1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Copyright (C) 2008 Oracle. All rights reserved.
6 #ifndef BTRFS_COMPRESSION_H
7 #define BTRFS_COMPRESSION_H
9 #include <linux/sizes.h>
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.
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.
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)
26 #define BTRFS_ZLIB_DEFAULT_LEVEL 3
28 struct compressed_bio {
29 /* number of bios pending for this compressed extent */
30 refcount_t pending_bios;
32 /* the pages with the compressed data on them */
33 struct page **compressed_pages;
35 /* inode that owns this data */
38 /* starting offset in the inode for our pages */
41 /* number of bytes in the inode we're working on */
44 /* number of bytes on disk */
45 unsigned long compressed_len;
47 /* the compression algorithm for this bio */
50 /* number of compressed pages in the array */
51 unsigned long nr_pages;
57 /* for reads, this is the bio we are copying the data into */
61 * the start of a variable length array of checksums only
67 static inline unsigned int btrfs_compress_type(unsigned int type_level)
69 return (type_level & 0xF);
72 static inline unsigned int btrfs_compress_level(unsigned int type_level)
74 return ((type_level & 0xF0) >> 4);
77 void __init btrfs_init_compress(void);
78 void __cold btrfs_exit_compress(void);
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,
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 blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
98 int mirror_num, unsigned long bio_flags);
100 unsigned btrfs_compress_str2level(const char *str);
102 enum btrfs_compression_type {
103 BTRFS_COMPRESS_NONE = 0,
104 BTRFS_COMPRESS_ZLIB = 1,
105 BTRFS_COMPRESS_LZO = 2,
106 BTRFS_COMPRESS_ZSTD = 3,
107 BTRFS_COMPRESS_TYPES = 3,
110 struct btrfs_compress_op {
111 struct list_head *(*alloc_workspace)(void);
113 void (*free_workspace)(struct list_head *workspace);
115 int (*compress_pages)(struct list_head *workspace,
116 struct address_space *mapping,
119 unsigned long *out_pages,
120 unsigned long *total_in,
121 unsigned long *total_out);
123 int (*decompress_bio)(struct list_head *workspace,
124 struct compressed_bio *cb);
126 int (*decompress)(struct list_head *workspace,
127 unsigned char *data_in,
128 struct page *dest_page,
129 unsigned long start_byte,
130 size_t srclen, size_t destlen);
132 void (*set_level)(struct list_head *ws, unsigned int type);
135 /* The heuristic workspaces are managed via the 0th workspace manager */
136 #define BTRFS_NR_WORKSPACE_MANAGERS (BTRFS_COMPRESS_TYPES + 1)
138 extern const struct btrfs_compress_op btrfs_heuristic_compress;
139 extern const struct btrfs_compress_op btrfs_zlib_compress;
140 extern const struct btrfs_compress_op btrfs_lzo_compress;
141 extern const struct btrfs_compress_op btrfs_zstd_compress;
143 const char* btrfs_compress_type2str(enum btrfs_compression_type type);
145 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);