storage: Use mount info instead of disk info for free space warning

Tests:

- In a container, fill up space. Start FreedomBox in develop mode wait 3 minutes
for storage warning to show.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/backups/views.py

@@ -107,7 +107,7 @@ class UploadArchiveView(SuccessMessageMixin, FormView):
         context = super().get_context_data(**kwargs)
         context['title'] = _('Upload and restore a backup')
         try:
-            disk_info = storage.get_disk_info('/')
+            mount_info = storage.get_mount_info('/')
         except PlinthError as exception:
             logger.exception(
                 'Error getting information about root partition: %s',
@@ -121,7 +121,7 @@ class UploadArchiveView(SuccessMessageMixin, FormView):
             # - For restoring it's highly advisable to have at least as much
             #   free disk space as the file size.
             context['max_filesize'] = storage.format_bytes(
-                disk_info['free_bytes'] / 2)
+                mount_info['free_bytes'] / 2)
 
         return context
 
@@ -164,6 +164,7 @@ class BaseRestoreView(SuccessMessageMixin, FormView):
 
 class RestoreFromUploadView(BaseRestoreView):
     """View to restore files from an (uploaded) exported archive."""
+
     def get(self, *args, **kwargs):
         path = self.request.session.get(SESSION_PATH_VARIABLE)
         if not os.path.isfile(path):
@@ -193,6 +194,7 @@ class RestoreFromUploadView(BaseRestoreView):
 
 class RestoreArchiveView(BaseRestoreView):
     """View to restore files from an archive."""
+
     def _get_included_apps(self):
         """Save some data used to instantiate the form."""
         name = unquote(self.kwargs['name'])
@@ -210,6 +212,7 @@ class RestoreArchiveView(BaseRestoreView):
 
 class DownloadArchiveView(View):
     """View to export and download an archive as stream."""
+
     def get(self, request, uuid, name):
         repository = get_instance(uuid)
         filename = f'{name}.tar.gz'

plinth/modules/storage/__init__.py

@@ -156,10 +156,12 @@ def get_filesystem_type(mount_point='/'):
     raise ValueError('No such mount point')
 
 
-def get_disk_info(mount_point):
-    """Get information about the free space of a drive"""
-    disks = get_disks()
-    list_root = [disk for disk in disks if mount_point in disk['mount_points']]
+def get_mount_info(mount_point):
+    """Get information about the free space of a mount point."""
+    mounts = get_mounts()
+    list_root = [
+        mount for mount in mounts if mount_point == mount['mount_point']
+    ]
     if not list_root:
         raise PlinthError('Mount point {} not found.'.format(mount_point))
 
@@ -289,7 +291,7 @@ def warn_about_low_disk_space(request):
     from plinth.notification import Notification
 
     try:
-        root_info = get_disk_info('/')
+        root_info = get_mount_info('/')
     except PlinthError:
         return