LXR linux/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#include <linux/sizes.h>
  10
  11/*
  12 * We want to make sure that amount of RAM required to uncompress an extent is
  13 * reasonable, so we limit the total size in ram of a compressed extent to
  14 * 128k.  This is a crucial number because it also controls how easily we can
  15 * spread reads across cpus for decompression.
  16 *
  17 * We also want to make sure the amount of IO required to do a random read is
  18 * reasonably small, so we limit the size of a compressed extent to 128k.
  19 */
  20
  21/* Maximum length of compressed data stored on disk */
  22#define BTRFS_MAX_COMPRESSED            (SZ_128K)
  23/* Maximum size of data before compression */
  24#define BTRFS_MAX_UNCOMPRESSED          (SZ_128K)
  25
  26#define BTRFS_ZLIB_DEFAULT_LEVEL                3
  27
  28struct compressed_bio {
  29        /* number of bios pending for this compressed extent */
  30        refcount_t pending_bios;
  31
  32        /* the pages with the compressed data on them */
  33        struct page **compressed_pages;
  34
  35        /* inode that owns this data */
  36        struct inode *inode;
  37
  38        /* starting offset in the inode for our pages */
  39        u64 start;
  40
  41        /* number of bytes in the inode we're working on */
  42        unsigned long len;
  43
  44        /* number of bytes on disk */
  45        unsigned long compressed_len;
  46
  47        /* the compression algorithm for this bio */
  48        int compress_type;
  49
  50        /* number of compressed pages in the array */
  51        unsigned long nr_pages;
  52
  53        /* IO errors */
  54        int errors;
  55        int mirror_num;
  56
  57        /* for reads, this is the bio we are copying the data into */
  58        struct bio *orig_bio;
  59
  60        /*
  61         * the start of a variable length array of checksums only
  62         * used by reads
  63         */
  64        u32 sums;
  65};
  66
  67void __init btrfs_init_compress(void);
  68void __cold btrfs_exit_compress(void);
  69
  70int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
  71                         u64 start, struct page **pages,
  72                         unsigned long *out_pages,
  73                         unsigned long *total_in,
  74                         unsigned long *total_out);
  75int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
  76                     unsigned long start_byte, size_t srclen, size_t destlen);
  77int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
  78                              unsigned long total_out, u64 disk_start,
  79                              struct bio *bio);
  80
  81blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
  82                                  unsigned long len, u64 disk_start,
  83                                  unsigned long compressed_len,
  84                                  struct page **compressed_pages,
  85                                  unsigned long nr_pages,
  86                                  unsigned int write_flags);
  87blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
  88                                 int mirror_num, unsigned long bio_flags);
  89
  90unsigned btrfs_compress_str2level(const char *str);
  91
  92enum btrfs_compression_type {
  93        BTRFS_COMPRESS_NONE  = 0,
  94        BTRFS_COMPRESS_ZLIB  = 1,
  95        BTRFS_COMPRESS_LZO   = 2,
  96        BTRFS_COMPRESS_ZSTD  = 3,
  97        BTRFS_COMPRESS_TYPES = 3,
  98};
  99
 100struct btrfs_compress_op {
 101        struct list_head *(*alloc_workspace)(void);
 102
 103        void (*free_workspace)(struct list_head *workspace);
 104
 105        int (*compress_pages)(struct list_head *workspace,
 106                              struct address_space *mapping,
 107                              u64 start,
 108                              struct page **pages,
 109                              unsigned long *out_pages,
 110                              unsigned long *total_in,
 111                              unsigned long *total_out);
 112
 113        int (*decompress_bio)(struct list_head *workspace,
 114                                struct compressed_bio *cb);
 115
 116        int (*decompress)(struct list_head *workspace,
 117                          unsigned char *data_in,
 118                          struct page *dest_page,
 119                          unsigned long start_byte,
 120                          size_t srclen, size_t destlen);
 121
 122        void (*set_level)(struct list_head *ws, unsigned int type);
 123};
 124
 125extern const struct btrfs_compress_op btrfs_zlib_compress;
 126extern const struct btrfs_compress_op btrfs_lzo_compress;
 127extern const struct btrfs_compress_op btrfs_zstd_compress;
 128
 129const char* btrfs_compress_type2str(enum btrfs_compression_type type);
 130
 131int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);
 132
 133#endif
 134