From 445d582f54883617b6666e522d781f659a1e208a Mon Sep 17 00:00:00 2001
From: Tao Huang <huangtao@rock-chips.com>
Date: Thu, 24 Sep 2020 19:56:29 +0800
Subject: [PATCH] Revert "Revert "ANDROID: fscrypt: add key removal notifier
 chain""

This reverts commit 4da740c10dc0f2de632686e8cc0274cfa52e67e4.

For sdcardfs.

Signed-off-by: Tao Huang <huangtao@rock-chips.com>
Change-Id: I863e5efdf4aeec130447b1a655659ce16db55bd4
---
 fs/crypto/keyring.c     | 22 ++++++++++++++++++++++
 include/linux/fscrypt.h | 14 ++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
index dea246b7493b..ae081f06e149 100644
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -867,12 +867,34 @@ static int check_for_busy_inodes(struct super_block *sb,
 	return -EBUSY;
 }
 
+static BLOCKING_NOTIFIER_HEAD(fscrypt_key_removal_notifiers);
+
+/*
+ * Register a function to be executed when the FS_IOC_REMOVE_ENCRYPTION_KEY
+ * ioctl has removed a key and is about to try evicting inodes.
+ */
+int fscrypt_register_key_removal_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&fscrypt_key_removal_notifiers,
+						nb);
+}
+EXPORT_SYMBOL_GPL(fscrypt_register_key_removal_notifier);
+
+int fscrypt_unregister_key_removal_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&fscrypt_key_removal_notifiers,
+						  nb);
+}
+EXPORT_SYMBOL_GPL(fscrypt_unregister_key_removal_notifier);
+
 static int try_to_lock_encrypted_files(struct super_block *sb,
 				       struct fscrypt_master_key *mk)
 {
 	int err1;
 	int err2;
 
+	blocking_notifier_call_chain(&fscrypt_key_removal_notifiers, 0, NULL);
+
 	/*
 	 * An inode can't be evicted while it is dirty or has dirty pages.
 	 * Thus, we first have to clean the inodes in ->mk_decrypted_inodes.
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 1337108a4a46..afc56580aebe 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -178,6 +178,8 @@ int fscrypt_ioctl_add_key(struct file *filp, void __user *arg);
 int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg);
 int fscrypt_ioctl_remove_key_all_users(struct file *filp, void __user *arg);
 int fscrypt_ioctl_get_key_status(struct file *filp, void __user *arg);
+int fscrypt_register_key_removal_notifier(struct notifier_block *nb);
+int fscrypt_unregister_key_removal_notifier(struct notifier_block *nb);
 
 /* keysetup.c */
 int fscrypt_get_encryption_info(struct inode *inode);
@@ -380,6 +382,18 @@ static inline int fscrypt_ioctl_get_key_status(struct file *filp,
 	return -EOPNOTSUPP;
 }
 
+static inline int fscrypt_register_key_removal_notifier(
+						struct notifier_block *nb)
+{
+	return 0;
+}
+
+static inline int fscrypt_unregister_key_removal_notifier(
+						struct notifier_block *nb)
+{
+	return 0;
+}
+
 /* keysetup.c */
 static inline int fscrypt_get_encryption_info(struct inode *inode)
 {