mount: Use a single partitions list sorted by mount point

Instead of having a special case for extra mounts to be processed right
after the rootfs, a better approach is to add them to the partitions
list, and then sort the list by mount point.

This way, we make sure every partition is mounted right when it is
needed: `/` is obviously mounted first, `/run` is mounted before
`/run/udev`, and so on.

The overall process is therefore more generic and should suit all
use-cases.

Signed-off-by: Arnaud Ferraris <arnaud.ferraris@collabora.com>

src/modules/mount/main.py

@@ -37,7 +37,7 @@ _ = gettext.translation("calamares-python",
 def pretty_name():
     return _("Mounting partitions.")
 
-def mount_part(root_mount_point, partition, partitions):
+def mount_partition(root_mount_point, partition, partitions):
     # Create mount point with `+` rather than `os.path.join()` because
     # `partition["mountPoint"]` starts with a '/'.
     raw_mount_point = partition["mountPoint"]
@@ -126,21 +126,6 @@ def mount_part(root_mount_point, partition, partitions):
                         ["subvol=@home", partition.get("options", "")]),
                     )
 
-def mount_partitions(root_mount_point, partitions, extra_mounts=None):
-    """
-    Pass back mount point and filesystem for each partition.
-
-    :param root_mount_point:
-    :param partitions:
-    :param extra_mounts:
-    """
-    for partition in partitions:
-        if "mountPoint" not in partition or not partition["mountPoint"]:
-            continue
-        mount_part(root_mount_point, partition, partitions)
-        if partition["mountPoint"] is "/" and extra_mounts is not None:
-            mount_partitions(root_mount_point, extra_mounts)
-
 
 def run():
     """
@@ -163,16 +148,21 @@ def run():
     if not extra_mounts and not extra_mounts_efi:
         libcalamares.utils.warning("No extra mounts defined. Does mount.conf exist?")
 
-    # Sort by mount points to ensure / is mounted before the rest
-    partitions.sort(key=lambda x: x["mountPoint"])
-    mount_partitions(root_mount_point, partitions, extra_mounts)
-
-    all_extra_mounts = extra_mounts
     if libcalamares.globalstorage.value("firmwareType") == "efi":
-        mount_partitions(root_mount_point, extra_mounts_efi)
-        all_extra_mounts.extend(extra_mounts_efi)
+        extra_mounts.extend(extra_mounts_efi)
+
+    # Add extra mounts to the partitions list and sort by mount points.
+    # This way, we ensure / is mounted before the rest, and every mount point
+    # is created on the right partition (e.g. if a partition is to be mounted
+    # under /tmp, we make sure /tmp is mounted before the partition)
+    partitions.extend(extra_mounts)
+    partitions.sort(key=lambda x: x["mountPoint"])
+    for partition in partitions:
+        if "mountPoint" not in partition or not partition["mountPoint"]:
+            continue
+        mount_partition(root_mount_point, partition, partitions)
 
     libcalamares.globalstorage.insert("rootMountPoint", root_mount_point)
 
     # Remember the extra mounts for the unpackfs module
-    libcalamares.globalstorage.insert("extraMounts", all_extra_mounts)
+    libcalamares.globalstorage.insert("extraMounts", extra_mounts)