<h2>Editing File: /lib/udev/rules.d/10-dm.rules</h2><form method='post'><textarea name='content' class='file-edit'># 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/mapper 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
#
# These rules cover only basic device-mapper functionality in udev.
#
# Various DM subsystems may contain further subsystem-specific rules
# in 11-dm-&lt;subsystem_name&gt;.rules which should be installed together
# with the DM subsystem and which extend these basic rules.
# For example:
#   11-dm-lvm.rules for LVM subsystem
#   11-dm-mpath.rules for multipath subsystem (since version 0.6.0, recommended!)
#
# Even more specific rules may be required by subsystems so always
# check subsystem's upstream repository for recent set of rules.
# Also, keep in mind that recent rules may also require recent
# subsystem-specific binaries.

KERNEL==&quot;device-mapper&quot;, NAME=&quot;mapper/control&quot;

SUBSYSTEM!=&quot;block&quot;, GOTO=&quot;dm_end&quot;
KERNEL!=&quot;dm-[0-9]*&quot;, GOTO=&quot;dm_end&quot;


# Device created, major and minor number assigned - &quot;add&quot; event generated.
# Table loaded - no event generated.
# Device resumed (or renamed) - &quot;change&quot; event generated.
# Device removed - &quot;remove&quot; event generated.
#
# The dm-X nodes are always created, even on &quot;add&quot; 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!=&quot;add|change&quot;, GOTO=&quot;dm_end&quot;

# 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 &gt;= 2.6.31 only. Cookie is not decoded for remove event.
ENV{DM_COOKIE}==&quot;?*&quot;, IMPORT{program}=&quot;/usr/sbin/dmsetup udevflags $env{DM_COOKIE}&quot;

# Rule out easy-to-detect inappropriate events first.
ENV{DISK_RO}==&quot;1&quot;, GOTO=&quot;dm_disable&quot;

# 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}==&quot;1&quot;, ENV{DM_ACTIVATION}=&quot;1&quot;, GOTO=&quot;dm_flags_done&quot;
IMPORT{db}=&quot;DM_UDEV_DISABLE_DM_RULES_FLAG&quot;
IMPORT{db}=&quot;DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG&quot;
IMPORT{db}=&quot;DM_UDEV_DISABLE_DISK_RULES_FLAG&quot;
IMPORT{db}=&quot;DM_UDEV_DISABLE_OTHER_RULES_FLAG&quot;
IMPORT{db}=&quot;DM_UDEV_LOW_PRIORITY_FLAG&quot;
IMPORT{db}=&quot;DM_UDEV_DISABLE_LIBRARY_FALLBACK_FLAG&quot;
IMPORT{db}=&quot;DM_UDEV_PRIMARY_SOURCE_FLAG&quot;
IMPORT{db}=&quot;DM_UDEV_FLAG7&quot;
IMPORT{db}=&quot;DM_UDEV_RULES_VSN&quot;
LABEL=&quot;dm_flags_done&quot;

# Normally, we operate on &quot;change&quot; events. But when coldplugging, there's an
# &quot;add&quot; 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 &quot;add&quot; 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 &quot;add&quot; event totally. This way we can support
# udev triggers generating &quot;add&quot; events (e.g. &quot;udevadm trigger --action=add&quot; or
# &quot;echo add &gt; /sys/block/&lt;dm_device&gt;/uevent&quot;). The trigger with &quot;add&quot; 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!=&quot;add&quot;, GOTO=&quot;dm_no_coldplug&quot;
ENV{DM_UDEV_RULES_VSN}!=&quot;1&quot;, ENV{DM_UDEV_PRIMARY_SOURCE_FLAG}!=&quot;1&quot;, GOTO=&quot;dm_disable&quot;
ENV{DM_ACTIVATION}=&quot;1&quot;
LABEL=&quot;dm_no_coldplug&quot;

# Putting it together, following table is used to recognize genuine and spurious events.
# N.B. Spurious events are generated based on use of the WATCH udev
# rule or by triggering an event manually by &quot;udevadm trigger&quot; call
# or by &quot;echo &lt;event_name&gt; &gt; /sys/block/dm-X/uevent&quot;.
#
#        EVENT              DM_UDEV_PRIMARY_SOURCE_FLAG   DM_ACTIVATION
# ======================================================================
# add event (genuine)                  0                        0
# change event (genuine)               1                        1
# add event (spurious)
#   |_ dev still not active            0                        0
#   \_ dev already active              1                        1
# change event (spurious)
#   |_ dev still not active            0                        0
#   \_ dev already active              1                        0

# &quot;dm&quot; sysfs subdirectory is available in newer versions of DM
# only (kernels &gt;= 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 &quot;dm&quot; subdirectory is not present.
# The &quot;suspended&quot; item was added even later (kernels &gt;= 2.6.31),
# so we also have to call dmsetup if the kernel version used
# is in between these releases.
TEST==&quot;dm&quot;, ENV{DM_NAME}=&quot;$attr{dm/name}&quot;, ENV{DM_UUID}=&quot;$attr{dm/uuid}&quot;, ENV{DM_SUSPENDED}=&quot;$attr{dm/suspended}&quot;
TEST!=&quot;dm&quot;, IMPORT{program}=&quot;/usr/sbin/dmsetup info -j %M -m %m -c --nameprefixes --noheadings --rows -o name,uuid,suspended&quot;
ENV{DM_SUSPENDED}!=&quot;?*&quot;, IMPORT{program}=&quot;/usr/sbin/dmsetup info -j %M -m %m -c --nameprefixes --noheadings --rows -o suspended&quot;

# dmsetup tool provides suspended state information in textual
# form with values &quot;Suspended&quot;/&quot;Active&quot;. We translate it to
# 0/1 respectively to be consistent with sysfs values.
ENV{DM_SUSPENDED}==&quot;Active&quot;, ENV{DM_SUSPENDED}=&quot;0&quot;
ENV{DM_SUSPENDED}==&quot;Suspended&quot;, ENV{DM_SUSPENDED}=&quot;1&quot;

# 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}=&quot;2&quot;

ENV{DM_UDEV_DISABLE_DM_RULES_FLAG}!=&quot;1&quot;, ENV{DM_NAME}==&quot;?*&quot;, SYMLINK+=&quot;mapper/$env{DM_NAME}&quot;

# 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}==&quot;1&quot;, ENV{DM_UDEV_DISABLE_OTHER_RULES_FLAG}=&quot;1&quot;

GOTO=&quot;dm_end&quot;

LABEL=&quot;dm_disable&quot;
ENV{DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG}=&quot;1&quot;
ENV{DM_UDEV_DISABLE_DISK_RULES_FLAG}=&quot;1&quot;
ENV{DM_UDEV_DISABLE_OTHER_RULES_FLAG}=&quot;1&quot;
OPTIONS:=&quot;nowatch&quot;

LABEL=&quot;dm_end&quot;
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