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

19 files changed, 1621 insertions, 5 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
diff --git a/sys/cddl/boot/zfs/README b/sys/cddl/boot/zfs/README
index d36e02e..f7c045d 100644
--- a/sys/cddl/boot/zfs/README
+++ b/sys/cddl/boot/zfs/README
@@ -5,6 +5,7 @@ are used by the ZFS bootstrap:
 
     fletcher.c			checksum support
     sha256.c			checksum support
+    lz4.c			compression support
     lzjb.c			compression support
     zfssubr.c			checksum, compression and raidz support
     zfsimpl.h			mostly describing the physical layout
diff --git a/sys/cddl/boot/zfs/lz4.c b/sys/cddl/boot/zfs/lz4.c
new file mode 100644
index 0000000..78af959
--- /dev/null
+++ b/sys/cddl/boot/zfs/lz4.c
@@ -0,0 +1,308 @@
+/*
+ * LZ4 - Fast LZ compression algorithm
+ * Header File
+ * Copyright (C) 2011-2013, Yann Collet.
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * You can contact the author at :
+ * - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
+ * - LZ4 source repository : http://code.google.com/p/lz4/
+ *
+ * $FreeBSD$
+ */
+
+static int LZ4_uncompress_unknownOutputSize(const char *source, char *dest,
+					    int isize, int maxOutputSize);
+
+/* ARGSUSED */
+static int
+lz4_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int dummy __unused)
+{
+	const uint8_t *src = s_start;
+	uint32_t bufsiz = htonl(*(uint32_t *)src);
+
+	/* invalid compressed buffer size encoded at start */
+	if (bufsiz + 4 > s_len)
+		return (1);
+
+	/*
+	 * Returns 0 on success (decompression function returned non-negative)
+	 * and non-zero on failure (decompression function returned negative).
+	 */
+	return (LZ4_uncompress_unknownOutputSize(s_start + 4, d_start, bufsiz,
+	    d_len) < 0);
+}
+
+/*
+ * CPU Feature Detection
+ */
+
+/* 32 or 64 bits ? */
+#if (defined(__x86_64__) || defined(__x86_64) || defined(__amd64__) || \
+	defined(__amd64) || defined(__ppc64__) || defined(_WIN64) || \
+	defined(__LP64__) || defined(_LP64))
+#define	LZ4_ARCH64	1
+#else
+#define	LZ4_ARCH64	0
+#endif
+
+/*
+ * Little Endian or Big Endian?
+ * Note: overwrite the below #define if you know your architecture endianess.
+ */
+#if BYTE_ORDER == BIG_ENDIAN
+#define	LZ4_BIG_ENDIAN	1
+#else
+	/*
+	 * Little Endian assumed. PDP Endian and other very rare endian format
+	 * are unsupported.
+	 */
+#endif
+
+/*
+ * Compiler Options
+ */
+#if __STDC_VERSION__ >= 199901L	/* C99 */
+/* "restrict" is a known keyword */
+#else
+/* Disable restrict */
+#define	restrict
+#endif
+
+#define	GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
+
+#define	lz4_bswap16(x) ((unsigned short int) ((((x) >> 8) & 0xffu) \
+	| (((x) & 0xffu) << 8)))
+
+#if (GCC_VERSION >= 302) || (__INTEL_COMPILER >= 800) || defined(__clang__)
+#define	expect(expr, value)    (__builtin_expect((expr), (value)))
+#else
+#define	expect(expr, value)    (expr)
+#endif
+
+#define	likely(expr)	expect((expr) != 0, 1)
+#define	unlikely(expr)	expect((expr) != 0, 0)
+
+/* Basic types */
+#define	BYTE	uint8_t
+#define	U16	uint16_t
+#define	U32	uint32_t
+#define	S32	int32_t
+#define	U64	uint64_t
+
+typedef struct _U16_S {
+	U16 v;
+} U16_S;
+typedef struct _U32_S {
+	U32 v;
+} U32_S;
+typedef struct _U64_S {
+	U64 v;
+} U64_S;
+
+#define	A64(x)	(((U64_S *)(x))->v)
+#define	A32(x)	(((U32_S *)(x))->v)
+#define	A16(x)	(((U16_S *)(x))->v)
+
+/*
+ * Constants
+ */
+#define	MINMATCH 4
+
+#define	COPYLENGTH 8
+#define	LASTLITERALS 5
+
+#define	ML_BITS 4
+#define	ML_MASK ((1U<<ML_BITS)-1)
+#define	RUN_BITS (8-ML_BITS)
+#define	RUN_MASK ((1U<<RUN_BITS)-1)
+
+/*
+ * Architecture-specific macros
+ */
+#if LZ4_ARCH64
+#define	STEPSIZE 8
+#define	UARCH U64
+#define	AARCH A64
+#define	LZ4_COPYSTEP(s, d)	A64(d) = A64(s); d += 8; s += 8;
+#define	LZ4_COPYPACKET(s, d)	LZ4_COPYSTEP(s, d)
+#define	LZ4_SECURECOPY(s, d, e)	if (d < e) LZ4_WILDCOPY(s, d, e)
+#define	HTYPE U32
+#define	INITBASE(base)		const BYTE* const base = ip
+#else
+#define	STEPSIZE 4
+#define	UARCH U32
+#define	AARCH A32
+#define	LZ4_COPYSTEP(s, d)	A32(d) = A32(s); d += 4; s += 4;
+#define	LZ4_COPYPACKET(s, d)	LZ4_COPYSTEP(s, d); LZ4_COPYSTEP(s, d);
+#define	LZ4_SECURECOPY		LZ4_WILDCOPY
+#define	HTYPE const BYTE*
+#define	INITBASE(base)		const int base = 0
+#endif
+
+#if (defined(LZ4_BIG_ENDIAN) && !defined(BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE))
+#define	LZ4_READ_LITTLEENDIAN_16(d, s, p) \
+	{ U16 v = A16(p); v = lz4_bswap16(v); d = (s) - v; }
+#define	LZ4_WRITE_LITTLEENDIAN_16(p, i) \
+	{ U16 v = (U16)(i); v = lz4_bswap16(v); A16(p) = v; p += 2; }
+#else
+#define	LZ4_READ_LITTLEENDIAN_16(d, s, p) { d = (s) - A16(p); }
+#define	LZ4_WRITE_LITTLEENDIAN_16(p, v)  { A16(p) = v; p += 2; }
+#endif
+
+/* Macros */
+#define	LZ4_WILDCOPY(s, d, e) do { LZ4_COPYPACKET(s, d) } while (d < e);
+
+/* Decompression functions */
+
+static int
+LZ4_uncompress_unknownOutputSize(const char *source,
+    char *dest, int isize, int maxOutputSize)
+{
+	/* Local Variables */
+	const BYTE *restrict ip = (const BYTE *) source;
+	const BYTE *const iend = ip + isize;
+	const BYTE *restrict ref;
+
+	BYTE *restrict op = (BYTE *) dest;
+	BYTE *const oend = op + maxOutputSize;
+	BYTE *cpy;
+
+	size_t dec[] = { 0, 3, 2, 3, 0, 0, 0, 0 };
+
+	/* Main Loop */
+	while (ip < iend) {
+		BYTE token;
+		int length;
+
+		/* get runlength */
+		token = *ip++;
+		if ((length = (token >> ML_BITS)) == RUN_MASK) {
+			int s = 255;
+			while ((ip < iend) && (s == 255)) {
+				s = *ip++;
+				length += s;
+			}
+		}
+		/* copy literals */
+		cpy = op + length;
+		if ((cpy > oend - COPYLENGTH) ||
+		    (ip + length > iend - COPYLENGTH)) {
+			if (cpy > oend)
+				/*
+				 * Error: request to write beyond destination
+				 * buffer.
+				 */
+				goto _output_error;
+			if (ip + length > iend)
+				/*
+				 * Error : request to read beyond source
+				 * buffer.
+				 */
+				goto _output_error;
+			memcpy(op, ip, length);
+			op += length;
+			ip += length;
+			if (ip < iend)
+				/* Error : LZ4 format violation */
+				goto _output_error;
+			/* Necessarily EOF, due to parsing restrictions. */
+			break;
+		}
+		LZ4_WILDCOPY(ip, op, cpy);
+		ip -= (op - cpy);
+		op = cpy;
+
+		/* get offset */
+		LZ4_READ_LITTLEENDIAN_16(ref, cpy, ip);
+		ip += 2;
+		if (ref < (BYTE * const) dest)
+			/*
+			 * Error: offset creates reference outside of
+			 * destination buffer.
+			 */
+			goto _output_error;
+
+		/* get matchlength */
+		if ((length = (token & ML_MASK)) == ML_MASK) {
+			while (ip < iend) {
+				int s = *ip++;
+				length += s;
+				if (s == 255)
+					continue;
+				break;
+			}
+		}
+		/* copy repeated sequence */
+		if unlikely(op - ref < STEPSIZE) {
+#if LZ4_ARCH64
+			size_t dec2table[] = { 0, 0, 0, -1, 0, 1, 2, 3 };
+			size_t dec2 = dec2table[op - ref];
+#else
+			const int dec2 = 0;
+#endif
+			*op++ = *ref++;
+			*op++ = *ref++;
+			*op++ = *ref++;
+			*op++ = *ref++;
+			ref -= dec[op - ref];
+			A32(op) = A32(ref);
+			op += STEPSIZE - 4;
+			ref -= dec2;
+		} else {
+			LZ4_COPYSTEP(ref, op);
+		}
+		cpy = op + length - (STEPSIZE - 4);
+		if (cpy > oend - COPYLENGTH) {
+			if (cpy > oend)
+				/*
+				 * Error: request to write outside of
+				 * destination buffer.
+				 */
+				goto _output_error;
+			LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
+			while (op < cpy)
+				*op++ = *ref++;
+			op = cpy;
+			if (op == oend)
+				/*
+				 * Check EOF (should never happen, since last
+				 * 5 bytes are supposed to be literals).
+				 */
+				break;
+			continue;
+		}
+		LZ4_SECURECOPY(ref, op, cpy);
+		op = cpy;	/* correction */
+	}
+
+	/* end of decoding */
+	return (int)(((char *)op) - dest);
+
+	/* write overflow error detected */
+	_output_error:
+	return (int)(-(((char *)ip) - source));
+}
diff --git a/sys/cddl/boot/zfs/zfsimpl.h b/sys/cddl/boot/zfs/zfsimpl.h
index a684c39..394a5e3 100644
--- a/sys/cddl/boot/zfs/zfsimpl.h
+++ b/sys/cddl/boot/zfs/zfsimpl.h
@@ -52,6 +52,9 @@
  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
+/*
+ * Copyright 2013 by Saso Kiselkov. All rights reserved.
+ */
 
