Add option none to zfs redundant_metadata property

include/sys/dmu.h

@@ -27,6 +27,7 @@
  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
  * Copyright 2013 Saso Kiselkov. All rights reserved.
  * Copyright (c) 2017, Intel Corporation.
+ * Copyright (c) 2022 Hewlett Packard Enterprise Development LP.
  */
 
 /* Portions Copyright 2010 Robert Milkowski */
@@ -142,6 +143,12 @@ typedef enum dmu_object_byteswap {
 #define	DMU_OT_IS_DDT(ot) \
 	((ot) == DMU_OT_DDT_ZAP)
 
+#define	DMU_OT_IS_CRITICAL(ot) \
+	(DMU_OT_IS_METADATA(ot) && \
+	(ot) != DMU_OT_DNODE && \
+	(ot) != DMU_OT_DIRECTORY_CONTENTS && \
+	(ot) != DMU_OT_SA)
+
 /* Note: ztest uses DMU_OT_UINT64_OTHER as a proxy for file blocks */
 #define	DMU_OT_IS_FILE(ot) \
 	((ot) == DMU_OT_PLAIN_FILE_CONTENTS || (ot) == DMU_OT_UINT64_OTHER)

include/sys/fs/zfs.h

@@ -29,6 +29,7 @@
  * Copyright (c) 2019 Datto Inc.
  * Portions Copyright 2010 Robert Milkowski
  * Copyright (c) 2021, Colm Buckley <[email protected]>
+ * Copyright (c) 2022 Hewlett Packard Enterprise Development LP.
  */
 
 #ifndef	_SYS_FS_ZFS_H
@@ -501,7 +502,9 @@ typedef enum {
 
 typedef enum {
 	ZFS_REDUNDANT_METADATA_ALL,
-	ZFS_REDUNDANT_METADATA_MOST
+	ZFS_REDUNDANT_METADATA_MOST,
+	ZFS_REDUNDANT_METADATA_SOME,
+	ZFS_REDUNDANT_METADATA_NONE
 } zfs_redundant_metadata_type_t;
 
 typedef enum {

man/man7/zfsprops.7

@@ -36,8 +36,9 @@
 .\" Copyright 2018 Nexenta Systems, Inc.
 .\" Copyright 2019 Joyent, Inc.
 .\" Copyright (c) 2019, Kjeld Schouten-Lebbing
+.\" Copyright (c) 2022 Hewlett Packard Enterprise Development LP.
 .\"
-.Dd May 24, 2021
+.Dd July 21, 2022
 .Dt ZFSPROPS 7
 .Os
 .
@@ -1454,7 +1455,7 @@ affects only files created afterward; existing files are unaffected.
 .Pp
 This property can also be referred to by its shortened column name,
 .Sy recsize .
-.It Sy redundant_metadata Ns = Ns Sy all Ns | Ns Sy most
+.It Sy redundant_metadata Ns = Ns Sy all Ns | Ns Sy most Ns | Ns Sy some Ns | Ns Sy none
 Controls what types of metadata are stored redundantly.
 ZFS stores an extra copy of metadata, so that if a single block is corrupted,
 the amount of user data lost is limited.
@@ -1486,7 +1487,7 @@ When set to
 ZFS stores an extra copy of most types of metadata.
 This can improve performance of random writes, because less metadata must be
 written.
-In practice, at worst about 100 blocks
+In practice, at worst about 1000 blocks
 .Po of
 .Sy recordsize
 bytes each
@@ -1495,6 +1496,17 @@ of user data can be lost if a single on-disk block is corrupt.
 The exact behavior of which metadata blocks are stored redundantly may change in
 future releases.
 .Pp
+When set to
+.Sy some ,
+ZFS stores an extra copy of only critical metadata.
+This can improve file create performance since less metadata needs to be written.
+If a single on-disk block is corrupt, at worst a single user file can be lost.
+.Pp
+When set to
+.Sy none ,
+ZFS does not store any copies of metadata redundantly.
+If a single on-disk block is corrupt, an entire dataset can be lost.
+.Pp
 The default value is
 .Sy all .
 .It Sy refquota Ns = Ns Ar size Ns | Ns Sy none

module/zcommon/zfs_prop.c

@@ -25,6 +25,7 @@
  * Copyright 2016, Joyent, Inc.
  * Copyright (c) 2019, Klara Inc.
  * Copyright (c) 2019, Allan Jude
+ * Copyright (c) 2022 Hewlett Packard Enterprise Development LP.
  */
 
