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         u8 sums[];
  65 };
  66
  67 static inline unsigned int btrfs_compress_type(unsigned int type_level)
  68 {
  69         return (type_level & 0xF);
  70 }
  71
  72 static inline unsigned int btrfs_compress_level(unsigned int type_level)
  73 {
  74         return ((type_level & 0xF0) >> 4);
  75 }
  76
  77 void __init btrfs_init_compress(void);
  78 void __cold btrfs_exit_compress(void);
  79
  80 int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
  81                          u64 start, struct page **pages,
  82                          unsigned long *out_pages,
  83                          unsigned long *total_in,
  84                          unsigned long *total_out);
  85 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
  86                      unsigned long start_byte, size_t srclen, size_t destlen);
  87 int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
  88                               unsigned long total_out, u64 disk_start,
  89                               struct bio *bio);
  90
  91 blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
  92                                   unsigned long len, u64 disk_start,
  93                                   unsigned long compressed_len,
  94                                   struct page **compressed_pages,
  95                                   unsigned long nr_pages,
  96                                   unsigned int write_flags,
  97                                   struct cgroup_subsys_state *blkcg_css);
  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 int btrfs_compress_str2level(unsigned int type, 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_NR_COMPRESS_TYPES = 4,
 109 };
 110
 111 struct workspace_manager {
 112         struct list_head idle_ws;
 113         spinlock_t ws_lock;
 114         /* Number of free workspaces */
 115         int free_ws;
 116         /* Total number of allocated workspaces */
 117         atomic_t total_ws;
 118         /* Waiters for a free workspace */
 119         wait_queue_head_t ws_wait;
 120 };
 121
 122 struct list_head *btrfs_get_workspace(int type, unsigned int level);
 123 void btrfs_put_workspace(int type, struct list_head *ws);
 124
 125 struct btrfs_compress_op {
 126         struct workspace_manager *workspace_manager;
 127         /* Maximum level supported by the compression algorithm */
 128         unsigned int max_level;
 129         unsigned int default_level;
 130 };
 131
 132 /* The heuristic workspaces are managed via the 0th workspace manager */
 133 #define BTRFS_NR_WORKSPACE_MANAGERS     BTRFS_NR_COMPRESS_TYPES
 134
 135 extern const struct btrfs_compress_op btrfs_heuristic_compress;
 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 unsigned int btrfs_compress_set_level(int type, unsigned level);
 144
 145 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);
 146
 147 #endif