 #define	MAXNAMELEN	256
 
@@ -439,6 +442,7 @@ enum zio_compress {
 	ZIO_COMPRESS_GZIP_8,
 	ZIO_COMPRESS_GZIP_9,
 	ZIO_COMPRESS_ZLE,
+	ZIO_COMPRESS_LZ4,
 	ZIO_COMPRESS_FUNCTIONS
 };
 
diff --git a/sys/cddl/boot/zfs/zfssubr.c b/sys/cddl/boot/zfs/zfssubr.c
index b2d2e13..0f01848 100644
--- a/sys/cddl/boot/zfs/zfssubr.c
+++ b/sys/cddl/boot/zfs/zfssubr.c
@@ -119,6 +119,7 @@ typedef struct zio_compress_info {
 
 #include "lzjb.c"
 #include "zle.c"
+#include "lz4.c"
 
 /*
  * Compression vectors.
@@ -139,6 +140,7 @@ static zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = {
 	{NULL,			NULL,			8,	"gzip-8"},
 	{NULL,			NULL,			9,	"gzip-9"},
 	{NULL,			zle_decompress,		64,	"zle"},
+	{NULL,			lz4_decompress,		0,	"lz4"},
 };
 
 static void
diff --git a/sys/cddl/compat/opensolaris/sys/byteorder.h b/sys/cddl/compat/opensolaris/sys/byteorder.h
index 72ae45b..c1a4388 100644
--- a/sys/cddl/compat/opensolaris/sys/byteorder.h
+++ b/sys/cddl/compat/opensolaris/sys/byteorder.h
@@ -42,6 +42,11 @@
 #ifndef _OPENSOLARIS_SYS_BYTEORDER_H_
 #define	_OPENSOLARIS_SYS_BYTEORDER_H_
 
+/* for htonl() */
+#ifndef _KERNEL
+#include <netinet/in.h>
+#endif
+
 /*
  * Macros to reverse byte order
  */
@@ -86,4 +91,6 @@
 #define	ntohll(x)	BSWAP_64(x)
 #endif
 
+#define BE_IN32(xa)	htonl(*((uint32_t *)(void *)(xa)))
+
 #endif /* _OPENSOLARIS_SYS_BYTEORDER_H_ */
diff --git a/sys/cddl/contrib/opensolaris/common/zfs/zfeature_common.c b/sys/cddl/contrib/opensolaris/common/zfs/zfeature_common.c
index 1a5948e..c2539d2 100644
--- a/sys/cddl/contrib/opensolaris/common/zfs/zfeature_common.c
+++ b/sys/cddl/contrib/opensolaris/common/zfs/zfeature_common.c
@@ -21,6 +21,7 @@
 
 /*
  * Copyright (c) 2012 by Delphix. All rights reserved.
+ * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  */
 
 #ifdef _KERNEL
@@ -155,4 +156,7 @@ zpool_feature_init(void)
 	zfeature_register(SPA_FEATURE_EMPTY_BPOBJ,
 	    "com.delphix:empty_bpobj", "empty_bpobj",
 	    "Snapshots use less space.", B_TRUE, B_FALSE, NULL);
+	zfeature_register(SPA_FEATURE_LZ4_COMPRESS,
+	    "org.illumos:lz4_compress", "lz4_compress",
+	    "LZ4 compression algorithm support.", B_FALSE, B_FALSE, NULL);
 }
diff --git a/sys/cddl/contrib/opensolaris/common/zfs/zfeature_common.h b/sys/cddl/contrib/opensolaris/common/zfs/zfeature_common.h
index cb786b2..3873317 100644
--- a/sys/cddl/contrib/opensolaris/common/zfs/zfeature_common.h
+++ b/sys/cddl/contrib/opensolaris/common/zfs/zfeature_common.h
@@ -21,6 +21,7 @@
 
 /*
  * Copyright (c) 2012 by Delphix. All rights reserved.
+ * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  */
 
 #ifndef _ZFEATURE_COMMON_H
@@ -51,6 +52,7 @@ typedef int (zfeature_func_t)(zfeature_info_t *fi, void *arg);
 static enum spa_feature {
 	SPA_FEATURE_ASYNC_DESTROY,
 	SPA_FEATURE_EMPTY_BPOBJ,
+	SPA_FEATURE_LZ4_COMPRESS,
 	SPA_FEATURES
 } spa_feature_t;
 
diff --git a/sys/cddl/contrib/opensolaris/common/zfs/zfs_prop.c b/sys/cddl/contrib/opensolaris/common/zfs/zfs_prop.c
index 5f5b8da..dc0cb33 100644
--- a/sys/cddl/contrib/opensolaris/common/zfs/zfs_prop.c
+++ b/sys/cddl/contrib/opensolaris/common/zfs/zfs_prop.c
@@ -21,6 +21,7 @@
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2011 by Delphix. All rights reserved.
+ * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  */
 
