aboutsummaryrefslogtreecommitdiff
path: root/fs/erofs/zpvec.h
blob: 1d67cbd3870421429dc7ac06c878001a873a8755 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2018 HUAWEI, Inc.
 *             https://www.huawei.com/
 * Created by Gao Xiang <gaoxiang25@huawei.com>
 */
#ifndef __EROFS_FS_ZPVEC_H
#define __EROFS_FS_ZPVEC_H

#include "tagptr.h"

/* page type in pagevec for decompress subsystem */
enum z_erofs_page_type {
	/* including Z_EROFS_VLE_PAGE_TAIL_EXCLUSIVE */
	Z_EROFS_PAGE_TYPE_EXCLUSIVE,

	Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED,

	Z_EROFS_VLE_PAGE_TYPE_HEAD,
	Z_EROFS_VLE_PAGE_TYPE_MAX
};

extern void __compiletime_error("Z_EROFS_PAGE_TYPE_EXCLUSIVE != 0")
	__bad_page_type_exclusive(void);

/* pagevec tagged pointer */
typedef tagptr2_t	erofs_vtptr_t;

/* pagevec collector */
struct z_erofs_pagevec_ctor {
	struct page *curr, *next;
	erofs_vtptr_t *pages;

	unsigned int nr, index;
};

static inline void z_erofs_pagevec_ctor_exit(struct z_erofs_pagevec_ctor *ctor,
					     bool atomic)
{
	if (!ctor->curr)
		return;

	if (atomic)
		kunmap_atomic(ctor->pages);
	else
		kunmap(ctor->curr);
}

static inline struct page *
z_erofs_pagevec_ctor_next_page(struct z_erofs_pagevec_ctor *ctor,
			       unsigned int nr)
{
	unsigned int index;

	/* keep away from occupied pages */
	if (ctor->next)
		return ctor->next;

	for (index = 0; index < nr; ++index) {
		const erofs_vtptr_t t = ctor->pages[index];
		const unsigned int tags = tagptr_unfold_tags(t);

		if (tags == Z_EROFS_PAGE_TYPE_EXCLUSIVE)
			return tagptr_unfold_ptr(t);
	}
	DBG_BUGON(nr >= ctor->nr);
	return NULL;
}

static inline void
z_erofs_pagevec_ctor_pagedown(struct z_erofs_pagevec_ctor *ctor,
			      bool atomic)
{
	struct page *next = z_erofs_pagevec_ctor_next_page(ctor, ctor->nr);

	z_erofs_pagevec_ctor_exit(ctor, atomic);

	ctor->curr = next;
	ctor->next = NULL;
	ctor->pages = atomic ?
		kmap_atomic(ctor->curr) : kmap(ctor->curr);

	ctor->nr = PAGE_SIZE / sizeof(struct page *);
	ctor->index = 0;
}

static inline void z_erofs_pagevec_ctor_init(struct z_erofs_pagevec_ctor *ctor,
					     unsigned int nr,
					     erofs_vtptr_t *pages,
					     unsigned int i)
{
	ctor->nr = nr;
	ctor->curr = ctor->next = NULL;
	ctor->pages = pages;

	if (i >= nr) {
		i -= nr;
		z_erofs_pagevec_ctor_pagedown(ctor, false);
		while (i > ctor->nr) {
			i -= ctor->nr;
			z_erofs_pagevec_ctor_pagedown(ctor, false);
		}
	}
	ctor->next = z_erofs_pagevec_ctor_next_page(ctor, i);
	ctor->index = i;
}

static inline bool z_erofs_pagevec_enqueue(struct z_erofs_pagevec_ctor *ctor,
					   struct page *page,
					   enum z_erofs_page_type type,
					   bool *occupied)
{
	*occupied = false;
	if (!ctor->next && type)
		if (ctor->index + 1 == ctor->nr)
			return false;

	if (ctor->index >= ctor->nr)
		z_erofs_pagevec_ctor_pagedown(ctor, false);

	/* exclusive page type must be 0 */
	if (Z_EROFS_PAGE_TYPE_EXCLUSIVE != (uintptr_t)NULL)
		__bad_page_type_exclusive();

	/* should remind that collector->next never equal to 1, 2 */
	if (type == (uintptr_t)ctor->next) {
		ctor->next = page;
		*occupied = true;
	}
	ctor->pages[ctor->index++] = tagptr_fold(erofs_vtptr_t, page, type);
	return true;
}

static inline struct page *
z_erofs_pagevec_dequeue(struct z_erofs_pagevec_ctor *ctor,
			enum z_erofs_page_type *type)
{
	erofs_vtptr_t t;

	if (ctor->index >= ctor->nr) {
		DBG_BUGON(!ctor->next);
		z_erofs_pagevec_ctor_pagedown(ctor, true);
	}

	t = ctor->pages[ctor->index];

	*type = tagptr_unfold_tags(t);

	/* should remind that collector->next never equal to 1, 2 */
	if (*type == (uintptr_t)ctor->next)
		ctor->next = tagptr_unfold_ptr(t);

	ctor->pages[ctor->index++] = tagptr_fold(erofs_vtptr_t, NULL, 0);
	return tagptr_unfold_ptr(t);
}
#endif