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
11 struct z_erofs_decompress_req {
12 struct super_block *sb;
13 struct page **in, **out;
14
15 unsigned short 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;
21 };
22
23 struct 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 */
z_erofs_is_shortlived_page(struct page * page)58 static 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
z_erofs_put_shortlivedpage(struct page ** pagepool,struct page * page)67 static 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)
erofs_page_is_managed(const struct erofs_sb_info * sbi,struct page * page)84 static 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
90 int z_erofs_decompress(struct z_erofs_decompress_req *rq,
91 struct page **pagepool);
92
93 /* prototypes for specific algorithms */
94 int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
95 struct page **pagepool);
96 #endif
97