LXR linux/fs/btrfs/compression.h

   1/*
   2 * Copyright (C) 2008 Oracle.  All rights reserved.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public
   6 * License v2 as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11 * General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public
  14 * License along with this program; if not, write to the
  15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16 * Boston, MA 021110-1307, USA.
  17 */
  18
  19#ifndef __BTRFS_COMPRESSION_
  20#define __BTRFS_COMPRESSION_
  21
  22/*
  23 * We want to make sure that amount of RAM required to uncompress an extent is
  24 * reasonable, so we limit the total size in ram of a compressed extent to
  25 * 128k.  This is a crucial number because it also controls how easily we can
  26 * spread reads across cpus for decompression.
  27 *
  28 * We also want to make sure the amount of IO required to do a random read is
  29 * reasonably small, so we limit the size of a compressed extent to 128k.
  30 */
  31
  32/* Maximum length of compressed data stored on disk */
  33#define BTRFS_MAX_COMPRESSED            (SZ_128K)
  34/* Maximum size of data before compression */
  35#define BTRFS_MAX_UNCOMPRESSED          (SZ_128K)
  36
  37#define BTRFS_ZLIB_DEFAULT_LEVEL                3
  38
  39struct compressed_bio {
  40        /* number of bios pending for this compressed extent */
  41        refcount_t pending_bios;
  42
  43        /* the pages with the compressed data on them */
  44        struct page **compressed_pages;
  45
  46        /* inode that owns this data */
  47        struct inode *inode;
  48
  49        /* starting offset in the inode for our pages */
  50        u64 start;
  51
  52        /* number of bytes in the inode we're working on */
  53        unsigned long len;
  54
  55        /* number of bytes on disk */
  56        unsigned long compressed_len;
  57
  58        /* the compression algorithm for this bio */
  59        int compress_type;
  60
  61        /* number of compressed pages in the array */
  62        unsigned long nr_pages;
  63
  64        /* IO errors */
  65        int errors;
  66        int mirror_num;
  67
  68        /* for reads, this is the bio we are copying the data into */
  69        struct bio *orig_bio;
  70
  71        /*
  72         * the start of a variable length array of checksums only
  73         * used by reads
  74         */
  75        u32 sums;
  76};
  77
  78void btrfs_init_compress(void);
  79void btrfs_exit_compress(void);
  80
  81int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
  82                         u64 start, struct page **pages,
  83                         unsigned long *out_pages,
  84                         unsigned long *total_in,
  85                         unsigned long *total_out);
  86int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
  87                     unsigned long start_byte, size_t srclen, size_t destlen);
  88int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
  89                              unsigned long total_out, u64 disk_start,
  90                              struct bio *bio);
  91
  92blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
  93                                  unsigned long len, u64 disk_start,
  94                                  unsigned long compressed_len,
  95                                  struct page **compressed_pages,
  96                                  unsigned long nr_pages,
  97                                  unsigned int write_flags);
  98blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
  99                                 int mirror_num, unsigned long bio_flags);
 100
 101unsigned btrfs_compress_str2level(const char *str);
 102
 103enum btrfs_compression_type {
 104        BTRFS_COMPRESS_NONE  = 0,
 105        BTRFS_COMPRESS_ZLIB  = 1,
 106        BTRFS_COMPRESS_LZO   = 2,
 107        BTRFS_COMPRESS_ZSTD  = 3,
 108        BTRFS_COMPRESS_TYPES = 3,
 109};
 110
 111struct btrfs_compress_op {
 112        struct list_head *(*alloc_workspace)(void);
 113
 114        void (*free_workspace)(struct list_head *workspace);
 115
 116        int (*compress_pages)(struct list_head *workspace,
 117                              struct address_space *mapping,
 118                              u64 start,
 119                              struct page **pages,
 120                              unsigned long *out_pages,
 121                              unsigned long *total_in,
 122                              unsigned long *total_out);
 123
 124        int (*decompress_bio)(struct list_head *workspace,
 125                                struct compressed_bio *cb);
 126
 127        int (*decompress)(struct list_head *workspace,
 128                          unsigned char *data_in,
 129                          struct page *dest_page,
 130                          unsigned long start_byte,
 131                          size_t srclen, size_t destlen);
 132
 133        void (*set_level)(struct list_head *ws, unsigned int type);
 134};
 135
 136extern const struct btrfs_compress_op btrfs_zlib_compress;
 137extern const struct btrfs_compress_op btrfs_lzo_compress;
 138extern const struct btrfs_compress_op btrfs_zstd_compress;
 139
 140int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);
 141
 142#endif
 143