Revert "Revert "Merge pull request #2449 from wkennington/master.grub""

This reverts commit 94205f5f21c4d9942bb4205c06229438051b6853.

Conflicts:
	nixos/modules/system/boot/loader/grub/install-grub.pl

2 files changed, 145 insertions, 27 deletions

diff --git a/nixos/modules/system/boot/loader/grub/grub.nix b/nixos/modules/system/boot/loader/grub/grub.nix
index 0cc060db8f90..bc9a155ac95b 100644
--- a/nixos/modules/system/boot/loader/grub/grub.nix
+++ b/nixos/modules/system/boot/loader/grub/grub.nix
@@ -6,7 +6,8 @@ let
 
   cfg = config.boot.loader.grub;
 
-  realGrub = if cfg.version == 1 then pkgs.grub else pkgs.grub2;
+  realGrub = if cfg.version == 1 then pkgs.grub
+    else pkgs.grub2.override { zfsSupport = cfg.zfsSupport; };
 
   grub =
     # Don't include GRUB if we're only generating a GRUB menu (e.g.,
@@ -25,11 +26,12 @@ let
       inherit (cfg)
         version extraConfig extraPerEntryConfig extraEntries
         extraEntriesBeforeNixOS extraPrepareConfig configurationLimit copyKernels timeout
-        default devices explicitBootRoot;
+        default devices fsIdentifier;
       path = (makeSearchPath "bin" [
-        pkgs.coreutils pkgs.gnused pkgs.gnugrep pkgs.findutils pkgs.diffutils
+        pkgs.coreutils pkgs.gnused pkgs.gnugrep pkgs.findutils pkgs.diffutils pkgs.btrfsProgs
+        pkgs.utillinux
       ]) + ":" + (makeSearchPath "sbin" [
-        pkgs.mdadm
+        pkgs.mdadm pkgs.utillinux
       ]);
     });
 
@@ -209,12 +211,26 @@ in
         '';
       };
 
-      explicitBootRoot = mkOption {
-        default = "";
-        type = types.str;
+      fsIdentifier = mkOption {
+        default = "uuid";
+        type = types.addCheck types.str
+          (type: type == "uuid" || type == "label" || type == "provided");
         description = ''
-          The relative path of /boot within the parent volume. Leave empty
-          if /boot is not a btrfs subvolume.
+          Determines how grub will identify devices when generating the
+          configuration file. A value of uuid / label signifies that grub
+          will always resolve the uuid or label of the device before using
+          it in the configuration. A value of provided means that grub will
+          use the device name as show in <command>df</command> or
+          <command>mount</command>. Note, zfs zpools / datasets are ignored
+          and will always be mounted using their labels.
+        '';
+      };
+
+      zfsSupport = mkOption {
+        default = false;
+        type = types.bool;
+        description = ''
+          Whether grub should be build against libzfs.
         '';
       };
 
@@ -260,6 +276,9 @@ in
           ${pkgs.coreutils}/bin/cp -pf "${v}" "/boot/${n}"
         '') config.boot.loader.grub.extraFiles);
 
+    assertions = [{ assertion = !cfg.zfsSupport || cfg.version == 2;
+                    message = "Only grub version 2 provides zfs support";}];
+
     })
 
   ];
diff --git a/nixos/modules/system/boot/loader/grub/install-grub.pl b/nixos/modules/system/boot/loader/grub/install-grub.pl
index b4900358a5dc..7ced51f57e16 100644
--- a/nixos/modules/system/boot/loader/grub/install-grub.pl
+++ b/nixos/modules/system/boot/loader/grub/install-grub.pl
@@ -1,5 +1,6 @@
 use strict;
 use warnings;
+use Class::Struct;
 use XML::LibXML;
 use File::Basename;
 use File::Path;
@@ -27,6 +28,14 @@ sub writeFile {
     close FILE or die;
 }
 
