super.h

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

/*
 * super_block operations
 */

#ifndef __AUFS_SUPER_H__
#define __AUFS_SUPER_H__

#ifdef __KERNEL__

#include <linux/fs.h>
#include <linux/kobject.h>
#include "rwsem.h"
#include "wkq.h"

struct au_branch;
struct au_sbinfo {
	/* nowait tasks in the system-wide workqueue */
	struct au_nowait_tasks	si_nowait;

	/*
	 * tried sb->s_umount, but failed due to the dependency between i_mutex.
	 * rwsem for au_sbinfo is necessary.
	 */
	struct au_rwsem		si_rwsem;

	/* branch management */
	unsigned int		si_generation;

	aufs_bindex_t		si_bbot;

	/* dirty trick to keep br_id plus */
	unsigned int		si_last_br_id :
				sizeof(aufs_bindex_t) * BITS_PER_BYTE - 1;
	struct au_branch	**si_branch;

	/* mount flags */
	/* include/asm-ia64/siginfo.h defines a macro named si_flags */
	unsigned int		si_mntflags;

	/*
	 * sysfs and lifetime management.
	 * this is not a small structure and it may be a waste of memory in case
	 * of sysfs is disabled, particularly when many aufs-es are mounted.
	 * but using sysfs is majority.
	 */
	struct kobject		si_kobj;
};

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

/* flags for si_read_lock()/aufs_read_lock()/di_read_lock() */
#define AuLock_DW		1		/* write-lock dentry */
#define AuLock_IR		(1 << 1)	/* read-lock inode */
#define AuLock_IW		(1 << 2)	/* write-lock inode */
#define AuLock_FLUSH		(1 << 3)	/* wait for 'nowait' tasks */
#define au_ftest_lock(flags, name)	((flags) & AuLock_##name)
#define au_fset_lock(flags, name) \
	do { (flags) |= AuLock_##name; } while (0)
#define au_fclr_lock(flags, name) \
	do { (flags) &= ~AuLock_##name; } while (0)

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

/* super.c */
struct inode *au_iget_locked(struct super_block *sb, ino_t ino);

/* sbinfo.c */
void au_si_free(struct kobject *kobj);
int au_si_alloc(struct super_block *sb);
int au_sbr_realloc(struct au_sbinfo *sbinfo, int nbr, int may_shrink);

unsigned int au_sigen_inc(struct super_block *sb);
aufs_bindex_t au_new_br_id(struct super_block *sb);

int si_read_lock(struct super_block *sb, int flags);
int si_write_lock(struct super_block *sb, int flags);

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

static inline struct au_sbinfo *au_sbi(struct super_block *sb)
{
	return sb->s_fs_info;
}

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

/* lock superblock. mainly for entry point functions */
#define __si_read_lock(sb)	au_rw_read_lock(&au_sbi(sb)->si_rwsem)
#define __si_write_lock(sb)	au_rw_write_lock(&au_sbi(sb)->si_rwsem)
#define __si_read_trylock(sb)	au_rw_read_trylock(&au_sbi(sb)->si_rwsem)
#define __si_write_trylock(sb)	au_rw_write_trylock(&au_sbi(sb)->si_rwsem)
/*
#define __si_read_trylock_nested(sb) \
	au_rw_read_trylock_nested(&au_sbi(sb)->si_rwsem)
#define __si_write_trylock_nested(sb) \
	au_rw_write_trylock_nested(&au_sbi(sb)->si_rwsem)
*/

#define __si_read_unlock(sb)	au_rw_read_unlock(&au_sbi(sb)->si_rwsem)
#define __si_write_unlock(sb)	au_rw_write_unlock(&au_sbi(sb)->si_rwsem)
#define __si_downgrade_lock(sb)	au_rw_dgrade_lock(&au_sbi(sb)->si_rwsem)

#define SiMustNoWaiters(sb)	AuRwMustNoWaiters(&au_sbi(sb)->si_rwsem)
#define SiMustAnyLock(sb)	AuRwMustAnyLock(&au_sbi(sb)->si_rwsem)
#define SiMustWriteLock(sb)	AuRwMustWriteLock(&au_sbi(sb)->si_rwsem)

static inline void si_noflush_read_lock(struct super_block *sb)
{
	__si_read_lock(sb);
	/* re-commit later */
}

static inline int si_noflush_read_trylock(struct super_block *sb)
{
	return __si_read_trylock(sb);	/* re-commit later */
}

static inline void si_noflush_write_lock(struct super_block *sb)
{
	__si_write_lock(sb);
	/* re-commit later */
}

static inline int si_noflush_write_trylock(struct super_block *sb)
{
	return __si_write_trylock(sb);	/* re-commit later */
}

#if 0 /* reserved */
static inline int si_read_trylock(struct super_block *sb, int flags)
{
	if (au_ftest_lock(flags, FLUSH))
		au_nwt_flush(&au_sbi(sb)->si_nowait);
	return si_noflush_read_trylock(sb);
}
#endif

static inline void si_read_unlock(struct super_block *sb)
{
	/* re-commit later */
	__si_read_unlock(sb);
}

#if 0 /* reserved */
static inline int si_write_trylock(struct super_block *sb, int flags)
{
	if (au_ftest_lock(flags, FLUSH))
		au_nwt_flush(&au_sbi(sb)->si_nowait);
	return si_noflush_write_trylock(sb);
}
#endif

static inline void si_write_unlock(struct super_block *sb)
{
	/* re-commit later */
	__si_write_unlock(sb);
}

#if 0 /* reserved */
static inline void si_downgrade_lock(struct super_block *sb)
{
	__si_downgrade_lock(sb);
}
#endif

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

static inline aufs_bindex_t au_sbbot(struct super_block *sb)
{
	SiMustAnyLock(sb);
	return au_sbi(sb)->si_bbot;
}

static inline unsigned int au_mntflags(struct super_block *sb)
{
	SiMustAnyLock(sb);
	return au_sbi(sb)->si_mntflags;
}

static inline unsigned int au_sigen(struct super_block *sb)
{
	SiMustAnyLock(sb);
	return au_sbi(sb)->si_generation;
}

static inline struct au_branch *au_sbr(struct super_block *sb,
				       aufs_bindex_t bindex)
{
	SiMustAnyLock(sb);
	return au_sbi(sb)->si_branch[0 + bindex];
}

#endif /* __KERNEL__ */
#endif /* __AUFS_SUPER_H__ */