[...]
This patch introduces that type as a thin wrapper around 'struct
lockfile', and updates the two aforementioned functions and their
callers to use it.

Signed-off-by: Taylor Blau <redacted>
---

diff --git a/shallow.h b/shallow.h

@@ -10,12 +10,22 @@ void set_alternate_shallow_file(struct repository *r, const char *path, int over
+/*
+ * shallow_lock is a thin wrapper around 'struct lock_file' in order to restrict
+ * which locks can be used with '{commit,rollback}_shallow_file()'.
+ */
+struct shallow_lock {
+       struct lock_file lk;
+};