socket文件

static const struct file_operations socket_file_ops = {.owner =THIS_MODULE,.llseek =no_llseek,.read_iter =sock_read_iter,.write_iter =sock_write_iter,.poll =sock_poll,.unlocked_ioctl = sock_ioctl,#ifdef CONFIG_COMPAT.compat_ioctl = compat_sock_ioctl,#endif.mmap =sock_mmap,.release =sock_close,.fasync =sock_fasync,.sendpage =sock_sendpage,.splice_write = generic_splice_sendpage,.splice_read =sock_splice_read,};

/* *Obtains the first available file descriptor and sets it up for use. * *These functions create file structures and maps them to fd space *of the current process. On success it returns file descriptor *and file struct implicitly stored in sock->file. *Note that another thread may close file descriptor before we return *from this function. We use the fact that now we do not refer *to socket after mapping. If one day we will need it, this *function will increment ref. count on file by 1. * *In any case returned fd MAY BE not valid! *This race condition is unavoidable *with shared fd spaces, we cannot solve it inside kernel, *but we take care of internal coherence yet. */struct file *sock_alloc_file(struct socket *sock, int flags, const char *dname){struct qstr name = { .name = "" };struct path path;struct file *file;if (dname) {name.name = dname;name.len = strlen(name.name);} else if (sock->sk) {name.name = sock->sk->sk_prot_creator->name;name.len = strlen(name.name);}path.dentry = d_alloc_pseudo(sock_mnt->mnt_sb, &name);if (unlikely(!path.dentry))return ERR_PTR(-ENOMEM);path.mnt = mntget(sock_mnt);d_instantiate(path.dentry, SOCK_INODE(sock));file = alloc_file(&path, FMODE_READ | FMODE_WRITE,  &socket_file_ops);if (IS_ERR(file)) {/* drop dentry, keep inode */ihold(d_inode(path.dentry));path_put(&path);return file;}sock->file = file;file->f_flags = O_RDWR | (flags & O_NONBLOCK);file->private_data = sock;return file;}