SCSI: fix scsi_wait_scan

commit 1ff2f403 upstream.

Commit  c7510859
Author: Rafael J. Wysocki <rjw@sisk.pl>
Date:   Sun Apr 12 20:06:56 2009 +0200

    PM/Hibernate: Wait for SCSI devices scan to complete during resume

Broke the scsi_wait_scan module in 2.6.30.  Apparently debian still uses it so
fix it and backport to stable before removing it in 3.6.

The breakage is caused because the function template in
include/scsi/scsi_scan.h is defined to be a nop unless SCSI is built in.
That means that in the modular case (which is every distro), the
scsi_wait_scan module does a simple async_synchronize_full() instead of
waiting for scans.
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>

drivers/scsi/scsi_priv.h

@@ -107,6 +107,7 @@ extern void scsi_exit_procfs(void);
 #endif /* CONFIG_PROC_FS */
 
 /* scsi_scan.c */
+extern int scsi_complete_async_scans(void);
 extern int scsi_scan_host_selected(struct Scsi_Host *, unsigned int,
 				   unsigned int, unsigned int, int);
 extern void scsi_forget_host(struct Scsi_Host *);

drivers/scsi/scsi_wait_scan.c

@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/device.h>
 #include <scsi/scsi_scan.h>
+#include "scsi_priv.h"
 
 static int __init wait_scan_init(void)
 {