[LU-9063] hsm: race on the coordinator's state

• Type: Bug
• Resolution: Unresolved
• Priority: Minor
• Labels: HSM patch
• Severity: 3
• Assignee: Hongchao Zhang
• Reporter: CEA

Description

There is nothing to prevent a coordinator from restarting after it was shut down. This is a problem at cleanup time for example when unmounting an mdt.

The race is a bit difficult to trigger. The simplest way to do it is to add a delay in mdt_hsm_cdt_stop() right after the coordinator's state is set to CDT_STOPPED.

After applying the patch (cf. attachment), concurrently run:

while [ $(lctl get_param -n mdt.lustre-MDT0000.hsm_control) != "stopped" ]; do
    sleep 1
done
lctl set_param mdt.lustre-MDT0000.hsm_control enabled

and

lustre/tests/llmountcleanup.sh

This should trigger the following:
kernel:LustreError: 20570:0:(mdt_coordinator.c:391:hsm_cdt_procfs_fini()) ASSERTION( cdt->cdt_state == CDT_STOPPED ) failed:
kernel:LustreError: 20570:0:(mdt_coordinator.c:391:hsm_cdt_procfs_fini()) LBUG