[linux-block.git] / fs / btrfs / compression.h

/*
 * Copyright (C) 2008 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#ifndef __BTRFS_COMPRESSION_
#define __BTRFS_COMPRESSION_

/*
 * 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)

void btrfs_init_compress(void);
void btrfs_exit_compress(void);

int btrfs_compress_pages(int type, struct address_space *mapping,
			 u64 start, struct page **pages,
			 unsigned long *out_pages,
			 unsigned long *total_in,
			 unsigned long *total_out,
			 unsigned long max_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);

int 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);
int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
				 int mirror_num, unsigned long bio_flags);

enum btrfs_compression_type {
	BTRFS_COMPRESS_NONE  = 0,
	BTRFS_COMPRESS_ZLIB  = 1,
	BTRFS_COMPRESS_LZO   = 2,
	BTRFS_COMPRESS_TYPES = 2,
	BTRFS_COMPRESS_LAST  = 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,
			      unsigned long max_out);

	int (*decompress_bio)(struct list_head *workspace,
				 struct page **pages_in,
				 u64 disk_start,
				 struct bio *orig_bio,
				 size_t srclen);

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

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

#endif
Commit	Line	Data
c8b97818 CM	1	/*
	2	* Copyright (C) 2008 Oracle. All rights reserved.
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public
	6	* License v2 as published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful,
	9	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	11	* General Public License for more details.
	12	*
	13	* You should have received a copy of the GNU General Public
	14	* License along with this program; if not, write to the
	15	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	16	* Boston, MA 021110-1307, USA.
	17	*/
	18
	19	#ifndef __BTRFS_COMPRESSION_
	20	#define __BTRFS_COMPRESSION_
	21
ff763866 DS	22	/*
	23	* We want to make sure that amount of RAM required to uncompress an extent is
	24	* reasonable, so we limit the total size in ram of a compressed extent to
	25	* 128k. This is a crucial number because it also controls how easily we can
	26	* spread reads across cpus for decompression.
	27	*
	28	* We also want to make sure the amount of IO required to do a random read is
	29	* reasonably small, so we limit the size of a compressed extent to 128k.
	30	*/
	31
	32	/* Maximum length of compressed data stored on disk */
	33	#define BTRFS_MAX_COMPRESSED (SZ_128K)
	34	/* Maximum size of data before compression */
	35	#define BTRFS_MAX_UNCOMPRESSED (SZ_128K)
	36
143bede5	37	void btrfs_init_compress(void);
261507a0 LZ	38	void btrfs_exit_compress(void);
	39
	40	int btrfs_compress_pages(int type, struct address_space *mapping,
38c31464	41	u64 start, struct page **pages,
261507a0 LZ	42	unsigned long *out_pages,
	43	unsigned long *total_in,
	44	unsigned long *total_out,
	45	unsigned long max_out);
261507a0 LZ	46	int btrfs_decompress(int type, unsigned char data_in, struct page dest_page,
261507a0 LZ	47	unsigned long start_byte, size_t srclen, size_t destlen);
14a3357b	48	int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
3a39c18d	49	unsigned long total_out, u64 disk_start,
974b1adc	50	struct bio *bio);
261507a0	51
c8b97818 CM	52	int btrfs_submit_compressed_write(struct inode *inode, u64 start,
	53	unsigned long len, u64 disk_start,
	54	unsigned long compressed_len,
	55	struct page **compressed_pages,
	56	unsigned long nr_pages);
	57	int btrfs_submit_compressed_read(struct inode inode, struct bio bio,
	58	int mirror_num, unsigned long bio_flags);
ebb8765b AJ	59
	60	enum btrfs_compression_type {
	61	BTRFS_COMPRESS_NONE = 0,
	62	BTRFS_COMPRESS_ZLIB = 1,
	63	BTRFS_COMPRESS_LZO = 2,
	64	BTRFS_COMPRESS_TYPES = 2,
	65	BTRFS_COMPRESS_LAST = 3,
	66	};
	67
261507a0 LZ	68	struct btrfs_compress_op {
	69	struct list_head (alloc_workspace)(void);
	70
	71	void (free_workspace)(struct list_head workspace);
	72
	73	int (compress_pages)(struct list_head workspace,
	74	struct address_space *mapping,
38c31464	75	u64 start,
261507a0	76	struct page **pages,
261507a0 LZ	77	unsigned long *out_pages,
	78	unsigned long *total_in,
	79	unsigned long *total_out,
	80	unsigned long max_out);
	81
974b1adc	82	int (decompress_bio)(struct list_head workspace,
261507a0 LZ	83	struct page **pages_in,
261507a0 LZ	84	u64 disk_start,
974b1adc	85	struct bio *orig_bio,
261507a0 LZ	86	size_t srclen);
	87
	88	int (decompress)(struct list_head workspace,
	89	unsigned char *data_in,
	90	struct page *dest_page,
	91	unsigned long start_byte,
	92	size_t srclen, size_t destlen);
	93	};
	94
e8c9f186 DS	95	extern const struct btrfs_compress_op btrfs_zlib_compress;
e8c9f186 DS	96	extern const struct btrfs_compress_op btrfs_lzo_compress;
261507a0	97
c8b97818	98	#endif