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 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 37 struct compressed_bio { 38 /* number of bios pending for this compressed extent */ 39 refcount_t pending_bios; 40 41 /* the pages with the compressed data on them */ 42 struct page **compressed_pages; 43 44 /* inode that owns this data */ 45 struct inode *inode; 46 47 /* starting offset in the inode for our pages */ 48 u64 start; 49 50 /* number of bytes in the inode we're working on */ 51 unsigned long len; 52 53 /* number of bytes on disk */ 54 unsigned long compressed_len; 55 56 /* the compression algorithm for this bio */ 57 int compress_type; 58 59 /* number of compressed pages in the array */ 60 unsigned long nr_pages; 61 62 /* IO errors */ 63 int errors; 64 int mirror_num; 65 66 /* for reads, this is the bio we are copying the data into */ 67 struct bio *orig_bio; 68 69 /* 70 * the start of a variable length array of checksums only 71 * used by reads 72 */ 73 u32 sums; 74 }; 75 76 void btrfs_init_compress(void); 77 void btrfs_exit_compress(void); 78 79 int btrfs_compress_pages(int type, struct address_space *mapping, 80 u64 start, struct page **pages, 81 unsigned long *out_pages, 82 unsigned long *total_in, 83 unsigned long *total_out); 84 int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page, 85 unsigned long start_byte, size_t srclen, size_t destlen); 86 int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start, 87 unsigned long total_out, u64 disk_start, 88 struct bio *bio); 89 90 blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start, 91 unsigned long len, u64 disk_start, 92 unsigned long compressed_len, 93 struct page **compressed_pages, 94 unsigned long nr_pages); 95 blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio, 96 int mirror_num, unsigned long bio_flags); 97 98 enum btrfs_compression_type { 99 BTRFS_COMPRESS_NONE = 0, 100 BTRFS_COMPRESS_ZLIB = 1, 101 BTRFS_COMPRESS_LZO = 2, 102 BTRFS_COMPRESS_TYPES = 2, 103 BTRFS_COMPRESS_LAST = 3, 104 }; 105 106 struct btrfs_compress_op { 107 struct list_head *(*alloc_workspace)(void); 108 109 void (*free_workspace)(struct list_head *workspace); 110 111 int (*compress_pages)(struct list_head *workspace, 112 struct address_space *mapping, 113 u64 start, 114 struct page **pages, 115 unsigned long *out_pages, 116 unsigned long *total_in, 117 unsigned long *total_out); 118 119 int (*decompress_bio)(struct list_head *workspace, 120 struct compressed_bio *cb); 121 122 int (*decompress)(struct list_head *workspace, 123 unsigned char *data_in, 124 struct page *dest_page, 125 unsigned long start_byte, 126 size_t srclen, size_t destlen); 127 }; 128 129 extern const struct btrfs_compress_op btrfs_zlib_compress; 130 extern const struct btrfs_compress_op btrfs_lzo_compress; 131 132 #endif 133