Merge pull request #1836 from enkore/f/smfsc

repository: check_free_space, special case small repos

src/borg/repository.py

@@ -428,8 +428,18 @@ class Repository:
 
         required_free_space += self.additional_free_space
         if not self.append_only:
-            # Keep one full worst-case segment free in non-append-only mode
-            required_free_space += self.max_segment_size + MAX_OBJECT_SIZE
+            full_segment_size = self.max_segment_size + MAX_OBJECT_SIZE
+            if len(self.compact) < 10:
+                # This is mostly for the test suite to avoid overestimated free space needs. This can be annoying
+                # if TMP is a small-ish tmpfs.
+                compact_working_space = sum(self.io.segment_size(segment) - free for segment, free in self.compact.items())
+                logger.debug('check_free_space: few segments, not requiring a full free segment')
+                compact_working_space = min(compact_working_space, full_segment_size)
+                logger.debug('check_free_space: calculated working space for compact as %d bytes', compact_working_space)
+                required_free_space += compact_working_space
+            else:
+                # Keep one full worst-case segment free in non-append-only mode
+                required_free_space += full_segment_size
         try:
             st_vfs = os.statvfs(self.path)
         except OSError as os_error: