pidfd: move struct pidfd_fops

Move the pidfd file operations over to their own file in preparation of
implementing pidfs and to isolate them from other mostly unrelated
functionality in other files.

Link: https://lore.kernel.org/r/20240213-vfs-pidfd_fs-v1-1-f863f58cfce1@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 0 insertions, 110 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 3f22ec90c5c6..662a61f340ce 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1993,116 +1993,6 @@ struct pid *pidfd_pid(const struct file *file)
 	return ERR_PTR(-EBADF);
 }
 
-static int pidfd_release(struct inode *inode, struct file *file)
-{
-	struct pid *pid = file->private_data;
-
-	file->private_data = NULL;
-	put_pid(pid);
-	return 0;
-}
-
-#ifdef CONFIG_PROC_FS
-/**
- * pidfd_show_fdinfo - print information about a pidfd
- * @m: proc fdinfo file
- * @f: file referencing a pidfd
- *
- * Pid:
- * This function will print the pid that a given pidfd refers to in the
- * pid namespace of the procfs instance.
- * If the pid namespace of the process is not a descendant of the pid
- * namespace of the procfs instance 0 will be shown as its pid. This is
- * similar to calling getppid() on a process whose parent is outside of
- * its pid namespace.
- *
- * NSpid:
- * If pid namespaces are supported then this function will also print
- * the pid of a given pidfd refers to for all descendant pid namespaces
- * starting from the current pid namespace of the instance, i.e. the
- * Pid field and the first entry in the NSpid field will be identical.
- * If the pid namespace of the process is not a descendant of the pid
- * namespace of the procfs instance 0 will be shown as its first NSpid
- * entry and no others will be shown.
- * Note that this differs from the Pid and NSpid fields in
- * /proc/<pid>/status where Pid and NSpid are always shown relative to
- * the  pid namespace of the procfs instance. The difference becomes
- * obvious when sending around a pidfd between pid namespaces from a
- * different branch of the tree, i.e. where no ancestral relation is
- * present between the pid namespaces:
- * - create two new pid namespaces ns1 and ns2 in the initial pid
- *   namespace (also take care to create new mount namespaces in the
- *   new pid namespace and mount procfs)
- * - create a process with a pidfd in ns1
- * - send pidfd from ns1 to ns2
- * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
- *   have exactly one entry, which is 0
- */
-static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
-{
-	struct pid *pid = f->private_data;
-	struct pid_namespace *ns;
-	pid_t nr = -1;
-
-	if (likely(pid_has_task(pid, PIDTYPE_PID))) {
-		ns = proc_pid_ns(file_inode(m->file)->i_sb);
-		nr = pid_nr_ns(pid, ns);
-	}
-
-	seq_put_decimal_ll(m, "Pid:\t", nr);
-
-#ifdef CONFIG_PID_NS
-	seq_put_decimal_ll(m, "\nNSpid:\t", nr);
-	if (nr > 0) {
-		int i;
-
-		/* If nr is non-zero it means that 'pid' is valid and that
-		 * ns, i.e. the pid namespace associated with the procfs
-		 * instance, is in the pid namespace hierarchy of pid.
-		 * Start at one below the already printed level.
-		 */
-		for (i = ns->level + 1; i <= pid->level; i++)
-			seq_put_decimal_ll(m, "\t", pid->numbers[i].nr);
-	}
-#endif
-	seq_putc(m, '\n');
-}
-#endif
-
-/*
- * Poll support for process exit notification.
- */
-static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
-{
-	struct pid *pid = file->private_data;
-	bool thread = file->f_flags & PIDFD_THREAD;
-	struct task_struct *task;
-	__poll_t poll_flags = 0;
-
-	poll_wait(file, &pid->wait_pidfd, pts);
-	/*
-	 * Depending on PIDFD_THREAD, inform pollers when the thread
-	 * or the whole thread-group exits.
-	 */
-	rcu_read_lock();
-	task = pid_task(pid, PIDTYPE_PID);
-	if (!task)
-		poll_flags = EPOLLIN | EPOLLRDNORM | EPOLLHUP;
-	else if (task->exit_state && (thread || thread_group_empty(task)))
-		poll_flags = EPOLLIN | EPOLLRDNORM;
-	rcu_read_unlock();
-
-	return poll_flags;
-}
-
-const struct file_operations pidfd_fops = {
-	.release = pidfd_release,
-	.poll = pidfd_poll,
-#ifdef CONFIG_PROC_FS
-	.show_fdinfo = pidfd_show_fdinfo,
-#endif
-};
-
 /**
  * __pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
  * @pid:   the struct pid for which to create a pidfd