blkid reports disk as zfs_member if it has a zfs_member partition

[James Dingwall]

Upstream bug report: https://github.com/karelzak/util-linux/issues/918

In summary if a disk partition used for zfs is at the end of the disk then libblkid identifies the _whole_ disk as a zfs member which causes udev information returned for other partitions to be incorrect. blkid used directly reports the correct information.

# udevadm info /dev/sdb | grep ID_FS_TYPE
E: ID_FS_TYPE=zfs_member

# udevadm info /dev/sdb3 | grep ID_FS_TYPE
E: ID_FS_TYPE=zfs_member

# blkid /dev/sdb3
/dev/sdb3: UUID="4dcL2M-osmP-8MNF-kB3G-VobX-m1UX-aWGYk1" TYPE="LVM2_member" PARTLABEL="bootvg" PARTUUID="3abeebf9-9699-49c1-9e6e-039afb3b04a2"

# gdisk -l /dev/sdb
GPT fdisk (gdisk) version 1.0.3

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.
Disk /dev/sdb: 3907029168 sectors, 1.8 TiB
Model: HUS722T2TALA600
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): 45A8D0F8-D347-4D68-8DA1-72CDB2CCAC38
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 3907029134
Partitions will be aligned on 2048-sector boundaries
Total free space is 4205 sectors (2.1 MiB)

Number Start (sector) End (sector) Size Code Name
   1 2048 4095 1024.0 KiB EF02 BIOSBOOT
   2 4096 2099199 1023.0 MiB EF00 EFI_DATA
   3 2099200 3147775 512.0 MiB 8E00 vg1
   4 3147776 7342079 2.0 GiB 8E00 vg2
   5 7342080 11536383 2.0 GiB 0700 recovery
   6 11536384 3907029133 1.8 TiB BF01 ztank

This is fixed for me by rebuilding the util-linux patch and adding commit f6e182078a3f05af3ce3b5e5a2d1956d4b9677e2 from the upstream git tree. Once that is applied:

# udevadm info /dev/sdb | grep ID_FS_TYPE
(no output)

# udevadm info /dev/sdb3 | grep ID_FS_TYPE
E: ID_FS_TYPE=LVM2_member

This has been observed on Ubuntu bionic.

$ apt-cache policy util-linux
util-linux:
  Installed: 2.31.1-0.4ubuntu3.7
  Candidate: 2.31.1-0.4ubuntu3.7
  Version table:
 *** 2.31.1-0.4ubuntu3.7 500
        500 http://gb.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
        100 /var/lib/dpkg/status
     2.31.1-0.4ubuntu3 500
        500 http://gb.archive.ubuntu.com/ubuntu bionic/main amd64 Packages

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.5 LTS
Release: 18.04
Codename: bionic

On Ubuntu focal an ID_FS_TYPE is also incorrectly reported for the whole disk but the information for individual partitions seems to be correct although I don't have a system with same partition table from the example. I haven't yet tried with the util-linux patch in focal.

[James Dingwall (a-james-launchpad)]

See also: https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/1808421