+sub runCommand {
+    my ($cmd) = @_;
+    open FILE, "$cmd 2>/dev/null |" or die "Failed to execute: $cmd\n";
+    my @ret = <FILE>;
+    close FILE;
+    return ($?, @ret);
+}
+
 my $grub = get("grub");
 my $grubVersion = int(get("version"));
 my $extraConfig = get("extraConfig");
@@ -39,7 +48,7 @@ my $configurationLimit = int(get("configurationLimit"));
 my $copyKernels = get("copyKernels") eq "true";
 my $timeout = int(get("timeout"));
 my $defaultEntry = int(get("default"));
-my $explicitBootRoot = get("explicitBootRoot");
+my $fsIdentifier = get("fsIdentifier");
 $ENV{'PATH'} = get("path");
 
 die "unsupported GRUB version\n" if $grubVersion != 1 && $grubVersion != 2;
@@ -48,22 +57,108 @@ print STDERR "updating GRUB $grubVersion menu...\n";
 
 mkpath("/boot/grub", 0, 0700);
 
-
 # Discover whether /boot is on the same filesystem as / and
 # /nix/store.  If not, then all kernels and initrds must be copied to
-# /boot, and all paths in the GRUB config file must be relative to the
-# root of the /boot filesystem.  `$bootRoot' is the path to be
-# prepended to paths under /boot.
-my $bootRoot = "/boot";
-if (stat("/")->dev != stat("/boot")->dev) {
-    $bootRoot = "";
-    $copyKernels = 1;
-} elsif (stat("/boot")->dev != stat("/nix/store")->dev) {
+# /boot.
+if (stat("/boot")->dev != stat("/nix/store")->dev) {
     $copyKernels = 1;
 }
 
-if ($explicitBootRoot ne "") {
-    $bootRoot = $explicitBootRoot;
+# Discover information about the location of /boot
+struct(Fs => {
+    device => '$',
+    type => '$',
+    mount => '$',
+});
+sub GetFs {
+    my ($dir) = @_;
+    my ($status, @dfOut) = runCommand("df -T $dir");
+    if ($status != 0 || $#dfOut != 1) {
+        die "Failed to retrieve output about $dir from `df`";
+    }
+    my @boot = split(/[ \n\t]+/, $dfOut[1]);
+    return Fs->new(device => $boot[0], type => $boot[1], mount => $boot[6]);
+}
+struct (Grub => {
+    path => '$',
+    search => '$',
+});
+my $driveid = 1;
+sub GrubFs {
+    my ($dir) = @_;
+    my $fs = GetFs($dir);
+    my $path = "/" . substr($dir, length($fs->mount));
+    my $search = "";
+
+    if ($grubVersion > 1) {
+        # ZFS is completely separate logic as zpools are always identified by a label
+        # or custom UUID
+        if ($fs->type eq 'zfs') {
+            my $sid = index($fs->device, '/');
+
+            if ($sid < 0) {
+                $search = '--label ' . $fs->device;
+                $path = '/@' . $path;
+            } else {
+                $search = '--label ' . substr($fs->device, 0, $sid);
+                $path = '/' . substr($fs->device, $sid) . '/@' . $path;
+            }
+        } else {
+            my %types = ('uuid' => '--fs-uuid', 'label' => '--label');
+
+            if ($fsIdentifier eq 'provided') {
+                # If the provided dev is identifying the partition using a label or uuid,
+                # we should get the label / uuid and do a proper search
+                my @matches = $fs->device =~ m/\/dev\/disk\/by-(label|uuid)\/(.*)/;
+                if ($#matches > 1) {
+                    die "Too many matched devices"
+                } elsif ($#matches == 1) {
+                    $search = "$types{$matches[0]} $matches[1]"
+                }
+            } else {
+                # Determine the identifying type
+                $search = $types{$fsIdentifier} . ' ';
+
+                # Based on the type pull in the identifier from the system
+                my ($status, @devInfo) = runCommand("blkid -o export @{[$fs->device]}");
+                if ($status != 0) {
+                    die "Failed to get blkid info for @{[$fs->device]}";
+                }
+                my @matches = join("", @devInfo) =~ m/@{[uc $fsIdentifier]}=([^\n]*)/;
+                if ($#matches != 0) {
+                    die "Couldn't find a $types{$fsIdentifier} for @{[$fs->device]}\n"
+                }
+                $search .= $matches[0];
+            }
+
+            # BTRFS is a special case in that we need to fix the referrenced path based on subvolumes
+            if ($fs->type eq 'btrfs') {
+                my ($status, @info) = runCommand("btrfs subvol show @{[$fs->mount]}");
+                if ($status != 0) {
+                    die "Failed to retreive subvolume info for @{[$fs->mount]}";
+                }
+                my @subvols = join("", @info) =~ m/Name:[ \t\n]*([^ \t\n]*)/;
+                if ($#subvols > 0) {
+                    die "Btrfs subvol name for @{[$fs->device]} listed multiple times in mount\n"
+                } elsif ($#subvols == 0) {
+                    $path = "/$subvols[0]$path";
+                }
+            }
+        }
+        if (not $search eq "") {
+            $search = "search --set=drive$driveid " . $search;
+            $path = "(\$drive$driveid)$path";
+            $driveid += 1;
+        }
+    }
+    return Grub->new(path => $path, search => $search);
+}
+my $grubBoot = GrubFs("/boot");
+my $grubStore = GrubFs("/nix");
+
+# We don't need to copy if we can read the kernels directly
+if ($grubStore->search ne "") {
+    $copyKernels = 0;
 }
 
