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lvm2/udev/10-dm.rules.in
Zdenek Kabelac 0e29db4a51 Update udev rules to skip DM flags decoding for removed devices
Skip decoding of DM flags when device is removed.

We currently need DM flags only for add|change events. So forking
dmsetup process for removed devices is a waste of CPU time.

Udev is already quite slow, so make it just a tiny bit faster.
2011-08-11 17:55:29 +00:00

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# Copyright (C) 2009 Red Hat, Inc. All rights reserved.
#
# This file is part of LVM2.
# Udev rules for device-mapper devices.
#
# These rules create a DM control node in /dev/(DM_DIR) directory.
# The rules also create nodes named dm-x (x is a number) in /dev
# directory and symlinks to these nodes with names given by
# the actual DM names. Some udev environment variables are set
# for use in later rules:
# DM_NAME - actual DM device's name
# DM_UUID - UUID set for DM device (blank if not specified)
# DM_SUSPENDED - suspended state of DM device (0 or 1)
# DM_UDEV_RULES_VSN - DM udev rules version
KERNEL=="device-mapper", NAME="(DM_DIR)/control"
SUBSYSTEM!="block", GOTO="dm_end"
KERNEL!="dm-[0-9]*", GOTO="dm_end"
# Set proper sbin path, /sbin has higher priority than /usr/sbin.
ENV{DM_SBIN_PATH}="/sbin"
TEST!="$env{DM_SBIN_PATH}/dmsetup", ENV{DM_SBIN_PATH}="/usr/sbin"
TEST!="$env{DM_SBIN_PATH}/dmsetup", GOTO="dm_end"
# Device created, major and minor number assigned - "add" event generated.
# Table loaded - no event generated.
# Device resumed (or renamed) - "change" event generated.
# Device removed - "remove" event generated.
#
# The dm-X nodes are always created, even on "add" event, we can't suppress
# that (the node is created even earlier with devtmpfs). All the symlinks
# (e.g. /dev/mapper) are created in right time after a device has its table
# loaded and is properly resumed. For this reason, direct use of dm-X nodes
# is not recommended.
ACTION!="add|change", GOTO="dm_end"
# Decode udev control flags and set environment variables appropriately.
# These flags are encoded in DM_COOKIE variable that was introduced in
# kernel version 2.6.31. Therefore, we can use this feature with
# kernels >= 2.6.31 only. Cookie is not decoded for remove event.
ENV{DM_COOKIE}=="?*", IMPORT{program}="$env{DM_SBIN_PATH}/dmsetup udevflags $env{DM_COOKIE}"
# Rule out easy-to-detect inappropriate events first.
ENV{DISK_RO}=="1", GOTO="dm_disable"
# There is no cookie set nor any flags encoded in events not originating
# in libdevmapper so we need to detect this and try to behave correctly.
# For such spurious events, regenerate all flags from current udev database content
# (this information would normally be inaccessible for spurious ADD and CHANGE events).
ENV{DM_UDEV_PRIMARY_SOURCE_FLAG}=="1", GOTO="dm_flags_done"
IMPORT{db}="DM_UDEV_DISABLE_DM_RULES_FLAG"
IMPORT{db}="DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG"
IMPORT{db}="DM_UDEV_DISABLE_DISK_RULES_FLAG"
IMPORT{db}="DM_UDEV_DISABLE_OTHER_RULES_FLAG"
IMPORT{db}="DM_UDEV_LOW_PRIORITY_FLAG"
IMPORT{db}="DM_UDEV_DISABLE_LIBRARY_FALLBACK_FLAG"
IMPORT{db}="DM_UDEV_PRIMARY_SOURCE_FLAG"
IMPORT{db}="DM_UDEV_FLAG7"
IMPORT{db}="DM_SUBSYSTEM_UDEV_FLAG0"
IMPORT{db}="DM_SUBSYSTEM_UDEV_FLAG1"
IMPORT{db}="DM_SUBSYSTEM_UDEV_FLAG2"
IMPORT{db}="DM_SUBSYSTEM_UDEV_FLAG3"
IMPORT{db}="DM_SUBSYSTEM_UDEV_FLAG4"
IMPORT{db}="DM_SUBSYSTEM_UDEV_FLAG5"
IMPORT{db}="DM_SUBSYSTEM_UDEV_FLAG6"
IMPORT{db}="DM_SUBSYSTEM_UDEV_FLAG7"
IMPORT{db}="DM_UDEV_RULES_VSN"
