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
  28 struct 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
  67 void __init btrfs_init_compress(void);
  68 void __cold btrfs_exit_compress(void);
  69
  70 int 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);
  75 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
  76                      unsigned long start_byte, size_t srclen, size_t destlen);
  77 int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
  78                               unsigned long total_out, u64 disk_start,
  79                               struct bio *bio);
  80
  81 blk_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);
  87 blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
  88                                  int mirror_num, unsigned long bio_flags);
  89
  90 unsigned btrfs_compress_str2level(const char *str);
  91
  92 enum 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
 100 struct 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
 125 extern const struct btrfs_compress_op btrfs_zlib_compress;
 126 extern const struct btrfs_compress_op btrfs_lzo_compress;
 127 extern const struct btrfs_compress_op btrfs_zstd_compress;
 128
 129 const char* btrfs_compress_type2str(enum btrfs_compression_type type);
 130
 131 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);
 132
 133 #endif