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 struct btrfs_inode;
  12
  13 /*
  14  * We want to make sure that amount of RAM required to uncompress an extent is
  15  * reasonable, so we limit the total size in ram of a compressed extent to
  16  * 128k.  This is a crucial number because it also controls how easily we can
  17  * spread reads across cpus for decompression.
  18  *
  19  * We also want to make sure the amount of IO required to do a random read is
  20  * reasonably small, so we limit the size of a compressed extent to 128k.
  21  */
  22
  23 /* Maximum length of compressed data stored on disk */
  24 #define BTRFS_MAX_COMPRESSED            (SZ_128K)
  25 /* Maximum size of data before compression */
  26 #define BTRFS_MAX_UNCOMPRESSED          (SZ_128K)
  27
  28 #define BTRFS_ZLIB_DEFAULT_LEVEL                3
  29
  30 struct compressed_bio {
  31         /* number of bios pending for this compressed extent */
  32         refcount_t pending_bios;
  33
  34         /* the pages with the compressed data on them */
  35         struct page **compressed_pages;
  36
  37         /* inode that owns this data */
  38         struct inode *inode;
  39
  40         /* starting offset in the inode for our pages */
  41         u64 start;
  42
  43         /* number of bytes in the inode we're working on */
  44         unsigned long len;
  45
  46         /* number of bytes on disk */
  47         unsigned long compressed_len;
  48
  49         /* the compression algorithm for this bio */
  50         int compress_type;
  51
  52         /* number of compressed pages in the array */
  53         unsigned long nr_pages;
  54
  55         /* IO errors */
  56         int errors;
  57         int mirror_num;
  58
  59         /* for reads, this is the bio we are copying the data into */
  60         struct bio *orig_bio;
  61
  62         /*
  63          * the start of a variable length array of checksums only
  64          * used by reads
  65          */
  66         u8 sums[];
  67 };
  68
  69 static inline unsigned int btrfs_compress_type(unsigned int type_level)
  70 {
  71         return (type_level & 0xF);
  72 }
  73
  74 static inline unsigned int btrfs_compress_level(unsigned int type_level)
  75 {
  76         return ((type_level & 0xF0) >> 4);
  77 }
  78
  79 void __init btrfs_init_compress(void);
  80 void __cold btrfs_exit_compress(void);
  81
  82 int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
  83                          u64 start, struct page **pages,
  84                          unsigned long *out_pages,
  85                          unsigned long *total_in,
  86                          unsigned long *total_out);
  87 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
  88                      unsigned long start_byte, size_t srclen, size_t destlen);
  89 int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
  90                               unsigned long total_out, u64 disk_start,
  91                               struct bio *bio);
  92
  93 blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
  94                                   unsigned long len, u64 disk_start,
  95                                   unsigned long compressed_len,
  96                                   struct page **compressed_pages,
  97                                   unsigned long nr_pages,
  98                                   unsigned int write_flags,
  99                                   struct cgroup_subsys_state *blkcg_css);
 100 blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 101                                  int mirror_num, unsigned long bio_flags);
 102
 103 unsigned int btrfs_compress_str2level(unsigned int type, const char *str);
 104
 105 enum btrfs_compression_type {
 106         BTRFS_COMPRESS_NONE  = 0,
 107         BTRFS_COMPRESS_ZLIB  = 1,
 108         BTRFS_COMPRESS_LZO   = 2,
 109         BTRFS_COMPRESS_ZSTD  = 3,
 110         BTRFS_NR_COMPRESS_TYPES = 4,
 111 };
 112
 113 struct workspace_manager {
 114         struct list_head idle_ws;
 115         spinlock_t ws_lock;
 116         /* Number of free workspaces */
 117         int free_ws;
 118         /* Total number of allocated workspaces */
 119         atomic_t total_ws;
 120         /* Waiters for a free workspace */
 121         wait_queue_head_t ws_wait;
 122 };
 123
 124 struct list_head *btrfs_get_workspace(int type, unsigned int level);
 125 void btrfs_put_workspace(int type, struct list_head *ws);
 126
 127 struct btrfs_compress_op {
 128         struct workspace_manager *workspace_manager;
 129         /* Maximum level supported by the compression algorithm */
 130         unsigned int max_level;
 131         unsigned int default_level;
 132 };
 133
 134 /* The heuristic workspaces are managed via the 0th workspace manager */
 135 #define BTRFS_NR_WORKSPACE_MANAGERS     BTRFS_NR_COMPRESS_TYPES
 136
 137 extern const struct btrfs_compress_op btrfs_heuristic_compress;
 138 extern const struct btrfs_compress_op btrfs_zlib_compress;
 139 extern const struct btrfs_compress_op btrfs_lzo_compress;
 140 extern const struct btrfs_compress_op btrfs_zstd_compress;
 141
 142 const char* btrfs_compress_type2str(enum btrfs_compression_type type);
 143 bool btrfs_compress_is_valid_type(const char *str, size_t len);
 144
 145 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);
 146
 147 #endif