[SCSI] iscsi class, libiscsi: add iscsi sysfs session state file

This adds a iscsi session state file which exports the session
state for both software and hardware iscsi. It also hooks libiscsi
in.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 104 insertions, 3 deletions

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 0d7b4e79415..f876b0ae521 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -30,7 +30,7 @@
 #include <scsi/scsi_transport_iscsi.h>
 #include <scsi/iscsi_if.h>
 
-#define ISCSI_SESSION_ATTRS 18
+#define ISCSI_SESSION_ATTRS 19
 #define ISCSI_CONN_ATTRS 11
 #define ISCSI_HOST_ATTRS 4
 #define ISCSI_TRANSPORT_VERSION "2.0-867"
@@ -221,6 +221,54 @@ static struct iscsi_cls_conn *iscsi_conn_lookup(uint32_t sid, uint32_t cid)
  * The following functions can be used by LLDs that allocate
  * their own scsi_hosts or by software iscsi LLDs
  */
+static struct {
+        int value;
+        char *name;
+} iscsi_session_state_names[] = {
+        { ISCSI_SESSION_LOGGED_IN,      "LOGGED_IN" },
+        { ISCSI_SESSION_FAILED,         "FAILED" },
+        { ISCSI_SESSION_FREE,           "FREE" },
+};
+
+const char *iscsi_session_state_name(int state)
+{
+        int i;
+        char *name = NULL;
+
+        for (i = 0; i < ARRAY_SIZE(iscsi_session_state_names); i++) {
+                if (iscsi_session_state_names[i].value == state) {
+                        name = iscsi_session_state_names[i].name;
+                        break;
+                }
+        }
+        return name;
+}
+
+int iscsi_session_chkready(struct iscsi_cls_session *session)
+{
+        unsigned long flags;
+        int err;
+
+        spin_lock_irqsave(&session->lock, flags);
+        switch (session->state) {
+        case ISCSI_SESSION_LOGGED_IN:
+                err = 0;
+                break;
+        case ISCSI_SESSION_FAILED:
+                err = DID_IMM_RETRY << 16;
+                break;
+        case ISCSI_SESSION_FREE:
+                err = DID_NO_CONNECT << 16;
+                break;
+        default:
+                err = DID_NO_CONNECT << 16;
+                break;
+        }
+        spin_unlock_irqrestore(&session->lock, flags);
+        return err;
+}
+EXPORT_SYMBOL_GPL(iscsi_session_chkready);
+
 static void iscsi_session_release(struct device *dev)
 {
         struct iscsi_cls_session *session = iscsi_dev_to_session(dev);
@@ -259,26 +307,57 @@ static void session_recovery_timedout(struct work_struct *work)
         struct iscsi_cls_session *session =
                 container_of(work, struct iscsi_cls_session,
                              recovery_work.work);
+        unsigned long flags;
 
         dev_printk(KERN_INFO, &session->dev, "iscsi: session recovery timed "
                   "out after %d secs\n", session->recovery_tmo);
 
+        spin_lock_irqsave(&session->lock, flags);
+        switch (session->state) {
+        case ISCSI_SESSION_FAILED:
+                session->state = ISCSI_SESSION_FREE;
+                break;
+        case ISCSI_SESSION_LOGGED_IN:
+        case ISCSI_SESSION_FREE:
+                /* we raced with the unblock's flush */
+                spin_unlock_irqrestore(&session->lock, flags);
+                return;
+        }
+        spin_unlock_irqrestore(&session->lock, flags);
+
         if (session->transport->session_recovery_timedout)
                 session->transport->session_recovery_timedout(session);
 
         scsi_target_unblock(&session->dev);
 }
 
-void iscsi_unblock_session(struct iscsi_cls_session *session)
+void __iscsi_unblock_session(struct iscsi_cls_session *session)
 {
         if (!cancel_delayed_work(&session->recovery_work))
                 flush_workqueue(iscsi_eh_timer_workq);
         scsi_target_unblock(&session->dev);
 }
+
+void iscsi_unblock_session(struct iscsi_cls_session *session)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&session->lock, flags);
+        session->state = ISCSI_SESSION_LOGGED_IN;
+        spin_unlock_irqrestore(&session->lock, flags);
+
+        __iscsi_unblock_session(session);
+}
 EXPORT_SYMBOL_GPL(iscsi_unblock_session);
 
