[SCSI] Make scsi_scan_host work for drivers which find their own targets

If a driver can find its own targets, it can now fill in scan_finished and
(optionally) scan_start in the scsi_host_template.  Then, when it calls
scsi_scan_host(), it will be called back (from a thread if asynchronous
discovery is enabled), first to start the scan, and then at intervals to
check if the scan is completed.

Also make scsi_prep_async_scan and scsi_finish_async_scan static.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

2 files changed, 38 insertions, 7 deletions

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 3ccaa4be92d8..4d656148bd67 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1642,7 +1642,7 @@ static void scsi_sysfs_add_devices(struct Scsi_Host *shost)
  * that other asynchronous scans started after this one won't affect the
  * ordering of the discovered devices.
  */
-struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost)
+static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost)
 {
         struct async_scan_data *data;
 
@@ -1686,7 +1686,7 @@ struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost)
  * This function announces all the devices it has found to the rest
  * of the system.
  */
-void scsi_finish_async_scan(struct async_scan_data *data)
+static void scsi_finish_async_scan(struct async_scan_data *data)
 {
         struct Scsi_Host *shost;
 
@@ -1719,12 +1719,25 @@ void scsi_finish_async_scan(struct async_scan_data *data)
         kfree(data);
 }
 
-static int do_scan_async(void *_data)
+static void do_scsi_scan_host(struct Scsi_Host *shost)
 {
-        struct async_scan_data *data = _data;
-        scsi_scan_host_selected(data->shost, SCAN_WILD_CARD, SCAN_WILD_CARD,
+        if (shost->hostt->scan_finished) {
+                unsigned long start = jiffies;
+                if (shost->hostt->scan_start)
+                        shost->hostt->scan_start(shost);
+
+                while (!shost->hostt->scan_finished(shost, jiffies - start))
+                        msleep(10);
+        } else {
+                scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD,
                                 SCAN_WILD_CARD, 0);
+        }
+}
 
+static int do_scan_async(void *_data)
+{
+        struct async_scan_data *data = _data;
+        do_scsi_scan_host(data->shost);
         scsi_finish_async_scan(data);
         return 0;
 }
@@ -1742,10 +1755,10 @@ void scsi_scan_host(struct Scsi_Host *shost)
 
         data = scsi_prep_async_scan(shost);
         if (!data) {
-                scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD,
-                                        SCAN_WILD_CARD, 0);
+                do_scsi_scan_host(shost);
                 return;
         }
+
         kthread_run(do_scan_async, data, "scsi_scan_%d", shost->host_no);
 }
 EXPORT_SYMBOL(scsi_scan_host);
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index e618e711ea57..6d8945d71c65 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -241,6 +241,24 @@ struct scsi_host_template {
         void (* target_destroy)(struct scsi_target *);
 
         /*
+         * If a host has the ability to discover targets on its own instead
+         * of scanning the entire bus, it can fill in this function and
+         * call scsi_scan_host().  This function will be called periodically
+         * until it returns 1 with the scsi_host and the elapsed time of
+         * the scan in jiffies.
+         *
+         * Status: OPTIONAL
+         */
+        int (* scan_finished)(struct Scsi_Host *, unsigned long);
+
+        /*
+         * If the host wants to be called before the scan starts, but
+         * after the midlayer has set up ready for the scan, it can fill
+         * in this function.
+         */
+        void (* scan_start)(struct Scsi_Host *);
+
+        /*
          * fill in this function to allow the queue depth of this host
          * to be changeable (on a per device basis).  returns either
          * the current queue depth setting (may be different from what