 /* Portions Copyright 2010 Robert Milkowski */
@@ -96,6 +97,7 @@ zfs_prop_init(void)
 		{ "gzip-8",	ZIO_COMPRESS_GZIP_8 },
 		{ "gzip-9",	ZIO_COMPRESS_GZIP_9 },
 		{ "zle",	ZIO_COMPRESS_ZLE },
+		{ "lz4",	ZIO_COMPRESS_LZ4 },
 		{ NULL }
 	};
 
@@ -211,8 +213,8 @@ zfs_prop_init(void)
 	zprop_register_index(ZFS_PROP_COMPRESSION, "compression",
 	    ZIO_COMPRESS_DEFAULT, PROP_INHERIT,
 	    ZFS_TYPE_FILESYSTEM | ZFS_TYPE_VOLUME,
-	    "on | off | lzjb | gzip | gzip-[1-9] | zle", "COMPRESS",
-	    compress_table);
+	    "on | off | lzjb | gzip | gzip-[1-9] | zle | lz4",
+	    "COMPRESS", compress_table);
 	zprop_register_index(ZFS_PROP_SNAPDIR, "snapdir", ZFS_SNAPDIR_HIDDEN,
 	    PROP_INHERIT, ZFS_TYPE_FILESYSTEM,
 	    "hidden | visible", "SNAPDIR", snapdir_table);
diff --git a/sys/cddl/contrib/opensolaris/uts/common/Makefile.files b/sys/cddl/contrib/opensolaris/uts/common/Makefile.files
index 30d4f79..40009e3 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/Makefile.files
+++ b/sys/cddl/contrib/opensolaris/uts/common/Makefile.files
@@ -22,6 +22,7 @@
 #
 # Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
 # Copyright (c) 2012 by Delphix. All rights reserved.
+# Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
 #
 #
 # This Makefile defines all file modules for the directory uts/common
@@ -56,6 +57,7 @@ ZFS_COMMON_OBJS +=		\
 	dsl_scan.o		\
 	zfeature.o		\
 	gzip.o			\
+	lz4.o			\
 	lzjb.o			\
 	metaslab.o		\
 	refcount.o		\
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/THIRDPARTYLICENSE.lz4 b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/THIRDPARTYLICENSE.lz4
new file mode 100644
index 0000000..722cc75
--- /dev/null
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/THIRDPARTYLICENSE.lz4
@@ -0,0 +1,30 @@
+LZ4 - Fast LZ compression algorithm
+Copyright (C) 2011-2013, Yann Collet.
+BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+ * Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+You can contact the author at :
+- LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
+- LZ4 source repository : http://code.google.com/p/lz4/
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/THIRDPARTYLICENSE.lz4.descrip b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/THIRDPARTYLICENSE.lz4.descrip
new file mode 100644
index 0000000..211f679
--- /dev/null
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/THIRDPARTYLICENSE.lz4.descrip
@@ -0,0 +1 @@
+LZ4 COMPRESSION FUNCTIONALITY IN ZFS
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c
new file mode 100644
index 0000000..b3939d4
--- /dev/null
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c
@@ -0,0 +1,1064 @@
+/*
+ * LZ4 - Fast LZ compression algorithm
+ * Header File
+ * Copyright (C) 2011-2013, Yann Collet.
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * You can contact the author at :
+ * - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
+ * - LZ4 source repository : http://code.google.com/p/lz4/
+ */
+
+#include <sys/zfs_context.h>
+
+static int real_LZ4_compress(const char *source, char *dest, int isize,
+    int osize);
+static int real_LZ4_uncompress(const char *source, char *dest, int osize);
+static int LZ4_compressBound(int isize);
+static int LZ4_uncompress_unknownOutputSize(const char *source, char *dest,
+    int isize, int maxOutputSize);
+static int LZ4_compressCtx(void *ctx, const char *source, char *dest,
+    int isize, int osize);
+static int LZ4_compress64kCtx(void *ctx, const char *source, char *dest,
+    int isize, int osize);
+
+/*ARGSUSED*/
+size_t
+lz4_compress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
+{
+	uint32_t bufsiz;
+	char *dest = d_start;
+
+	ASSERT(d_len >= sizeof (bufsiz));
+
+	bufsiz = real_LZ4_compress(s_start, &dest[sizeof (bufsiz)], s_len,
+	    d_len - sizeof (bufsiz));
+
+	/* Signal an error if the compression routine returned zero. */
+	if (bufsiz == 0)
+		return (s_len);
+
+	/*
+	 * Encode the compresed buffer size at the start. We'll need this in
+	 * decompression to counter the effects of padding which might be
+	 * added to the compressed buffer and which, if unhandled, would
+	 * confuse the hell out of our decompression function.
+	 */
+	*(uint32_t *)dest = BE_32(bufsiz);
+
+	return (bufsiz + sizeof (bufsiz));
+}
+
+/*ARGSUSED*/
+int
+lz4_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
+{
+	const char *src = s_start;
+	uint32_t bufsiz = BE_IN32(src);
+
+	/* invalid compressed buffer size encoded at start */
+	if (bufsiz + sizeof (bufsiz) > s_len)
+		return (1);
+
+	/*
+	 * Returns 0 on success (decompression function returned non-negative)
+	 * and non-zero on failure (decompression function returned negative.
+	 */
+	return (LZ4_uncompress_unknownOutputSize(&src[sizeof (bufsiz)],
+	    d_start, bufsiz, d_len) < 0);
+}
+
+/*
+ * LZ4 API Description:
+ *
+ * Simple Functions:
+ * real_LZ4_compress() :
+ * 	isize  : is the input size. Max supported value is ~1.9GB
+ * 	return : the number of bytes written in buffer dest
+ *		 or 0 if the compression fails (if LZ4_COMPRESSMIN is set).
+ * 	note : destination buffer must be already allocated.
+ * 		destination buffer must be sized to handle worst cases
+ * 		situations (input data not compressible) worst case size
+ * 		evaluation is provided by function LZ4_compressBound().
+ *
+ * real_LZ4_uncompress() :
+ * 	osize  : is the output size, therefore the original size
+ * 	return : the number of bytes read in the source buffer.
+ * 		If the source stream is malformed, the function will stop
+ * 		decoding and return a negative result, indicating the byte
+ * 		position of the faulty instruction. This function never
+ * 		writes beyond dest + osize, and is therefore protected
+ * 		against malicious data packets.
+ * 	note : destination buffer must be already allocated
+ *
+ * Advanced Functions
+ *
+ * LZ4_compressBound() :
+ * 	Provides the maximum size that LZ4 may output in a "worst case"
+ * 	scenario (input data not compressible) primarily useful for memory
+ * 	allocation of output buffer.
+ *
+ * 	isize  : is the input size. Max supported value is ~1.9GB
+ * 	return : maximum output size in a "worst case" scenario
+ * 	note : this function is limited by "int" range (2^31-1)
+ *
+ * LZ4_uncompress_unknownOutputSize() :
+ * 	isize  : is the input size, therefore the compressed size
+ * 	maxOutputSize : is the size of the destination buffer (which must be
+ * 		already allocated)
+ * 	return : the number of bytes decoded in the destination buffer
+ * 		(necessarily <= maxOutputSize). If the source stream is
+ * 		malformed, the function will stop decoding and return a
+ * 		negative result, indicating the byte position of the faulty
+ * 		instruction. This function never writes beyond dest +
+ * 		maxOutputSize, and is therefore protected against malicious
+ * 		data packets.
+ * 	note   : Destination buffer must be already allocated.
+ *		This version is slightly slower than real_LZ4_uncompress()
+ *
+ * LZ4_compressCtx() :
+ * 	This function explicitly handles the CTX memory structure.
+ *
+ * 	ILLUMOS CHANGES: the CTX memory structure must be explicitly allocated
+ * 	by the caller (either on the stack or using kmem_zalloc). Passing NULL
+ * 	isn't valid.
+ *
+ * LZ4_compress64kCtx() :
+ * 	Same as LZ4_compressCtx(), but specific to small inputs (<64KB).
+ * 	isize *Must* be <64KB, otherwise the output will be corrupted.
+ *
+ * 	ILLUMOS CHANGES: the CTX memory structure must be explicitly allocated
