2010-07-30 Robert Millan <rmh@gnu.org>

Enable `grub-probe -t device' resolution on ZFS.
	
	* configure.ac: Check for getfsstat(), libzfs and libnvpair.
	* include/grub/util/libnvpair.h: New file.
	* include/grub/util/libzfs.h: New file.
	
	* kern/emu/getroot.c: Include `<assert.h>' and `<error.h>'.
	[HAVE_LIBZFS && HAVE_LIBNVPAIR]: Include `<grub/util/libzfs.h>' and
	`<grub/util/libnvpair.h>'.
	[HAVE_GETFSSTAT]: Include `<sys/mount.h>'.
	
	(find_mount_point_from_dir): New static function.
	[HAVE_LIBZFS && HAVE_LIBNVPAIR] (find_root_device_from_libzfs): New
	function.
	[HAVE_LIBZFS && HAVE_LIBNVPAIR] (grub_guess_root_device): Use
	find_root_device_from_libzfs() before ressorting to find_root_device().
	
	* include/grub/util/misc.h (grub_util_init_libzfs): New function
	prototype.
	* util/misc.c: Include `<grub/util/libzfs.h>'.
	(grub_util_init_libzfs): New function.
	[HAVE_LIBZFS] (libzfs_handle): New global variable.
	[HAVE_LIBZFS] (fini_libzfs): New static function.
	(grub_util_init_libzfs): New function.
	* util/grub-probe.c (main): Call grub_util_init_libzfs().

kern/emu/getroot.c

@@ -20,11 +20,13 @@
 #include <config.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <assert.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <string.h>
 #include <dirent.h>
 #include <errno.h>
+#include <error.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
@@ -41,6 +43,15 @@
 # include <sys/wait.h>
 #endif
 
+#if defined(HAVE_LIBZFS) && defined(HAVE_LIBNVPAIR)
+# include <grub/util/libzfs.h>
+# include <grub/util/libnvpair.h>
+#endif
+
+#ifdef HAVE_GETFSSTAT
+# include <sys/mount.h>
+#endif
+
 #include <grub/mm.h>
 #include <grub/misc.h>
 #include <grub/emu/misc.h>
@@ -86,6 +97,62 @@ xgetcwd (void)
   return path;
 }
 
+static char *
+find_mount_point_from_dir (const char *dir)
+{
+  struct stat st;
+  typeof (st.st_dev) fs;
+  char *prev, *next, *slash, *statdir;
+
+  if (stat (dir, &st) == -1)
+    error (1, errno, "stat (%s)", dir);
+
+  fs = st.st_dev;
+
+  prev = xstrdup (dir);
+
+  while (1)
+    {
+      /* Remove last slash.  */
+      next = xstrdup (prev);
+      slash = strrchr (next, '/');
+      if (! slash)
+	{
+	  free (next);
+	  free (prev);
+	  return NULL;
+	}
+      *slash = '\0';
+
+      /* A next empty string counts as /.  */
+      if (next[0] == '\0')
+	statdir = "/";
+      else
+	statdir = next;
+
+      if (stat (statdir, &st) == -1)
+	error (1, errno, "stat (%s)", next);
+
+      if (st.st_dev != fs)
+	{
+	  /* Found mount point.  */
+	  free (next);
+	  return prev;
+	}
+
+      free (prev);
+      prev = next;
+
+      /* We've already seen an empty string, which means we
+         reached /.  Nothing left to do.  */
+      if (prev[0] == '\0')
+	{
+	  free (prev);
+	  return xstrdup ("/");
+	}
+    }
+}
+
 #ifdef __linux__
 
 /* Statting something on a btrfs filesystem always returns a virtual device
@@ -166,6 +233,88 @@ find_root_device_from_mountinfo (const char *dir)
 
 #endif /* __linux__ */
 
+#if defined(HAVE_LIBZFS) && defined(HAVE_LIBNVPAIR)
+
+/* ZFS has similar problems to those of btrfs (see above).  */
+static char *
+find_root_device_from_libzfs (const char *dir)
+{
+  char *device = NULL;
+  char *poolname = NULL;
+  char *poolfs = NULL;
+  char *mnt_point;
+  char *slash;
+
+  mnt_point = find_mount_point_from_dir (dir);
+
+#ifdef HAVE_GETFSSTAT
+  {
+    int mnt_count = getfsstat (NULL, 0, MNT_WAIT);
+    if (mnt_count == -1)
+      error (1, errno, "getfsstat");
+
+    struct statfs *mnt = xmalloc (mnt_count * sizeof (*mnt));
+
+    mnt_count = getfsstat (mnt, mnt_count * sizeof (*mnt), MNT_WAIT);
+    if (mnt_count == -1)
+      error (1, errno, "getfsstat");
+
+    unsigned int i;
+    for (i = 0; i < (unsigned) mnt_count; i++)
+      if (!strcmp (mnt[i].f_fstypename, "zfs")
+	  && !strcmp (mnt[i].f_mntonname, mnt_point))
+	{
+	  poolname = xstrdup (mnt[i].f_mntfromname);
+	  break;
+	}
+
+    free (mnt);
+  }
+#endif
+
+  if (! poolname)
+    return NULL;
+
+  slash = strchr (poolname, '/');
+  if (slash)
+    {
+      *slash = '\0';
+      poolfs = slash + 1;
+    }
+
+  {
+    zpool_handle_t *zpool;
+    nvlist_t *nvlist;
+    nvlist_t **nvlist_array;
+    unsigned int nvlist_count;
+
+    zpool = zpool_open (libzfs_handle, poolname);
+    nvlist = zpool_get_config (zpool, NULL);
+
+    if (nvlist_lookup_nvlist (nvlist, "vdev_tree", &nvlist) != 0)
+      error (1, errno, "nvlist_lookup_nvlist (\"vdev_tree\")");
+
+    if (nvlist_lookup_nvlist_array (nvlist, "children", &nvlist_array, &nvlist_count) != 0)
+      error (1, errno, "nvlist_lookup_nvlist_array (\"children\")");
+
+    do
+      {
+	assert (nvlist_count > 0);
+      } while (nvlist_lookup_nvlist_array (nvlist_array[0], "children",
+					   &nvlist_array, &nvlist_count) == 0);
+
+    if (nvlist_lookup_string (nvlist_array[0], "path", &device) != 0)
+      error (1, errno, "nvlist_lookup_string (\"path\")");
+
+    zpool_close (zpool);
+  }
+
+  free (poolname);
+
+  return device;
+}
+#endif
+
 #ifdef __MINGW32__
 
 static char *
@@ -458,6 +607,12 @@ grub_guess_root_device (const char *dir)
     return os_dev;
 #endif /* __linux__ */
 
+#if defined(HAVE_LIBZFS) && defined(HAVE_LIBNVPAIR)
+  os_dev = find_root_device_from_libzfs (dir);
+  if (os_dev)
+    return os_dev;
+#endif
+
   if (stat (dir, &st) < 0)
     grub_util_error ("cannot stat `%s'", dir);