branch.h

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

/*
 * branch filesystems and xino for them
 */

#ifndef __AUFS_BRANCH_H__
#define __AUFS_BRANCH_H__

#ifdef __KERNEL__

#include <linux/mount.h>
#include "dynop.h"
#include "lcnt.h"
#include "rwsem.h"
#include "super.h"

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

/* a xino file */
struct au_xino {
	struct file		**xi_file;
	unsigned int		xi_nfile;

	struct {
		spinlock_t		spin;
		ino_t			*array;
		int			total;
		/* reserved for future use */
		/* unsigned long	*bitmap; */
		wait_queue_head_t	wqh;
	} xi_nondir;

	struct mutex		xi_mtx;	/* protects xi_file array */
	struct hlist_bl_head	xi_writing;

	atomic_t		xi_truncating;

	struct kref		xi_kref;
};

/* members for writable branch only */
enum {AuBrWh_BASE, AuBrWh_PLINK, AuBrWh_ORPH, AuBrWh_Last};
struct au_wbr {
	struct au_rwsem		wbr_wh_rwsem;
	struct dentry		*wbr_wh[AuBrWh_Last];
	atomic_t		wbr_wh_running;
#define wbr_whbase		wbr_wh[AuBrWh_BASE]	/* whiteout base */
#define wbr_plink		wbr_wh[AuBrWh_PLINK]	/* pseudo-link dir */
#define wbr_orph		wbr_wh[AuBrWh_ORPH]	/* dir for orphans */

	/* mfs mode */
	unsigned long long	wbr_bytes;
};

/* ext2 has 3 types of operations at least, ext3 has 4 */
#define AuBrDynOp (AuDyLast * 4)

#ifdef CONFIG_AUFS_HFSNOTIFY
/* support for asynchronous destruction */
struct au_br_hfsnotify {
	struct fsnotify_group	*hfsn_group;
};
#endif

/* sysfs entries */
struct au_brsysfs {
	char			name[16];
	struct attribute	attr;
};

enum {
	AuBrSysfs_BR,
	AuBrSysfs_BRID,
	AuBrSysfs_Last
};

/* protected by superblock rwsem */
struct au_branch {
	struct au_xino		*br_xino;

	aufs_bindex_t		br_id;

	int			br_perm;
	struct path		br_path;
	spinlock_t		br_dykey_lock;
	struct au_dykey		*br_dykey[AuBrDynOp];
	au_lcnt_t		br_nfiles;	/* opened files */
	au_lcnt_t		br_count;	/* in-use for other */

	struct au_wbr		*br_wbr;

#ifdef CONFIG_AUFS_HFSNOTIFY
	struct au_br_hfsnotify	*br_hfsn;
#endif

#ifdef CONFIG_SYSFS
	/* entries under sysfs per mount-point */
	struct au_brsysfs	br_sysfs[AuBrSysfs_Last];
#endif
};

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

static inline struct vfsmount *au_br_mnt(struct au_branch *br)
{
	return br->br_path.mnt;
}

static inline struct dentry *au_br_dentry(struct au_branch *br)
{
	return br->br_path.dentry;
}

static inline struct super_block *au_br_sb(struct au_branch *br)
{
	return au_br_mnt(br)->mnt_sb;
}

static inline int au_br_rdonly(struct au_branch *br)
{
	return (sb_rdonly(au_br_sb(br))
		|| !au_br_writable(br->br_perm))
		? -EROFS : 0;
}

static inline int au_br_hnotifyable(int brperm __maybe_unused)
{
#ifdef CONFIG_AUFS_HNOTIFY
	return !(brperm & AuBrPerm_RR);
#else
	return 0;
#endif
}

static inline int au_br_test_oflag(int oflag, struct au_branch *br)
{
	int err, exec_flag;

	err = 0;
	exec_flag = oflag & __FMODE_EXEC;
	if (unlikely(exec_flag && path_noexec(&br->br_path)))
		err = -EACCES;

	return err;
}

static inline void au_xino_get(struct au_branch *br)
{
	struct au_xino *xi;

	xi = br->br_xino;
	if (xi)
		kref_get(&xi->xi_kref);
}

static inline int au_xino_count(struct au_branch *br)
{
	int v;
	struct au_xino *xi;

	v = 0;
	xi = br->br_xino;
	if (xi)
		v = kref_read(&xi->xi_kref);

	return v;
}

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

/* branch.c */
struct au_sbinfo;
void au_br_free(struct au_sbinfo *sinfo);
int au_br_index(struct super_block *sb, aufs_bindex_t br_id);
struct au_opt_add;
int au_br_add(struct super_block *sb, struct au_opt_add *add);