+ * 	by the caller (either on the stack or using kmem_zalloc). Passing NULL
+ * 	isn't valid.
+ */
+
+/*
+ * Tuning parameters
+ */
+
+/*
+ * COMPRESSIONLEVEL: Increasing this value improves compression ratio
+ *	 Lowering this value reduces memory usage. Reduced memory usage
+ *	typically improves speed, due to cache effect (ex: L1 32KB for Intel,
+ *	L1 64KB for AMD). Memory usage formula : N->2^(N+2) Bytes
+ *	(examples : 12 -> 16KB ; 17 -> 512KB)
+ */
+#define	COMPRESSIONLEVEL 12
+
+/*
+ * NOTCOMPRESSIBLE_CONFIRMATION: Decreasing this value will make the
+ *	algorithm skip faster data segments considered "incompressible".
+ *	This may decrease compression ratio dramatically, but will be
+ *	faster on incompressible data. Increasing this value will make
+ *	the algorithm search more before declaring a segment "incompressible".
+ *	This could improve compression a bit, but will be slower on
+ *	incompressible data. The default value (6) is recommended.
+ */
+#define	NOTCOMPRESSIBLE_CONFIRMATION 6
+
+/*
+ * BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE: This will provide a boost to
+ * performance for big endian cpu, but the resulting compressed stream
+ * will be incompatible with little-endian CPU. You can set this option
+ * to 1 in situations where data will stay within closed environment.
+ * This option is useless on Little_Endian CPU (such as x86).
+ */
+/* #define	BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE 1 */
+
+/*
+ * CPU Feature Detection
+ */
+
+/* 32 or 64 bits ? */
+#if (defined(__x86_64__) || defined(__x86_64) || defined(__amd64__) || \
+    defined(__amd64) || defined(__ppc64__) || defined(_WIN64) || \
+    defined(__LP64__) || defined(_LP64))
+#define	LZ4_ARCH64 1
+/*
+ * Illumos: On amd64 we have 20k of stack and 24k on sun4u and sun4v, so we
+ * can spend 16k on the algorithm
+ */
+/* FreeBSD: Use heap for all platforms for now */
+#define	STACKLIMIT 0
+#else
+#define	LZ4_ARCH64 0
+/*
+ * Illumos: On i386 we only have 12k of stack, so in order to maintain the
+ * same COMPRESSIONLEVEL we have to use heap allocation. Performance will
+ * suck, but alas, it's ZFS on 32-bit we're talking about, so...
+ */
+#define	STACKLIMIT 0
+#endif
+
+/*
+ * Little Endian or Big Endian?
+ * Note: overwrite the below #define if you know your architecture endianess.
+ */
+#if BYTE_ORDER == BIG_ENDIAN
+#define	LZ4_BIG_ENDIAN 1
+#else
+/*
+ * Little Endian assumed. PDP Endian and other very rare endian format
+ * are unsupported.
+ */
+#endif
+
+/*
+ * Unaligned memory access is automatically enabled for "common" CPU,
+ * such as x86. For others CPU, the compiler will be more cautious, and
+ * insert extra code to ensure aligned access is respected. If you know
+ * your target CPU supports unaligned memory access, you may want to
+ * force this option manually to improve performance
+ */
+#if defined(__ARM_FEATURE_UNALIGNED)
+#define	LZ4_FORCE_UNALIGNED_ACCESS 1
+#endif
+
+/*
+ * Compiler Options
+ */
+#if __STDC_VERSION__ >= 199901L	/* C99 */
+/* "restrict" is a known keyword */
+#else
+/* Disable restrict */
+#define	restrict
+#endif
+
+#define	lz4_bswap16(x) ((unsigned short int) ((((x) >> 8) & 0xffu) | \
+	(((x) & 0xffu) << 8)))
+
+#define	expect(expr, value)    (__builtin_expect((expr), (value)))
+
+#if defined(likely)
+#undef likely
+#endif
+#if defined(unlikely)
+#undef unlikely
+#endif
+
+#define	likely(expr)	expect((expr) != 0, 1)
+#define	unlikely(expr)	expect((expr) != 0, 0)
+
+/* Basic types */
+#define	BYTE	uint8_t
+#define	U16	uint16_t
+#define	U32	uint32_t
+#define	S32	int32_t
+#define	U64	uint64_t
+
+#ifndef LZ4_FORCE_UNALIGNED_ACCESS
+#pragma pack(1)
+#endif
+
+typedef struct _U16_S {
+	U16 v;
+} U16_S;
+typedef struct _U32_S {
+	U32 v;
+} U32_S;
+typedef struct _U64_S {
+	U64 v;
+} U64_S;
+
+#ifndef LZ4_FORCE_UNALIGNED_ACCESS
+#pragma pack()
+#endif
+
+#define	A64(x) (((U64_S *)(x))->v)
+#define	A32(x) (((U32_S *)(x))->v)
+#define	A16(x) (((U16_S *)(x))->v)
+
+/*
+ * Constants
+ */
+#define	MINMATCH 4
+
+#define	HASH_LOG COMPRESSIONLEVEL
+#define	HASHTABLESIZE (1 << HASH_LOG)
+#define	HASH_MASK (HASHTABLESIZE - 1)
+
+#define	SKIPSTRENGTH (NOTCOMPRESSIBLE_CONFIRMATION > 2 ? \
+	NOTCOMPRESSIBLE_CONFIRMATION : 2)
+
+/*
+ * Defines if memory is allocated into the stack (local variable),
+ * or into the heap (kmem_alloc()).
+ */
+#define	HEAPMODE (HASH_LOG > STACKLIMIT)
+#define	COPYLENGTH 8
+#define	LASTLITERALS 5
+#define	MFLIMIT (COPYLENGTH + MINMATCH)
+#define	MINLENGTH (MFLIMIT + 1)
+
+#define	MAXD_LOG 16
+#define	MAX_DISTANCE ((1 << MAXD_LOG) - 1)
+
+#define	ML_BITS 4
+#define	ML_MASK ((1U<<ML_BITS)-1)
+#define	RUN_BITS (8-ML_BITS)
+#define	RUN_MASK ((1U<<RUN_BITS)-1)
+
+
+/*
+ * Architecture-specific macros
+ */
+#if LZ4_ARCH64
+#define	STEPSIZE 8
+#define	UARCH U64
+#define	AARCH A64
+#define	LZ4_COPYSTEP(s, d)	A64(d) = A64(s); d += 8; s += 8;
+#define	LZ4_COPYPACKET(s, d)	LZ4_COPYSTEP(s, d)
+#define	LZ4_SECURECOPY(s, d, e)	if (d < e) LZ4_WILDCOPY(s, d, e)
+#define	HTYPE U32
+#define	INITBASE(base)		const BYTE* const base = ip
+#else /* !LZ4_ARCH64 */
+#define	STEPSIZE 4
+#define	UARCH U32
+#define	AARCH A32
+#define	LZ4_COPYSTEP(s, d)	A32(d) = A32(s); d += 4; s += 4;
+#define	LZ4_COPYPACKET(s, d)	LZ4_COPYSTEP(s, d); LZ4_COPYSTEP(s, d);
+#define	LZ4_SECURECOPY		LZ4_WILDCOPY
+#define	HTYPE const BYTE *
+#define	INITBASE(base)		const int base = 0
+#endif /* !LZ4_ARCH64 */
+
+#if (defined(LZ4_BIG_ENDIAN) && !defined(BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE))
+#define	LZ4_READ_LITTLEENDIAN_16(d, s, p) \
+	{ U16 v = A16(p); v = lz4_bswap16(v); d = (s) - v; }
+#define	LZ4_WRITE_LITTLEENDIAN_16(p, i) \
+	{ U16 v = (U16)(i); v = lz4_bswap16(v); A16(p) = v; p += 2; }
+#else
+#define	LZ4_READ_LITTLEENDIAN_16(d, s, p) { d = (s) - A16(p); }
+#define	LZ4_WRITE_LITTLEENDIAN_16(p, v)  { A16(p) = v; p += 2; }
+#endif
+
+
+/* Local structures */
+struct refTables {
+	HTYPE hashTable[HASHTABLESIZE];
+};
+
+
+/* Macros */
+#define	LZ4_HASH_FUNCTION(i) (((i) * 2654435761U) >> ((MINMATCH * 8) - \
+	HASH_LOG))
+#define	LZ4_HASH_VALUE(p) LZ4_HASH_FUNCTION(A32(p))
+#define	LZ4_WILDCOPY(s, d, e) do { LZ4_COPYPACKET(s, d) } while (d < e);
+#define	LZ4_BLINDCOPY(s, d, l) { BYTE* e = (d) + l; LZ4_WILDCOPY(s, d, e); \
+	d = e; }
+
+
+/* Private functions */
+#if LZ4_ARCH64
+
+static inline int
+LZ4_NbCommonBytes(register U64 val)
+{
+#if defined(LZ4_BIG_ENDIAN)
+	return (__builtin_clzll(val) >> 3);
+#else
+	return (__builtin_ctzll(val) >> 3);
+#endif
+}
+
+#else
+
+static inline int
+LZ4_NbCommonBytes(register U32 val)
+{
+#if defined(LZ4_BIG_ENDIAN)
+	return (__builtin_clz(val) >> 3);
+#else
+	return (__builtin_ctz(val) >> 3);
+#endif
+}
+
+#endif
+
+/* Public functions */
+
+static int
+LZ4_compressBound(int isize)
+{
+	return (isize + (isize / 255) + 16);
+}
+
+/* Compression functions */
+
+/*ARGSUSED*/
+static int
+LZ4_compressCtx(void *ctx, const char *source, char *dest, int isize,
+    int osize)
+{
+#if HEAPMODE
+	struct refTables *srt = (struct refTables *)ctx;
+	HTYPE *HashTable = (HTYPE *) (srt->hashTable);
+#else
+	HTYPE HashTable[HASHTABLESIZE] = { 0 };
+#endif
+
+	const BYTE *ip = (BYTE *) source;
+	INITBASE(base);
+	const BYTE *anchor = ip;
+	const BYTE *const iend = ip + isize;
+	const BYTE *const oend = (BYTE *) dest + osize;
+	const BYTE *const mflimit = iend - MFLIMIT;
+#define	matchlimit (iend - LASTLITERALS)
+
+	BYTE *op = (BYTE *) dest;
+