LABEL="dm_flags_done"
# Normally, we operate on "change" events. But when coldplugging, there's an
# "add" event present. We have to recognize this and do our actions in this
# particular situation, too. Also, we don't want the nodes to be created
# prematurely on "add" events while not coldplugging. We check
# DM_UDEV_PRIMARY_SOURCE_FLAG to see if the device was activated correctly
# before and if not, we ignore the "add" event totally. This way we can support
# udev triggers generating "add" events (e.g. "udevadm trigger --action=add" or
# "echo add > /sys/block/<dm_device>/uevent"). The trigger with "add" event is
# also used at boot to reevaluate udev rules for all existing devices activated
# before (e.g. in initrd). If udev is used in initrd, we require the udev init
# script to not remove the existing udev database so we can reuse the information
# stored at the time of device activation in the initrd.
ACTION=="add", ENV{DM_UDEV_RULES_VSN}!="1", ENV{DM_UDEV_PRIMARY_SOURCE_FLAG}!="1", GOTO="dm_disable"
# "dm" sysfs subdirectory is available in newer versions of DM
# only (kernels >= 2.6.29). We have to check for its existence
# and use dmsetup tool instead to get the DM name, uuid and
# suspended state if the "dm" subdirectory is not present.
# The "suspended" item was added even later (kernels >= 2.6.31),
# so we also have to call dmsetup if the kernel version used
# is in between these releases.
TEST=="dm", ENV{DM_NAME}="$attr{dm/name}", ENV{DM_UUID}="$attr{dm/uuid}", ENV{DM_SUSPENDED}="$attr{dm/suspended}"
TEST!="dm", IMPORT{program}="$env{DM_SBIN_PATH}/dmsetup info -j %M -m %m -c --nameprefixes --noheadings --rows -o name,uuid,suspended"
ENV{DM_SUSPENDED}!="?*", IMPORT{program}="$env{DM_SBIN_PATH}/dmsetup info -j %M -m %m -c --nameprefixes --noheadings --rows -o suspended"
# dmsetup tool provides suspended state information in textual
# form with values "Suspended"/"Active". We translate it to
# 0/1 respectively to be consistent with sysfs values.
ENV{DM_SUSPENDED}=="Active", ENV{DM_SUSPENDED}="0"
ENV{DM_SUSPENDED}=="Suspended", ENV{DM_SUSPENDED}="1"
# This variable provides a reliable way to check that device-mapper
# rules were installed. It means that all needed variables are set
# by these rules directly so there's no need to acquire them again
# later. Other rules can alternate the functionality based on this
# fact (e.g. fallback to rules that behave correctly even without
# these rules installed). It also provides versioning for any
# possible future changes.
# VSN 1 - original rules
# VSN 2 - add support for synthesized events
ENV{DM_UDEV_RULES_VSN}="2"
ENV{DM_UDEV_DISABLE_DM_RULES_FLAG}!="1", ENV{DM_NAME}=="?*", SYMLINK+="(DM_DIR)/$env{DM_NAME}"
# We have to ignore further rule application for inappropriate events
# and devices. But still send the notification if cookie exists.
ENV{DM_UUID}=="mpath-?*", ENV{DM_ACTION}=="PATH_FAILED", GOTO="dm_disable"
ENV{DM_UUID}=="CRYPT-TEMP-?*", GOTO="dm_disable"
ENV{DM_UUID}!="?*", ENV{DM_NAME}=="temporary-cryptsetup-?*", GOTO="dm_disable"
# Avoid processing and scanning a DM device in the other (foreign)
# rules if it is in suspended state. However, we still keep 'disk'
# and 'DM subsystem' related rules enabled in this case.
ENV{DM_SUSPENDED}=="1", ENV{DM_UDEV_DISABLE_OTHER_RULES_FLAG}="1"
GOTO="dm_end"
LABEL="dm_disable"
ENV{DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG}="1"
ENV{DM_UDEV_DISABLE_DISK_RULES_FLAG}="1"
ENV{DM_UDEV_DISABLE_OTHER_RULES_FLAG}="1"
OPTIONS:="nowatch"
LABEL="dm_end"