From fbb8eb09fb851bfadea0afe68ec80d928e94488a Mon Sep 17 00:00:00 2001
From: Ryan Harper <ryan.harper@canonical.com>
Date: Tue, 1 Sep 2015 17:01:07 -0500
Subject: [PATCH] Adjust partition alignment for GPT and curtin sgdisk

Curtin uses sgdisk to create partitions.  To avoid sgdisk
fixing alignment issues we ensure that all partitions are
1M aligned.

GPT partitions also require space at the end, reserve the
same number of sectors (1K, 2048 512b sectors) at the
start and end of the disk.

Signed-off-by: Ryan Harper <ryan.harper@canonical.com>
---
 subiquity/controllers/filesystem.py | 15 +++++++++------
 subiquity/models/blockdev.py        | 18 ++++++++++++++++--
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/subiquity/controllers/filesystem.py b/subiquity/controllers/filesystem.py
index 8b26dba6..b4a8f093 100644
--- a/subiquity/controllers/filesystem.py
+++ b/subiquity/controllers/filesystem.py
@@ -16,7 +16,6 @@
 import logging
 from subiquity.controller import ControllerPolicy
 from subiquity.models import FilesystemModel
-from subiquity.models.blockdev import FIRST_PARTITION_OFFSET
 from subiquity.ui.views import (DiskPartitionView, AddPartitionView,
                                 FilesystemView)
 from subiquity.ui.dummy import DummyView
@@ -97,14 +96,18 @@ class FilesystemController(ControllerPolicy):
             if current_disk.parttype == 'gpt' and \
                len(current_disk.disk.partitions) == 0:
                 log.debug('Adding grub_bios gpt partition first')
-                current_disk.add_partition(partnum=1,
-                                           size=BIOS_GRUB_SIZE_BYTES,
-                                           fstype=None,
-                                           flag='bios_grub')
+                size_added = \
+                    current_disk.add_partition(partnum=1,
+                                               size=BIOS_GRUB_SIZE_BYTES,
+                                               fstype=None,
+                                               flag='bios_grub')
 
                 # adjust downward the partition size to accommodate
                 # the offset and bios/grub partition
-                spec['bytes'] -= FIRST_PARTITION_OFFSET + BIOS_GRUB_SIZE_BYTES
+                log.debug("Adjusting request down:" +
+                          "{} - {} = {}".format(spec['bytes'], size_added,
+                                                spec['bytes'] - size_added))
+                spec['bytes'] -= size_added
                 spec['partnum'] = 2
 
             if spec["fstype"] in ["swap"]:
diff --git a/subiquity/models/blockdev.py b/subiquity/models/blockdev.py
index 4fc14e29..fad466e0 100644
--- a/subiquity/models/blockdev.py
+++ b/subiquity/models/blockdev.py
@@ -29,6 +29,7 @@ from .actions import (
 
 log = logging.getLogger("subiquity.filesystem.blockdev")
 FIRST_PARTITION_OFFSET = 1 << 20  # 1K offset/aligned
+GPT_END_RESERVE = 1 << 20  # save room at the end for GPT
 
 
 # TODO: Bcachepart class
@@ -215,12 +216,23 @@ class Blockdev():
         if fstype in ["swap"]:
             fstype = "linux-swap(v1)"
 
+        # round up length by 1M
+        def _align_up(size, block_size=1 << 30):
+            return size + (block_size - (size % block_size))
+
         if len(self.disk.partitions) == 0:
             offset = FIRST_PARTITION_OFFSET
         else:
             offset = 0
 
-        log.debug('requested start: {} length: {}'.format(offset, size))
+        log.debug('Aligning start and length on 1M boundaries')
+        new_size = _align_up(size + offset)
+        if new_size > self.freespace - GPT_END_RESERVE:
+            new_size = self.freespace - GPT_END_RESERVE
+        log.debug('Old size: {} New size: {}'.format(size, new_size))
+
+        log.debug('requested start: {} length: {}'.format(offset,
+                                                          new_size - offset))
         valid_flags = [
             "boot",
             "lvm",
@@ -232,7 +244,8 @@ class Blockdev():
 
         # create partition and add
         part_action = PartitionAction(self.baseaction, partnum,
-                                      offset, size, flag)
+                                      offset, new_size - offset, flag)
+
         log.debug('PartitionAction:\n{}'.format(part_action.get()))
 
         self.disk.partitions.update({partnum: part_action})
@@ -250,6 +263,7 @@ class Blockdev():
             self._mounts[partpath] = mountpoint
 
         log.debug('Partition Added')
+        return new_size
 
     def is_mounted(self):
         with open('/proc/mounts') as pm: