1/* SPDX-License-Identifier: GPL-2.0-only */
 2/*
 3 * Copyright (C) 2019 HUAWEI, Inc.
 4 *             https://www.huawei.com/
 5 */
 6#ifndef __EROFS_FS_COMPRESS_H
 7#define __EROFS_FS_COMPRESS_H
 8
 9#include "internal.h"
10
11struct z_erofs_decompress_req {
12	struct super_block *sb;
13	struct page **in, **out;
14
15	unsigned short pageofs_in, pageofs_out;
16	unsigned int inputsize, outputsize;
17
18	/* indicate the algorithm will be used for decompression */
19	unsigned int alg;
20	bool inplace_io, partial_decoding, fillgaps;
21};
22
23struct z_erofs_decompressor {
24	int (*decompress)(struct z_erofs_decompress_req *rq,
25			  struct page **pagepool);
26	char *name;
27};
28
29/* some special page->private (unsigned long, see below) */
30#define Z_EROFS_SHORTLIVED_PAGE		(-1UL << 2)
31#define Z_EROFS_PREALLOCATED_PAGE	(-2UL << 2)
32
33/*
34 * For all pages in a pcluster, page->private should be one of
35 * Type                         Last 2bits      page->private
36 * short-lived page             00              Z_EROFS_SHORTLIVED_PAGE
37 * preallocated page (tryalloc) 00              Z_EROFS_PREALLOCATED_PAGE
38 * cached/managed page          00              pointer to z_erofs_pcluster
39 * online page (file-backed,    01/10/11        sub-index << 2 | count
40 *              some pages can be used for inplace I/O)
41 *
42 * page->mapping should be one of
43 * Type                 page->mapping
44 * short-lived page     NULL
45 * preallocated page    NULL
46 * cached/managed page  non-NULL or NULL (invalidated/truncated page)
47 * online page          non-NULL
48 *
49 * For all managed pages, PG_private should be set with 1 extra refcount,
50 * which is used for page reclaim / migration.
51 */
52
53/*
54 * short-lived pages are pages directly from buddy system with specific
55 * page->private (no need to set PagePrivate since these are non-LRU /
56 * non-movable pages and bypass reclaim / migration code).
57 */
58static inline bool z_erofs_is_shortlived_page(struct page *page)
59{
60	if (page->private != Z_EROFS_SHORTLIVED_PAGE)
61		return false;
62
63	DBG_BUGON(page->mapping);
64	return true;
65}
66
67static inline bool z_erofs_put_shortlivedpage(struct page **pagepool,
68					      struct page *page)
69{
70	if (!z_erofs_is_shortlived_page(page))
71		return false;
72
73	/* short-lived pages should not be used by others at the same time */
74	if (page_ref_count(page) > 1) {
75		put_page(page);
76	} else {
77		/* follow the pcluster rule above. */
78		erofs_pagepool_add(pagepool, page);
79	}
80	return true;
81}
82
83#define MNGD_MAPPING(sbi)	((sbi)->managed_cache->i_mapping)
84static inline bool erofs_page_is_managed(const struct erofs_sb_info *sbi,
85					 struct page *page)
86{
87	return page->mapping == MNGD_MAPPING(sbi);
88}
89
90int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
91			 unsigned int padbufsize);
92int z_erofs_decompress(struct z_erofs_decompress_req *rq,
93		       struct page **pagepool);
94
95/* prototypes for specific algorithms */
96int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
97			    struct page **pagepool);
98#endif