Re: [PATCH 02/10] scsi: iscsi: Fix offload conn cleanup when iscsid restarts

Chris Leech
2022-04-09T01:36:36Z

On Thu, Apr 07, 2022 at 07:13:06PM -0500, Mike Christie wrote:
> When userspace restarts during boot or upgrades it won't know about the
> offload driver's endpoint and connection mappings. iscsid will start by
> cleaning up the old session by doing a stop_conn call. Later if we are
> able to create a new connection, we cleanup the old endpoint during the
> binding stage. The problem is that if we do stop_conn before doing the
> ep_disconnect call offload drivers can still be executing IO. We then
> might free tasks from the under the card/driver.
>
> This moves the ep_disconnect call to before we do the stop_conn call for
> this case. It will then work and look like a normal recovery/cleanup
> procedure from the driver's point of view.
>
> Signed-off-by: Mike Christie <michael.christie@oracle.com>
> ---
> drivers/scsi/scsi_transport_iscsi.c | 48 +++++++++++++++++------------
> 1 file changed, 28 insertions(+), 20 deletions(-)

Reviewed-by: Chris Leech <cleech@redhat.com>

> diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
> index 4e10457e3ab9..bf39fb5569b6 100644
> --- a/drivers/scsi/scsi_transport_iscsi.c
> +++ b/drivers/scsi/scsi_transport_iscsi.c
> @@ -2236,6 +2236,23 @@ static void iscsi_ep_disconnect(struct iscsi_cls_conn *conn, bool is_active)
> ISCSI_DBG_TRANS_CONN(conn, "disconnect ep done.\n");
> }
>
> +static void iscsi_if_disconnect_bound_ep(struct iscsi_cls_conn *conn,
> + struct iscsi_endpoint *ep,
> + bool is_active)
> +{
> + /* Check if this was a conn error and the kernel took ownership */
> + if (!test_bit(ISCSI_CLS_CONN_BIT_CLEANUP, &conn->flags)) {
> + iscsi_ep_disconnect(conn, is_active);
> + } else {
> + ISCSI_DBG_TRANS_CONN(conn, "flush kernel conn cleanup.\n");
> + mutex_unlock(&conn->ep_mutex);
> +
> + flush_work(&conn->cleanup_work);
> +
> + mutex_lock(&conn->ep_mutex);
> + }
> +}
> +
> static int iscsi_if_stop_conn(struct iscsi_transport *transport,
> struct iscsi_uevent *ev)
> {
> @@ -2256,6 +2273,16 @@ static int iscsi_if_stop_conn(struct iscsi_transport *transport,
> cancel_work_sync(&conn->cleanup_work);
> iscsi_stop_conn(conn, flag);
> } else {
> + /*
> + * For offload, when iscsid is restarted it won't know about
> + * existing endpoints so it can't do a ep_disconnect. We clean
> + * it up here for userspace.
> + */
> + mutex_lock(&conn->ep_mutex);
> + if (conn->ep)
> + iscsi_if_disconnect_bound_ep(conn, conn->ep, true);
> + mutex_unlock(&conn->ep_mutex);
> +
> /*
> * Figure out if it was the kernel or userspace initiating this.
> */
> @@ -2984,16 +3011,7 @@ static int iscsi_if_ep_disconnect(struct iscsi_transport *transport,
> }
>
> mutex_lock(&conn->ep_mutex);
> - /* Check if this was a conn error and the kernel took ownership */
> - if (test_bit(ISCSI_CLS_CONN_BIT_CLEANUP, &conn->flags)) {
> - ISCSI_DBG_TRANS_CONN(conn, "flush kernel conn cleanup.\n");
> - mutex_unlock(&conn->ep_mutex);
> -
> - flush_work(&conn->cleanup_work);
> - goto put_ep;
> - }
> -
> - iscsi_ep_disconnect(conn, false);
> + iscsi_if_disconnect_bound_ep(conn, ep, false);
> mutex_unlock(&conn->ep_mutex);
> put_ep:
> iscsi_put_endpoint(ep);
> @@ -3704,16 +3722,6 @@ static int iscsi_if_transport_conn(struct iscsi_transport *transport,
>
> switch (nlh->nlmsg_type) {
> case ISCSI_UEVENT_BIND_CONN:
> - if (conn->ep) {
> - /*
> - * For offload boot support where iscsid is restarted
> - * during the pivot root stage, the ep will be intact
> - * here when the new iscsid instance starts up and
> - * reconnects.
> - */
> - iscsi_ep_disconnect(conn, true);
> - }
> -
> session = iscsi_session_lookup(ev->u.b_conn.sid);
> if (!session) {
> err = -EINVAL;
> --
> 2.25.1
>