[SCSI] FC transport: Add dev_loss_tmo callbacks, and new fast_io_fail_tmo w/ callback

This patch adds the following functionality to the FC transport:

- dev_loss_tmo LLDD callback :
  Called to essentially confirm the deletion of an rport. Thus, it is
  called whenever the dev_loss_tmo fires, or when the rport is deleted
  due to other circumstances (module unload, etc).  It is expected that
  the callback will initiate the termination of any outstanding i/o on
  the rport.

- fast_io_fail_tmo and LLD callback:
  There are some cases where it may take a long while to truly determine
  device loss, but the system is in a multipathing configuration that if
  the i/o was failed quickly (faster than dev_loss_tmo), it could be
  redirected to a different path and completed sooner.

Many thanks to Mike Reed who cleaned up the initial RFC in support
of this post.

The original RFC is at:
http://marc.theaimsgroup.com/?l=linux-scsi&m=115505981027246&w=2

Signed-off-by: James Smart <James.Smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

2 files changed, 128 insertions, 11 deletions

diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index 293188cbff8c..4ab176ed480d 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -242,6 +242,7 @@ fc_bitfield_name_search(remote_port_roles, fc_remote_port_role_names)
 
 
 static void fc_timeout_deleted_rport(void *data);
+static void fc_timeout_fail_rport_io(void *data);
 static void fc_scsi_scan_rport(void *data);
 
 /*
@@ -249,7 +250,7 @@ static void fc_scsi_scan_rport(void *data);
  * Increase these values if you add attributes
  */
 #define FC_STARGET_NUM_ATTRS    3
-#define FC_RPORT_NUM_ATTRS      9
+#define FC_RPORT_NUM_ATTRS      10
 #define FC_HOST_NUM_ATTRS       17
 
 struct fc_internal {
@@ -622,11 +623,14 @@ store_fc_rport_##field(struct class_device *cdev, const char *buf,	\
         struct fc_rport *rport = transport_class_to_rport(cdev);        \
         struct Scsi_Host *shost = rport_to_shost(rport);                \
         struct fc_internal *i = to_fc_internal(shost->transportt);      \
+        char *cp;                                                       \
         if ((rport->port_state == FC_PORTSTATE_BLOCKED) ||              \
             (rport->port_state == FC_PORTSTATE_DELETED) ||              \
             (rport->port_state == FC_PORTSTATE_NOTPRESENT))             \
                 return -EBUSY;                                          \
-        val = simple_strtoul(buf, NULL, 0);                             \
+        val = simple_strtoul(buf, &cp, 0);                              \
+        if (*cp && (*cp != '\n'))                                       \
+                return -EINVAL;                                         \
         i->f->set_rport_##field(rport, val);                            \
         return count;                                                   \
 }
@@ -708,6 +712,13 @@ static FC_CLASS_DEVICE_ATTR(rport, title, S_IRUGO,			\
         if (i->f->show_rport_##field)                                   \
                 count++
 
+#define SETUP_PRIVATE_RPORT_ATTRIBUTE_RW(field)                         \
+{                                                                       \
+        i->private_rport_attrs[count] = class_device_attr_rport_##field; \
+        i->rport_attrs[count] = &i->private_rport_attrs[count];         \
+        count++;                                                        \
+}
+
 
