Hi,
I'm seeing this bug in a different usecase on Debian Bookworm with LVM
2.03.16-2: multipath is set up, the multipath device is an LVM
physical volume in a volume group with a thin pool. To prevent LVM from
picking up on the multipath components, /etc/lvm/lvm.conf has a
global_filter that rejects the multipath components by matching on their
/dev/disk/by-id symlink paths.
I have replicated this setup in a VM, with the following global_filter
in /etc/lvm/lvm.conf:
devices {
global_filter=["r|/dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_drive-scsi1|","r|/dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_drive-scsi2|"]
}
The relevant portion of /dev/disk/by-id:
lrwxrwxrwx 1 root root 9 Aug 29 16:31
scsi-0QEMU_QEMU_HARDDISK_drive-scsi1 -> ../../sdb
lrwxrwxrwx 1 root root 9 Aug 29 16:31
scsi-0QEMU_QEMU_HARDDISK_drive-scsi2 -> ../../sdc
After running update-initramfs and rebooting, pvs and other LVM
tooling reports the following warning:
# pvs
WARNING: Device mismatch detected for somegroup/somethinpool_tmeta
which is accessing /dev/sdb instead of /dev/mapper/mpatha.
WARNING: Device mismatch detected for somegroup/somethinpool_tdata
which is accessing /dev/sdb instead of /dev/mapper/mpatha.
PV VG Fmt Attr PSize PFree
/dev/mapper/mpatha somegroup lvm2 a-- <4.00g <2.99g
>From reading this report and the now-resolved upstream report, this
seems to happen because the /dev/disk/by-id symlinks are not available
by the time the LVM udev hooks run, so the r|...| filters do not have
any effect. Indeed, if I use r|/dev/sdb| and r|/dev/sdc| instead, run
update-initramfs and reboot, the warning does not appear anymore.
However, being able to use the /dev/disk/by-id paths would be preferable.
With the following four patches applied, I can use /dev/disk/by-id in
the filters and the warning does not appear:
https://sourceware.org/git/?p=lvm2.git;a=commit;h=17a3585cbb55d9a15ced9775a18b50c53a50ee8e
https://sourceware.org/git/?p=lvm2.git;a=commit;h=c9fdc828ff0504bc2e57f65862bc382f7663a8a2
https://sourceware.org/git/?p=lvm2.git;a=commit;h=6d14144d311fb347e4225ad6a48d4900b39445c4
https://sourceware.org/git/?p=lvm2.git;a=commit;h=bd05318ba2fc588be6339f5dc61f09195996b0e9
The first three patches are mentioned in the upstream bug report [1] and
cause pvscan to read symlink names from udev's DEVLINKS environment
variable under certain conditions. One of the conditions is that at
least one of the filter regexes refer to a symlink. However, this check
only considers a|...| filters [2], so it doesn't trigger if only r|...|
filters are used as above. Hence, in my case the fourth patch is also
needed, as it removes the filter regex check altogether.
Is there a chance the patches could be backported? All four patches seem
to be included in upstream release 2.03.19 [3].
Happy to provide any more information if needed!
Thanks and best wishes,
Friedrich
[1] https://github.com/lvmteam/lvm2/issues/104
[2]
https://sourceware.org/git/?p=lvm2.git;a=blob;f=lib/filters/filter-regex.c;h=ecc32914b0e15ba9cbac5c101cffddf25eddd8ad;hb=6d14144d311fb347e4225ad6a48d4900b39445c4#l272
[3] https://sourceware.org/git/?p=lvm2.git;a=shortlog;h=refs/tags/v2_03_19
