+++ This bug was initially created as a clone of Bug #674354 +++

In looking through the sosreports, I think it would be helpful to add
"dmsetup ls --tree" to the commands we run.  Although the info is
available with other existing dmsetup commands, it is an excellent way
to get a summary of complex setups.

Here's an example of an LVM mirror, with mirror images on partitions
created on top of multipath devices.  The multipath devices are on
simple block devices.  As you can see, it is easy to see the stacking
from the "dmsetup ls --tree" output:

# dmsetup ls --tree
vgmpathtest-lvmpathmir (253:14)
 ├─vgmpathtest-lvmpathmir_mimage_1 (253:13)
 │  └─mpath5p1 (253:5)
 │     └─mpath5 (253:2)
 │        ├─ (8:16)
 │        └─ (8:0)
 ├─vgmpathtest-lvmpathmir_mimage_0 (253:12)
 │  └─mpath6p1 (253:6)
 │     └─mpath6 (253:3)
 │        ├─ (8:48)
 │        └─ (8:32)
 └─vgmpathtest-lvmpathmir_mlog (253:11)
    └─mpath7 (253:4)
       ├─ (8:80)
       └─ (8:64)
VolGroup00-LogVol01 (253:1)
 └─ (202:2)
vgtest-lvmir (253:10)
 ├─vgtest-lvmir_mimage_1 (253:9)
 │  └─ (7:1)
 ├─vgtest-lvmir_mimage_0 (253:8)
 │  └─ (7:0)
 └─vgtest-lvmir_mlog (253:7)
    └─ (7:3)
VolGroup00-LogVol00 (253:0)
 └─ (202:2)


But it is much harder to see the stacking with what is there today in
sos - the output from "dmsetup info", "dmsetup status", and "dmsetup
table".  We could piece together the stacking from "dmsetup table" but
it requires further processing (take output from "dmsetup info to get
map name to major/minor, then parse "dmsetup table", etc):
# dmsetup table
mpath5p1: 0 188731557 linear 253:2 63
mpath6p1: 0 3328769 linear 253:3 1
vgmpathtest-lvmpathmir: 0 8192 mirror disk 3 253:11 1024 block_on_error 2 253:12 0 253:13 0
vgtest-lvmir_mimage_1: 0 24576 linear 7:1 384
vgtest-lvmir_mimage_0: 0 24576 linear 7:0 384
vgmpathtest-lvmpathmir_mlog: 0 8192 linear 253:4 384
mpath7: 0 20971520 multipath 1 queue_if_no_path 0 1 1 round-robin 0 2 1 8:64 128 8:80 128 
mpath6: 0 209715200 multipath 1 queue_if_no_path 0 1 1 round-robin 0 2 1 8:32 128 8:48 128 
vgmpathtest-lvmpathmir_mimage_1: 0 8192 linear 253:5 384
VolGroup00-LogVol01: 0 2162688 linear 202:2 9896320
vgtest-lvmir_mlog: 0 8192 linear 7:3 384
mpath5: 0 188743680 multipath 1 queue_if_no_path 0 1 1 round-robin 0 2 1 8:0 128 8:16 128 
vgmpathtest-lvmpathmir_mimage_0: 0 8192 linear 253:6 384
vgtest-lvmir: 0 24576 mirror disk 3 253:7 1024 block_on_error 2 253:8 0 253:9 0
VolGroup00-LogVol00: 0 9895936 linear 202:2 384
# dmsetup info -c
Name                            Maj Min Stat Open Targ Event  UUID                                                                
mpath5p1                        253   5 L--w    1    1      0 part1-mpath-360a980006e424b626d34613047437766                       
mpath6p1                        253   6 L--w    1    1      0 part1-mpath-360a980006e424b626d34613047447078                       
vgmpathtest-lvmpathmir          253  14 L--w    0    1      1 LVM-rNO5kEQCdfoUfpsFXIguleIF0o6PPu1MEuHA9ADD5dtr1kLTVRBZHhojFfJHmZul
vgtest-lvmir_mimage_1           253   9 L--w    1    1      0 LVM-ROXcWNEt1MK767i4QdV09EeHTAZrDDzX2OfO6aPv5wcTpD63a8RIjRiuMJkJOiQl
vgtest-lvmir_mimage_0           253   8 L--w    1    1      0 LVM-ROXcWNEt1MK767i4QdV09EeHTAZrDDzX2vnjsbnbu75wW6WciLbpYaGCdndR87Vt
vgmpathtest-lvmpathmir_mlog     253  11 L--w    1    1      0 LVM-rNO5kEQCdfoUfpsFXIguleIF0o6PPu1MupiMHiphrhRdgTYGflsKHiwKE71QHb40
mpath7                          253   4 L--w    1    1      0 mpath-360a980006e424b626d34614b79707454                             
mpath6                          253   3 L--w    1    1      0 mpath-360a980006e424b626d34613047447078                             
vgmpathtest-lvmpathmir_mimage_1 253  13 L--w    1    1      0 LVM-rNO5kEQCdfoUfpsFXIguleIF0o6PPu1MElzffHWferZ5Kb4ooBAmM6vE0xhcQkFz
VolGroup00-LogVol01             253   1 L--w    1    1      0 LVM-fCGl4gutrN5reXkPYS9JA1FWtML6Yra8UrrjM6GWF92jZPlQ9vIwOauAAZgyZK4e
vgtest-lvmir_mlog               253   7 L--w    1    1      0 LVM-ROXcWNEt1MK767i4QdV09EeHTAZrDDzX7vzVcxdky4dpJLeW8sR74wtmGPI2fMQq
mpath5                          253   2 L--w    1    1      0 mpath-360a980006e424b626d34613047437766                             
vgmpathtest-lvmpathmir_mimage_0 253  12 L--w    1    1      0 LVM-rNO5kEQCdfoUfpsFXIguleIF0o6PPu1MGlTprEAoONIpMzzTiug5XaPnlrMFowYx
vgtest-lvmir                    253  10 L--w    0    1      1 LVM-ROXcWNEt1MK767i4QdV09EeHTAZrDDzXQhCKjGKnr2XSlplayeSSdziSAB3zrAB3
VolGroup00-LogVol00             253   0 L--w    1    1      0 LVM-fCGl4gutrN5reXkPYS9JA1FWtML6Yra8cE4dd5B6091CiMG2mCTywmo9gsYbVR14

--- Additional comment from dwysocha on 2011-02-01 10:43:47 EST ---

Created attachment 476421 [details]
One line simple patch which adds "dmsetup ls --tree"

--- Additional comment from dwysocha on 2011-02-03 09:34:25 EST ---

I've added "dmsetup ls --tree" to lvmdump command upstream in lvm2 project. Should be in lvm2 release 2.02.83.