compress: add "slack" compression option

The "slack" option simply searches from the end of the block backwards to the last non-zero byte, and sets that position as the "compressed" size. Signed-off-by: Rob Norris <[email protected]> Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc.
openzfs · Jul 3, 2024 · 3dc96e0 · 3dc96e0
1 parent fd51786
commit 3dc96e0
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Showing 18 changed files with 171 additions and 13 deletions.
diff --git a/cmd/dbufstat.in b/cmd/dbufstat.in
@@ -359,7 +359,8 @@ def get_compstring(c):
                     "ZIO_COMPRESS_GZIP_6",  "ZIO_COMPRESS_GZIP_7",
                     "ZIO_COMPRESS_GZIP_8",  "ZIO_COMPRESS_GZIP_9",
                     "ZIO_COMPRESS_ZLE",     "ZIO_COMPRESS_LZ4",
-                    "ZIO_COMPRESS_ZSTD",    "ZIO_COMPRESS_FUNCTION"]
+                    "ZIO_COMPRESS_ZSTD",    "ZIO_COMPRESS_SLACK",
+                    "ZIO_COMPRESS_FUNCTION"]
 
     # If "-rr" option is used, don't convert to string representation
     if raw > 1:

diff --git a/cmd/zstream/zstream_decompress.c b/cmd/zstream/zstream_decompress.c
@@ -123,14 +123,16 @@ zstream_do_decompress(int argc, char *argv[])
 				type = ZIO_COMPRESS_LZJB;
 			else if (0 == strcmp("gzip", argv[i]))
 				type = ZIO_COMPRESS_GZIP_1;
+			else if (0 == strcmp("slack", argv[i]))
+				type = ZIO_COMPRESS_SLACK;
 			else if (0 == strcmp("zle", argv[i]))
 				type = ZIO_COMPRESS_ZLE;
 			else if (0 == strcmp("zstd", argv[i]))
 				type = ZIO_COMPRESS_ZSTD;
 			else {
 				fprintf(stderr, "Invalid compression type %s.\n"
-				    "Supported types are off, lz4, lzjb, gzip, "
-				    "zle, and zstd\n",
+				    "Supported types are off, lz4, lzjb, "
+				    "gzip, slack, zle, and zstd\n",
 				    argv[i]);
 				exit(2);
 			}
@@ -278,6 +280,9 @@ zstream_do_decompress(int argc, char *argv[])
 				case ZIO_COMPRESS_ZSTD:
 					xfunc = zfs_zstd_decompress;
 					break;
+				case ZIO_COMPRESS_SLACK:
+					xfunc = slack_decompress;
+					break;
 				default:
 					assert(B_FALSE);
 				}

diff --git a/include/sys/zio_compress.h b/include/sys/zio_compress.h
@@ -54,6 +54,7 @@ enum zio_compress {
 	ZIO_COMPRESS_ZLE,
 	ZIO_COMPRESS_LZ4,
 	ZIO_COMPRESS_ZSTD,
+	ZIO_COMPRESS_SLACK,
 	ZIO_COMPRESS_FUNCTIONS
 };
 
@@ -179,6 +180,10 @@ extern size_t lz4_compress_zfs(void *src, void *dst, size_t s_len, size_t d_len,
     int level);
 extern int lz4_decompress_zfs(void *src, void *dst, size_t s_len, size_t d_len,
     int level);
+extern size_t slack_compress(void *src, void *dst, size_t s_len, size_t d_len,
+    int level);
+extern int slack_decompress(void *src, void *dst, size_t s_len, size_t d_len,
+    int level);
 
 /*
  * Compress and decompress data if necessary.

diff --git a/include/zfeature_common.h b/include/zfeature_common.h
@@ -82,6 +82,7 @@ typedef enum spa_feature {
 	SPA_FEATURE_AVZ_V2,
 	SPA_FEATURE_REDACTION_LIST_SPILL,
 	SPA_FEATURE_RAIDZ_EXPANSION,
+	SPA_FEATURE_SLACK_COMPRESS,
 	SPA_FEATURES
 } spa_feature_t;
 

