// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2005-2019 Junjiro R. Okajima
 */

/*
 * sub-routines for dentry cache
 */

#include "aufs.h"

static void au_dpage_free(struct au_dpage *dpage)
{
	int i;
	struct dentry **p;

	p = dpage->dentries;
	for (i = 0; i < dpage->ndentry; i++)
		dput(*p++);
	free_page((unsigned long)dpage->dentries);
}

int au_dpages_init(struct au_dcsub_pages *dpages, gfp_t gfp)
{
	int err;
	void *p;

	err = -ENOMEM;
	dpages->dpages = kmalloc(sizeof(*dpages->dpages), gfp);
	if (unlikely(!dpages->dpages))
		goto out;

	p = (void *)__get_free_page(gfp);
	if (unlikely(!p))
		goto out_dpages;

	dpages->dpages[0].ndentry = 0;
	dpages->dpages[0].dentries = p;
	dpages->ndpage = 1;
	return 0; /* success */

out_dpages:
	au_kfree_try_rcu(dpages->dpages);
out:
	return err;
}

void au_dpages_free(struct au_dcsub_pages *dpages)
{
	int i;
	struct au_dpage *p;

	p = dpages->dpages;
	for (i = 0; i < dpages->ndpage; i++)
		au_dpage_free(p++);
	au_kfree_try_rcu(dpages->dpages);
}

static int au_dpages_append(struct au_dcsub_pages *dpages,
			    struct dentry *dentry, gfp_t gfp)
{
	int err, sz;
	struct au_dpage *dpage;
	void *p;

	dpage = dpages->dpages + dpages->ndpage - 1;
	sz = PAGE_SIZE / sizeof(dentry);
	if (unlikely(dpage->ndentry >= sz)) {
		AuLabel(new dpage);
		err = -ENOMEM;
		sz = dpages->ndpage * sizeof(*dpages->dpages);
		p = au_kzrealloc(dpages->dpages, sz,
				 sz + sizeof(*dpages->dpages), gfp,
				 /*may_shrink*/0);
		if (unlikely(!p))
			goto out;

		dpages->dpages = p;
		dpage = dpages->dpages + dpages->ndpage;
		p = (void *)__get_free_page(gfp);
		if (unlikely(!p))
			goto out;

		dpage->ndentry = 0;
		dpage->dentries = p;
		dpages->ndpage++;
	}

	AuDebugOn(au_dcount(dentry) <= 0);
	dpage->dentries[dpage->ndentry++] = dget_dlock(dentry);
	return 0; /* success */

out:
	return err;
}

int au_dcsub_pages_rev(struct au_dcsub_pages *dpages, struct dentry *dentry,
		       int do_include, au_dpages_test test, void *arg)
{
	int err;

	err = 0;
	write_seqlock(&rename_lock);
	spin_lock(&dentry->d_lock);
	if (do_include
	    && au_dcount(dentry) > 0
	    && (!test || test(dentry, arg)))
		err = au_dpages_append(dpages, dentry, GFP_ATOMIC);
	spin_unlock(&dentry->d_lock);
	if (unlikely(err))
		goto out;

	/*
	 * RCU for vfsmount is unnecessary since this is a traverse in a single
	 * mount
	 */
	while (!IS_ROOT(dentry)) {
		dentry = dentry->d_parent; /* rename_lock is locked */
		spin_lock(&dentry->d_lock);
		if (au_dcount(dentry) > 0
		    && (!test || test(dentry, arg)))
			err = au_dpages_append(dpages, dentry, GFP_ATOMIC);
		spin_unlock(&dentry->d_lock);
		if (unlikely(err))
			break;
	}

out:
	write_sequnlock(&rename_lock);
	return err;
}

static inline int au_dcsub_dpages_aufs(struct dentry *dentry, void *arg)
{
	return au_di(dentry) && dentry->d_sb == arg;
}

int au_dcsub_pages_rev_aufs(struct au_dcsub_pages *dpages,
			    struct dentry *dentry, int do_include)
{
	return au_dcsub_pages_rev(dpages, dentry, do_include,
				  au_dcsub_dpages_aufs, dentry->d_sb);
}

int au_test_subdir(struct dentry *d1, struct dentry *d2)
{
	struct path path[2] = {
		{
			.dentry = d1
		},
		{
			.dentry = d2
		}
	};

	return path_is_under(path + 0, path + 1);
}