xref: /openbmc/linux/fs/erofs/compress.h (revision 586814ed)
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_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 
23 struct z_erofs_decompressor {
24 	int (*config)(struct super_block *sb, struct erofs_super_block *dsb,
25 		      void *data, int size);
26 	int (*decompress)(struct z_erofs_decompress_req *rq,
27 			  struct page **pagepool);
28 	char *name;
29 };
30 
31 /* some special page->private (unsigned long, see below) */
32 #define Z_EROFS_SHORTLIVED_PAGE		(-1UL << 2)
33 #define Z_EROFS_PREALLOCATED_PAGE	(-2UL << 2)
34 
35 /*
36  * For all pages in a pcluster, page->private should be one of
37  * Type                         Last 2bits      page->private
38  * short-lived page             00              Z_EROFS_SHORTLIVED_PAGE
39  * preallocated page (tryalloc) 00              Z_EROFS_PREALLOCATED_PAGE
40  * cached/managed page          00              pointer to z_erofs_pcluster
41  * online page (file-backed,    01/10/11        sub-index << 2 | count
42  *              some pages can be used for inplace I/O)
43  *
44  * page->mapping should be one of
45  * Type                 page->mapping
46  * short-lived page     NULL
47  * preallocated page    NULL
48  * cached/managed page  non-NULL or NULL (invalidated/truncated page)
49  * online page          non-NULL
50  *
51  * For all managed pages, PG_private should be set with 1 extra refcount,
52  * which is used for page reclaim / migration.
53  */
54 
55 /*
56  * short-lived pages are pages directly from buddy system with specific
57  * page->private (no need to set PagePrivate since these are non-LRU /
58  * non-movable pages and bypass reclaim / migration code).
59  */
z_erofs_is_shortlived_page(struct page * page)60 static inline bool z_erofs_is_shortlived_page(struct page *page)
61 {
62 	if (page->private != Z_EROFS_SHORTLIVED_PAGE)
63 		return false;
64 
65 	DBG_BUGON(page->mapping);
66 	return true;
67 }
68 
z_erofs_put_shortlivedpage(struct page ** pagepool,struct page * page)69 static inline bool z_erofs_put_shortlivedpage(struct page **pagepool,
70 					      struct page *page)
71 {
72 	if (!z_erofs_is_shortlived_page(page))
73 		return false;
74 
75 	/* short-lived pages should not be used by others at the same time */
76 	if (page_ref_count(page) > 1) {
77 		put_page(page);
78 	} else {
79 		/* follow the pcluster rule above. */
80 		erofs_pagepool_add(pagepool, page);
81 	}
82 	return true;
83 }
84 
85 #define MNGD_MAPPING(sbi)	((sbi)->managed_cache->i_mapping)
erofs_page_is_managed(const struct erofs_sb_info * sbi,struct page * page)86 static inline bool erofs_page_is_managed(const struct erofs_sb_info *sbi,
87 					 struct page *page)
88 {
89 	return page->mapping == MNGD_MAPPING(sbi);
90 }
91 
92 int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
93 			 unsigned int padbufsize);
94 extern const struct z_erofs_decompressor erofs_decompressors[];
95 
96 /* prototypes for specific algorithms */
97 int z_erofs_load_lzma_config(struct super_block *sb,
98 			struct erofs_super_block *dsb, void *data, int size);
99 int z_erofs_load_deflate_config(struct super_block *sb,
100 			struct erofs_super_block *dsb, void *data, int size);
101 int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
102 			    struct page **pagepool);
103 int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
104 			       struct page **pagepool);
105 #endif
106