+	int len, length;
+	const int skipStrength = SKIPSTRENGTH;
+	U32 forwardH;
+
+
+	/* Init */
+	if (isize < MINLENGTH)
+		goto _last_literals;
+
+	/* First Byte */
+	HashTable[LZ4_HASH_VALUE(ip)] = ip - base;
+	ip++;
+	forwardH = LZ4_HASH_VALUE(ip);
+
+	/* Main Loop */
+	for (;;) {
+		int findMatchAttempts = (1U << skipStrength) + 3;
+		const BYTE *forwardIp = ip;
+		const BYTE *ref;
+		BYTE *token;
+
+		/* Find a match */
+		do {
+			U32 h = forwardH;
+			int step = findMatchAttempts++ >> skipStrength;
+			ip = forwardIp;
+			forwardIp = ip + step;
+
+			if unlikely(forwardIp > mflimit) {
+				goto _last_literals;
+			}
+
+			forwardH = LZ4_HASH_VALUE(forwardIp);
+			ref = base + HashTable[h];
+			HashTable[h] = ip - base;
+
+		} while ((ref < ip - MAX_DISTANCE) || (A32(ref) != A32(ip)));
+
+		/* Catch up */
+		while ((ip > anchor) && (ref > (BYTE *) source) &&
+		    unlikely(ip[-1] == ref[-1])) {
+			ip--;
+			ref--;
+		}
+
+		/* Encode Literal length */
+		length = ip - anchor;
+		token = op++;
+
+		/* Check output limit */
+		if unlikely(op + length + (2 + 1 + LASTLITERALS) +
+		    (length >> 8) > oend)
+			return (0);
+
+		if (length >= (int)RUN_MASK) {
+			*token = (RUN_MASK << ML_BITS);
+			len = length - RUN_MASK;
+			for (; len > 254; len -= 255)
+				*op++ = 255;
+			*op++ = (BYTE)len;
+		} else
+			*token = (length << ML_BITS);
+
+		/* Copy Literals */
+		LZ4_BLINDCOPY(anchor, op, length);
+
+		_next_match:
+		/* Encode Offset */
+		LZ4_WRITE_LITTLEENDIAN_16(op, ip - ref);
+
+		/* Start Counting */
+		ip += MINMATCH;
+		ref += MINMATCH;	/* MinMatch verified */
+		anchor = ip;
+		while likely(ip < matchlimit - (STEPSIZE - 1)) {
+			UARCH diff = AARCH(ref) ^ AARCH(ip);
+			if (!diff) {
+				ip += STEPSIZE;
+				ref += STEPSIZE;
+				continue;
+			}
+			ip += LZ4_NbCommonBytes(diff);
+			goto _endCount;
+		}
+#if LZ4_ARCH64
+		if ((ip < (matchlimit - 3)) && (A32(ref) == A32(ip))) {
+			ip += 4;
+			ref += 4;
+		}
+#endif
+		if ((ip < (matchlimit - 1)) && (A16(ref) == A16(ip))) {
+			ip += 2;
+			ref += 2;
+		}
+		if ((ip < matchlimit) && (*ref == *ip))
+			ip++;
+		_endCount:
+
+		/* Encode MatchLength */
+		len = (ip - anchor);
+		/* Check output limit */
+		if unlikely(op + (1 + LASTLITERALS) + (len >> 8) > oend)
+			return (0);
+		if (len >= (int)ML_MASK) {
+			*token += ML_MASK;
+			len -= ML_MASK;
+			for (; len > 509; len -= 510) {
+				*op++ = 255;
+				*op++ = 255;
+			}
+			if (len > 254) {
+				len -= 255;
+				*op++ = 255;
+			}
+			*op++ = (BYTE)len;
+		} else
+			*token += len;
+
+		/* Test end of chunk */
+		if (ip > mflimit) {
+			anchor = ip;
+			break;
+		}
+		/* Fill table */
+		HashTable[LZ4_HASH_VALUE(ip - 2)] = ip - 2 - base;
+
+		/* Test next position */
+		ref = base + HashTable[LZ4_HASH_VALUE(ip)];
+		HashTable[LZ4_HASH_VALUE(ip)] = ip - base;
+		if ((ref > ip - (MAX_DISTANCE + 1)) && (A32(ref) == A32(ip))) {
+			token = op++;
+			*token = 0;
+			goto _next_match;
+		}
+		/* Prepare next loop */
+		anchor = ip++;
+		forwardH = LZ4_HASH_VALUE(ip);
+	}
+
+	_last_literals:
+	/* Encode Last Literals */
+	{
+		int lastRun = iend - anchor;
+		if (op + lastRun + 1 + ((lastRun + 255 - RUN_MASK) / 255) >
+		    oend)
+			return (0);
+		if (lastRun >= (int)RUN_MASK) {
+			*op++ = (RUN_MASK << ML_BITS);
+			lastRun -= RUN_MASK;
+			for (; lastRun > 254; lastRun -= 255) {
+				*op++ = 255;
+			}
+			*op++ = (BYTE)lastRun;
+		} else
+			*op++ = (lastRun << ML_BITS);
+		(void) memcpy(op, anchor, iend - anchor);
+		op += iend - anchor;
+	}
+
+	/* End */
+	return (int)(((char *)op) - dest);
+}
+
+
+
+/* Note : this function is valid only if isize < LZ4_64KLIMIT */
+#define	LZ4_64KLIMIT ((1 << 16) + (MFLIMIT - 1))
+#define	HASHLOG64K (HASH_LOG + 1)
+#define	HASH64KTABLESIZE (1U << HASHLOG64K)
+#define	LZ4_HASH64K_FUNCTION(i)	(((i) * 2654435761U) >> ((MINMATCH*8) - \
+	HASHLOG64K))
+#define	LZ4_HASH64K_VALUE(p)	LZ4_HASH64K_FUNCTION(A32(p))
+
+/*ARGSUSED*/
+static int
+LZ4_compress64kCtx(void *ctx, const char *source, char *dest, int isize,
+    int osize)
+{
+#if HEAPMODE
+	struct refTables *srt = (struct refTables *)ctx;
+	U16 *HashTable = (U16 *) (srt->hashTable);
+#else
+	U16 HashTable[HASH64KTABLESIZE] = { 0 };
+#endif
+
+	const BYTE *ip = (BYTE *) source;
+	const BYTE *anchor = ip;
+	const BYTE *const base = ip;
+	const BYTE *const iend = ip + isize;
+	const BYTE *const oend = (BYTE *) dest + osize;
+	const BYTE *const mflimit = iend - MFLIMIT;
+#define	matchlimit (iend - LASTLITERALS)
+
+	BYTE *op = (BYTE *) dest;
+
+	int len, length;
+	const int skipStrength = SKIPSTRENGTH;
+	U32 forwardH;
+
+	/* Init */
+	if (isize < MINLENGTH)
+		goto _last_literals;
+
+	/* First Byte */
+	ip++;
+	forwardH = LZ4_HASH64K_VALUE(ip);
+
+	/* Main Loop */
+	for (;;) {
+		int findMatchAttempts = (1U << skipStrength) + 3;
+		const BYTE *forwardIp = ip;
+		const BYTE *ref;
+		BYTE *token;
+
+		/* Find a match */
+		do {
+			U32 h = forwardH;
+			int step = findMatchAttempts++ >> skipStrength;
+			ip = forwardIp;
+			forwardIp = ip + step;
+
+			if (forwardIp > mflimit) {
+				goto _last_literals;
+			}
+
+			forwardH = LZ4_HASH64K_VALUE(forwardIp);
+			ref = base + HashTable[h];
+			HashTable[h] = ip - base;
+
+		} while (A32(ref) != A32(ip));
+
+		/* Catch up */
+		while ((ip > anchor) && (ref > (BYTE *) source) &&
+		    (ip[-1] == ref[-1])) {
+			ip--;
+			ref--;
+		}
+
+		/* Encode Literal length */
+		length = ip - anchor;
+		token = op++;
+
+		/* Check output limit */
+		if unlikely(op + length + (2 + 1 + LASTLITERALS) +
+		    (length >> 8) > oend)
+			return (0);
+
+		if (length >= (int)RUN_MASK) {
+			*token = (RUN_MASK << ML_BITS);
+			len = length - RUN_MASK;
+			for (; len > 254; len -= 255)
+				*op++ = 255;
+			*op++ = (BYTE)len;
+		} else
+			*token = (length << ML_BITS);
+
+		/* Copy Literals */
+		LZ4_BLINDCOPY(anchor, op, length);
+
+		_next_match:
+		/* Encode Offset */
+		LZ4_WRITE_LITTLEENDIAN_16(op, ip - ref);
+
+		/* Start Counting */
+		ip += MINMATCH;
+		ref += MINMATCH;	/* MinMatch verified */
+		anchor = ip;
+		while (ip < matchlimit - (STEPSIZE - 1)) {
+			UARCH diff = AARCH(ref) ^ AARCH(ip);
+			if (!diff) {
+				ip += STEPSIZE;
+				ref += STEPSIZE;
+				continue;
+			}
+			ip += LZ4_NbCommonBytes(diff);
+			goto _endCount;
+		}
+#if LZ4_ARCH64
+		if ((ip < (matchlimit - 3)) && (A32(ref) == A32(ip))) {
+			ip += 4;
+			ref += 4;
+		}
+#endif
+		if ((ip < (matchlimit - 1)) && (A16(ref) == A16(ip))) {
+			ip += 2;
+			ref += 2;
+		}
+		if ((ip < matchlimit) && (*ref == *ip))
+			ip++;
+		_endCount:
+
+		/* Encode MatchLength */
+		len = (ip - anchor);
+		/* Check output limit */
+		if unlikely(op + (1 + LASTLITERALS) + (len >> 8) > oend)
+			return (0);
+		if (len >= (int)ML_MASK) {
+			*token += ML_MASK;
+			len -= ML_MASK;
+			for (; len > 509; len -= 510) {
+				*op++ = 255;
+				*op++ = 255;
+			}
+			if (len > 254) {
+				len -= 255;
+				*op++ = 255;
+			}
+			*op++ = (BYTE)len;
+		} else
+			*token += len;
+
+		/* Test end of chunk */
+		if (ip > mflimit) {
+			anchor = ip;
+			break;
+		}
+		/* Fill table */
+		HashTable[LZ4_HASH64K_VALUE(ip - 2)] = ip - 2 - base;
+
+		/* Test next position */
+		ref = base + HashTable[LZ4_HASH64K_VALUE(ip)];
+		HashTable[LZ4_HASH64K_VALUE(ip)] = ip - base;
+		if (A32(ref) == A32(ip)) {
+			token = op++;
+			*token = 0;
+			goto _next_match;
+		}
+		/* Prepare next loop */
+		anchor = ip++;
+		forwardH = LZ4_HASH64K_VALUE(ip);
+	}
+
+	_last_literals:
