MFV r245512:

 * Illumos zfs issue #3035 [1] LZ4 compression support in ZFS.

LZ4 is a new high-speed BSD-licensed compression algorithm created
by Yann Collet that delivers very high compression and decompression
performance compared to lzjb (>50% faster on compression, >80% faster
on decompression and around 3x faster on compression of incompressible
data), while giving better compression ratio [1].

This version of LZ4 corresponds to upstream's [2] revision 85.

Please note that for obvious reasons this is not backward read
compatible.  This means once a pool have LZ4 compressed data, these
data can no longer be read by older ZFS implementations.

Local changes:

 - On-stack hash table disabled and using kernel slab allocator
   instead, at this time.  This requires larger kernel thread stack
   for zio workers.  This may change in the future should we adjusted
   the zio workers' thread stack size.
 - likely and unlikely will be undefined if they are already defined,
   this is required for i386 XEN build.
 - Removed De Bruijn sequence based __builtin_ctz family of builtins
   in favor of the latter.  Both GCC and clang supports these builtins.
 - Changed the way the LZ4 code detects endianness.
 - Manual pages modifications to mention the feature based on Illumos
   counterpart.
 - Boot loader changes to make it support LZ4 decompression.

[1] https://www.illumos.org/issues/3035
[2] http://code.google.com/p/lz4/source/list

Obtained from:	Illumos (13921:9d721847e469)
Tested on:	FreeBSD/amd64
MFC after:	1 month

2 files changed, 68 insertions, 3 deletions

diff --git a/cddl/contrib/opensolaris/cmd/zfs/zfs.8 b/cddl/contrib/opensolaris/cmd/zfs/zfs.8
index 3a75681..7b3069d 100644
--- a/cddl/contrib/opensolaris/cmd/zfs/zfs.8
+++ b/cddl/contrib/opensolaris/cmd/zfs/zfs.8
@@ -24,10 +24,11 @@
 .\" Copyright (c) 2011, Pawel Jakub Dawidek <pjd@FreeBSD.org>
 .\" Copyright (c) 2012, Glen Barber <gjb@FreeBSD.org>
 .\" Copyright (c) 2012, Bryan Drewery <bdrewery@FreeBSD.org>
+.\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
 .\"
 .\" $FreeBSD$
 .\"
-.Dd November 26, 2012
+.Dd February 8, 2012
 .Dt ZFS 8
 .Os
 .Sh NAME
@@ -866,7 +867,7 @@ but this may change in future releases). The value
 disables integrity checking on user data. Disabling checksums is
 .Em NOT
 a recommended practice.
-.It Sy compression Ns = Ns Cm on | off | lzjb | gzip | gzip- Ns Ar N | Cm zle
+.It Sy compression Ns = Ns Cm on | off | lzjb | gzip | gzip- Ns Ar N | zle | Cm lz4
 Controls the compression algorithm used for this dataset. The
 .Cm lzjb
 compression algorithm is optimized for performance while providing decent data
@@ -894,6 +895,26 @@ The
 .Cm zle
 compression algorithm compresses runs of zeros.
 .Pp
+The
+.Sy lz4
+compression algorithm is a high-performance replacement
+for the
+.Sy lzjb
+algorithm. It features significantly faster
+compression and decompression, as well as a moderately higher
+compression ratio than
+.Sy lzjb ,
+but can only be used on pools with
+the
+.Sy lz4_compress
+feature set to
+.Sy enabled .
+See
+.Xr zpool-features 7
+for details on ZFS feature flags and the
+.Sy lz4_compress
+feature.
+.Pp
 This property can also be referred to by its shortened column name
 .Cm compress .
 Changing this property affects only newly-written data.
diff --git a/cddl/contrib/opensolaris/cmd/zpool/zpool-features.7 b/cddl/contrib/opensolaris/cmd/zpool/zpool-features.7
index 999212c..2768ef5 100644
--- a/cddl/contrib/opensolaris/cmd/zpool/zpool-features.7
+++ b/cddl/contrib/opensolaris/cmd/zpool/zpool-features.7
@@ -18,10 +18,11 @@
 .\" information: Portions Copyright [yyyy] [name of copyright owner]
 .\"
 .\" Copyright (c) 2012 by Delphix. All rights reserved.
+.\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
 .\"
 .\" $FreeBSD$
 .\"
-.Dd Aug 28, 2012
+.Dd February 8, 2012
 .Dt ZPOOL-FEATURES 7
 .Os
 .Sh NAME
@@ -185,6 +186,49 @@ This feature is
 .Sy active
 while there are any filesystems, volumes, or snapshots which were created
 after enabling this feature.
+.It Sy lz4_compress
+.Bl -column "READ\-ONLY COMPATIBLE" "org.illumos:lz4_compress"
+.It GUID Ta org.illumos:lz4_compress
+.It READ\-ONLY COMPATIBLE Ta no
+.It DEPENDENCIES Ta none
+.El
+.Pp
+.Sy lz4
+is a high-performance real-time compression algorithm that
+features significantly faster compression and decompression as well as a
+higher compression ratio than the older
+.Sy lzjb
+compression.
+Typically, 
+.Sy lz4
+compression is approximately 50% faster on
+compressible data and 200% faster on incompressible data than
+.Sy lzjb .
+It is also approximately 80% faster on decompression, while
+giving approximately 10% better compression ratio.
+.Pp
+When the 
+.Sy lz4_compress
+feature is set to
+.Sy enabled ,
+the
+administrator can turn on 
+.Sy lz4
+compression on any dataset on the
+pool using the
+.Xr zfs 8
+command. Please note that doing so will
+immediately activate the
+.Sy lz4_compress
+feature on the underlying
+pool (even before any data is written). Since this feature is not
+read-only compatible, this operation will render the pool unimportable
+on systems without support for the
+.Sy lz4_compress
+feature. At the
+moment, this operation cannot be reversed. Booting off of
+.Sy lz4
+-compressed root pools is supported.
 .El
 .Sh SEE ALSO
 .Xr zpool 8