From 22760c76db0843082609efeb62e32f351f02c059 Mon Sep 17 00:00:00 2001
From: Tiago Ilieve <tiago.myhro@gmail.com>
Date: Sat, 25 Apr 2015 19:24:55 -0300
Subject: [PATCH] Revert a2cf28b (#213)

Looks like we may or may not need to create those uuid links by
ourselves. This patch also adds a verification to not create/delete the
link if it already exists or not, respectively.
---
 bootstrapvz/base/fs/partitions/base.py | 31 ++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/bootstrapvz/base/fs/partitions/base.py b/bootstrapvz/base/fs/partitions/base.py
index 67234e0..696a92a 100644
--- a/bootstrapvz/base/fs/partitions/base.py
+++ b/bootstrapvz/base/fs/partitions/base.py
@@ -1,3 +1,4 @@
+import os
 from abstract import AbstractPartition
 from bootstrapvz.common.sectors import Sectors
 
@@ -31,6 +32,8 @@ class BasePartition(AbstractPartition):
 		self.previous = previous
 		# List of flags that parted should put on the partition
 		self.flags = []
+		# Path to symlink in /dev/disk/by-uuid (manually maintained by this class)
+		self.disk_by_uuid_path = None
 		super(BasePartition, self).__init__(size, filesystem, format_command)
 
 	def create(self, volume):
@@ -71,6 +74,25 @@ class BasePartition(AbstractPartition):
 		"""
 		self.fsm.map(device_path=device_path)
 
+	def link_uuid(self):
+		# /lib/udev/rules.d/60-kpartx.rules does not create symlinks in /dev/disk/by-{uuid,label}
+		# This patch would fix that: http://www.redhat.com/archives/dm-devel/2013-July/msg00080.html
+		# For now we just do the uuid part ourselves.
+		# This is mainly to fix a problem in update-grub where /etc/grub.d/10_linux
+		# checks if the $GRUB_DEVICE_UUID exists in /dev/disk/by-uuid and falls
+		# back to $GRUB_DEVICE if it doesn't.
+		# $GRUB_DEVICE is /dev/mapper/xvd{f,g...}# (on ec2), opposed to /dev/xvda# when booting.
+		# Creating the symlink ensures that grub consistently uses
+		# $GRUB_DEVICE_UUID when creating /boot/grub/grub.cfg
+		self.disk_by_uuid_path = os.path.join('/dev/disk/by-uuid', self.get_uuid())
+		if not os.path.exists(self.disk_by_uuid_path):
+			os.symlink(self.device_path, self.disk_by_uuid_path)
+
+	def unlink_uuid(self):
+		if os.path.isfile(self.disk_by_uuid_path):
+			os.remove(self.disk_by_uuid_path)
+		self.disk_by_uuid_path = None
+
 	def _before_create(self, e):
 		"""Creates the partition
 		"""
@@ -92,7 +114,16 @@ class BasePartition(AbstractPartition):
 	def _before_map(self, e):
 		# Set the device path
 		self.device_path = e.device_path
+		if e.src == 'unmapped_fmt':
+			# Only link the uuid if the partition is formatted
+			self.link_uuid()
+
+	def _after_format(self, e):
+		# We do this after formatting because there otherwise would be no UUID
+		self.link_uuid()
 
 	def _before_unmap(self, e):
 		# When unmapped, the device_path information becomes invalid, so we delete it
 		self.device_path = None
+		if e.src == 'formatted':
+			self.unlink_uuid()