illumos gate

dmu_objset_clone_check() has the following code:

        error = dsl_dir_hold(dp, doca->doca_clone, FTAG, &pdd, &tail);
...
        /* You can't clone across pools. */
        if (pdd->dd_pool != dp) {
                dsl_dir_rele(pdd, FTAG);
                return (SET_ERROR(EXDEV));
        }

But, in fact, that code is NOP, because the synctask is assigned to the clone's pool, so dp is that pool and dsl_dir_hold() is called on the clone as well.

Then there is another check:

        error = dsl_dataset_hold(dp, doca->doca_origin, FTAG, &origin);
        if (error != 0)
                return (error);

        /* You can't clone across pools. */
        if (origin->ds_dir->dd_pool != dp) {
                dsl_dataset_rele(origin, FTAG);
                return (SET_ERROR(EXDEV));
        }

But the check is unreachable in exactly the scenario it is supposed to check: dsl_dataset_hold() calls dsl_dir_hold() before doing anything else, and if it is called with a dataset name that does not belong to the pool, then the function returns EINVAL.

        err = getcomponent(name, buf, &next);
        if (err != 0)
                return (err);

        /* Make sure the name is in the specified pool. */
        spaname = spa_name(dp->dp_spa);
        if (strcmp(buf, spaname) != 0)
                return (SET_ERROR(EINVAL));

I see two possibilities:
- dmu_objset_clone_check() can convert EINVAL returned from dsl_dataset_hold() to EXDEV
- dsl_dir_hold() could return EXDEV when the name is not in the pool