// SPDX-License-Identifier: GPL-2.0-only
/* Miscellaneous routines.
 *
 * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/swap.h>
#include "internal.h"

/**
 * netfs_dirty_folio - Mark folio dirty and pin a cache object for writeback
 * @mapping: The mapping the folio belongs to.
 * @folio: The folio being dirtied.
 *
 * Set the dirty flag on a folio and pin an in-use cache object in memory so
 * that writeback can later write to it.  This is intended to be called from
 * the filesystem's ->dirty_folio() method.
 *
 * Return: true if the dirty flag was set on the folio, false otherwise.
 */
bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio)
{
	struct inode *inode = mapping->host;
	struct netfs_inode *ictx = netfs_inode(inode);
	struct fscache_cookie *cookie = netfs_i_cookie(ictx);
	bool need_use = false;

	_enter("");

	if (!filemap_dirty_folio(mapping, folio))
		return false;
	if (!fscache_cookie_valid(cookie))
		return true;

	if (!(inode->i_state & I_PINNING_NETFS_WB)) {
		spin_lock(&inode->i_lock);
		if (!(inode->i_state & I_PINNING_NETFS_WB)) {
			inode->i_state |= I_PINNING_NETFS_WB;
			need_use = true;
		}
		spin_unlock(&inode->i_lock);

		if (need_use)
			fscache_use_cookie(cookie, true);
	}
	return true;
}
EXPORT_SYMBOL(netfs_dirty_folio);

/**
 * netfs_unpin_writeback - Unpin writeback resources
 * @inode: The inode on which the cookie resides
 * @wbc: The writeback control
 *
 * Unpin the writeback resources pinned by netfs_dirty_folio().  This is
 * intended to be called as/by the netfs's ->write_inode() method.
 */
int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc)
{
	struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));

	if (wbc->unpinned_netfs_wb)
		fscache_unuse_cookie(cookie, NULL, NULL);
	return 0;
}
EXPORT_SYMBOL(netfs_unpin_writeback);

/**
 * netfs_clear_inode_writeback - Clear writeback resources pinned by an inode
 * @inode: The inode to clean up
 * @aux: Auxiliary data to apply to the inode
 *
 * Clear any writeback resources held by an inode when the inode is evicted.
 * This must be called before clear_inode() is called.
 */
void netfs_clear_inode_writeback(struct inode *inode, const void *aux)
{
	struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));

	if (inode->i_state & I_PINNING_NETFS_WB) {
		loff_t i_size = i_size_read(inode);
		fscache_unuse_cookie(cookie, aux, &i_size);
	}
}
EXPORT_SYMBOL(netfs_clear_inode_writeback);