f2fs: introduce a new mount option test_dummy_encryption

This patch introduces a new mount option `test_dummy_encryption'
to allow fscrypt to create a fake fscrypt context. This is used
by xfstests.

Signed-off-by: Sheng Yong <shengyong1@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index f4ae462..d5098ef 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -78,7 +78,8 @@ static struct inode *f2fs_new_inode(struct inode *dir, umode_t mode)
 	set_inode_flag(inode, FI_NEW_INODE);
 
 	/* If the directory encrypted, then we should encrypt the inode. */
-	if (f2fs_encrypted_inode(dir) && f2fs_may_encrypt(inode))
+	if ((f2fs_encrypted_inode(dir) || DUMMY_ENCRYPTION_ENABLED(sbi)) &&
+				f2fs_may_encrypt(inode))
 		f2fs_set_encrypted_inode(inode);
 
 	if (f2fs_sb_has_extra_attr(sbi->sb)) {
@@ -787,10 +788,12 @@ static int __f2fs_tmpfile(struct inode *dir, struct dentry *dentry,
 
 static int f2fs_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 {
-	if (unlikely(f2fs_cp_error(F2FS_I_SB(dir))))
+	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
+
+	if (unlikely(f2fs_cp_error(sbi)))
 		return -EIO;
 
-	if (f2fs_encrypted_inode(dir)) {
+	if (f2fs_encrypted_inode(dir) || DUMMY_ENCRYPTION_ENABLED(sbi)) {
 		int err = fscrypt_get_encryption_info(dir);
 		if (err)
 			return err;