 /* The FC Transport Remote Port Attributes: */
 
@@ -740,12 +751,14 @@ store_fc_rport_dev_loss_tmo(struct class_device *cdev, const char *buf,
         struct fc_rport *rport = transport_class_to_rport(cdev);
         struct Scsi_Host *shost = rport_to_shost(rport);
         struct fc_internal *i = to_fc_internal(shost->transportt);
+        char *cp;
         if ((rport->port_state == FC_PORTSTATE_BLOCKED) ||
             (rport->port_state == FC_PORTSTATE_DELETED) ||
             (rport->port_state == FC_PORTSTATE_NOTPRESENT))
                 return -EBUSY;
-        val = simple_strtoul(buf, NULL, 0);
-        if ((val < 0) || (val > SCSI_DEVICE_BLOCK_MAX_TIMEOUT))
+        val = simple_strtoul(buf, &cp, 0);
+        if ((*cp && (*cp != '\n')) ||
+            (val < 0) || (val > SCSI_DEVICE_BLOCK_MAX_TIMEOUT))
                 return -EINVAL;
         i->f->set_rport_dev_loss_tmo(rport, val);
         return count;
@@ -795,6 +808,44 @@ static FC_CLASS_DEVICE_ATTR(rport, roles, S_IRUGO,
 fc_private_rport_rd_enum_attr(port_state, FC_PORTSTATE_MAX_NAMELEN);
 fc_private_rport_rd_attr(scsi_target_id, "%d\n", 20);
 
+/*
+ * fast_io_fail_tmo attribute
+ */
+static ssize_t
+show_fc_rport_fast_io_fail_tmo (struct class_device *cdev, char *buf)
+{
+        struct fc_rport *rport = transport_class_to_rport(cdev);
+
+        if (rport->fast_io_fail_tmo == -1)
+                return snprintf(buf, 5, "off\n");
+        return snprintf(buf, 20, "%d\n", rport->fast_io_fail_tmo);
+}
+
+static ssize_t
+store_fc_rport_fast_io_fail_tmo(struct class_device *cdev, const char *buf,
+                           size_t count)
+{
+        int val;
+        char *cp;
+        struct fc_rport *rport = transport_class_to_rport(cdev);
+
+        if ((rport->port_state == FC_PORTSTATE_BLOCKED) ||
+            (rport->port_state == FC_PORTSTATE_DELETED) ||
+            (rport->port_state == FC_PORTSTATE_NOTPRESENT))
+                return -EBUSY;
+        if (strncmp(buf, "off", 3) == 0)
+                rport->fast_io_fail_tmo = -1;
+        else {
+                val = simple_strtoul(buf, &cp, 0);
+                if ((*cp && (*cp != '\n')) ||
+                    (val < 0) || (val >= rport->dev_loss_tmo))
+                        return -EINVAL;
+                rport->fast_io_fail_tmo = val;
+        }
+        return count;
+}
+static FC_CLASS_DEVICE_ATTR(rport, fast_io_fail_tmo, S_IRUGO | S_IWUSR,
+        show_fc_rport_fast_io_fail_tmo, store_fc_rport_fast_io_fail_tmo);
 
 
 /*
@@ -880,8 +931,11 @@ store_fc_host_##field(struct class_device *cdev, const char *buf,	\
         int val;                                                        \
         struct Scsi_Host *shost = transport_class_to_shost(cdev);       \
         struct fc_internal *i = to_fc_internal(shost->transportt);      \
+        char *cp;                                                       \
                                                                         \
-        val = simple_strtoul(buf, NULL, 0);                             \
+        val = simple_strtoul(buf, &cp, 0);                              \
+        if (*cp && (*cp != '\n'))                                       \
+                return -EINVAL;                                         \
         i->f->set_host_##field(shost, val);                             \
         return count;                                                   \
 }
@@ -1481,6 +1535,8 @@ fc_attach_transport(struct fc_function_template *ft)
         SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(roles);
         SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(port_state);
         SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(scsi_target_id);
+        if (ft->terminate_rport_io)
+                SETUP_PRIVATE_RPORT_ATTRIBUTE_RW(fast_io_fail_tmo);
 
         BUG_ON(count > FC_RPORT_NUM_ATTRS);
 
@@ -1552,7 +1608,7 @@ fc_flush_work(struct Scsi_Host *shost)
  * @delay:      jiffies to delay the work queuing
  *
  * Return value:
- *      0 on success / != 0 for error
+ *      1 on success / 0 already queued / < 0 for error
  **/
 static int
 fc_queue_devloss_work(struct Scsi_Host *shost, struct work_struct *work,
@@ -1567,6 +1623,9 @@ fc_queue_devloss_work(struct Scsi_Host *shost, struct work_struct *work,
                 return -EINVAL;
         }
 
