[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>

3 files changed, 45 insertions, 11 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 62307bd794a9..d2884bffa1b9 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);
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 2926baaac31e..334862e26a1b 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -730,6 +730,8 @@ static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result,
 static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
                 int *bflags, int async)
 {
+        int ret;
+
         /*
          * XXX do not save the inquiry, since it can change underneath us,
          * save just vendor/model/rev.
@@ -885,7 +887,17 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 
         /* set the device running here so that slave configure
          * may do I/O */
-        scsi_device_set_state(sdev, SDEV_RUNNING);
+        ret = scsi_device_set_state(sdev, SDEV_RUNNING);
+        if (ret) {
+                ret = scsi_device_set_state(sdev, SDEV_BLOCK);
+
+                if (ret) {
+                        sdev_printk(KERN_ERR, sdev,
+                                    "in wrong state %s to complete scan\n",
+                                    scsi_device_state_name(sdev->sdev_state));
+                        return SCSI_SCAN_NO_RESPONSE;
+                }
+        }
 
         if (*bflags & BLIST_MS_192_BYTES_FOR_3F)
                 sdev->use_192_bytes_for_3f = 1;
@@ -899,7 +911,7 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
         transport_configure_device(&sdev->sdev_gendev);
 
         if (sdev->host->hostt->slave_configure) {
-                int ret = sdev->host->hostt->slave_configure(sdev);
+                ret = sdev->host->hostt->slave_configure(sdev);
                 if (ret) {
                         /*
                          * if LLDD reports slave not present, don't clutter
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index ab3c71869be5..09d311d559d1 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -34,6 +34,7 @@ static const struct {
         { SDEV_QUIESCE, "quiesce" },
         { SDEV_OFFLINE, "offline" },
         { SDEV_BLOCK,   "blocked" },
+        { SDEV_CREATED_BLOCK, "created-blocked" },
 };
 
 const char *scsi_device_state_name(enum scsi_device_state state)