
         LSBLK_FIELDS = 'NAME,KNAME,PKNAME,SIZE,LOG-SEC,TYPE,MOUNTPOINT,WWN'
+        # The device major numbers we have on an xcp-ng host, except 254 (tapdev) and 202 (xvd)
+        # From /dev/devices:
+        #   8 sd
+        #   9 md
+        #  65 sd
+        #  66 sd
+        #  67 sd
+        #  68 sd
+        #  69 sd
+        #  70 sd
+        #  71 sd
+        # 128 sd
+        # 129 sd
+        # 130 sd
+        # 131 sd
+        # 132 sd
+        # 133 sd
+        # 134 sd
+        # 135 sd
+        # 252 mdp
+        # 253 device-mapper
+        # 259 blkext
+        LSBLK_MAJOR_NUMBERS = '8,9,65,66,67,68,69,70,71,128,129,130,131,132,133,134,135,252,253,259'
 
         devices: list[Host.BlockDeviceInfo] = []
 
-        raw = self.ssh(f'lsblk --pairs --bytes --output {LSBLK_FIELDS}')
+        raw = self.ssh(f'lsblk --pairs --bytes --output {LSBLK_FIELDS} --include {LSBLK_MAJOR_NUMBERS}')
 
         def _split_keys(line: str) -> list[tuple[str, str]]:
             return re.findall(r'(\S+)=(".*?"|\S+)', line)