/*
 * Copyright (c) 2015, The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/spinlock.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>

#include "../internal.h"

void ecryptfs_drop_pagecache_sb(struct super_block *sb, void *unused)
{
	struct inode *inode, *toput_inode = NULL;

	spin_lock(&inode_sb_list_lock);
	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
		spin_lock(&inode->i_lock);
		if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
		    (inode->i_mapping->nrpages == 0)) {
			spin_unlock(&inode->i_lock);
			continue;
		}
		__iget(inode);
		spin_unlock(&inode->i_lock);
		spin_unlock(&inode_sb_list_lock);
		invalidate_mapping_pages(inode->i_mapping, 0, -1);
		iput(toput_inode);
		toput_inode = inode;
		spin_lock(&inode_sb_list_lock);
	}
	spin_unlock(&inode_sb_list_lock);
	iput(toput_inode);
}

void clean_inode_pages(struct address_space *mapping,
		pgoff_t start, pgoff_t end)
{
	struct pagevec pvec;
	pgoff_t index = start;
	int i;

	pagevec_init(&pvec, 0);
	while (index <= end && pagevec_lookup(&pvec, mapping, index,
		min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
		for (i = 0; i < pagevec_count(&pvec); i++) {
			struct page *page = pvec.pages[i];

			/**
			 * We rely upon deletion
			 * not changing page->index
			 */
			index = page->index;
			if (index > end)
				break;
			if (!trylock_page(page))
				continue;
			WARN_ON(page->index != index);
			zero_user(page, 0, PAGE_CACHE_SIZE);
			unlock_page(page);
		}
		pagevec_release(&pvec);
		cond_resched();
		index++;
	}
}