From 2b75e98c92177cdc99720887bcc8e0161e15c3a7 Mon Sep 17 00:00:00 2001
From: Thomas Waldmann <tw@waldmann-edv.de>
Date: Sat, 3 Jan 2026 19:45:39 +0100
Subject: [PATCH] fuse: add thread/async safety warning

---
 src/borg/fuse.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/borg/fuse.py b/src/borg/fuse.py
index fe23c4e37..15c1e13d4 100644
--- a/src/borg/fuse.py
+++ b/src/borg/fuse.py
@@ -1,3 +1,19 @@
+"""
+FUSE filesystem implementation for `borg mount`.
+
+IMPORTANT
+=========
+
+This code is only safe for single-threaded and synchronous (non-async) usage.
+
+- llfuse is synchronous and used with workers=1, so there is only 1 thread,
+  and we are safe.
+- pyfuse3 uses Trio, which only uses 1 thread, but could use this code in an
+  asynchronous manner. However, as long as we do not use any asynchronous
+  operations (like using "await") in this code, it is still de facto
+  synchronous, and we are safe.
+"""
+
 import errno
 import functools
 import io