diff --git a/lib/libzfs/libzfs.abi b/lib/libzfs/libzfs.abi
@@ -607,7 +607,7 @@
     <elf-symbol name='fletcher_4_superscalar_ops' size='128' type='object-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='libzfs_config_ops' size='16' type='object-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='sa_protocol_names' size='16' type='object-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
-    <elf-symbol name='spa_feature_table' size='2296' type='object-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
+    <elf-symbol name='spa_feature_table' size='2352' type='object-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfeature_checks_disable' size='4' type='object-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_deleg_perm_tab' size='512' type='object-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_history_event_names' size='328' type='object-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
@@ -5963,7 +5963,8 @@
       <enumerator name='SPA_FEATURE_AVZ_V2' value='38'/>
       <enumerator name='SPA_FEATURE_REDACTION_LIST_SPILL' value='39'/>
       <enumerator name='SPA_FEATURE_RAIDZ_EXPANSION' value='40'/>
-      <enumerator name='SPA_FEATURES' value='41'/>
+      <enumerator name='SPA_FEATURE_SLACK_COMPRESS' value='41'/>
+      <enumerator name='SPA_FEATURES' value='42'/>
     </enum-decl>
     <typedef-decl name='spa_feature_t' type-id='33ecb627' id='d6618c78'/>
     <qualified-type-def type-id='22cce67b' const='yes' id='d2816df0'/>
@@ -9025,8 +9026,8 @@
     </function-decl>
   </abi-instr>
   <abi-instr address-size='64' path='module/zcommon/zfeature_common.c' language='LANG_C99'>
-    <array-type-def dimensions='1' type-id='83f29ca2' size-in-bits='18368' id='b93e4d14'>
-      <subrange length='41' type-id='7359adad' id='cb834f44'/>
+    <array-type-def dimensions='1' type-id='83f29ca2' size-in-bits='18816' id='b937914f'>
+      <subrange length='42' type-id='7359adad' id='cb7c937f'/>
     </array-type-def>
     <enum-decl name='zfeature_flags' id='6db816a4'>
       <underlying-type type-id='9cac1fee'/>
@@ -9103,7 +9104,7 @@
     <pointer-type-def type-id='611586a1' size-in-bits='64' id='2e243169'/>
     <qualified-type-def type-id='eaa32e2f' const='yes' id='83be723c'/>
     <pointer-type-def type-id='83be723c' size-in-bits='64' id='7acd98a2'/>
-    <var-decl name='spa_feature_table' type-id='b93e4d14' mangled-name='spa_feature_table' visibility='default' elf-symbol-id='spa_feature_table'/>
+    <var-decl name='spa_feature_table' type-id='b937914f' mangled-name='spa_feature_table' visibility='default' elf-symbol-id='spa_feature_table'/>
     <var-decl name='zfeature_checks_disable' type-id='c19b74c3' mangled-name='zfeature_checks_disable' visibility='default' elf-symbol-id='zfeature_checks_disable'/>
     <function-decl name='opendir' visibility='default' binding='global' size-in-bits='64'>
       <parameter type-id='80f4b756'/>

diff --git a/lib/libzpool/Makefile.am b/lib/libzpool/Makefile.am
@@ -122,6 +122,7 @@ nodist_libzpool_la_SOURCES = \
 	module/zfs/rrwlock.c \
 	module/zfs/sa.c \
 	module/zfs/sha2_zfs.c \
+	module/zfs/slack.c \
 	module/zfs/skein_zfs.c \
 	module/zfs/spa.c \
 	module/zfs/spa_checkpoint.c \

diff --git a/man/man7/zfsprops.7 b/man/man7/zfsprops.7
@@ -37,8 +37,9 @@
 .\" Copyright 2019 Joyent, Inc.
 .\" Copyright (c) 2019, Kjeld Schouten-Lebbing
 .\" Copyright (c) 2022 Hewlett Packard Enterprise Development LP.
+.\" Copyright (c) 2024, Klara, Inc.
 .\"
-.Dd August 8, 2023
+.Dd July 3, 2024
 .Dt ZFSPROPS 7
 .Os
 .
@@ -796,7 +797,7 @@ Changing this property affects only newly-written data.
 .It Xo
 .Sy compression Ns = Ns Sy on Ns | Ns Sy off Ns | Ns Sy gzip Ns | Ns
 .Sy gzip- Ns Ar N Ns | Ns Sy lz4 Ns | Ns Sy lzjb Ns | Ns Sy zle Ns | Ns Sy zstd Ns | Ns
-.Sy zstd- Ns Ar N Ns | Ns Sy zstd-fast Ns | Ns Sy zstd-fast- Ns Ar N
+.Sy zstd- Ns Ar N Ns | Ns Sy zstd-fast Ns | Ns Sy zstd-fast- Ns | Ns Sy slack Ns Ar N
 .Xc
 Controls the compression algorithm used for this dataset.
 .Pp
@@ -906,6 +907,11 @@ The
 .Sy zle
 compression algorithm compresses runs of zeros.
 .Pp
+The
+.Sy slack
+compression algorithm removes runs of zeroes from the end of blocks.
+It is useful when using very large block sizes with incompressible data.
+.Pp
 This property can also be referred to by its shortened column name
 .Sy compress .
 Changing this property affects only newly-written data.

