vfs_real: forget a path when its file is gone

The path cache holds weak references, but nothing erased an entry once
its file was destroyed, so every path ever opened stayed in the cache
until the filesystem was destroyed (title 1's loose RomFS: 206k paths,
24 MB of keys, kept after the game stops). The entry is erased when the
file's last reference is dropped, unless the path was opened again
meanwhile.

2 files changed, 9 insertions, 3 deletions

diff --git a/src/core/file_sys/vfs/vfs_real.cpp b/src/core/file_sys/vfs/vfs_real.cpp
index 5b5b54017c..e178bcab58 100644
--- a/src/core/file_sys/vfs/vfs_real.cpp
+++ b/src/core/file_sys/vfs/vfs_real.cpp
@@ -257,7 +257,8 @@ std::unique_lock<std::mutex> RealVfsFilesystem::RefreshReference(const std::stri
     return lk;
 }
 
-void RealVfsFilesystem::DropReference(std::unique_ptr<FileReference>&& reference) {
+void RealVfsFilesystem::DropReference(std::unique_ptr<FileReference>&& reference,
+                                      const std::string& path) {
     if (in_dtor)
         return;
 
@@ -266,6 +267,11 @@ void RealVfsFilesystem::DropReference(std::unique_ptr<FileReference>&& reference
     // Remove from list.
     this->RemoveReferenceFromListLocked(*reference);
 
+    // Forget the path, unless it was opened again since this file's last reference went away.
+    if (const auto it = cache.find(path); it != cache.end() && it->second.expired()) {
+        cache.erase(it);
+    }
+
     // Close the file.
     if (reference->file) {
         reference->file.reset();
@@ -316,7 +322,7 @@ RealVfsFile::RealVfsFile(RealVfsFilesystem& base_, std::unique_ptr<FileReference
       path_components(FS::SplitPathComponentsCopy(path_)), size(size_), perms(perms_) {}
 
 RealVfsFile::~RealVfsFile() {
-    base.DropReference(std::move(reference));
+    base.DropReference(std::move(reference), path);
 }
 
 std::string RealVfsFile::GetName() const {
diff --git a/src/core/file_sys/vfs/vfs_real.h b/src/core/file_sys/vfs/vfs_real.h
index a97f7d32ea..9c769c667c 100644
--- a/src/core/file_sys/vfs/vfs_real.h
+++ b/src/core/file_sys/vfs/vfs_real.h
@@ -62,7 +62,7 @@ private:
     friend class RealVfsFile;
     std::unique_lock<std::mutex> RefreshReference(const std::string& path, OpenMode perms,
                                                   FileReference& reference);
-    void DropReference(std::unique_ptr<FileReference>&& reference);
+    void DropReference(std::unique_ptr<FileReference>&& reference, const std::string& path);
 
 private:
     friend class RealVfsDirectory;