kernel: core_hook: tweak and rename path_umount handler

rename function to ksu_path_umount to clearly differntiate it from
sys_umount. Pass mnt string directly to avoid redundant resolution
for debug logging. Small touches, to make it neater.

- also fix missed path_put

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

Author: backslashxx

kernel/core_hook.c

@@ -16,7 +16,7 @@
 #include <linux/mount.h>
 #include <linux/fs.h>
 #include <linux/namei.h>
-#ifndef KSU_HAS_PATH_UMOUNT
+#if !(LINUX_VERSION_CODE >= KERNEL_VERSION(5, 9, 0)) && !defined(KSU_HAS_PATH_UMOUNT) 
 #include <linux/syscalls.h> // sys_umount
 #endif
 
@@ -509,13 +509,11 @@ static bool should_umount(struct path *path)
 	return false;
 }
 
-#ifdef KSU_HAS_PATH_UMOUNT
-static void ksu_umount_mnt(struct path *path, int flags)
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 9, 0) || defined(KSU_HAS_PATH_UMOUNT)
+static void ksu_path_umount(const char *mnt, struct path *path, int flags)
 {
 	int err = path_umount(path, flags);
-	if (err) {
-		pr_info("umount %s failed: %d\n", path->dentry->d_iname, err);
-	}
+	pr_info("%s: path: %s code: %d\n", __func__, mnt, err);
 }
 #else
 static void ksu_sys_umount(const char *mnt, int flags)
@@ -543,20 +541,23 @@ static void try_umount(const char *mnt, bool check_mnt, int flags)
 	}
 
 	if (path.dentry != path.mnt->mnt_root) {
+		path_put(&path);
 		// it is not root mountpoint, maybe umounted by others already.
 		return;
 	}
 
 	// we are only interest in some specific mounts
 	if (check_mnt && !should_umount(&path)) {
+		path_put(&path);
 		return;
 	}
 
-#ifdef KSU_HAS_PATH_UMOUNT
-	ksu_umount_mnt(&path, flags);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 9, 0) || defined(KSU_HAS_PATH_UMOUNT)
+	ksu_path_umount(mnt, &path, flags);
 #else
 	ksu_sys_umount(mnt, flags);
 #endif
+	path_put(&path);
 }
 
 int ksu_handle_setuid(struct cred *new, const struct cred *old)