 # Generate the header.
@@ -76,12 +171,14 @@ if ($grubVersion == 1) {
     ";
     if ($splashImage) {
         copy $splashImage, "/boot/background.xpm.gz" or die "cannot copy $splashImage to /boot\n";
-        $conf .= "splashimage $bootRoot/background.xpm.gz\n";
+        $conf .= "splashimage " . $grubBoot->path . "/background.xpm.gz\n";
     }
 }
 
 else {
     $conf .= "
+        " . $grubBoot->search . "
+        " . $grubStore->search . "
         if [ -s \$prefix/grubenv ]; then
           load_env
         fi
@@ -102,7 +199,7 @@ else {
           set timeout=$timeout
         fi
 
-        if loadfont $bootRoot/grub/fonts/unicode.pf2; then
+        if loadfont " . $grubBoot->path . "/grub/fonts/unicode.pf2; then
           set gfxmode=640x480
           insmod gfxterm
           insmod vbe
@@ -116,7 +213,7 @@ else {
         copy $splashImage, "/boot/background.png" or die "cannot copy $splashImage to /boot\n";
         $conf .= "
             insmod png
-            if background_image $bootRoot/background.png; then
+            if background_image " . $grubBoot->path . "/background.png; then
               set color_normal=white/black
               set color_highlight=black/white
             else
@@ -138,7 +235,7 @@ mkpath("/boot/kernels", 0, 0755) if $copyKernels;
 
 sub copyToKernelsDir {
     my ($path) = @_;
-    return $path unless $copyKernels;
+    return $grubStore->path . substr($path, length("/nix")) unless $copyKernels;
     $path =~ /\/nix\/store\/(.*)/ or die;
     my $name = $1; $name =~ s/\//-/g;
     my $dst = "/boot/kernels/$name";
@@ -151,7 +248,7 @@ sub copyToKernelsDir {
         rename $tmp, $dst or die "cannot rename $tmp to $dst\n";
     }
     $copied{$dst} = 1;
-    return "$bootRoot/kernels/$name";
+    return $grubBoot->path . "/kernels/$name";
 }
 
 sub addEntry {
@@ -178,6 +275,8 @@ sub addEntry {
         $conf .= "  " . ($xen ? "module" : "initrd") . " $initrd\n\n";
     } else {
         $conf .= "menuentry \"$name\" {\n";
+        $conf .= $grubBoot->search . "\n";
+        $conf .= $grubStore->search . "\n";
         $conf .= "  $extraPerEntryConfig\n" if $extraPerEntryConfig;
         $conf .= "  multiboot $xen $xenParams\n" if $xen;
         $conf .= "  " . ($xen ? "module" : "linux") . " $kernel $kernelParams\n";
@@ -195,7 +294,7 @@ addEntry("NixOS - Default", $defaultConfig);
 $conf .= "$extraEntries\n" unless $extraEntriesBeforeNixOS;
 
 # extraEntries could refer to @bootRoot@, which we have to substitute
-$conf =~ s/\@bootRoot\@/$bootRoot/g;
+$conf =~ s/\@bootRoot\@/$grubBoot->path/g;
 
 # Emit submenus for all system profiles.
 sub addProfile {