97 lines
3.2 KiB
C
97 lines
3.2 KiB
C
/*
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* Copyright (C) 2008 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef __BTRFS_COMPRESSION_
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#define __BTRFS_COMPRESSION_
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/*
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* We want to make sure that amount of RAM required to uncompress an extent is
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* reasonable, so we limit the total size in ram of a compressed extent to
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* 128k. This is a crucial number because it also controls how easily we can
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* spread reads across cpus for decompression.
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*
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* We also want to make sure the amount of IO required to do a random read is
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* reasonably small, so we limit the size of a compressed extent to 128k.
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*/
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/* Maximum length of compressed data stored on disk */
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#define BTRFS_MAX_COMPRESSED (SZ_128K)
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/* Maximum size of data before compression */
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#define BTRFS_MAX_UNCOMPRESSED (SZ_128K)
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void btrfs_init_compress(void);
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void btrfs_exit_compress(void);
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int btrfs_compress_pages(int type, struct address_space *mapping,
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u64 start, struct page **pages,
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unsigned long *out_pages,
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unsigned long *total_in,
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unsigned long *total_out);
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int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
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unsigned long start_byte, size_t srclen, size_t destlen);
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int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
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unsigned long total_out, u64 disk_start,
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struct bio *bio);
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int btrfs_submit_compressed_write(struct inode *inode, u64 start,
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unsigned long len, u64 disk_start,
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unsigned long compressed_len,
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struct page **compressed_pages,
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unsigned long nr_pages);
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int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
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int mirror_num, unsigned long bio_flags);
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enum btrfs_compression_type {
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BTRFS_COMPRESS_NONE = 0,
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BTRFS_COMPRESS_ZLIB = 1,
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BTRFS_COMPRESS_LZO = 2,
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BTRFS_COMPRESS_TYPES = 2,
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BTRFS_COMPRESS_LAST = 3,
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};
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struct btrfs_compress_op {
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struct list_head *(*alloc_workspace)(void);
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void (*free_workspace)(struct list_head *workspace);
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int (*compress_pages)(struct list_head *workspace,
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struct address_space *mapping,
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u64 start,
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struct page **pages,
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unsigned long *out_pages,
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unsigned long *total_in,
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unsigned long *total_out);
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int (*decompress_bio)(struct list_head *workspace,
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struct page **pages_in,
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u64 disk_start,
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struct bio *orig_bio,
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size_t srclen);
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int (*decompress)(struct list_head *workspace,
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unsigned char *data_in,
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struct page *dest_page,
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unsigned long start_byte,
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size_t srclen, size_t destlen);
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};
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extern const struct btrfs_compress_op btrfs_zlib_compress;
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extern const struct btrfs_compress_op btrfs_lzo_compress;
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#endif
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