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Lzo is a much faster compression algorithm than gzib, so would allow
more users to enable transparent compression, and some users can
choose from compression ratio and speed for different applications
Usage:
# mount -t btrfs -o compress[=<zlib,lzo>] dev /mnt
or
# mount -t btrfs -o compress-force[=<zlib,lzo>] dev /mnt
"-o compress" without argument is still allowed for compatability.
Compatibility:
If we mount a filesystem with lzo compression, it will not be able be
mounted in old kernels. One reason is, otherwise btrfs will directly
dump compressed data, which sits in inline extent, to user.
Performance:
The test copied a linux source tarball (~400M) from an ext4 partition
to the btrfs partition, and then extracted it.
(time in second)
lzo zlib nocompress
copy: 10.6 21.7 14.9
extract: 70.1 94.4 66.6
(data size in MB)
lzo zlib nocompress
copy: 185.87 108.69 394.49
extract: 193.80 132.36 381.21
Changelog:
v1 -> v2:
- Select LZO_COMPRESS and LZO_DECOMPRESS in btrfs Kconfig.
- Add incompability flag.
- Fix error handling in compress code.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
79 lines
2.6 KiB
C
79 lines
2.6 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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int 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, unsigned long len,
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struct page **pages,
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unsigned long nr_dest_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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unsigned long max_out);
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int btrfs_decompress_biovec(int type, struct page **pages_in, u64 disk_start,
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struct bio_vec *bvec, int vcnt, size_t srclen);
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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_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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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, unsigned long len,
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struct page **pages,
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unsigned long nr_dest_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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unsigned long max_out);
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int (*decompress_biovec)(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_vec *bvec,
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int vcnt,
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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 struct btrfs_compress_op btrfs_zlib_compress;
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extern struct btrfs_compress_op btrfs_lzo_compress;
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#endif
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