Release 4.17 fs/btrfs/compression.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 2008 Oracle.  All rights reserved.
 */

#ifndef BTRFS_COMPRESSION_H

#define BTRFS_COMPRESSION_H

/*
 * We want to make sure that amount of RAM required to uncompress an extent is
 * reasonable, so we limit the total size in ram of a compressed extent to
 * 128k.  This is a crucial number because it also controls how easily we can
 * spread reads across cpus for decompression.
 *
 * We also want to make sure the amount of IO required to do a random read is
 * reasonably small, so we limit the size of a compressed extent to 128k.
 */

/* Maximum length of compressed data stored on disk */

#define BTRFS_MAX_COMPRESSED		(SZ_128K)
/* Maximum size of data before compression */

#define BTRFS_MAX_UNCOMPRESSED		(SZ_128K)


#define	BTRFS_ZLIB_DEFAULT_LEVEL		3


struct compressed_bio {
	/* number of bios pending for this compressed extent */
	
refcount_t pending_bios;

	/* the pages with the compressed data on them */
	
struct page **compressed_pages;

	/* inode that owns this data */
	
struct inode *inode;

	/* starting offset in the inode for our pages */
	
u64 start;

	/* number of bytes in the inode we're working on */
	
unsigned long len;

	/* number of bytes on disk */
	
unsigned long compressed_len;

	/* the compression algorithm for this bio */
	
int compress_type;

	/* number of compressed pages in the array */
	
unsigned long nr_pages;

	/* IO errors */
	
int errors;
	
int mirror_num;

	/* for reads, this is the bio we are copying the data into */
	
struct bio *orig_bio;

	/*
         * the start of a variable length array of checksums only
         * used by reads
         */
	
u32 sums;
};

void __init btrfs_init_compress(void);
void __cold btrfs_exit_compress(void);

int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
			 u64 start, struct page **pages,
			 unsigned long *out_pages,
			 unsigned long *total_in,
			 unsigned long *total_out);
int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
		     unsigned long start_byte, size_t srclen, size_t destlen);
int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
			      unsigned long total_out, u64 disk_start,
			      struct bio *bio);

blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
				  unsigned long len, u64 disk_start,
				  unsigned long compressed_len,
				  struct page **compressed_pages,
				  unsigned long nr_pages,
				  unsigned int write_flags);
blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
				 int mirror_num, unsigned long bio_flags);

unsigned btrfs_compress_str2level(const char *str);


enum btrfs_compression_type {
	
BTRFS_COMPRESS_NONE  = 0,
	
BTRFS_COMPRESS_ZLIB  = 1,
	
BTRFS_COMPRESS_LZO   = 2,
	
BTRFS_COMPRESS_ZSTD  = 3,
	
BTRFS_COMPRESS_TYPES = 3,
};


struct btrfs_compress_op {
	
struct list_head *(*alloc_workspace)(void);

	
void (*free_workspace)(struct list_head *workspace);

	
int (*compress_pages)(struct list_head *workspace,
			      struct address_space *mapping,
			      u64 start,
			      struct page **pages,
			      unsigned long *out_pages,
			      unsigned long *total_in,
			      unsigned long *total_out);

	
int (*decompress_bio)(struct list_head *workspace,
				struct compressed_bio *cb);

	
int (*decompress)(struct list_head *workspace,
			  unsigned char *data_in,
			  struct page *dest_page,
			  unsigned long start_byte,
			  size_t srclen, size_t destlen);

	
void (*set_level)(struct list_head *ws, unsigned int type);
};

extern const struct btrfs_compress_op btrfs_zlib_compress;
extern const struct btrfs_compress_op btrfs_lzo_compress;
extern const struct btrfs_compress_op btrfs_zstd_compress;

const char* btrfs_compress_type2str(enum btrfs_compression_type type);

int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);

#endif
Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Li Zefan
180
39.30%
3
14.29%
Chris Mason
98
21.40%
1
4.76%
Anand Jain
83
18.12%
2
9.52%
David Sterba
56
12.23%
7
33.33%
Timofey Titovets
15
3.28%
1
4.76%
Nick Terrell
11
2.40%
1
4.76%
Liu Bo
5
1.09%
2
9.52%
Christoph Hellwig
5
1.09%
2
9.52%
Qu Wenruo
4
0.87%
1
4.76%
Jeff Mahoney
1
0.22%
1
4.76%
Total
458
100.00%
21
100.00%
Directory: fs/btrfs

Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.