cgroup: Add cgroup_get_from_fd

						       struct cgroup_subsys *ss);

struct cgroup *cgroup_get_from_path(const char *path);

struct cgroup *cgroup_get_from_fd(int fd);

int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);

int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);

#include <linux/proc_ns.h>

#include <linux/nsproxy.h>

#include <linux/proc_ns.h>

#include <linux/file.h>

#include <net/sock.h>

/*

}

EXPORT_SYMBOL_GPL(cgroup_get_from_path);

/**

 * cgroup_get_from_fd - get a cgroup pointer from a fd

 * @fd: fd obtained by open(cgroup2_dir)

 *

 * Find the cgroup from a fd which should be obtained

 * by opening a cgroup directory.  Returns a pointer to the

 * cgroup on success. ERR_PTR is returned if the cgroup

 * cannot be found.

 */

struct cgroup *cgroup_get_from_fd(int fd)

{

	struct cgroup_subsys_state *css;

	struct cgroup *cgrp;

	struct file *f;

	f = fget_raw(fd);

	if (!f)

		return ERR_PTR(-EBADF);

	css = css_tryget_online_from_dir(f->f_path.dentry, NULL);

	fput(f);

	if (IS_ERR(css))

		return ERR_CAST(css);

	cgrp = css->cgroup;

	if (!cgroup_on_dfl(cgrp)) {

		cgroup_put(cgrp);

		return ERR_PTR(-EBADF);

	}

	return cgrp;

}

EXPORT_SYMBOL_GPL(cgroup_get_from_fd);

/*

 * sock->sk_cgrp_data handling.  For more info, see sock_cgroup_data

 * definition in cgroup-defs.h.