CODEWITHSUNDEEP
linuxfilelinux-kernellinux-device-driver
user1343318
user1343318

Reputation: 2141

Relationship between file created with dentry inode and open syscall inode?

I am creating a simple debugfs file inside /sys/kernel/debug/test/testFile using the following code:

pDebugfs = debugfs_create_dir(name, NULL);

if (!pDebugfs)
            goto fail;          

if (!debugfs_create_file("testFile", MODE_T, pDebugfs,
        NULL,  &debugfs_fops)) {
    goto fail;
}

And now when I write to this file, open method will be called which has the definition:

static ssize_t debugfs_open(struct inode *inode, struct file *filp)

Now the pDebugfs which is of type dentry has a pointer to an inode called d_inode as defined here.

My question is what is the relationship between this inode pointer and the one called in open? Are they related? If yes, how? I tried to print the i_flags value in both the i_node definitions but they don't match, I assign i_flags in init and just check its value in open but they don't match.

Upvotes: 0

Views: 238

Answers (1)

Federico
Federico

Reputation: 3892

In your code you have two dentry. One that create the directory in /sys/kernel/debug/

pDebugfs = debugfs_create_dir(name, NULL);

and, you are not storing it but it is there, one that create the file you open(2):

pDebugfs_file = debugfs_create_file("testFile", MODE_T, pDebugfs, NULL,  &debugfs_fops)

The inode you see in debugfs_open is the one associated to the file and not to the directory.

Upvotes: 1

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