2 * Copyright (C) 2008 Oracle. All rights reserved.
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.
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.
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.
19 #ifndef __BTRFS_COMPRESSION_
20 #define __BTRFS_COMPRESSION_
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.
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.
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)
37 void btrfs_init_compress(void);
38 void btrfs_exit_compress(void);
40 int btrfs_compress_pages(int type
, struct address_space
*mapping
,
41 u64 start
, struct page
**pages
,
42 unsigned long *out_pages
,
43 unsigned long *total_in
,
44 unsigned long *total_out
);
45 int btrfs_decompress(int type
, unsigned char *data_in
, struct page
*dest_page
,
46 unsigned long start_byte
, size_t srclen
, size_t destlen
);
47 int btrfs_decompress_buf2page(const char *buf
, unsigned long buf_start
,
48 unsigned long total_out
, u64 disk_start
,
51 blk_status_t
btrfs_submit_compressed_write(struct inode
*inode
, u64 start
,
52 unsigned long len
, u64 disk_start
,
53 unsigned long compressed_len
,
54 struct page
**compressed_pages
,
55 unsigned long nr_pages
);
56 blk_status_t
btrfs_submit_compressed_read(struct inode
*inode
, struct bio
*bio
,
57 int mirror_num
, unsigned long bio_flags
);
59 enum btrfs_compression_type
{
60 BTRFS_COMPRESS_NONE
= 0,
61 BTRFS_COMPRESS_ZLIB
= 1,
62 BTRFS_COMPRESS_LZO
= 2,
63 BTRFS_COMPRESS_TYPES
= 2,
64 BTRFS_COMPRESS_LAST
= 3,
67 struct btrfs_compress_op
{
68 struct list_head
*(*alloc_workspace
)(void);
70 void (*free_workspace
)(struct list_head
*workspace
);
72 int (*compress_pages
)(struct list_head
*workspace
,
73 struct address_space
*mapping
,
76 unsigned long *out_pages
,
77 unsigned long *total_in
,
78 unsigned long *total_out
);
80 int (*decompress_bio
)(struct list_head
*workspace
,
81 struct page
**pages_in
,
86 int (*decompress
)(struct list_head
*workspace
,
87 unsigned char *data_in
,
88 struct page
*dest_page
,
89 unsigned long start_byte
,
90 size_t srclen
, size_t destlen
);
93 extern const struct btrfs_compress_op btrfs_zlib_compress
;
94 extern const struct btrfs_compress_op btrfs_lzo_compress
;