projects / linux-block.git / blame
| Commit | Line | Data |
|---|---|---|
| f0ba4377 MCC |
1 | ==================== |
| 2 | device-mapper uevent | |
| 3 | ==================== | |
| 4 | ||
| 5 | The device-mapper uevent code adds the capability to device-mapper to create | |
| 6 | and send kobject uevents (uevents). Previously device-mapper events were only | |
| 7 | available through the ioctl interface. The advantage of the uevents interface | |
| 8 | is the event contains environment attributes providing increased context for | |
| 9 | the event avoiding the need to query the state of the device-mapper device after | |
| 10 | the event is received. | |
| 11 | ||
| 12 | There are two functions currently for device-mapper events. The first function | |
| 13 | listed creates the event and the second function sends the event(s):: | |
| 14 | ||
| 15 | void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti, | |
| 16 | const char *path, unsigned nr_valid_paths) | |
| 17 | ||
| 18 | void dm_send_uevents(struct list_head *events, struct kobject *kobj) | |
| 19 | ||
| 20 | ||
| 21 | The variables added to the uevent environment are: | |
| 22 | ||
| 23 | Variable Name: DM_TARGET | |
| 24 | ------------------------ | |
| 25 | :Uevent Action(s): KOBJ_CHANGE | |
| 26 | :Type: string | |
| 27 | :Description: | |
| 28 | :Value: Name of device-mapper target that generated the event. | |
| 29 | ||
| 30 | Variable Name: DM_ACTION | |
| 31 | ------------------------ | |
| 32 | :Uevent Action(s): KOBJ_CHANGE | |
| 33 | :Type: string | |
| 34 | :Description: | |
| 35 | :Value: Device-mapper specific action that caused the uevent action. | |
| 36 | PATH_FAILED - A path has failed; | |
| 37 | PATH_REINSTATED - A path has been reinstated. | |
| 38 | ||
| 39 | Variable Name: DM_SEQNUM | |
| 40 | ------------------------ | |
| 41 | :Uevent Action(s): KOBJ_CHANGE | |
| 42 | :Type: unsigned integer | |
| 43 | :Description: A sequence number for this specific device-mapper device. | |
| 44 | :Value: Valid unsigned integer range. | |
| 45 | ||
| 46 | Variable Name: DM_PATH | |
| 47 | ---------------------- | |
| 48 | :Uevent Action(s): KOBJ_CHANGE | |
| 49 | :Type: string | |
| 50 | :Description: Major and minor number of the path device pertaining to this | |
| 51 | event. | |
| 52 | :Value: Path name in the form of "Major:Minor" | |
| 53 | ||
| 54 | Variable Name: DM_NR_VALID_PATHS | |
| 55 | -------------------------------- | |
| 56 | :Uevent Action(s): KOBJ_CHANGE | |
| 57 | :Type: unsigned integer | |
| 58 | :Description: | |
| 59 | :Value: Valid unsigned integer range. | |
| 60 | ||
| 61 | Variable Name: DM_NAME | |
| 62 | ---------------------- | |
| 63 | :Uevent Action(s): KOBJ_CHANGE | |
| 64 | :Type: string | |
| 65 | :Description: Name of the device-mapper device. | |
| 66 | :Value: Name | |
| 67 | ||
| 68 | Variable Name: DM_UUID | |
| 69 | ---------------------- | |
| 70 | :Uevent Action(s): KOBJ_CHANGE | |
| 71 | :Type: string | |
| 72 | :Description: UUID of the device-mapper device. | |
| 73 | :Value: UUID. (Empty string if there isn't one.) | |
| 74 | ||
| 75 | An example of the uevents generated as captured by udevmonitor is shown | |
| 76 | below | |
| 77 | ||
| 78 | 1.) Path failure:: | |
| 79 | ||
| 80 | UEVENT[1192521009.711215] change@/block/dm-3 | |
| 81 | ACTION=change | |
| 82 | DEVPATH=/block/dm-3 | |
| 83 | SUBSYSTEM=block | |
| 84 | DM_TARGET=multipath | |
| 85 | DM_ACTION=PATH_FAILED | |
| 86 | DM_SEQNUM=1 | |
| 87 | DM_PATH=8:32 | |
| 88 | DM_NR_VALID_PATHS=0 | |
| 89 | DM_NAME=mpath2 | |
| 90 | DM_UUID=mpath-35333333000002328 | |
| 91 | MINOR=3 | |
| 92 | MAJOR=253 | |
| 93 | SEQNUM=1130 | |
| 94 | ||
| 95 | 2.) Path reinstate:: | |
| 96 | ||
| 97 | UEVENT[1192521132.989927] change@/block/dm-3 | |
| 98 | ACTION=change | |
| 99 | DEVPATH=/block/dm-3 | |
| 100 | SUBSYSTEM=block | |
| 101 | DM_TARGET=multipath | |
| 102 | DM_ACTION=PATH_REINSTATED | |
| 103 | DM_SEQNUM=2 | |
| 104 | DM_PATH=8:32 | |
| 105 | DM_NR_VALID_PATHS=1 | |
| 106 | DM_NAME=mpath2 | |
| 107 | DM_UUID=mpath-35333333000002328 | |
| 108 | MINOR=3 | |
| 109 | MAJOR=253 | |
| 110 | SEQNUM=1131 |