/* xino.c */
static const loff_t au_loff_max = LLONG_MAX;

aufs_bindex_t au_xi_root(struct super_block *sb, struct dentry *dentry);
struct file *au_xino_create(struct super_block *sb, char *fpath, int silent);
struct file *au_xino_create2(struct super_block *sb, struct path *base,
			     struct file *copy_src);
struct au_xi_new {
	struct au_xino *xi;	/* switch between xino and xigen */
	int idx;
	struct path *base;
	struct file *copy_src;
};
struct file *au_xi_new(struct super_block *sb, struct au_xi_new *xinew);

int au_xino_read(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
		 ino_t *ino);
int au_xino_write(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
		  ino_t ino);
ssize_t xino_fread(vfs_readf_t func, struct file *file, void *buf, size_t size,
		   loff_t *pos);
ssize_t xino_fwrite(vfs_writef_t func, struct file *file, void *buf,
		    size_t size, loff_t *pos);

int au_xib_trunc(struct super_block *sb);
int au_xino_trunc(struct super_block *sb, aufs_bindex_t bindex, int idx_begin);

struct au_xino *au_xino_alloc(unsigned int nfile);
int au_xino_put(struct au_branch *br);
struct file *au_xino_file1(struct au_xino *xi);

struct au_opt_xino;
void au_xino_clr(struct super_block *sb);
int au_xino_set(struct super_block *sb, struct au_opt_xino *xiopt);
struct file *au_xino_def(struct super_block *sb);
int au_xino_init_br(struct super_block *sb, struct au_branch *br, ino_t hino,
		    struct path *base);

ino_t au_xino_new_ino(struct super_block *sb);
void au_xino_delete_inode(struct inode *inode, const int unlinked);

void au_xinondir_leave(struct super_block *sb, aufs_bindex_t bindex,
		       ino_t h_ino, int idx);
int au_xinondir_enter(struct super_block *sb, aufs_bindex_t bindex, ino_t h_ino,
		      int *idx);

int au_xino_path(struct seq_file *seq, struct file *file);

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

/* @idx is signed to accept -1 meaning the first file */
static inline struct file *au_xino_file(struct au_xino *xi, int idx)
{
	struct file *file;

	file = NULL;
	if (!xi)
		goto out;

	if (idx >= 0) {
		if (idx < xi->xi_nfile)
			file = xi->xi_file[idx];
	} else
		file = au_xino_file1(xi);

out:
	return file;
}

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

/* Superblock to branch */
static inline
aufs_bindex_t au_sbr_id(struct super_block *sb, aufs_bindex_t bindex)
{
	return au_sbr(sb, bindex)->br_id;
}

static inline
struct vfsmount *au_sbr_mnt(struct super_block *sb, aufs_bindex_t bindex)
{
	return au_br_mnt(au_sbr(sb, bindex));
}

static inline
struct super_block *au_sbr_sb(struct super_block *sb, aufs_bindex_t bindex)
{
	return au_br_sb(au_sbr(sb, bindex));
}

static inline int au_sbr_perm(struct super_block *sb, aufs_bindex_t bindex)
{
	return au_sbr(sb, bindex)->br_perm;
}

static inline int au_sbr_whable(struct super_block *sb, aufs_bindex_t bindex)
{
	return au_br_whable(au_sbr_perm(sb, bindex));
}

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

#define wbr_wh_read_lock(wbr)	au_rw_read_lock(&(wbr)->wbr_wh_rwsem)
#define wbr_wh_write_lock(wbr)	au_rw_write_lock(&(wbr)->wbr_wh_rwsem)
#define wbr_wh_read_trylock(wbr)	au_rw_read_trylock(&(wbr)->wbr_wh_rwsem)
#define wbr_wh_write_trylock(wbr) au_rw_write_trylock(&(wbr)->wbr_wh_rwsem)
/*
#define wbr_wh_read_trylock_nested(wbr) \
	au_rw_read_trylock_nested(&(wbr)->wbr_wh_rwsem)
#define wbr_wh_write_trylock_nested(wbr) \
	au_rw_write_trylock_nested(&(wbr)->wbr_wh_rwsem)
*/

#define wbr_wh_read_unlock(wbr)	au_rw_read_unlock(&(wbr)->wbr_wh_rwsem)
#define wbr_wh_write_unlock(wbr)	au_rw_write_unlock(&(wbr)->wbr_wh_rwsem)
#define wbr_wh_downgrade_lock(wbr)	au_rw_dgrade_lock(&(wbr)->wbr_wh_rwsem)

#define WbrWhMustNoWaiters(wbr)	AuRwMustNoWaiters(&(wbr)->wbr_wh_rwsem)
#define WbrWhMustAnyLock(wbr)	AuRwMustAnyLock(&(wbr)->wbr_wh_rwsem)
#define WbrWhMustWriteLock(wbr)	AuRwMustWriteLock(&(wbr)->wbr_wh_rwsem)

#endif /* __KERNEL__ */
#endif /* __AUFS_BRANCH_H__ */