3 Commits

Author	SHA1	Message	Date
Li Zefan	ca9b688c1c	Btrfs: Avoid accessing unmapped kernel address ... When decompressing a chunk of data, we'll copy the data out to a working buffer if the data is stored in more than one page, otherwise we'll use the mapped page directly to avoid memory copy. In the latter case, we'll end up accessing the kernel address after we've unmapped the page in a corner case. Reported-by: Juan Francisco Cantero Hurtado <iam@juanfra.info> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>	2011-02-16 15:37:58 -05:00
Li Zefan	3a39c18d63	btrfs: Extract duplicate decompress code ... Add a common function to copy decompressed data from working buffer to bio pages. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>	2010-12-22 23:15:50 +08:00
Li Zefan	a6fa6fae40	btrfs: Add lzo compression support ... 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>	2010-12-22 23:15:47 +08:00