+	/* Encode Last Literals */
+	{
+		int lastRun = iend - anchor;
+		if (op + lastRun + 1 + ((lastRun + 255 - RUN_MASK) / 255) >
+		    oend)
+			return (0);
+		if (lastRun >= (int)RUN_MASK) {
+			*op++ = (RUN_MASK << ML_BITS);
+			lastRun -= RUN_MASK;
+			for (; lastRun > 254; lastRun -= 255)
+				*op++ = 255;
+			*op++ = (BYTE)lastRun;
+		} else
+			*op++ = (lastRun << ML_BITS);
+		(void) memcpy(op, anchor, iend - anchor);
+		op += iend - anchor;
+	}
+
+	/* End */
+	return (int)(((char *)op) - dest);
+}
+
+static int
+real_LZ4_compress(const char *source, char *dest, int isize, int osize)
+{
+#if HEAPMODE
+	void *ctx = kmem_zalloc(sizeof (struct refTables), KM_NOSLEEP);
+	int result;
+
+	/*
+	 * out of kernel memory, gently fall through - this will disable
+	 * compression in zio_compress_data
+	 */
+	if (ctx == NULL)
+		return (0);
+
+	if (isize < LZ4_64KLIMIT)
+		result = LZ4_compress64kCtx(ctx, source, dest, isize, osize);
+	else
+		result = LZ4_compressCtx(ctx, source, dest, isize, osize);
+
+	kmem_free(ctx, sizeof (struct refTables));
+	return (result);
+#else
+	if (isize < (int)LZ4_64KLIMIT)
+		return (LZ4_compress64kCtx(NULL, source, dest, isize, osize));
+	return (LZ4_compressCtx(NULL, source, dest, isize, osize));
+#endif
+}
+
+/* Decompression functions */
+
+/*
+ * Note: The decoding functions real_LZ4_uncompress() and
+ *	LZ4_uncompress_unknownOutputSize() are safe against "buffer overflow"
+ *	attack type. They will never write nor read outside of the provided
+ *	output buffers. LZ4_uncompress_unknownOutputSize() also insures that
+ *	it will never read outside of the input buffer. A corrupted input
+ *	will produce an error result, a negative int, indicating the position
+ *	of the error within input stream.
+ */
+
+static int
+real_LZ4_uncompress(const char *source, char *dest, int osize)
+{
+	/* Local Variables */
+	const BYTE *restrict ip = (const BYTE *) source;
+	const BYTE *ref;
+
+	BYTE *op = (BYTE *) dest;
+	BYTE *const oend = op + osize;
+	BYTE *cpy;
+
+	unsigned token;
+
+	size_t length;
+	size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};
+#if LZ4_ARCH64
+	size_t dec64table[] = {0, 0, 0, (size_t)-1, 0, 1, 2, 3};
+#endif
+
+	/* Main Loop */
+	for (;;) {
+		/* get runlength */
+		token = *ip++;
+		if ((length = (token >> ML_BITS)) == RUN_MASK) {
+			size_t len;
+			for (; (len = *ip++) == 255; length += 255) {
+			}
+			length += len;
+		}
+		/* copy literals */
+		cpy = op + length;
+		if unlikely(cpy > oend - COPYLENGTH) {
+			if (cpy != oend)
+				/* Error: we must necessarily stand at EOF */
+				goto _output_error;
+			(void) memcpy(op, ip, length);
+			ip += length;
+			break;	/* EOF */
+			}
+		LZ4_WILDCOPY(ip, op, cpy);
+		ip -= (op - cpy);
+		op = cpy;
+
+		/* get offset */
+		LZ4_READ_LITTLEENDIAN_16(ref, cpy, ip);
+		ip += 2;
+		if unlikely(ref < (BYTE * const) dest)
+			/*
+			 * Error: offset create reference outside destination
+			 * buffer
+			 */
+			goto _output_error;
+
+		/* get matchlength */
+		if ((length = (token & ML_MASK)) == ML_MASK) {
+			for (; *ip == 255; length += 255) {
+				ip++;
+			}
+			length += *ip++;
+		}
+		/* copy repeated sequence */
+		if unlikely(op - ref < STEPSIZE) {
+#if LZ4_ARCH64
+			size_t dec64 = dec64table[op-ref];
+#else
+			const int dec64 = 0;
+#endif
+			op[0] = ref[0];
+			op[1] = ref[1];
+			op[2] = ref[2];
+			op[3] = ref[3];
+			op += 4;
+			ref += 4;
+			ref -= dec32table[op-ref];
+			A32(op) = A32(ref);
+			op += STEPSIZE - 4;
+			ref -= dec64;
+		} else {
+			LZ4_COPYSTEP(ref, op);
+		}
+		cpy = op + length - (STEPSIZE - 4);
+		if (cpy > oend - COPYLENGTH) {
+			if (cpy > oend)
+				/*
+				 * Error: request to write beyond destination
+				 * buffer
+				 */
+				goto _output_error;
+			LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
+			while (op < cpy)
+				*op++ = *ref++;
+			op = cpy;
+			if (op == oend)
+				/*
+				 * Check EOF (should never happen, since last
+				 * 5 bytes are supposed to be literals)
+				 */
+				goto _output_error;
+			continue;
+		}
+		LZ4_SECURECOPY(ref, op, cpy);
+		op = cpy;	/* correction */
+	}
+
+	/* end of decoding */
+	return (int)(((char *)ip) - source);
+
+	/* write overflow error detected */
+	_output_error:
+	return (int)(-(((char *)ip) - source));
+}
+
+static int
+LZ4_uncompress_unknownOutputSize(const char *source, char *dest, int isize,
+    int maxOutputSize)
+{
+	/* Local Variables */
+	const BYTE *restrict ip = (const BYTE *) source;
+	const BYTE *const iend = ip + isize;
+	const BYTE *ref;
+
+	BYTE *op = (BYTE *) dest;
+	BYTE *const oend = op + maxOutputSize;
+	BYTE *cpy;
+
+	size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};
+#if LZ4_ARCH64
+	size_t dec64table[] = {0, 0, 0, (size_t)-1, 0, 1, 2, 3};
+#endif
+
+	/* Main Loop */
+	while (ip < iend) {
+		unsigned token;
+		size_t length;
+
+		/* get runlength */
+		token = *ip++;
+		if ((length = (token >> ML_BITS)) == RUN_MASK) {
+			int s = 255;
+			while ((ip < iend) && (s == 255)) {
+				s = *ip++;
+				length += s;
+			}
+		}
+		/* copy literals */
+		cpy = op + length;
+		if ((cpy > oend - COPYLENGTH) ||
+		    (ip + length > iend - COPYLENGTH)) {
+			if (cpy > oend)
+				/* Error: writes beyond output buffer */
+				goto _output_error;
+			if (ip + length != iend)
+				/*
+				 * Error: LZ4 format requires to consume all
+				 * input at this stage
+				 */
+				goto _output_error;
+			(void) memcpy(op, ip, length);
+			op += length;
+			/* Necessarily EOF, due to parsing restrictions */
+			break;
+		}
+		LZ4_WILDCOPY(ip, op, cpy);
+		ip -= (op - cpy);
+		op = cpy;
+
+		/* get offset */
+		LZ4_READ_LITTLEENDIAN_16(ref, cpy, ip);
+		ip += 2;
+		if (ref < (BYTE * const) dest)
+			/*
+			 * Error: offset creates reference outside of
+			 * destination buffer
+			 */
+			goto _output_error;
+
+		/* get matchlength */
+		if ((length = (token & ML_MASK)) == ML_MASK) {
+			while (ip < iend) {
+				int s = *ip++;
+				length += s;
+				if (s == 255)
+					continue;
+				break;
+			}
+		}
+		/* copy repeated sequence */
+		if unlikely(op - ref < STEPSIZE) {
+#if LZ4_ARCH64
+			size_t dec64 = dec64table[op-ref];
+#else
+			const int dec64 = 0;
+#endif
+			op[0] = ref[0];
+			op[1] = ref[1];
+			op[2] = ref[2];
+			op[3] = ref[3];
+			op += 4;
+			ref += 4;
+			ref -= dec32table[op-ref];
+			A32(op) = A32(ref);
+			op += STEPSIZE - 4;
+			ref -= dec64;
+		} else {
+			LZ4_COPYSTEP(ref, op);
+		}
+		cpy = op + length - (STEPSIZE - 4);
+		if (cpy > oend - COPYLENGTH) {
+			if (cpy > oend)
+				/*
+				 * Error: request to write outside of
+				 * destination buffer
+				 */
+				goto _output_error;
+			LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
+			while (op < cpy)
+				*op++ = *ref++;
+			op = cpy;
+			if (op == oend)
+				/*
+				 * Check EOF (should never happen, since
+				 * last 5 bytes are supposed to be literals)
+				 */
+				goto _output_error;
+			continue;
+		}
+		LZ4_SECURECOPY(ref, op, cpy);
+		op = cpy;	/* correction */
+	}
+
+	/* end of decoding */
+	return (int)(((char *)op) - dest);
+
+	/* write overflow error detected */
+	_output_error:
+	return (int)(-(((char *)ip) - source));
+}
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h
index b6dc9f5..a58937f 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h
@@ -22,6 +22,7 @@
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2012 by Delphix. All rights reserved.
+ * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  */
 
