fs/btrfs/compression.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright (C) 2008 Oracle.  All rights reserved.
   4  */
   5
   6 #ifndef BTRFS_COMPRESSION_H
   7 #define BTRFS_COMPRESSION_H
   8
   9 /*
  10  * We want to make sure that amount of RAM required to uncompress an extent is
  11  * reasonable, so we limit the total size in ram of a compressed extent to
  12  * 128k.  This is a crucial number because it also controls how easily we can
  13  * spread reads across cpus for decompression.
  14  *
  15  * We also want to make sure the amount of IO required to do a random read is
  16  * reasonably small, so we limit the size of a compressed extent to 128k.
  17  */
  18
  19 /* Maximum length of compressed data stored on disk */
  20 #define BTRFS_MAX_COMPRESSED            (SZ_128K)
  21 /* Maximum size of data before compression */
  22 #define BTRFS_MAX_UNCOMPRESSED          (SZ_128K)
  23
  24 #define BTRFS_ZLIB_DEFAULT_LEVEL                3
  25
  26 struct compressed_bio {
  27         /* number of bios pending for this compressed extent */
  28         refcount_t pending_bios;
  29
  30         /* the pages with the compressed data on them */
  31         struct page **compressed_pages;
  32
  33         /* inode that owns this data */
  34         struct inode *inode;
  35
  36         /* starting offset in the inode for our pages */
  37         u64 start;
  38
  39         /* number of bytes in the inode we're working on */
  40         unsigned long len;
  41
  42         /* number of bytes on disk */
  43         unsigned long compressed_len;
  44
  45         /* the compression algorithm for this bio */
  46         int compress_type;
  47
  48         /* number of compressed pages in the array */
  49         unsigned long nr_pages;
  50
  51         /* IO errors */
  52         int errors;
  53         int mirror_num;
  54
  55         /* for reads, this is the bio we are copying the data into */
  56         struct bio *orig_bio;
  57
  58         /*
  59          * the start of a variable length array of checksums only
  60          * used by reads
  61          */
  62         u32 sums;
  63 };
  64
  65 void __init btrfs_init_compress(void);
  66 void __cold btrfs_exit_compress(void);
  67
  68 int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
  69                          u64 start, struct page **pages,
  70                          unsigned long *out_pages,
  71                          unsigned long *total_in,
  72                          unsigned long *total_out);
  73 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
  74                      unsigned long start_byte, size_t srclen, size_t destlen);
  75 int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
  76                               unsigned long total_out, u64 disk_start,
  77                               struct bio *bio);
  78
  79 blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
  80                                   unsigned long len, u64 disk_start,
  81                                   unsigned long compressed_len,
  82                                   struct page **compressed_pages,
  83                                   unsigned long nr_pages,
  84                                   unsigned int write_flags);
  85 blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
  86                                  int mirror_num, unsigned long bio_flags);
  87
  88 unsigned btrfs_compress_str2level(const char *str);
  89
  90 enum btrfs_compression_type {
  91         BTRFS_COMPRESS_NONE  = 0,
  92         BTRFS_COMPRESS_ZLIB  = 1,
  93         BTRFS_COMPRESS_LZO   = 2,
  94         BTRFS_COMPRESS_ZSTD  = 3,
  95         BTRFS_COMPRESS_TYPES = 3,
  96 };
  97
  98 struct btrfs_compress_op {
  99         struct list_head *(*alloc_workspace)(void);
 100
 101         void (*free_workspace)(struct list_head *workspace);
 102
 103         int (*compress_pages)(struct list_head *workspace,
 104                               struct address_space *mapping,
 105                               u64 start,
 106                               struct page **pages,
 107                               unsigned long *out_pages,
 108                               unsigned long *total_in,
 109                               unsigned long *total_out);
 110
 111         int (*decompress_bio)(struct list_head *workspace,
 112                                 struct compressed_bio *cb);
 113
 114         int (*decompress)(struct list_head *workspace,
 115                           unsigned char *data_in,
 116                           struct page *dest_page,
 117                           unsigned long start_byte,
 118                           size_t srclen, size_t destlen);
 119
 120         void (*set_level)(struct list_head *ws, unsigned int type);
 121 };
 122
 123 extern const struct btrfs_compress_op btrfs_zlib_compress;
 124 extern const struct btrfs_compress_op btrfs_lzo_compress;
 125 extern const struct btrfs_compress_op btrfs_zstd_compress;
 126
 127 const char* btrfs_compress_type2str(enum btrfs_compression_type type);
 128
 129 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);
 130
 131 #endif