f2fs crypto: add f2fs encryption Kconfig

This patch adds f2fs encryption config.

This patch integrates:

"ext4 crypto: require CONFIG_CRYPTO_CTR if ext4 encryption is enabled

On arm64 this is apparently needed for CTS mode to function correctly.
Otherwise attempts to use CTS return ENOENT."
Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/Kconfig

@@ -72,6 +72,25 @@ config F2FS_CHECK_FS
 
 	  If you want to improve the performance, say N.
 
+config F2FS_FS_ENCRYPTION
+	bool "F2FS Encryption"
+	depends on F2FS_FS
+	depends on F2FS_FS_XATTR
+	select CRYPTO_AES
+	select CRYPTO_CBC
+	select CRYPTO_ECB
+	select CRYPTO_XTS
+	select CRYPTO_CTS
+	select CRYPTO_CTR
+	select CRYPTO_SHA256
+	select KEYS
+	select ENCRYPTED_KEYS
+	help
+	  Enable encryption of f2fs files and directories.  This
+	  feature is similar to ecryptfs, but it is more memory
+	  efficient since it avoids caching the encrypted and
+	  decrypted pages in the page cache.
+
 config F2FS_IO_TRACE
 	bool "F2FS IO tracer"
 	depends on F2FS_FS