 #ifndef _ZIO_H
@@ -106,14 +107,17 @@ enum zio_compress {
 	ZIO_COMPRESS_GZIP_8,
 	ZIO_COMPRESS_GZIP_9,
 	ZIO_COMPRESS_ZLE,
+	ZIO_COMPRESS_LZ4,
 	ZIO_COMPRESS_FUNCTIONS
 };
 
+/* N.B. when altering this value, also change BOOTFS_COMPRESS_VALID below */
 #define	ZIO_COMPRESS_ON_VALUE	ZIO_COMPRESS_LZJB
 #define	ZIO_COMPRESS_DEFAULT	ZIO_COMPRESS_OFF
 
 #define	BOOTFS_COMPRESS_VALID(compress)			\
 	((compress) == ZIO_COMPRESS_LZJB ||		\
+	(compress) == ZIO_COMPRESS_LZ4 ||		\
 	((compress) == ZIO_COMPRESS_ON &&		\
 	ZIO_COMPRESS_ON_VALUE == ZIO_COMPRESS_LZJB) ||	\
 	(compress) == ZIO_COMPRESS_OFF)
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio_compress.h b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio_compress.h
index 30bed1a..34a82a8 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio_compress.h
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio_compress.h
@@ -23,6 +23,9 @@
  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
+/*
+ * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
+ */
 
