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
  39 struct 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
  78 void btrfs_init_compress(void);
  79 void btrfs_exit_compress(void);
  80
  81 int 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);
  86 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
  87                      unsigned long start_byte, size_t srclen, size_t destlen);
  88 int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
  89                               unsigned long total_out, u64 disk_start,
  90                               struct bio *bio);
  91
  92 blk_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);
  98 blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
  99                                  int mirror_num, unsigned long bio_flags);
 100
 101 unsigned btrfs_compress_str2level(const char *str);
 102
 103 enum 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
 111 struct 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
 136 extern const struct btrfs_compress_op btrfs_zlib_compress;
 137 extern const struct btrfs_compress_op btrfs_lzo_compress;
 138 extern const struct btrfs_compress_op btrfs_zstd_compress;
 139
 140 const char* btrfs_compress_type2str(enum btrfs_compression_type type);
 141 bool btrfs_compress_is_valid_type(const char *str, size_t len);
 142
 143 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);
 144
 145 #endif