fs/erofs/compress.h

   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