ZFS on Linux Improvements

1. `zpool status` can output disk names which are under /dev/disk.
2. `zpool status` outputs the whole disk device for wholedisk pools,
   but GRUB needs the partition device.
3. Support native ZFS on Linux.

Index: grub/util/getroot.c
===================================================================
--- grub.orig/util/getroot.c	2012-02-03 05:54:39.540539000 -0600
+++ grub/util/getroot.c	2012-02-03 06:04:29.465275000 -0600
@@ -304,7 +304,87 @@
 		if (name[0] == '/')
 		  devices[ndevices++] = xstrdup (name);
 		else
+#ifdef __linux__
+		  {
+		    /* The name returned by zpool isn't necessarily directly under /dev. */
+		    char *device = xasprintf ("/dev/%s", name);
+		    struct stat sb;
+		    char *real_device;
+		    char *c;
+		    char *partition;
+
+		    if (stat (device, &sb) != 0)
+		      {
+			DIR *dev;
+			struct dirent *subdir;
+
+			free (device);
+			device = NULL;
+			dev = opendir ("/dev/disk");
+			if (dev)
+			  {
+			    while ((subdir = readdir (dev)))
+			      {
+				if (subdir->d_name[0] == '.')
+				  continue;
+				if (subdir->d_type == DT_UNKNOWN)
+				  {
+				    char *subdir_path = xasprintf ("/dev/disk/%s", subdir->d_name);
+				    ret = stat (subdir_path, &sb);
+				    free (subdir_path);
+				    if (ret != 0)
+				      continue;
+				    if (!S_ISDIR (sb.st_mode))
+				      continue;
+				  }
+				else if (subdir->d_type != DT_DIR)
+				  continue;
+				device = xasprintf ("/dev/disk/%s/%s", subdir->d_name, name);
+				if (stat (device, &sb) == 0)
+				  break;
+				else
+				  {
+				    free (device);
+				    device = NULL;
+				  }
+			      }
+			    closedir (dev);
+			    if (! device)
+			      grub_util_error (_("failed to find device %s"), device);
+			  }
+		      }
+
+		    /* Resolve the symlink to something like /dev/sda. */
+		    real_device = canonicalize_file_name (device);
+		    if (! real_device)
+		      grub_util_error (_("failed to get canonical path of %s"), device);
+		    free(device);
+
+		    /* It ends in a number; assume it's a partition and stop. */
+		    for (c = real_device ; *(c+1) ; c++);
+		    if (*c >= '0' && *c <= '9')
+		      {
+			devices[ndevices++] = real_device;
+			break;
+		      }
+
+		    /* Otherwise, it might be a partitioned wholedisk device. */
+		    partition = xasprintf ("%s1", real_device);
+		    if (stat (partition, &sb) == 0)
+		      {
+			free (real_device);
+			devices[ndevices++] = partition;
+			break;
+		      }
+		    free (partition);
+
+		    /* The device is not partitioned. */
+		    devices[ndevices++] = real_device;
+		    break;
+		  }
+#else
 		  devices[ndevices++] = xasprintf ("/dev/%s", name);
+#endif
 	      }
 	    break;
 	  }
@@ -478,7 +558,8 @@
       if (!*entries[i].device)
 	continue;
 
-      if (grub_strcmp (entries[i].fstype, "fuse.zfs") == 0)
+      if (grub_strcmp (entries[i].fstype, "fuse.zfs") == 0 ||
+          grub_strcmp (entries[i].fstype, "zfs") == 0)
 	{
 	  char *slash;
 	  slash = strchr (entries[i].device, '/');