+        if (delay == 0)
+                return queue_work(fc_host_devloss_work_q(shost), work);
+
         return queue_delayed_work(fc_host_devloss_work_q(shost), work, delay);
 }
 
@@ -1659,10 +1718,23 @@ fc_starget_delete(void *data)
         struct fc_rport *rport = (struct fc_rport *)data;
         struct Scsi_Host *shost = rport_to_shost(rport);
         unsigned long flags;
+        struct fc_internal *i = to_fc_internal(shost->transportt);
+
+        /*
+         * Involve the LLDD if possible. All io on the rport is to
+         * be terminated, either as part of the dev_loss_tmo callback
+         * processing, or via the terminate_rport_io function.
+         */
+        if (i->f->dev_loss_tmo_callbk)
+                i->f->dev_loss_tmo_callbk(rport);
+        else if (i->f->terminate_rport_io)
+                i->f->terminate_rport_io(rport);
 
         spin_lock_irqsave(shost->host_lock, flags);
         if (rport->flags & FC_RPORT_DEVLOSS_PENDING) {
                 spin_unlock_irqrestore(shost->host_lock, flags);
+                if (!cancel_delayed_work(&rport->fail_io_work))
+                        fc_flush_devloss(shost);
                 if (!cancel_delayed_work(&rport->dev_loss_work))
                         fc_flush_devloss(shost);
                 spin_lock_irqsave(shost->host_lock, flags);
@@ -1685,10 +1757,7 @@ fc_rport_final_delete(void *data)
         struct fc_rport *rport = (struct fc_rport *)data;
         struct device *dev = &rport->dev;
         struct Scsi_Host *shost = rport_to_shost(rport);
-
-        /* Delete SCSI target and sdevs */
-        if (rport->scsi_target_id != -1)
-                fc_starget_delete(data);
+        struct fc_internal *i = to_fc_internal(shost->transportt);
 
         /*
          * if a scan is pending, flush the SCSI Host work_q so that 
@@ -1697,6 +1766,14 @@ fc_rport_final_delete(void *data)
         if (rport->flags & FC_RPORT_SCAN_PENDING)
                 scsi_flush_work(shost);
 
+        /* Delete SCSI target and sdevs */
+        if (rport->scsi_target_id != -1)
+                fc_starget_delete(data);
+        else if (i->f->dev_loss_tmo_callbk)
+                i->f->dev_loss_tmo_callbk(rport);
+        else if (i->f->terminate_rport_io)
+                i->f->terminate_rport_io(rport);
+
         transport_remove_device(dev);
         device_del(dev);
         transport_destroy_device(dev);
@@ -1748,8 +1825,10 @@ fc_rport_create(struct Scsi_Host *shost, int channel,
         if (fci->f->dd_fcrport_size)
                 rport->dd_data = &rport[1];
         rport->channel = channel;
+        rport->fast_io_fail_tmo = -1;
 
         INIT_WORK(&rport->dev_loss_work, fc_timeout_deleted_rport, rport);
+        INIT_WORK(&rport->fail_io_work, fc_timeout_fail_rport_io, rport);
         INIT_WORK(&rport->scan_work, fc_scsi_scan_rport, rport);
         INIT_WORK(&rport->stgt_delete_work, fc_starget_delete, rport);
         INIT_WORK(&rport->rport_delete_work, fc_rport_final_delete, rport);
@@ -1913,11 +1992,13 @@ fc_remote_port_add(struct Scsi_Host *shost, int channel,
                                 /* restart the target */
 
                                 /*
-                                 * Stop the target timer first. Take no action
+                                 * Stop the target timers first. Take no action
                                  * on the del_timer failure as the state
                                  * machine state change will validate the
                                  * transaction.
                                  */
+                                if (!cancel_delayed_work(&rport->fail_io_work))
+                                        fc_flush_devloss(shost);
                                 if (!cancel_delayed_work(work))
                                         fc_flush_devloss(shost);
 
