LZ4 is a lossless data compression algorithm that is focused on compression and decompression speed. LZ4 gives a slightly worse compression ratio compared with LZO (and much worse than Zlib) but compression speeds are *generally* similar to LZO. Decompression tends to be much faster under LZ4 compared with LZO hence it makes more sense to use LZ4 compression when your workload involves a higher proportion of reads. The following patch set adds LZ4 compression support to BTRFS using the existing kernel implementation. It is based on the changeset for LZO support in 2011. Once a filesystem has been mounted with LZ4 compression enabled older versions of BTRFS will be unable to read it. This implementation is however backwards compatible with filesystems that currently use LZO or Zlib compression. Existing data will remain unchanged but any new files that you create will be compressed with LZ4. Usage: Apply the following 8 patches to the current git tree (as of 20140531) and compile/load the btrfs module. # mount -t btrfs -o compress=lz4 device mountpoint or # mount -t btrfs -o compress-force=lz4 device mountpoint Philip Worrall (8): Btrfs: Add kernel config options for LZ4 Btrfs: Add lz4.c to the Makefile Btrfs: Add lz4 compression to avaialble compression ops Btrfs: Add definition for external lz4 compression struct Btrfs: Add feature flags for LZ4 support Btrfs: Ensure LZ4 feature flags are set when mounting with LZ4 Btrfs: Add lz4 compression/decompression struct ops Btrfs: Check for compress=lz4 in mount options fs/btrfs/Kconfig | 2 + fs/btrfs/Makefile | 2 +- fs/btrfs/compression.c | 1 + fs/btrfs/compression.h | 2 +- fs/btrfs/ctree.h | 10 +- fs/btrfs/disk-io.c | 3 +- fs/btrfs/lz4.c | 436 +++++++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/super.c | 12 +- 8 files changed, 461 insertions(+), 7 deletions(-) create mode 100644 fs/btrfs/lz4.c -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html