 void iscsi_block_session(struct iscsi_cls_session *session)
 {
+        unsigned long flags;
+
+        spin_lock_irqsave(&session->lock, flags);
+        session->state = ISCSI_SESSION_FAILED;
+        spin_unlock_irqrestore(&session->lock, flags);
+
         scsi_target_block(&session->dev);
         queue_delayed_work(iscsi_eh_timer_workq, &session->recovery_work,
                            session->recovery_tmo * HZ);
@@ -327,10 +406,12 @@ iscsi_alloc_session(struct Scsi_Host *shost,
 
         session->transport = transport;
         session->recovery_tmo = 120;
+        session->state = ISCSI_SESSION_FREE;
         INIT_DELAYED_WORK(&session->recovery_work, session_recovery_timedout);
         INIT_LIST_HEAD(&session->host_list);
         INIT_LIST_HEAD(&session->sess_list);
         INIT_WORK(&session->unbind_work, __iscsi_unbind_session);
+        spin_lock_init(&session->lock);
 
         /* this is released in the dev's release function */
         scsi_host_get(shost);
@@ -444,7 +525,10 @@ void iscsi_remove_session(struct iscsi_cls_session *session)
          * If we are blocked let commands flow again. The lld or iscsi
          * layer should set up the queuecommand to fail commands.
          */
-        iscsi_unblock_session(session);
+        spin_lock_irqsave(&session->lock, flags);
+        session->state = ISCSI_SESSION_FREE;
+        spin_unlock_irqrestore(&session->lock, flags);
+        __iscsi_unblock_session(session);
         iscsi_unbind_session(session);
         /*
          * If the session dropped while removing devices then we need to make
@@ -661,16 +745,23 @@ EXPORT_SYMBOL_GPL(iscsi_recv_pdu);
 
 void iscsi_conn_error(struct iscsi_cls_conn *conn, enum iscsi_err error)
 {
+        struct iscsi_cls_session *session = iscsi_conn_to_session(conn);
         struct nlmsghdr *nlh;
         struct sk_buff  *skb;
         struct iscsi_uevent *ev;
         struct iscsi_internal *priv;
         int len = NLMSG_SPACE(sizeof(*ev));
+        unsigned long flags;
 
         priv = iscsi_if_transport_lookup(conn->transport);
         if (!priv)
                 return;
 
+        spin_lock_irqsave(&session->lock, flags);
+        if (session->state == ISCSI_SESSION_LOGGED_IN)
+                session->state = ISCSI_SESSION_FAILED;
+        spin_unlock_irqrestore(&session->lock, flags);
+
         skb = alloc_skb(len, GFP_ATOMIC);
         if (!skb) {
                 dev_printk(KERN_ERR, &conn->dev, "iscsi: gracefully ignored "
@@ -1246,6 +1337,15 @@ iscsi_session_attr(fast_abort, ISCSI_PARAM_FAST_ABORT, 0);
 iscsi_session_attr(abort_tmo, ISCSI_PARAM_ABORT_TMO, 0);
 iscsi_session_attr(lu_reset_tmo, ISCSI_PARAM_LU_RESET_TMO, 0);
 
+static ssize_t
+show_priv_session_state(struct class_device *cdev, char *buf)
+{
+        struct iscsi_cls_session *session = iscsi_cdev_to_session(cdev);
+        return sprintf(buf, "%s\n", iscsi_session_state_name(session->state));
+}
+static ISCSI_CLASS_ATTR(priv_sess, state, S_IRUGO, show_priv_session_state,
+                        NULL);
+
 #define iscsi_priv_session_attr_show(field, format)                     \
 static ssize_t                                                          \
 show_priv_session_##field(struct class_device *cdev, char *buf)         \
@@ -1472,6 +1572,7 @@ iscsi_register_transport(struct iscsi_transport *tt)
         SETUP_SESSION_RD_ATTR(abort_tmo, ISCSI_ABORT_TMO);
         SETUP_SESSION_RD_ATTR(lu_reset_tmo,ISCSI_LU_RESET_TMO);
         SETUP_PRIV_SESSION_RD_ATTR(recovery_tmo);
+        SETUP_PRIV_SESSION_RD_ATTR(state);
 
         BUG_ON(count > ISCSI_SESSION_ATTRS);
         priv->session_attrs[count] = NULL;