[SCSI] Update the SCSI state model to allow blocking in the created state

Brian King <brking@linux.vnet.ibm.com> reported that fibre channel
devices can oops during scanning if their ports block (because the
device goes from CREATED -> BLOCK -> RUNNING rather than CREATED ->
BLOCK -> CREATED).

Fix this by adding a new state: CREATED_BLOCK which can only transition
back to CREATED and disallow the CREATED -> BLOCK transition.  Now both
the created and blocked states that the mid-layer recognises can include
CREATED_BLOCK.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 30 insertions, 9 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 62307bd794a..d2884bffa1b 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1251,6 +1251,7 @@ int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
                         break;
                 case SDEV_QUIESCE:
                 case SDEV_BLOCK:
+                case SDEV_CREATED_BLOCK:
                         /*
                          * If the devices is blocked we defer normal commands.
                          */
@@ -2064,10 +2065,13 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
 
         switch (state) {
         case SDEV_CREATED:
-                /* There are no legal states that come back to
-                 * created.  This is the manually initialised start
-                 * state */
-                goto illegal;
+                switch (oldstate) {
+                case SDEV_CREATED_BLOCK:
+                        break;
+                default:
+                        goto illegal;
+                }
+                break;
                         
         case SDEV_RUNNING:
                 switch (oldstate) {
@@ -2105,8 +2109,17 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
 
         case SDEV_BLOCK:
                 switch (oldstate) {
-                case SDEV_CREATED:
                 case SDEV_RUNNING:
+                case SDEV_CREATED_BLOCK:
+                        break;
+                default:
+                        goto illegal;
+                }
+                break;
+
+        case SDEV_CREATED_BLOCK:
+                switch (oldstate) {
+                case SDEV_CREATED:
                         break;
                 default:
                         goto illegal;
@@ -2394,8 +2407,12 @@ scsi_internal_device_block(struct scsi_device *sdev)
         int err = 0;
 
         err = scsi_device_set_state(sdev, SDEV_BLOCK);
-        if (err)
-                return err;
+        if (err) {
+                err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
+
+                if (err)
+                        return err;
+        }
 
         /* 
          * The device has transitioned to SDEV_BLOCK.  Stop the
@@ -2438,8 +2455,12 @@ scsi_internal_device_unblock(struct scsi_device *sdev)
          * and goose the device queue if successful.  
          */
         err = scsi_device_set_state(sdev, SDEV_RUNNING);
-        if (err)
-                return err;
+        if (err) {
+                err = scsi_device_set_state(sdev, SDEV_CREATED);
+
+                if (err)
+                        return err;
+        }
 
         spin_lock_irqsave(q->queue_lock, flags);
         blk_start_queue(q);