kernel: core_hook: no ext4_unregister_sysfs, no problem

If ext4_unregister_sysfs ain't there, we don't care.

This is mostly for UL builds.

Signed-off-by: backslashxx <[email protected]>

Author: backslashxx

kernel/Makefile

@@ -56,6 +56,11 @@ $(info -- KernelSU Manager signature hash: $(KSU_EXPECTED_HASH))
 ccflags-y += -DEXPECTED_SIZE=$(KSU_EXPECTED_SIZE)
 ccflags-y += -DEXPECTED_HASH=\"$(KSU_EXPECTED_HASH)\"
 
+# UL, look for "ext4_unregister_sysfs" on fs/ext4
+ifeq ($(shell grep -q "^extern void ext4_unregister_sysfs" $(srctree)/fs/ext4/ext4.h 2>/dev/null; echo $$?),0)
+ccflags-y += -DKSU_HAS_MODERN_EXT4
+endif
+
 # enable functions that use stuct filename when ksu_handle_execveat is found
 ifeq ($(shell grep -q "ksu_handle_execveat" $(srctree)/fs/exec.c; echo $$?),0)
 ccflags-y += -DKSU_USE_STRUCT_FILENAME

kernel/core_hook.c

@@ -224,6 +224,7 @@ LSM_HANDLER_TYPE ksu_handle_rename(struct dentry *old_dentry, struct dentry *new
 	return 0;
 }
 
+#if defined(KSU_HAS_MODERN_EXT4) && defined(CONFIG_EXT4_FS)
 static void nuke_ext4_sysfs() {
 	struct path path;
 	int err = kern_path("/data/adb/modules", 0, &path);
@@ -243,6 +244,9 @@ static void nuke_ext4_sysfs() {
 	ext4_unregister_sysfs(sb);
  	path_put(&path);
 }
+#else
+static void nuke_ext4_sysfs() { }
+#endif
 
 LSM_HANDLER_TYPE ksu_handle_prctl(int option, unsigned long arg2, unsigned long arg3,
 		     unsigned long arg4, unsigned long arg5)