diff --git a/man/man7/zpool-features.7 b/man/man7/zpool-features.7
@@ -14,11 +14,11 @@
 .\" CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your
 .\" own identifying information:
 .\" Portions Copyright [yyyy] [name of copyright owner]
-.\" Copyright (c) 2019, Klara Inc.
+.\" Copyright (c) 2019, 2024, Klara, Inc.
 .\" Copyright (c) 2019, Allan Jude
 .\" Copyright (c) 2021, Colm Buckley <[email protected]>
 .\"
-.Dd June 23, 2022
+.Dd July 3, 2024
 .Dt ZPOOL-FEATURES 7
 .Os
 .
@@ -858,6 +858,41 @@ preventing hash collision attacks on systems with dedup.
 .Pp
 .checksum-spiel skein
 .
+.feature com.klarasystems slack_compress no extensible_dataset
+.Sy slack
+is a compression option that simply removes the trailing run of zero bytes at
+the end of each block.
+It is designed for when very large block sizes are used with to store largely
+incompressible data.
+Normally in this scenario
+.Sy compress Ns = Ns Sy none
+would be used,
+but with large block sizes that can often leave a multi-megabyte run of zeroes
+at the end of a block, adding memory and checksumming overhead.
+.Pp
+When the
+.Sy slack_compress
+feature is set to
+.Sy enabled ,
+the administrator can turn on
+.Sy slack
+compression of any dataset using
+.Nm zfs Cm set Sy compress Ns = Ns Sy slack Ar dset
+.Po see Xr zfs-set 8 Pc .
+This feature becomes
+.Sy active
+once a
+.Sy compress
+property has been set to
+.Sy slack ,
+and will return to being
+.Sy enabled
+once all filesystems that have ever had their
+.Sy compress
+property set to
+.Sy slack
+are destroyed.
+.
 .feature com.delphix spacemap_histogram yes
 This features allows ZFS to maintain more information about how free space
 is organized within the pool.

diff --git a/man/man8/zstream.8 b/man/man8/zstream.8
@@ -104,6 +104,7 @@ Valid compression types include
 .Sy gzip ,
 .Sy lz4 ,
 .Sy lzjb ,
+.Sy slack ,
 .Sy zstd ,
 and
 .Sy zle .

diff --git a/module/Kbuild.in b/module/Kbuild.in
@@ -366,6 +366,7 @@ ZFS_OBJS := \
 	sa.o \
 	sha2_zfs.o \
 	skein_zfs.o \
+	slack.o \
 	spa.o \
 	spa_checkpoint.o \
 	spa_config.o \

diff --git a/module/Makefile.bsd b/module/Makefile.bsd
@@ -295,6 +295,7 @@ SRCS+=	abd.c \
 	sa.c \
 	sha2_zfs.c \
 	skein_zfs.c \
+	slack.c \
 	spa.c \
 	space_map.c \
 	space_reftree.c \

diff --git a/module/zcommon/zfeature_common.c b/module/zcommon/zfeature_common.c
@@ -754,6 +754,20 @@ zpool_feature_init(void)
 	    "Support for raidz expansion",
 	    ZFEATURE_FLAG_MOS, ZFEATURE_TYPE_BOOLEAN, NULL, sfeatures);
 
+	{
+		{
+		static const spa_feature_t slack_deps[] = {
+			SPA_FEATURE_EXTENSIBLE_DATASET,
+			SPA_FEATURE_NONE
+		};
+		zfeature_register(SPA_FEATURE_SLACK_COMPRESS,
+		    "com.klarasystems:slack_compress", "slack_compress",
+		    "slack compression support",
+		    ZFEATURE_FLAG_PER_DATASET, ZFEATURE_TYPE_BOOLEAN,
+		    slack_deps, sfeatures);
+		}
+	}
+
 	zfs_mod_list_supported_free(sfeatures);
 }
 

diff --git a/module/zcommon/zfs_prop.c b/module/zcommon/zfs_prop.c
@@ -130,6 +130,7 @@ zfs_prop_init(void)
 		{ "gzip-9",	ZIO_COMPRESS_GZIP_9 },
 		{ "zle",	ZIO_COMPRESS_ZLE },
 		{ "lz4",	ZIO_COMPRESS_LZ4 },
+		{ "slack",	ZIO_COMPRESS_SLACK },
 		{ "zstd",	ZIO_COMPRESS_ZSTD },
 		{ "zstd-fast",
 		    ZIO_COMPLEVEL_ZSTD(ZIO_ZSTD_LEVEL_FAST_DEFAULT) },

