CHROMIUM: make dm= boot path wait for devices

init/do_mounts_dm.c

 /* do_mounts_dm.c
  * Copyright (C) 2010 The Chromium OS Authors <chromium-os-dev@chromium.org>
  *                    All Rights Reserved.
  * Based on do_mounts_md.c
  *
  * This file is released under the GPL.
  */
+#include <linux/async.h>
 #include <linux/device-mapper.h>
 #include <linux/fs.h>
 #include <linux/string.h>
 
 #include "do_mounts.h"
 
 #define DM_MAX_NAME 32
 #define DM_MAX_UUID 129
 #define DM_NO_UUID "none"
 
@@ skipping 174 matching lines @@
                         continue;
 
                 /* Temporarily terminate with a nul */
                 candidate_end--;
                 old_char = *candidate_end;
                 *candidate_end = '\0';
 
                 DMDEBUG("converting candidate device '%s' to dev_t", candidate);
                 /* Use the boot-time specific device naming */
                 dev = name_to_dev_t(candidate);
+
+                /* If it failed, but the candidate starts with /dev/, then try
+                 * after device probing ends.
+                 */
+                if (!dev && strncmp(candidate, "/dev/", 5) == 0) {
+                        DMINFO("waiting to resolve device '%s'...",
+                               candidate);
+                        while (driver_probe_done() != 0 ||
+                                (dev = name_to_dev_t(candidate)) == 0)
+                                msleep(100);
+                        async_synchronize_full();
+                }
+                DMDEBUG(" -> %u", dev);
+
                 *candidate_end = old_char;
-
-                DMDEBUG(" -> %u", dev);
                 /* No suitable replacement found */
                 if (!dev)
                         continue;
 
                 /* Rewrite the /dev/path as a major:minor */
                 len = snprintf(candidate, len, "%u:%u", MAJOR(dev), MINOR(dev));
                 if (!len) {
                         DMERR("error substituting device major/minor.");
                         break;
                 }
@@ skipping 203 matching lines @@
 
 __setup("dm=", dm_setup);
 
 void __init dm_run_setup(void)
 {
         if (!dm_early_setup)
                 return;
         printk(KERN_INFO "dm: attempting early device configuration.\n");
         dm_setup_drive();
 }