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55-dm.rules
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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/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-<subsystem_name>.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=="device-mapper", NAME="mapper/control" SUBSYSTEM!="block", GOTO="dm_end" KERNEL!="dm-[0-9]*", 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}="/sbin/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", ENV{DM_ACTIVATION}="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_UDEV_RULES" 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", GOTO="dm_no_coldplug" ENV{DM_UDEV_PRIMARY_SOURCE_FLAG}!="1", GOTO="dm_disable" ENV{DM_ACTIVATION}="1" LABEL="dm_no_coldplug" # 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 "udevadm trigger" call # or by "echo <event_name> > /sys/block/dm-X/uevent". # # 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 # "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}="/sbin/dmsetup info -j %M -m %m -c --nameprefixes --noheadings --rows -o name,uuid,suspended" ENV{DM_SUSPENDED}!="?*", IMPORT{program}="/sbin/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}="1" ENV{DM_UDEV_RULES_VSN}="2" ENV{DM_UDEV_DISABLE_DM_RULES_FLAG}!="1", ENV{DM_NAME}=="?*", SYMLINK+="mapper/$env{DM_NAME}" # 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"