@@ -2061,6 +2142,7 @@ void
 fc_remote_port_delete(struct fc_rport  *rport)
 {
         struct Scsi_Host *shost = rport_to_shost(rport);
+        struct fc_internal *i = to_fc_internal(shost->transportt);
         int timeout = rport->dev_loss_tmo;
         unsigned long flags;
 
@@ -2091,6 +2173,12 @@ fc_remote_port_delete(struct fc_rport  *rport)
 
         scsi_target_block(&rport->dev);
 
+        /* see if we need to kill io faster than waiting for device loss */
+        if ((rport->fast_io_fail_tmo != -1) &&
+            (rport->fast_io_fail_tmo < timeout) && (i->f->terminate_rport_io))
+                fc_queue_devloss_work(shost, &rport->fail_io_work,
+                                        rport->fast_io_fail_tmo * HZ);
+
         /* cap the length the devices can be blocked until they are deleted */
         fc_queue_devloss_work(shost, &rport->dev_loss_work, timeout * HZ);
 }
@@ -2150,6 +2238,8 @@ fc_remote_port_rolechg(struct fc_rport  *rport, u32 roles)
                  * machine state change will validate the
                  * transaction.
                  */
+                if (!cancel_delayed_work(&rport->fail_io_work))
+                        fc_flush_devloss(shost);
                 if (!cancel_delayed_work(&rport->dev_loss_work))
                         fc_flush_devloss(shost);
 
@@ -2271,6 +2361,28 @@ fc_timeout_deleted_rport(void  *data)
 }
 
 /**
+ * fc_timeout_fail_rport_io - Timeout handler for a fast io failing on a
+ *                       disconnected SCSI target.
+ *
+ * @data:       rport to terminate io on.
+ *
+ * Notes: Only requests the failure of the io, not that all are flushed
+ *    prior to returning.
+ **/
+static void
+fc_timeout_fail_rport_io(void  *data)
+{
+        struct fc_rport *rport = (struct fc_rport *)data;
+        struct Scsi_Host *shost = rport_to_shost(rport);
+        struct fc_internal *i = to_fc_internal(shost->transportt);
+
+        if (rport->port_state != FC_PORTSTATE_BLOCKED)
+                return;
+
+        i->f->terminate_rport_io(rport);
+}
+
+/**
  * fc_scsi_scan_rport - called to perform a scsi scan on a remote port.
  *
  * @data:       remote port to be scanned.
diff --git a/include/scsi/scsi_transport_fc.h b/include/scsi/scsi_transport_fc.h
index 0b11eff989e0..fd352323378b 100644
--- a/include/scsi/scsi_transport_fc.h
+++ b/include/scsi/scsi_transport_fc.h
@@ -195,6 +195,7 @@ struct fc_rport {	/* aka fc_starget_attrs */
         u32 roles;
         enum fc_port_state port_state;  /* Will only be ONLINE or UNKNOWN */
         u32 scsi_target_id;
+        u32 fast_io_fail_tmo;
 
         /* exported data */
         void *dd_data;                  /* Used for driver-specific storage */
@@ -207,6 +208,7 @@ struct fc_rport {	/* aka fc_starget_attrs */
         struct device dev;
         struct work_struct dev_loss_work;
         struct work_struct scan_work;
+        struct work_struct fail_io_work;
         struct work_struct stgt_delete_work;
         struct work_struct rport_delete_work;
 } __attribute__((aligned(sizeof(unsigned long))));
@@ -445,6 +447,9 @@ struct fc_function_template {
 
         int     (*issue_fc_host_lip)(struct Scsi_Host *);
 
+        void    (*dev_loss_tmo_callbk)(struct fc_rport *);
+        void    (*terminate_rport_io)(struct fc_rport *);
+
         /* allocation lengths for host-specific data */
         u32                             dd_fcrport_size;