[dm-devel] 'multipath add path' returns ok but the path is missing in the topology

[Gioh Kim]

Hi,

I would like to report a bug.
I am using network storage via SRP/SRPT over Infiniband.
When a new sd device is created by SRP, I execute 'multipathd add path
sdX' command and then a new map device is created automatically.

I used to use the kernel 4.14 version and had no problem.
But after upgrading to kernel 4.19, I have a problem that 'multipath
add path sdX' returns ok but sdX is not included in the topology.

For example, I ran 'multipath add path sdaj' and 'multipath add path
sdak' and they returned ok.
Then I check the topology with 'multipathd show topology' and sdak is missing.

Following is the log message from multipathd daemon.
I found that
1. adding sdaj was done correctly and map
3600144f033337cfc3ca5222200196002 and dm-11 was created
2. daemon started adding sdak (according to "sdak: add path (operator)" message)
3. suddenly map dm-11 was removed and created
4. adding sdak returned ok but there was no "sdak: path added to
devmap .." message.  I waited some minutes but it did not show up.
I guess there would be some corner case for error handling.
The multipathd might have an error but not return an error.


<log message>
multipathd[1920]: sdaj: add path (operator)
multipathd[1920]: 3600144f033337cfc3ca5222200196002: load table [0
2105344 multipath 1 retain_attached_hw_handler 0 1 1 service-time 0 1
1 66:48 1]
multipathd[1920]: 3600144f033337cfc3ca5222200196002: event checker started
multipathd[1920]: sdaj [66:48]: path added to devmap
3600144f033337cfc3ca5222200196002
multipathd[1920]: sdak: add path (operator)
multipathd[1920]: dm-11: remove map (uevent)
multipathd[1920]: 3600144f033337cfc3ca5222200196002: stop event
checker thread (139976177456896)
multipathd[1920]: dm-11: remove map (uevent)
multipathd[1920]: 3600144f033337cfc3ca5222200196002: adding map
multipathd[1920]: 3600144f033337cfc3ca5222200196002: event checker started
multipathd[1920]: 3600144f033337cfc3ca5222200196002: devmap dm-11 registered

<multipathd show topology>
3600144f033337cfc3ca5222200196002 dm-11 SCST_BIO,e21f6f605c1dfff7
size=1.0G features='1 retain_attached_hw_handler' hwhandler='0' wp=ro
`-+- policy='service-time 0' prio=1 status=enabled
`- 7:0:0:489 sdaj 66:48  active ready running

I welcome any comment.
I thank you in advance.
Stay healthy!

-- 
Gioh Kim

Cloud server kernel maintainer
Quality Management (IONOS Cloud)

1&1 IONOS SE | Greifswalder Str. 207 | 10405 Berlin | Germany
Phone: +49 176 26978962
E-mail: gi-oh.kim at cloud.ionos.com | Web: www.ionos.de

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