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lvm2/udev/69-dm-lvm.rules.in
David Teigland ee73875ff0 udev: ignore LVs containing PVs
If LVM LVs happen to contain PVs, they are passed to the lvm udev
rule for processing, where they should be ignored.  PVs on LVs
most likely belong to VM images, and don't belong to the host
which sees the LV.  It's unsafe for the host to use these PVs.
Without this change, the LV would be processed by pvscan which
would generally ignore it, either because of the devices file,
or because of the default lvm policy to not consider LVs as
potential PVs.  This change makes the udev rule consistent
with that policy and avoids the unnecessary system messages
produced when pvscan ignores the LV.
2024-02-08 14:51:46 -06:00

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# Copyright (C) 2012,2021 Red Hat, Inc. All rights reserved.
#
# This file is part of LVM.
#
# This rule requires blkid to be called on block devices before so only devices
# used as LVM PVs are processed (ID_FS_TYPE="LVM2_member").
SUBSYSTEM!="block", GOTO="lvm_end"
(LVM_EXEC_RULE)
ENV{DM_UDEV_DISABLE_OTHER_RULES_FLAG}=="1", GOTO="lvm_end"
# Ignore PVs on LVs.
# This is usually a case of an LV being used for a guest VM
# image, where the guest is using lvm. The host should
# ignore lvm data from the guest and not attempt to scan or
# activate guest PVs/LVs. (To enable functions in this file
# for PVs layered on LVs, set LVM_PVSCAN_ON_LVS="1" from a
# custom udev rule.)
ENV{ID_FS_TYPE}=="LVM2_member", ENV{DM_UUID}=="LVM-?*", ENV{LVM_PVSCAN_ON_LVS}!="1", GOTO="lvm_end"
# Only process devices already marked as a PV - this requires blkid to be called before.
ENV{ID_FS_TYPE}!="LVM2_member", GOTO="lvm_end"
ENV{DM_MULTIPATH_DEVICE_PATH}=="1", GOTO="lvm_end"
ACTION=="remove", GOTO="lvm_end"
# Create /dev/disk/by-id/lvm-pv-uuid-<PV_UUID> symlink for each PV
ENV{ID_FS_UUID_ENC}=="?*", SYMLINK+="disk/by-id/lvm-pv-uuid-$env{ID_FS_UUID_ENC}"
# If the PV is a special device listed below, scan only if the device is
# properly activated. These devices are not usable after an ADD event,
# but they require an extra setup and they are ready after a CHANGE event.
# Also support coldplugging with ADD event but only if the device is already
# properly activated.
# This logic should be eventually moved to rules where those particular
# devices are processed primarily (MD and loop).
# DM device:
KERNEL!="dm-[0-9]*", GOTO="next"
ENV{DM_UDEV_PRIMARY_SOURCE_FLAG}=="1", ENV{DM_ACTIVATION}=="1", GOTO="lvm_scan"
GOTO="lvm_end"
# MD device:
LABEL="next"
KERNEL!="md[0-9]*", GOTO="next"
IMPORT{db}="LVM_MD_PV_ACTIVATED"
ACTION=="add", ENV{LVM_MD_PV_ACTIVATED}=="1", GOTO="lvm_scan"
ACTION=="change", ENV{LVM_MD_PV_ACTIVATED}!="1", TEST=="md/array_state", ENV{LVM_MD_PV_ACTIVATED}="1", GOTO="lvm_scan"
ACTION=="add", KERNEL=="md[0-9]*p[0-9]*", GOTO="lvm_scan"
GOTO="lvm_end"
# Loop device:
LABEL="next"
KERNEL!="loop[0-9]*", GOTO="next"
ACTION=="add", ENV{LVM_LOOP_PV_ACTIVATED}=="1", GOTO="lvm_scan"
ACTION=="change", ENV{LVM_LOOP_PV_ACTIVATED}!="1", TEST=="loop/backing_file", ENV{LVM_LOOP_PV_ACTIVATED}="1", GOTO="lvm_scan"
GOTO="lvm_end"
LABEL="next"
ACTION!="add", GOTO="lvm_end"
LABEL="lvm_scan"
# pvscan will check if this device completes a VG,
# i.e. all PVs in the VG are now present with the
# arrival of this PV. If so, it prints to stdout:
# LVM_VG_NAME_COMPLETE='foo'
#
# When the VG is complete it can be activated, so
# vgchange -aay <vgname> is run. It is run via
# systemd since it can take longer to run than
# udev wants to block when processing rules.
# (if there are hundreds of LVs to activate,
# the vgchange can take many seconds.)
#
# pvscan only reads the single device specified,
# and uses temp files under /run/lvm to check if
# other PVs in the VG are present.
#
# If event_activation=0 in lvm.conf, this pvscan
# (using checkcomplete) will do nothing, so that
# no event-based autoactivation will be happen.
#
# TODO: adjust the output of vgchange -aay so that
# it's better suited to appearing in the journal.
IMPORT{program}="(LVM_EXEC)/lvm pvscan --cache --listvg --checkcomplete --vgonline --autoactivation event --udevoutput --journal=output $env{DEVNAME}"
ENV{LVM_VG_NAME_COMPLETE}=="?*", RUN+="(SYSTEMDRUN) --no-block --property DefaultDependencies=no --unit lvm-activate-$env{LVM_VG_NAME_COMPLETE} (LVM_EXEC)/lvm vgchange -aay --autoactivation event $env{LVM_VG_NAME_COMPLETE}"
GOTO="lvm_end"
LABEL="lvm_end"