From d18c2732937a420e911575baf66d080005412d44 Mon Sep 17 00:00:00 2001
From: trapexit <trapexit@spawn.link>
Date: Tue, 7 Oct 2025 22:52:13 -0400
Subject: [PATCH] Allow setting of passthrough max-stack-depth (#1542)

---
 libfuse/lib/debug.cpp         | 16 +++++++++++++++-
 libfuse/lib/fuse_i.h          |  1 +
 libfuse/lib/fuse_lowlevel.cpp |  4 +++-
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/libfuse/lib/debug.cpp b/libfuse/lib/debug.cpp
index 0c8d99b5..b82bce98 100644
--- a/libfuse/lib/debug.cpp
+++ b/libfuse/lib/debug.cpp
@@ -861,11 +861,25 @@ fuse_syslog_fuse_init_out(const struct fuse_init_out *arg_)
   output = fmt::format("fuse_init_out:"
                        " major={};"
                        " minor={};"
+                       " max_readahead={};"
+                       " max_background={};"
+                       " congestion_threshold={};"
+                       " max_write={};"
+                       " time_gran={};"
                        " max_pages={};"
+                       " map_alignment={};"
+                       " max_stack_depth={};"
                        " flags=(",
                        arg_->major,
                        arg_->minor,
-                       arg_->max_pages);
+                       arg_->max_readahead,
+                       arg_->max_background,
+                       arg_->congestion_threshold,
+                       arg_->max_write,
+                       arg_->time_gran,
+                       arg_->max_pages,
+                       arg_->map_alignment,
+                       arg_->max_stack_depth);
 
   for(uint64_t i = 0; i < (sizeof(flags)*8); i++)
     {
diff --git a/libfuse/lib/fuse_i.h b/libfuse/lib/fuse_i.h
index e702971d..93ca59d2 100644
--- a/libfuse/lib/fuse_i.h
+++ b/libfuse/lib/fuse_i.h
@@ -54,6 +54,7 @@ struct fuse_notify_req
 
 struct fuse_ll
 {
+  unsigned passthrough_max_stack_depth;
   int debug;
   int no_remote_posix_lock;
   int no_remote_flock;
diff --git a/libfuse/lib/fuse_lowlevel.cpp b/libfuse/lib/fuse_lowlevel.cpp
index 4319e642..81472423 100644
--- a/libfuse/lib/fuse_lowlevel.cpp
+++ b/libfuse/lib/fuse_lowlevel.cpp
@@ -1288,7 +1288,7 @@ do_init(fuse_req_t             req,
   if(f->conn.want & FUSE_CAP_PASSTHROUGH)
     {
       outargflags |= FUSE_PASSTHROUGH;
-      outarg.max_stack_depth = 2;
+      outarg.max_stack_depth = f->passthrough_max_stack_depth;
     }
 
   if(inargflags & FUSE_INIT_EXT)
@@ -1810,6 +1810,7 @@ static const struct fuse_opt fuse_ll_opts[] =
     { "no_remote_lock", offsetof(struct fuse_ll, no_remote_flock), 1},
     { "no_remote_flock", offsetof(struct fuse_ll, no_remote_flock), 1},
     { "no_remote_posix_lock", offsetof(struct fuse_ll, no_remote_posix_lock), 1},
+    { "passthrough-max-stack-depth=%u", offsetof(struct fuse_ll, passthrough_max_stack_depth), 0},
     FUSE_OPT_KEY("max_read=", FUSE_OPT_KEY_DISCARD),
     FUSE_OPT_KEY("-h", KEY_HELP),
     FUSE_OPT_KEY("--help", KEY_HELP),
@@ -2072,6 +2073,7 @@ fuse_lowlevel_new_common(struct fuse_args               *args,
 
   f->conn.max_write = UINT_MAX;
   f->conn.max_readahead = UINT_MAX;
+  f->passthrough_max_stack_depth = 2;
   list_init_nreq(&f->notify_list);
   f->notify_ctr = 1;
   mutex_init(&f->lock);