dentry.h

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

/*
 * lookup and dentry operations
 */

#ifndef __AUFS_DENTRY_H__
#define __AUFS_DENTRY_H__

#ifdef __KERNEL__

#include <linux/dcache.h>
#include "rwsem.h"

struct au_hdentry {
	struct dentry		*hd_dentry;
	aufs_bindex_t		hd_id;
};

struct au_dinfo {
	atomic_t		di_generation;

	struct au_rwsem		di_rwsem;
	aufs_bindex_t		di_btop, di_bbot;
	struct au_hdentry	*di_hdentry;
	struct rcu_head		rcu;
} ____cacheline_aligned_in_smp;

/* ---------------------------------------------------------------------- */

/* dinfo.c */
void au_di_init_once(void *_di);
struct au_dinfo *au_di_alloc(struct super_block *sb, unsigned int lsc);
void au_di_free(struct au_dinfo *dinfo);
int au_di_init(struct dentry *dentry);
void au_di_fin(struct dentry *dentry);
int au_di_realloc(struct au_dinfo *dinfo, int nbr, int may_shrink);

void di_read_lock(struct dentry *d, int flags, unsigned int lsc);
void di_read_unlock(struct dentry *d, int flags);
void di_downgrade_lock(struct dentry *d, int flags);
void di_write_lock(struct dentry *d, unsigned int lsc);
void di_write_unlock(struct dentry *d);

struct dentry *au_h_dptr(struct dentry *dentry, aufs_bindex_t bindex);

void au_set_h_dptr(struct dentry *dentry, aufs_bindex_t bindex,
		   struct dentry *h_dentry);
int au_digen_test(struct dentry *dentry, unsigned int sigen);
void au_update_digen(struct dentry *dentry);
void au_update_dbtop(struct dentry *dentry);
void au_update_dbbot(struct dentry *dentry);
int au_find_dbindex(struct dentry *dentry, struct dentry *h_dentry);

/* ---------------------------------------------------------------------- */

static inline struct au_dinfo *au_di(struct dentry *dentry)
{
	return dentry->d_fsdata;
}

/* ---------------------------------------------------------------------- */

/* lock subclass for dinfo */
enum {
	AuLsc_DI_CHILD,		/* child first */
	AuLsc_DI_CHILD2,	/* rename(2), link(2), and cpup at hnotify */
	AuLsc_DI_CHILD3,	/* copyup dirs */
	AuLsc_DI_PARENT,
	AuLsc_DI_PARENT2,
	AuLsc_DI_PARENT3,
	AuLsc_DI_TMP		/* temp for replacing dinfo */
};

/*
 * di_read_lock_child, di_write_lock_child,
 * di_read_lock_child2, di_write_lock_child2,
 * di_read_lock_child3, di_write_lock_child3,
 * di_read_lock_parent, di_write_lock_parent,
 * di_read_lock_parent2, di_write_lock_parent2,
 * di_read_lock_parent3, di_write_lock_parent3,
 */
#define AuReadLockFunc(name, lsc) \
static inline void di_read_lock_##name(struct dentry *d, int flags) \
{ di_read_lock(d, flags, AuLsc_DI_##lsc); }

#define AuWriteLockFunc(name, lsc) \
static inline void di_write_lock_##name(struct dentry *d) \
{ di_write_lock(d, AuLsc_DI_##lsc); }

#define AuRWLockFuncs(name, lsc) \
	AuReadLockFunc(name, lsc) \
	AuWriteLockFunc(name, lsc)

AuRWLockFuncs(child, CHILD);
AuRWLockFuncs(child2, CHILD2);
AuRWLockFuncs(child3, CHILD3);
AuRWLockFuncs(parent, PARENT);
AuRWLockFuncs(parent2, PARENT2);
AuRWLockFuncs(parent3, PARENT3);

#undef AuReadLockFunc
#undef AuWriteLockFunc
#undef AuRWLockFuncs

#define DiMustNoWaiters(d)	AuRwMustNoWaiters(&au_di(d)->di_rwsem)
#define DiMustAnyLock(d)	AuRwMustAnyLock(&au_di(d)->di_rwsem)
#define DiMustWriteLock(d)	AuRwMustWriteLock(&au_di(d)->di_rwsem)

/* ---------------------------------------------------------------------- */

/* todo: memory barrier? */
static inline unsigned int au_digen(struct dentry *d)
{
	return atomic_read(&au_di(d)->di_generation);
}

static inline void au_h_dentry_init(struct au_hdentry *hdentry)
{
	hdentry->hd_dentry = NULL;
}

static inline struct au_hdentry *au_hdentry(struct au_dinfo *di,
					    aufs_bindex_t bindex)
{
	return di->di_hdentry + bindex;
}

static inline void au_hdput(struct au_hdentry *hd)
{
	if (hd)
		dput(hd->hd_dentry);
}

static inline aufs_bindex_t au_dbtop(struct dentry *dentry)
{
	DiMustAnyLock(dentry);
	return au_di(dentry)->di_btop;
}

static inline aufs_bindex_t au_dbbot(struct dentry *dentry)
{
	DiMustAnyLock(dentry);
	return au_di(dentry)->di_bbot;
}

/* todo: hard/soft set? */
static inline void au_set_dbtop(struct dentry *dentry, aufs_bindex_t bindex)
{
	DiMustWriteLock(dentry);
	au_di(dentry)->di_btop = bindex;
}

static inline void au_set_dbbot(struct dentry *dentry, aufs_bindex_t bindex)
{
	DiMustWriteLock(dentry);
	au_di(dentry)->di_bbot = bindex;
}

#endif /* __KERNEL__ */
#endif /* __AUFS_DENTRY_H__ */