UPSTREAM: f2fs: wire up FS_IOC_GET_ENCRYPTION_NONCE

This new ioctl retrieves a file's encryption nonce, which is useful for
testing.  See the corresponding fs/crypto/ patch for more details.

Link: https://lore.kernel.org/r/20200314205052.93294-4-ebiggers@kernel.org
(cherry picked from commit ee446e1af4ff90945e2273ae0af322b8b745b8cc)
Bug: 151100202
Change-Id: I26037efc77774c04951da887d8557a15ce6a23ed
Signed-off-by: Eric Biggers <ebiggers@google.com>

fs/f2fs/file.c

@@ -2440,6 +2440,14 @@ static int f2fs_ioc_get_encryption_key_status(struct file *filp,
 	return fscrypt_ioctl_get_key_status(filp, (void __user *)arg);
 }
 
+static int f2fs_ioc_get_encryption_nonce(struct file *filp, unsigned long arg)
+{
+	if (!f2fs_sb_has_encrypt(F2FS_I_SB(file_inode(filp))))
+		return -EOPNOTSUPP;
+
+	return fscrypt_ioctl_get_nonce(filp, (void __user *)arg);
+}
+
 static int f2fs_ioc_gc(struct file *filp, unsigned long arg)
 {
 	struct inode *inode = file_inode(filp);
@@ -3392,6 +3400,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		return f2fs_ioc_remove_encryption_key_all_users(filp, arg);
 	case FS_IOC_GET_ENCRYPTION_KEY_STATUS:
 		return f2fs_ioc_get_encryption_key_status(filp, arg);
+	case FS_IOC_GET_ENCRYPTION_NONCE:
+		return f2fs_ioc_get_encryption_nonce(filp, arg);
 	case F2FS_IOC_GARBAGE_COLLECT:
 		return f2fs_ioc_gc(filp, arg);
 	case F2FS_IOC_GARBAGE_COLLECT_RANGE:
@@ -3561,6 +3571,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case FS_IOC_REMOVE_ENCRYPTION_KEY:
 	case FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS:
 	case FS_IOC_GET_ENCRYPTION_KEY_STATUS:
+	case FS_IOC_GET_ENCRYPTION_NONCE:
 	case F2FS_IOC_GARBAGE_COLLECT:
 	case F2FS_IOC_GARBAGE_COLLECT_RANGE:
 	case F2FS_IOC_WRITE_CHECKPOINT: