issue openzfs#14223: fix generation of linux kernel uevent for snapsh…

…ot rename

`zvol_rename_minors()` needs to be given the full path not just the
snapshot name.  Use code removed in
a0bd735 as a guide to providing the
necessary values.

Closes openzfs#14223

Signed-off-by: James Dingwall <james@dingwall.me.uk>

module/zfs/dsl_dataset.c

@@ -2987,6 +2987,7 @@ dsl_dataset_rename_snapshot_sync_impl(dsl_pool_t *dp,
 	dsl_dataset_t *ds;
 	uint64_t val;
 	dmu_tx_t *tx = ddrsa->ddrsa_tx;
+	char *oldname, *newname;
 	int error;
 
 	error = dsl_dataset_snap_lookup(hds, ddrsa->ddrsa_oldsnapname, &val);
@@ -3011,8 +3012,14 @@ dsl_dataset_rename_snapshot_sync_impl(dsl_pool_t *dp,
 	VERIFY0(zap_add(dp->dp_meta_objset,
 	    dsl_dataset_phys(hds)->ds_snapnames_zapobj,
 	    ds->ds_snapname, 8, 1, &ds->ds_object, tx));
-	zvol_rename_minors(dp->dp_spa, ddrsa->ddrsa_oldsnapname,
-	    ddrsa->ddrsa_newsnapname, B_TRUE);
+
+	oldname = kmem_asprintf("%s@%s", ddrsa->ddrsa_fsname,
+	    ddrsa->ddrsa_oldsnapname);
+	newname = kmem_asprintf("%s@%s", ddrsa->ddrsa_fsname,
+	    ddrsa->ddrsa_newsnapname);
+	zvol_rename_minors(dp->dp_spa, oldname, newname, B_TRUE);
+	kmem_strfree(oldname);
+	kmem_strfree(newname);
 
 	dsl_dataset_rele(ds, FTAG);
 	return (0);