 /* Portions Copyright 2010 Robert Milkowski */
@@ -369,6 +370,8 @@ zfs_prop_init(void)
 	static const zprop_index_t redundant_metadata_table[] = {
 		{ "all",	ZFS_REDUNDANT_METADATA_ALL },
 		{ "most",	ZFS_REDUNDANT_METADATA_MOST },
+		{ "some",	ZFS_REDUNDANT_METADATA_SOME },
+		{ "none",	ZFS_REDUNDANT_METADATA_NONE },
 		{ NULL }
 	};
 
@@ -388,7 +391,7 @@ zfs_prop_init(void)
 	zprop_register_index(ZFS_PROP_REDUNDANT_METADATA, "redundant_metadata",
 	    ZFS_REDUNDANT_METADATA_ALL,
 	    PROP_INHERIT, ZFS_TYPE_FILESYSTEM | ZFS_TYPE_VOLUME,
-	    "all | most", "REDUND_MD",
+	    "all | most | some | none", "REDUND_MD",
 	    redundant_metadata_table, sfeatures);
 	zprop_register_index(ZFS_PROP_SYNC, "sync", ZFS_SYNC_STANDARD,
 	    PROP_INHERIT, ZFS_TYPE_FILESYSTEM | ZFS_TYPE_VOLUME,

module/zfs/dmu.c

@@ -28,6 +28,7 @@
  * Copyright (c) 2019 Datto Inc.
  * Copyright (c) 2019, Klara Inc.
  * Copyright (c) 2019, Allan Jude
+ * Copyright (c) 2022 Hewlett Packard Enterprise Development LP.
  */
 
 #include <sys/dmu.h>
@@ -1992,12 +1993,22 @@ dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp, zio_prop_t *zp)
 		    ZCHECKSUM_FLAG_EMBEDDED))
 			checksum = ZIO_CHECKSUM_FLETCHER_4;
 
-		if (os->os_redundant_metadata == ZFS_REDUNDANT_METADATA_ALL ||
-		    (os->os_redundant_metadata ==
-		    ZFS_REDUNDANT_METADATA_MOST &&
-		    (level >= zfs_redundant_metadata_most_ditto_level ||
-		    DMU_OT_IS_METADATA(type) || (wp & WP_SPILL))))
+		switch (os->os_redundant_metadata) {
+		case ZFS_REDUNDANT_METADATA_ALL:
 			copies++;
+			break;
+		case ZFS_REDUNDANT_METADATA_MOST:
+			if (level >= zfs_redundant_metadata_most_ditto_level ||
+			    DMU_OT_IS_METADATA(type) || (wp & WP_SPILL))
+				copies++;
+			break;
+		case ZFS_REDUNDANT_METADATA_SOME:
+			if (DMU_OT_IS_CRITICAL(type))
+				copies++;
+			break;
+		case ZFS_REDUNDANT_METADATA_NONE:
+			break;
+		}
 	} else if (wp & WP_NOFILL) {
 		ASSERT(level == 0);
 

module/zfs/dmu_objset.c

@@ -32,6 +32,7 @@
  * Copyright (c) 2018, loli10K <[email protected]>. All rights reserved.
  * Copyright (c) 2019, Klara Inc.
  * Copyright (c) 2019, Allan Jude
+ * Copyright (c) 2022 Hewlett Packard Enterprise Development LP.
  */
 
 /* Portions Copyright 2010 Robert Milkowski */
@@ -287,7 +288,9 @@ redundant_metadata_changed_cb(void *arg, uint64_t newval)
 	 * Inheritance and range checking should have been done by now.
 	 */
 	ASSERT(newval == ZFS_REDUNDANT_METADATA_ALL ||
-	    newval == ZFS_REDUNDANT_METADATA_MOST);
+	    newval == ZFS_REDUNDANT_METADATA_MOST ||
+	    newval == ZFS_REDUNDANT_METADATA_SOME ||
+	    newval == ZFS_REDUNDANT_METADATA_NONE);
 
 	os->os_redundant_metadata = newval;
 }

module/zfs/dsl_prop.c

@@ -23,6 +23,7 @@
  * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
  * Copyright (c) 2013 Martin Matuska. All rights reserved.
  * Copyright 2019 Joyent, Inc.
+ * Copyright (c) 2022 Hewlett Packard Enterprise Development LP.
  */
 
