[SCSI] Add target alloc/destroy callbacks to the host template

This gives the HBA driver notice when a target is created and
destroyed to allow it to manage its own target based allocations
accordingly.

This is a much reduced verson of the original patch sent in by
James.Smart@Emulex.com

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

2 files changed, 28 insertions, 1 deletions

diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index c018020d9160..63c91dd85ca1 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -154,7 +154,9 @@ struct scsi_target {
         unsigned int            id; /* target id ... replace
                                      * scsi_device.id eventually */
         unsigned long           create:1; /* signal that it needs to be added */
-        unsigned long           starget_data[0];
+        void                    *hostdata; /* available to low-level driver */
+        unsigned long           starget_data[0]; /* for the transport */
+        /* starget_data must be the last element!!!! */
 } __attribute__((aligned(sizeof(unsigned long))));
 
 #define to_scsi_target(d)       container_of(d, struct scsi_target, dev)
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 1cee1e100943..db9914adeac9 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -10,6 +10,7 @@ struct block_device;
 struct module;
 struct scsi_cmnd;
 struct scsi_device;
+struct scsi_target;
 struct Scsi_Host;
 struct scsi_host_cmd_pool;
 struct scsi_transport_template;
@@ -228,6 +229,30 @@ struct scsi_host_template {
         void (* slave_destroy)(struct scsi_device *);
 
         /*
+         * Before the mid layer attempts to scan for a new device attached
+         * to a target where no target currently exists, it will call this
+         * entry in your driver.  Should your driver need to allocate any
+         * structs or perform any other init items in order to send commands
+         * to a currently unused target, then this is where you can perform
+         * those allocations.
+         *
+         * Return values: 0 on success, non-0 on failure
+         *
+         * Status: OPTIONAL
+         */
+        int (* target_alloc)(struct scsi_target *);
+
+        /*
+         * Immediately prior to deallocating the target structure, and
+         * after all activity to attached scsi devices has ceased, the
+         * midlayer calls this point so that the driver may deallocate
+         * and terminate any references to the target.
+         *
+         * Status: OPTIONAL
+         */
+        void (* target_destroy)(struct scsi_target *);
+
+        /*
          * 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