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 	u32 sums;
65 };
66 
67 void __init btrfs_init_compress(void);
68 void __cold btrfs_exit_compress(void);
69 
70 int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
71 			 u64 start, struct page **pages,
72 			 unsigned long *out_pages,
73 			 unsigned long *total_in,
74 			 unsigned long *total_out);
75 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
76 		     unsigned long start_byte, size_t srclen, size_t destlen);
77 int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
78 			      unsigned long total_out, u64 disk_start,
79 			      struct bio *bio);
80 
81 blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
82 				  unsigned long len, u64 disk_start,
83 				  unsigned long compressed_len,
84 				  struct page **compressed_pages,
85 				  unsigned long nr_pages,
86 				  unsigned int write_flags);
87 blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
88 				 int mirror_num, unsigned long bio_flags);
89 
90 unsigned btrfs_compress_str2level(const char *str);
91 
92 enum btrfs_compression_type {
93 	BTRFS_COMPRESS_NONE  = 0,
94 	BTRFS_COMPRESS_ZLIB  = 1,
95 	BTRFS_COMPRESS_LZO   = 2,
96 	BTRFS_COMPRESS_ZSTD  = 3,
97 	BTRFS_COMPRESS_TYPES = 3,
98 };
99 
100 struct btrfs_compress_op {
101 	struct list_head *(*alloc_workspace)(void);
102 
103 	void (*free_workspace)(struct list_head *workspace);
104 
105 	int (*compress_pages)(struct list_head *workspace,
106 			      struct address_space *mapping,
107 			      u64 start,
108 			      struct page **pages,
109 			      unsigned long *out_pages,
110 			      unsigned long *total_in,
111 			      unsigned long *total_out);
112 
113 	int (*decompress_bio)(struct list_head *workspace,
114 				struct compressed_bio *cb);
115 
116 	int (*decompress)(struct list_head *workspace,
117 			  unsigned char *data_in,
118 			  struct page *dest_page,
119 			  unsigned long start_byte,
120 			  size_t srclen, size_t destlen);
121 
122 	void (*set_level)(struct list_head *ws, unsigned int type);
123 };
124 
125 extern const struct btrfs_compress_op btrfs_zlib_compress;
126 extern const struct btrfs_compress_op btrfs_lzo_compress;
127 extern const struct btrfs_compress_op btrfs_zstd_compress;
128 
129 const char* btrfs_compress_type2str(enum btrfs_compression_type type);
130 bool btrfs_compress_is_valid_type(const char *str, size_t len);
131 
132 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);
133 
134 #endif
135