 #include <sys/zfs_context.h>
@@ -41,6 +42,7 @@
 
 #define	ZPROP_INHERIT_SUFFIX "$inherit"
 #define	ZPROP_RECVD_SUFFIX "$recvd"
+#define	ZPROP_IUV_SUFFIX "$iuv"
 
 static int
 dodefault(zfs_prop_t prop, int intsz, int numints, void *buf)
@@ -69,6 +71,16 @@ dodefault(zfs_prop_t prop, int intsz, int numints, void *buf)
 	return (0);
 }
 
+static int
+dsl_prop_known_index(zfs_prop_t prop, uint64_t value)
+{
+	const char *str = NULL;
+	if (zfs_prop_get_type(prop) == PROP_TYPE_INDEX)
+		return (!zfs_prop_index_to_string(prop, value, &str));
+
+	return (-1);
+}
+
 int
 dsl_prop_get_dd(dsl_dir_t *dd, const char *propname,
     int intsz, int numints, void *buf, char *setpoint, boolean_t snapshot)
@@ -81,6 +93,7 @@ dsl_prop_get_dd(dsl_dir_t *dd, const char *propname,
 	boolean_t inheriting = B_FALSE;
 	char *inheritstr;
 	char *recvdstr;
+	char *iuvstr;
 
 	ASSERT(dsl_pool_config_held(dd->dd_pool));
 
@@ -91,6 +104,7 @@ dsl_prop_get_dd(dsl_dir_t *dd, const char *propname,
 	inheritable = (prop == ZPROP_USERPROP || zfs_prop_inheritable(prop));
 	inheritstr = kmem_asprintf("%s%s", propname, ZPROP_INHERIT_SUFFIX);
 	recvdstr = kmem_asprintf("%s%s", propname, ZPROP_RECVD_SUFFIX);
+	iuvstr = kmem_asprintf("%s%s", propname, ZPROP_IUV_SUFFIX);
 
 	/*
 	 * Note: dd may become NULL, therefore we shouldn't dereference it
@@ -105,6 +119,18 @@ dsl_prop_get_dd(dsl_dir_t *dd, const char *propname,
 			inheriting = B_TRUE;
 		}
 
+		/* Check for a iuv value. */
+		err = zap_lookup(mos, dsl_dir_phys(dd)->dd_props_zapobj,
+		    iuvstr, intsz, numints, buf);
+		if (dsl_prop_known_index(zfs_name_to_prop(propname),
+		    *(uint64_t *)buf) != 1)
+			err = ENOENT;
+		if (err != ENOENT) {
+			if (setpoint != NULL && err == 0)
+				dsl_dir_name(dd, setpoint);
+			break;
+		}
+
 		/* Check for a local value. */
 		err = zap_lookup(mos, dsl_dir_phys(dd)->dd_props_zapobj,
 		    propname, intsz, numints, buf);
@@ -155,6 +181,7 @@ dsl_prop_get_dd(dsl_dir_t *dd, const char *propname,
 
 	kmem_strfree(inheritstr);
 	kmem_strfree(recvdstr);
+	kmem_strfree(iuvstr);
 
 	return (err);
 }
@@ -647,6 +674,45 @@ dsl_prop_changed_notify(dsl_pool_t *dp, uint64_t ddobj,
 	dsl_dir_rele(dd, FTAG);
 }
 
+
+/*
+ * For newer values in zfs index type properties, we add a new key
+ * propname$iuv (iuv = Ignore Unknown Values) to the properties zap object
+ * to store the new property value and store the default value in the
+ * existing prop key. So that the propname$iuv key is ignored by the older zfs
+ * versions and the default property value from the existing prop key is
+ * used.
+ */
+static void
+dsl_prop_set_iuv(objset_t *mos, uint64_t zapobj, const char *propname,
+    int intsz, int numints, const void *value, dmu_tx_t *tx)
+{
+	char *iuvstr = kmem_asprintf("%s%s", propname, ZPROP_IUV_SUFFIX);
+	boolean_t iuv = B_FALSE;
+	zfs_prop_t prop = zfs_name_to_prop(propname);
+
+	switch (prop) {
+	case ZFS_PROP_REDUNDANT_METADATA:
+		if (*(uint64_t *)value == ZFS_REDUNDANT_METADATA_SOME ||
+		    *(uint64_t *)value == ZFS_REDUNDANT_METADATA_NONE)
+			iuv = B_TRUE;
+		break;
+	default:
+		break;
+	}
+
+	if (iuv) {
+		VERIFY0(zap_update(mos, zapobj, iuvstr, intsz, numints,
+		    value, tx));
+		uint64_t val = zfs_prop_default_numeric(prop);
+		VERIFY0(zap_update(mos, zapobj, propname, intsz, numints,
+		    &val, tx));
+	} else {
+		zap_remove(mos, zapobj, iuvstr, tx);
+	}
+	kmem_strfree(iuvstr);
+}
+
 void
 dsl_prop_set_sync_impl(dsl_dataset_t *ds, const char *propname,
     zprop_source_t source, int intsz, int numints, const void *value,
@@ -659,6 +725,7 @@ dsl_prop_set_sync_impl(dsl_dataset_t *ds, const char *propname,
 	const char *valstr = NULL;
 	char *inheritstr;
 	char *recvdstr;
+	char *iuvstr;
 	char *tbuf = NULL;
 	int err;
 	uint64_t version = spa_version(ds->ds_dir->dd_pool->dp_spa);
@@ -692,6 +759,7 @@ dsl_prop_set_sync_impl(dsl_dataset_t *ds, const char *propname,
 
