Add rootflags=subvol=<name> if / is on a btrfs subvolume (LP: #712029).

debian/changelog

@@ -7,6 +7,7 @@ grub2 (1.99~rc1-2) UNRELEASED; urgency=low
     Uggla).
   * Handle empty dir passed to grub_find_root_device_from_mountinfo; fixes
     grub-mkrelpath on btrfs subvolumes (LP: #712029).
+  * Add rootflags=subvol=<name> if / is on a btrfs subvolume (LP: #712029).
 
  -- Colin Watson <cjwatson@debian.org>  Tue, 18 Jan 2011 11:44:48 +0000
 

debian/patches/btrfs_rootflags.patch

@@ -0,0 +1,27 @@
+Description: Add rootflags=subvol=<name> if / is on a btrfs subvolume
+ Not yet forwarded upstream because rootflags= is distribution-specific.
+ It's not clear how to do this portably.
+Author: Colin Watson <cjwatson@ubuntu.com>
+Forwarded: no
+Bug-Ubuntu: https://bugs.launchpad.net/bugs/712029
+Last-Update: 2011-02-04
+
+Index: b/util/grub.d/10_linux.in
+===================================================================
+--- a/util/grub.d/10_linux.in
++++ b/util/grub.d/10_linux.in
+@@ -51,6 +51,14 @@
+   LINUX_ROOT_DEVICE=UUID=${GRUB_DEVICE_UUID}
+ fi
+ 
++if [ "x`${grub_probe} --device ${GRUB_DEVICE} --target=fs 2>/dev/null || true`" = xbtrfs ]; then
++  rootsubvol="`make_system_path_relative_to_its_root /`"
++  rootsubvol="${rootsubvol#/}"
++  if [ "x${rootsubvol}" != x ]; then
++    GRUB_CMDLINE_LINUX="rootflags=subvol=${rootsubvol} ${GRUB_CMDLINE_LINUX}"
++  fi
++fi
++
+ linux_entry ()
+ {
+   os="$1"

debian/patches/series

@@ -16,3 +16,4 @@ branch_squash.patch
 branch_longlinuxcmd.patch
 branch_parse-color.patch
 branch_embed-sectors.patch
+btrfs_rootflags.patch