[LU-7874] Suspect locking cleanup issue in mdt_create()

• Type: Bug
• Resolution: Not a Bug
• Priority: Minor
• Fix Version/s: Lustre 2.11.0
• Severity: 3
• Assignee: Lai Siyao
• Reporter: Oleg Drokin

Description

In mdt_create():

                        if (!mdt_object_remote(parent)) {
                                mdt_object_unlock(info, parent, lh, 1);
                                mdt_lock_pdo_init(lh, LCK_PW, &rr->rr_name);
                                rc = mdt_reint_object_lock(info, parent, lh,
                                                           MDS_INODELOCK_UPDATE,
                                                           true);
                                if (rc)
                                        GOTO(put_child, rc);
                        }
...
put_child:
        mdt_object_put(info->mti_env, child);
unlock_parent:
        mdt_object_unlock(info, parent, lh, rc);
put_parent:
        mdt_object_put(info->mti_env, parent);
        RETURN(rc);

So if we cannot lock parent we jump to put child and then unlock parent? that sounds wrong.

Comments

[Lai Siyao]

this is not a bug IMO, mdt_object_unlock() is safe to call multiple times, because it will clear lock handle after unlock, so this GOTO is to make sure child is put, and it's written this way to simplify failure cleanup.

[Peter Jones]

Lai

Can you please look into this?

Peter