Move logic for raid start sector to raid_utils

A starting tentative in reducing size of raid related functions.

Change-Id: I81f912d0dc0ad138d8cc776cdb4ee3b5251ec3ba

1 files changed, 40 insertions, 0 deletions

diff --git a/ironic_python_agent/raid_utils.py b/ironic_python_agent/raid_utils.py
index 7f718ac4..b50164e8 100644
--- a/ironic_python_agent/raid_utils.py
+++ b/ironic_python_agent/raid_utils.py
@@ -15,6 +15,7 @@ import copy
 from ironic_lib import utils as il_utils
 
 from ironic_python_agent import errors
+from ironic_python_agent import utils
 
 
 def get_block_devices_for_raid(block_devices, logical_disks):
@@ -63,3 +64,42 @@ def get_block_devices_for_raid(block_devices, logical_disks):
         logical_disk['block_devices'] = matching
 
     return result, logical_disks
+
+
+def calculate_raid_start(target_boot_mode, partition_table_type, dev_name):
+    """Define the start sector for the raid partition.
+
+    :param target_boot_mode: the node boot mode.
+    :param partition_table_type: the node partition label, gpt or msdos.
+    :param dev_name: block device in the raid configuration.
+    :return: The start sector for the raid partition.
+    """
+    # TODO(rg): TBD, several options regarding boot part slots here:
+    # 1. Create boot partitions in prevision
+    # 2. Just leave space
+    # 3. Do nothing: rely on the caller to specify target_raid_config
+    # correctly according to what they intend to do (e.g. not set MAX
+    # if they know they will need some space for bios boot or efi
+    # parts). Best option imo, if we accept that the target volume
+    # granularity is GiB, so you lose up to 1GiB just for a bios boot
+    # partition...
+    if target_boot_mode == 'uefi':
+        # Leave 129MiB - start_sector s for the esp (approx 128MiB)
+        # NOTE: any image efi partition is expected to be less
+        # than 128MiB
+        # TBD: 129MiB is a waste in most cases.
+        raid_start = '129MiB'
+    else:
+        if partition_table_type == 'gpt':
+            # Leave 8MiB - start_sector s (approx 7MiB)
+            # for the bios boot partition or the ppc prepboot part
+            # This should avoid grub errors saying that it cannot
+            # install boot stage 1.5/2 (since the mbr gap does not
+            # exist on disk holders with gpt tables)
+            raid_start = '8MiB'
+        else:
+            # sgdisk works fine for display data on mbr tables too
+            out, _u = utils.execute('sgdisk', '-F', dev_name)
+            raid_start = "{}s".format(out.splitlines()[-1])
+
+    return raid_start