/*
 * Copyright (C) 2005-2015 Junjiro R. Okajima
 */

/*
 * poll operation
 * There is only one filesystem which implements ->poll operation, currently.
 */

#include "aufs.h"

unsigned int aufs_poll(struct file *file, poll_table *wait)
{
	unsigned int mask;
	int err;
	struct file *h_file;
	struct super_block *sb;

	/* We should pretend an error happened. */
	mask = POLLERR /* | POLLIN | POLLOUT */;
	sb = file->f_path.dentry->d_sb;
	si_read_lock(sb, AuLock_FLUSH | AuLock_NOPLMW);

	h_file = au_read_pre(file, /*keep_fi*/0);
	err = PTR_ERR(h_file);
	if (IS_ERR(h_file))
		goto out;

	/* it is not an error if h_file has no operation */
	mask = DEFAULT_POLLMASK;
	if (h_file->f_op->poll)
		mask = h_file->f_op->poll(h_file, wait);
	fput(h_file); /* instead of au_read_post() */

out:
	si_read_unlock(sb);
	AuTraceErr((int)mask);
	return mask;
}