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
10 * We want to make sure that amount of RAM required to uncompress an extent is
11 * reasonable, so we limit the total size in ram of a compressed extent to
12 * 128k. This is a crucial number because it also controls how easily we can
13 * spread reads across cpus for decompression.
15 * We also want to make sure the amount of IO required to do a random read is
16 * reasonably small, so we limit the size of a compressed extent to 128k.
19 /* Maximum length of compressed data stored on disk */
20 #define BTRFS_MAX_COMPRESSED (SZ_128K)
21 /* Maximum size of data before compression */
22 #define BTRFS_MAX_UNCOMPRESSED (SZ_128K)
24 #define BTRFS_ZLIB_DEFAULT_LEVEL 3
26 struct compressed_bio {
27 /* number of bios pending for this compressed extent */
28 refcount_t pending_bios;
30 /* the pages with the compressed data on them */
31 struct page **compressed_pages;
33 /* inode that owns this data */
36 /* starting offset in the inode for our pages */
39 /* number of bytes in the inode we're working on */
42 /* number of bytes on disk */
43 unsigned long compressed_len;
45 /* the compression algorithm for this bio */
48 /* number of compressed pages in the array */
49 unsigned long nr_pages;
55 /* for reads, this is the bio we are copying the data into */
59 * the start of a variable length array of checksums only
65 void __init btrfs_init_compress(void);
66 void __cold btrfs_exit_compress(void);
68 int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
69 u64 start, struct page **pages,
70 unsigned long *out_pages,
71 unsigned long *total_in,
72 unsigned long *total_out);
73 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
74 unsigned long start_byte, size_t srclen, size_t destlen);
75 int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
76 unsigned long total_out, u64 disk_start,
79 blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
80 unsigned long len, u64 disk_start,
81 unsigned long compressed_len,
82 struct page **compressed_pages,
83 unsigned long nr_pages,
84 unsigned int write_flags);
85 blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
86 int mirror_num, unsigned long bio_flags);
88 unsigned btrfs_compress_str2level(const char *str);
90 enum btrfs_compression_type {
91 BTRFS_COMPRESS_NONE = 0,
92 BTRFS_COMPRESS_ZLIB = 1,
93 BTRFS_COMPRESS_LZO = 2,
94 BTRFS_COMPRESS_ZSTD = 3,
95 BTRFS_COMPRESS_TYPES = 3,
98 struct btrfs_compress_op {
99 struct list_head *(*alloc_workspace)(void);
101 void (*free_workspace)(struct list_head *workspace);
103 int (*compress_pages)(struct list_head *workspace,
104 struct address_space *mapping,
107 unsigned long *out_pages,
108 unsigned long *total_in,
109 unsigned long *total_out);
111 int (*decompress_bio)(struct list_head *workspace,
112 struct compressed_bio *cb);
114 int (*decompress)(struct list_head *workspace,
115 unsigned char *data_in,
116 struct page *dest_page,
117 unsigned long start_byte,
118 size_t srclen, size_t destlen);
120 void (*set_level)(struct list_head *ws, unsigned int type);
123 extern const struct btrfs_compress_op btrfs_zlib_compress;
124 extern const struct btrfs_compress_op btrfs_lzo_compress;
125 extern const struct btrfs_compress_op btrfs_zstd_compress;
127 const char* btrfs_compress_type2str(enum btrfs_compression_type type);
129 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);