Revert "kernel: expose umount list to ioctl interface #2950"

This reverts commit 029ae8d389.

kernel/kernel_umount.c

@@ -43,6 +43,24 @@ static const struct ksu_feature_handler kernel_umount_handler = {
     .set_handler = kernel_umount_feature_set,
 };
 
+static bool should_umount(struct path *path)
+{
+    if (!path) {
+        return false;
+    }
+
+    if (current->nsproxy->mnt_ns == init_nsproxy.mnt_ns) {
+        pr_info("ignore global mnt namespace process: %d\n", current_uid().val);
+        return false;
+    }
+
+    if (path->mnt && path->mnt->mnt_sb && path->mnt->mnt_sb->s_type) {
+        const char *fstype = path->mnt->mnt_sb->s_type->name;
+        return strcmp(fstype, "overlay") == 0;
+    }
+    return false;
+}
+
 extern int path_umount(struct path *path, int flags);
 
 static void ksu_umount_mnt(struct path *path, int flags)
@@ -53,7 +71,7 @@ static void ksu_umount_mnt(struct path *path, int flags)
     }
 }
 
-void try_umount(const char *mnt, int flags)
+void try_umount(const char *mnt, bool check_mnt, int flags)
 {
     struct path path;
     int err = kern_path(mnt, 0, &path);
@@ -67,6 +85,12 @@ void try_umount(const char *mnt, int flags)
         return;
     }
 
+    // we are only interest in some specific mounts
+    if (check_mnt && !should_umount(&path)) {
+        path_put(&path);
+        return;
+    }
+
     ksu_umount_mnt(&path, flags);
 }
 
@@ -83,14 +107,8 @@ static void umount_tw_func(struct callback_head *cb)
         saved = override_creds(tw->old_cred);
     }
 
-    struct mount_entry *entry;
-    down_read(&mount_list_lock);
-    list_for_each_entry(entry, &mount_list, list) {
-        pr_info("%s: unmounting: %s flags 0x%x\n", __func__, entry->umountable, entry->flags);
-        try_umount(entry->umountable, entry->flags);
-    }
-    up_read(&mount_list_lock);
-
+    // fixme: use `collect_mounts` and `iterate_mount` to iterate all mountpoint and
+    // filter the mountpoint whose target is `/data/adb`
     ksu_umount_manager_execute_all(tw->old_cred);
 
     if (saved)