Linux Kernel Module - Create Directory

Question

I've got a problem about creating a directory within a linux kernel module.

What I want: Creating a directory within a kernel module.

Here is my actual code:

struct file *fp = (struct file *) NULL;
fp = filp_open("/home/testdir", O_DIRECTORY|O_CREAT, S_IRUSR);

But it creates a file instead of directory.

I tried to same code as above without the flag "O_DIRECTORY":

struct file *fp = (struct file *) NULL;
fp = filp_open("/home/testdir", O_CREAT, S_IRUSR);

And the result is similar to the previous result.

I don't understand the behaviour. What am I doing wrong?

Edit 1: I am coding on a Raspberry PI, Raspbian, kernel version: 4.4.43-v7

Answer 1

I got it by myself. The solution is:

struct file *fp = (struct file *) NULL;
fp = filp_open("/home/testdir/", O_DIRECTORY|O_CREAT, S_IRUSR);

Note the "/" at the end of the path.

Thanks @all for the try!

Answer 2

This doesn't create a directory but opens a directory like opendir does (the directory should exists).

Answer 3

something that worked for me: its also similar to how they create a dir in devtmpfs

int mkdir_(const char *dirPath, umode_t mode) {

struct path path;
struct dentry *dentry = kern_path_create(AT_FDCWD, dirPath, &path, mode);

int err = PTR_ERR(dentry);
if (IS_ERR(dentry)) {
    return -1;
}

err = vfs_mkdir(path.dentry->d_inode, dentry, mode);
done_path_create(&path, dentry);

return err;

}