[LU-3882] mounting a Lustre FS when already running an HSM CT causes the new mount to register as a CT

• Type: Technical task
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.5.0
• Affects Version/s: Lustre 2.5.0
• Labels: HSM
• Assignee: John Hammond
• Reporter: John Hammond

Description

Due to the global KUC lists, seeing IMP_EVENT_ACTIVE on any MDC import will cause any already registered CT archive masks to be registered with the MDT behind that import.

mdc_import_event(..., ..., imp, IMP_EVENT_ACTIVE)
    mdc_kuc_reregister(imp)
        libcfs_kkuc_group_foreach(KUC_GRP_HSM, mdc_hsm_ct_reregister, imp)
                                         (void *)imp)
            cfs_list_for_each_entry(reg, ... KUC_GRP_HSM, ...)
                mdc_hsm_ct_reregister(reg->kr_reg = archives, imp)
                    mdc_ioc_hsm_ct_register(imp, archives)
                        /* Send MDS_HSM_CT_REGISTER. */

Comments

[Peter Jones]

Landed for 2.5.0

[Henri Doreau (Inactive)]

Thanks a lot John.

Patch is at http://review.whamcloud.com/7612

[John Hammond]

I agree with Thomas' approach but think it can be refined somewhat. Here is what I suggest:

1. In struct struct kkuc_reg change kr_data from __u32 to void *.
2. Define struct kkuc_ct_data as follows to hold some magic, an obd_uuid, and the __u32 archive formerly placed in kr_data.
3. In lmv_hsm_ct_register() allocate a kkuc_ct_data and initialize it with the UUID of the LMV obd and with the passed in archives.
4. In libcfs_kkuc_group_rem() add a void **data parameter to receive the data on removal.
5. In lmv_hsm_ct_unregister() recover the kkuc_ct_data and free it.
6. Adjust mdc_hsm_ct_reregister() to use kkuc_ct_data and check its UUID against that of the MDC import.

[Henri Doreau (Inactive)]

Thomas is off for the next days. I can work on a patch if needed.
We would appreciate comments/suggestions from Intel on the proposed approach though.

[Jodi Levi (Inactive)]

Thomas,
Are you planning to submit a patch for this?