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 unsigned short pageofs_in, pageofs_out;
15 unsigned int inputsize, outputsize;
16
17 unsigned int alg; /* the algorithm for decompression */
18 bool inplace_io, partial_decoding, fillgaps;
19 gfp_t gfp; /* allocation flags for extra temporary buffers */
20 };
21
22 struct z_erofs_decompressor {
23 int (*config)(struct super_block *sb, struct erofs_super_block *dsb,
24 void *data, int size);
25 int (*decompress)(struct z_erofs_decompress_req *rq,
26 struct page **pagepool);
27 int (*init)(void);
28 void (*exit)(void);
29 char *name;
30 };
31
32 /* some special page->private (unsigned long, see below) */
33 #define Z_EROFS_SHORTLIVED_PAGE (-1UL << 2)
34 #define Z_EROFS_PREALLOCATED_PAGE (-2UL << 2)
35
36 /*
37 * For all pages in a pcluster, page->private should be one of
38 * Type Last 2bits page->private
39 * short-lived page 00 Z_EROFS_SHORTLIVED_PAGE
40 * preallocated page (tryalloc) 00 Z_EROFS_PREALLOCATED_PAGE
41 * cached/managed page 00 pointer to z_erofs_pcluster
42 * online page (file-backed, 01/10/11 sub-index << 2 | count
43 * some pages can be used for inplace I/O)
44 *
45 * page->mapping should be one of
46 * Type page->mapping
47 * short-lived page NULL
48 * preallocated page NULL
49 * cached/managed page non-NULL or NULL (invalidated/truncated page)
50 * online page non-NULL
51 *
52 * For all managed pages, PG_private should be set with 1 extra refcount,
53 * which is used for page reclaim / migration.
54 */
55
56 /*
57 * Currently, short-lived pages are pages directly from buddy system
58 * with specific page->private (Z_EROFS_SHORTLIVED_PAGE).
59 * In the future world of Memdescs, it should be type 0 (Misc) memory
60 * which type can be checked with a new helper.
61 */
62 static inline bool z_erofs_is_shortlived_page(struct page *page)
63 {
64 return page->private == Z_EROFS_SHORTLIVED_PAGE;
65 }
66
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 erofs_pagepool_add(pagepool, page);
73 return true;
74 }
75
76 extern const struct z_erofs_decompressor z_erofs_lzma_decomp;
77 extern const struct z_erofs_decompressor z_erofs_deflate_decomp;
78 extern const struct z_erofs_decompressor z_erofs_zstd_decomp;
79 extern const struct z_erofs_decompressor *z_erofs_decomp[];
80
81 struct z_erofs_stream_dctx {
82 struct z_erofs_decompress_req *rq;
83 unsigned int inpages, outpages; /* # of {en,de}coded pages */
84 int no, ni; /* the current {en,de}coded page # */
85
86 unsigned int avail_out; /* remaining bytes in the decoded buffer */
87 unsigned int inbuf_pos, inbuf_sz;
88 /* current status of the encoded buffer */
89 u8 *kin, *kout; /* buffer mapped pointers */
90 void *bounce; /* bounce buffer for inplace I/Os */
91 bool bounced; /* is the bounce buffer used now? */
92 };
93
94 int z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx, void **dst,
95 void **src, struct page **pgpl);
96 int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
97 unsigned int padbufsize);
98 int __init z_erofs_init_decompressor(void);
99 void z_erofs_exit_decompressor(void);
100 #endif
101
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