 #ifndef _SYS_ZIO_COMPRESS_H
 #define	_SYS_ZIO_COMPRESS_H
@@ -68,6 +71,10 @@ extern size_t zle_compress(void *src, void *dst, size_t s_len, size_t d_len,
     int level);
 extern int zle_decompress(void *src, void *dst, size_t s_len, size_t d_len,
     int level);
+extern size_t lz4_compress(void *src, void *dst, size_t s_len, size_t d_len,
+    int level);
+extern int lz4_decompress(void *src, void *dst, size_t s_len, size_t d_len,
+    int level);
 
 /*
  * Compress and decompress data if necessary.
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
index 6fa9cea..7a2334b 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
@@ -27,6 +27,7 @@
  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2012 by Delphix. All rights reserved.
  * Copyright (c) 2012, Joyent, Inc. All rights reserved.
+ * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  */
 
 #include <sys/types.h>
@@ -75,6 +76,7 @@
 #include <sys/zvol.h>
 #include <sys/dsl_scan.h>
 #include <sys/dmu_objset.h>
+#include <sys/zfeature.h>
 
 #include "zfs_namecheck.h"
 #include "zfs_prop.h"
@@ -131,6 +133,12 @@ int zfs_set_prop_nvlist(const char *, zprop_source_t, nvlist_t *, nvlist_t **);
  
 static void zfsdev_close(void *data);
 
+static int zfs_prop_activate_feature(dsl_pool_t *dp, zfeature_info_t *feature);
+static int zfs_prop_activate_feature_check(void *arg1, void *arg2,
+    dmu_tx_t *tx);
+static void zfs_prop_activate_feature_sync(void *arg1, void *arg2,
+    dmu_tx_t *tx);
+
 /* _NOTE(PRINTFLIKE(4)) - this is printf-like, but lint is too whiney */
 void
 __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
@@ -2264,6 +2272,40 @@ zfs_prop_set_special(const char *dsname, zprop_source_t source,
 		}
 		break;
 	}
+	case ZFS_PROP_COMPRESSION:
+	{
+		if (intval == ZIO_COMPRESS_LZ4) {
+			zfeature_info_t *feature =
+			    &spa_feature_table[SPA_FEATURE_LZ4_COMPRESS];
+			spa_t *spa;
+			dsl_pool_t *dp;
+
+			if ((err = spa_open(dsname, &spa, FTAG)) != 0)
+				return (err);
+
+			dp = spa->spa_dsl_pool;
+
+			/*
+			 * Setting the LZ4 compression algorithm activates
+			 * the feature.
+			 */
+			if (!spa_feature_is_active(spa, feature)) {
+				if ((err = zfs_prop_activate_feature(dp,
+				    feature)) != 0) {
+					spa_close(spa, FTAG);
+					return (err);
+				}
+			}
+
+			spa_close(spa, FTAG);
+		}
+		/*
+		 * We still want the default set action to be performed in the
+		 * caller, we only performed zfeature settings here.
+		 */
+		err = -1;
+		break;
+	}
 
 	default:
 		err = -1;
@@ -3481,6 +3523,22 @@ zfs_check_settable(const char *dsname, nvpair_t *pair, cred_t *cr)
 			    SPA_VERSION_ZLE_COMPRESSION))
 				return (ENOTSUP);
 
+			if (intval == ZIO_COMPRESS_LZ4) {
+				zfeature_info_t *feature =
+				    &spa_feature_table[
+				    SPA_FEATURE_LZ4_COMPRESS];
+				spa_t *spa;
+
+				if ((err = spa_open(dsname, &spa, FTAG)) != 0)
+					return (err);
+
+				if (!spa_feature_is_enabled(spa, feature)) {
+					spa_close(spa, FTAG);
+					return (ENOTSUP);
+				}
+				spa_close(spa, FTAG);
+			}
+
 			/*
 			 * If this is a bootable dataset then
 			 * verify that the compression algorithm
@@ -3525,6 +3583,56 @@ zfs_check_settable(const char *dsname, nvpair_t *pair, cred_t *cr)
 }
 
 /*
+ * Activates a feature on a pool in response to a property setting. This
+ * creates a new sync task which modifies the pool to reflect the feature
+ * as being active.
+ */
+static int
+zfs_prop_activate_feature(dsl_pool_t *dp, zfeature_info_t *feature)
+{
+	int err;
+
+	/* EBUSY here indicates that the feature is already active */
+	err = dsl_sync_task_do(dp, zfs_prop_activate_feature_check,
+	    zfs_prop_activate_feature_sync, dp->dp_spa, feature, 2);
+
+	if (err != 0 && err != EBUSY)
+		return (err);
+	else
+		return (0);
+}
+
+/*
+ * Checks for a race condition to make sure we don't increment a feature flag
+ * multiple times.
+ */
+/*ARGSUSED*/
+static int
+zfs_prop_activate_feature_check(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+	spa_t *spa = arg1;
+	zfeature_info_t *feature = arg2;
+
+	if (!spa_feature_is_active(spa, feature))
+		return (0);
+	else
+		return (EBUSY);
+}
+
+/*
+ * The callback invoked on feature activation in the sync task caused by
+ * zfs_prop_activate_feature.
+ */
+static void
+zfs_prop_activate_feature_sync(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+	spa_t *spa = arg1;
+	zfeature_info_t *feature = arg2;
+
+	spa_feature_incr(spa, feature, tx);
+}
+
+/*
  * Removes properties from the given props list that fail permission checks
  * needed to clear them and to restore them in case of a receive error. For each
  * property, make sure we have both set and inherit permissions.
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio_compress.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio_compress.c
index f148977..1dc780d 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio_compress.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio_compress.c
@@ -23,6 +23,9 @@
  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
+/*
+ * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
+ */
 
 #include <sys/zfs_context.h>
 #include <sys/compress.h>
@@ -50,6 +53,7 @@ zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = {
 	{gzip_compress,		gzip_decompress,	8,	"gzip-8"},
 	{gzip_compress,		gzip_decompress,	9,	"gzip-9"},
 	{zle_compress,		zle_decompress,		64,	"zle"},
+	{lz4_compress,		lz4_decompress,		0,	"lz4"},
 };
 
 enum zio_compress
diff --git a/sys/conf/files b/sys/conf/files
index f4961e9..8078840 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -202,6 +202,7 @@ cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_prop.c			optional zfs compile-wit
 cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c			optional zfs compile-with "${ZFS_C}"
 cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_synctask.c		optional zfs compile-with "${ZFS_C}"
 cddl/contrib/opensolaris/uts/common/fs/zfs/gzip.c			optional zfs compile-with "${ZFS_C}"
+cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c			optional zfs compile-with "${ZFS_C}"
 cddl/contrib/opensolaris/uts/common/fs/zfs/lzjb.c			optional zfs compile-with "${ZFS_C}"
 cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c			optional zfs compile-with "${ZFS_C}"
 cddl/contrib/opensolaris/uts/common/fs/zfs/refcount.c			optional zfs compile-with "${ZFS_C}"