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