cregit-Linux how code gets into the kernel

Release 4.11 fs/btrfs/compression.h

Directory: fs/btrfs
/*
 * 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);
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);

	
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

Overall Contributors

PersonTokensPropCommitsCommitProp
Li Zefan19457.06%330.00%
Chris Mason10230.00%110.00%
Anand Jain247.06%110.00%
David Sterba144.12%330.00%
Christoph Hellwig51.47%110.00%
Jeff Mahoney10.29%110.00%
Total340100.00%10100.00%
Directory: fs/btrfs
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