Hello every one,
I get something confused about unlink function of filesystem. I have dput function in my unlink function to destory the dentry, but after doing this, I get error message "Unable to handle kernel NULL pointer dereference at virtual address 00000080". Conversely, removing the dput function from my unlink function, it work well. Refering to Ramfs filesystem, I find it have dput in it's unlink function, simple_unlink. But looking into ext2 filesystem, the dput function is not in it's unlink function.

The bellow is the vfs_unlink code

int vfs_unlink(struct inode *dir, struct dentry *dentry){

.............

if (d_mountpoint(dentry))
error = -EBUSY;
else {
error = security_inode_unlink(dir, dentry);
if (!error)
error = dir->i_op->unlink(dir, dentry);
}

if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
d_delete(dentry);
}

return error;
}
I think the dentry will be destoried by my unlink function(dir->i_op->unlink) when I let dput in my unlink funcion. And d_delete will destory the dentry again, so I get the error message.
mmmmh~ Why the ramfs can work well with dput in the simple_unlink function?

Something must be wrong in my thought ><

Thank you,
Regards