diff --git a/module/zfs/slack.c b/module/zfs/slack.c
@@ -0,0 +1,67 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2024, Klara, Inc.
+ */
+
+#include <sys/zio_compress.h>
+#include <sys/types.h>
+
+/*
+ * Slack compression simply searches for the last non-zero byte in the buffer,
+ * and sets the position as the size of the "compressed" data.
+ */
+
+size_t
+slack_compress(void *src, void *dst, size_t s_len, size_t d_len, int level)
+{
+	(void) level;
+
+	ASSERT3U(s_len, >, 0);
+	ASSERT0(P2PHASE(s_len, sizeof (uint64_t)));
+
+	uint64_t *buf = (uint64_t *)src;
+
+	int p = (s_len / sizeof (uint64_t)) - 1;
+	for (; p >= 0; p--)
+		if (buf[p] != 0)
+			break;
+
+	if (p < 0)
+		return (s_len);
+
+	size_t c_len = (p + 1) * sizeof (uint64_t);
+	if (c_len > d_len)
+		return (s_len);
+
+	memcpy(dst, src, c_len);
+	return (c_len);
+}
+
+int
+slack_decompress(void *src, void *dst, size_t s_len, size_t d_len, int level)
+{
+	(void) level;
+	ASSERT3U(d_len, >=, s_len);
+	memcpy(dst, src, s_len);
+	return (0);
+}
diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
@@ -4670,6 +4670,20 @@ zfs_check_settable(const char *dsname, nvpair_t *pair, cred_t *cr)
 				}
 				spa_close(spa, FTAG);
 			}
+
+			if (compval == ZIO_COMPRESS_SLACK) {
+				spa_t *spa;
+
+				if ((err = spa_open(dsname, &spa, FTAG)) != 0)
+					return (err);
+
+				if (!spa_feature_is_enabled(spa,
+				    SPA_FEATURE_SLACK_COMPRESS)) {
+					spa_close(spa, FTAG);
+					return (SET_ERROR(ENOTSUP));
+				}
+				spa_close(spa, FTAG);
+			}
 		}
 		break;
 

diff --git a/module/zfs/zio_compress.c b/module/zfs/zio_compress.c
@@ -68,6 +68,7 @@ zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = {
 	{"lz4",		0,	lz4_compress_zfs, lz4_decompress_zfs, NULL},
 	{"zstd",	ZIO_ZSTD_LEVEL_DEFAULT,	zfs_zstd_compress_wrap,
 	    zfs_zstd_decompress, zfs_zstd_decompress_level},
+	{"slack",	0,	slack_compress,	slack_decompress, NULL },
 };
 
 uint8_t
@@ -218,6 +219,8 @@ zio_compress_to_feature(enum zio_compress comp)
 	switch (comp) {
 	case ZIO_COMPRESS_ZSTD:
 		return (SPA_FEATURE_ZSTD_COMPRESS);
+	case ZIO_COMPRESS_SLACK:
+		return (SPA_FEATURE_SLACK_COMPRESS);
 	default:
 		break;
 	}

diff --git a/tests/zfs-tests/include/properties.shlib b/tests/zfs-tests/include/properties.shlib
@@ -16,7 +16,7 @@
 
 . $STF_SUITE/include/libtest.shlib
 
-typeset -a compress_prop_vals=('off' 'lzjb' 'lz4' 'gzip' 'zle' 'zstd')
+typeset -a compress_prop_vals=('off' 'lzjb' 'lz4' 'gzip' 'zle' 'zstd' 'slack')
 typeset -a checksum_prop_vals=('on' 'off' 'fletcher2' 'fletcher4' 'sha256'
     'noparity' 'sha512' 'skein' 'blake3')
 if ! is_freebsd; then

diff --git a/tests/zfs-tests/tests/functional/cli_root/zpool_get/zpool_get.cfg b/tests/zfs-tests/tests/functional/cli_root/zpool_get/zpool_get.cfg
@@ -107,5 +107,6 @@ if is_linux || is_freebsd; then
 	    "feature@block_cloning"
 	    "feature@vdev_zaps_v2"
 	    "feature@raidz_expansion"
+	    "feature@slack_compress"
 	)
 fi