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110 lines
2.9 KiB
110 lines
2.9 KiB
==================== |
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device-mapper uevent |
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==================== |
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The device-mapper uevent code adds the capability to device-mapper to create |
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and send kobject uevents (uevents). Previously device-mapper events were only |
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available through the ioctl interface. The advantage of the uevents interface |
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is the event contains environment attributes providing increased context for |
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the event avoiding the need to query the state of the device-mapper device after |
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the event is received. |
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There are two functions currently for device-mapper events. The first function |
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listed creates the event and the second function sends the event(s):: |
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void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti, |
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const char *path, unsigned nr_valid_paths) |
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void dm_send_uevents(struct list_head *events, struct kobject *kobj) |
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The variables added to the uevent environment are: |
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Variable Name: DM_TARGET |
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------------------------ |
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:Uevent Action(s): KOBJ_CHANGE |
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:Type: string |
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:Description: |
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:Value: Name of device-mapper target that generated the event. |
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Variable Name: DM_ACTION |
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------------------------ |
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:Uevent Action(s): KOBJ_CHANGE |
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:Type: string |
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:Description: |
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:Value: Device-mapper specific action that caused the uevent action. |
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PATH_FAILED - A path has failed; |
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PATH_REINSTATED - A path has been reinstated. |
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Variable Name: DM_SEQNUM |
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------------------------ |
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:Uevent Action(s): KOBJ_CHANGE |
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:Type: unsigned integer |
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:Description: A sequence number for this specific device-mapper device. |
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:Value: Valid unsigned integer range. |
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Variable Name: DM_PATH |
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---------------------- |
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:Uevent Action(s): KOBJ_CHANGE |
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:Type: string |
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:Description: Major and minor number of the path device pertaining to this |
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event. |
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:Value: Path name in the form of "Major:Minor" |
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Variable Name: DM_NR_VALID_PATHS |
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-------------------------------- |
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:Uevent Action(s): KOBJ_CHANGE |
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:Type: unsigned integer |
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:Description: |
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:Value: Valid unsigned integer range. |
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Variable Name: DM_NAME |
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---------------------- |
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:Uevent Action(s): KOBJ_CHANGE |
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:Type: string |
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:Description: Name of the device-mapper device. |
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:Value: Name |
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Variable Name: DM_UUID |
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---------------------- |
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:Uevent Action(s): KOBJ_CHANGE |
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:Type: string |
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:Description: UUID of the device-mapper device. |
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:Value: UUID. (Empty string if there isn't one.) |
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An example of the uevents generated as captured by udevmonitor is shown |
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below |
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1.) Path failure:: |
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UEVENT[1192521009.711215] change@/block/dm-3 |
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ACTION=change |
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DEVPATH=/block/dm-3 |
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SUBSYSTEM=block |
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DM_TARGET=multipath |
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DM_ACTION=PATH_FAILED |
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DM_SEQNUM=1 |
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DM_PATH=8:32 |
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DM_NR_VALID_PATHS=0 |
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DM_NAME=mpath2 |
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DM_UUID=mpath-35333333000002328 |
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MINOR=3 |
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MAJOR=253 |
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SEQNUM=1130 |
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2.) Path reinstate:: |
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UEVENT[1192521132.989927] change@/block/dm-3 |
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ACTION=change |
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DEVPATH=/block/dm-3 |
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SUBSYSTEM=block |
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DM_TARGET=multipath |
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DM_ACTION=PATH_REINSTATED |
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DM_SEQNUM=2 |
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DM_PATH=8:32 |
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DM_NR_VALID_PATHS=1 |
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DM_NAME=mpath2 |
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DM_UUID=mpath-35333333000002328 |
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MINOR=3 |
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MAJOR=253 |
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SEQNUM=1131
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