 	inheritstr = kmem_asprintf("%s%s", propname, ZPROP_INHERIT_SUFFIX);
 	recvdstr = kmem_asprintf("%s%s", propname, ZPROP_RECVD_SUFFIX);
+	iuvstr = kmem_asprintf("%s%s", propname, ZPROP_IUV_SUFFIX);
 
 	switch ((int)source) {
 	case ZPROP_SRC_NONE:
@@ -709,11 +777,14 @@ dsl_prop_set_sync_impl(dsl_dataset_t *ds, const char *propname,
 		/*
 		 * remove propname$inherit
 		 * set propname -> value
+		 * set propname$iuv -> new property value
 		 */
 		err = zap_remove(mos, zapobj, inheritstr, tx);
 		ASSERT(err == 0 || err == ENOENT);
 		VERIFY0(zap_update(mos, zapobj, propname,
 		    intsz, numints, value, tx));
+		(void) dsl_prop_set_iuv(mos, zapobj, propname, intsz,
+		    numints, value, tx);
 		break;
 	case ZPROP_SRC_INHERITED:
 		/*
@@ -723,6 +794,8 @@ dsl_prop_set_sync_impl(dsl_dataset_t *ds, const char *propname,
 		 */
 		err = zap_remove(mos, zapobj, propname, tx);
 		ASSERT(err == 0 || err == ENOENT);
+		err = zap_remove(mos, zapobj, iuvstr, tx);
+		ASSERT(err == 0 || err == ENOENT);
 		if (version >= SPA_VERSION_RECVD_PROPS &&
 		    dsl_prop_get_int_ds(ds, ZPROP_HAS_RECVD, &dummy) == 0) {
 			dummy = 0;
@@ -763,6 +836,7 @@ dsl_prop_set_sync_impl(dsl_dataset_t *ds, const char *propname,
 
 	kmem_strfree(inheritstr);
 	kmem_strfree(recvdstr);
+	kmem_strfree(iuvstr);
 
 	/*
 	 * If we are left with an empty snap zap we can destroy it.
@@ -1012,6 +1086,14 @@ dsl_prop_get_all_impl(objset_t *mos, uint64_t propobj,
 
 			propname = za.za_name;
 			source = setpoint;
+
+			/* Skip if iuv entries are preset. */
+			valstr = kmem_asprintf("%s%s", propname,
+			    ZPROP_IUV_SUFFIX);
+			err = zap_contains(mos, propobj, valstr);
+			kmem_strfree(valstr);
+			if (err == 0)
+				continue;
 		} else if (strcmp(suffix, ZPROP_INHERIT_SUFFIX) == 0) {
 			/* Skip explicitly inherited entries. */
 			continue;
@@ -1044,6 +1126,16 @@ dsl_prop_get_all_impl(objset_t *mos, uint64_t propobj,
 
 			source = ((flags & DSL_PROP_GET_INHERITING) ?
 			    setpoint : ZPROP_SOURCE_VAL_RECVD);
+		} else if (strcmp(suffix, ZPROP_IUV_SUFFIX) == 0) {
+			(void) strlcpy(buf, za.za_name,
+			    MIN(sizeof (buf), suffix - za.za_name + 1));
+			propname = buf;
+			source = setpoint;
+			prop = zfs_name_to_prop(propname);
+
+			if (dsl_prop_known_index(prop,
+			    za.za_first_integer) != 1)
+				continue;
 		} else {
 			/*
 			 * For backward compatibility, skip suffixes we don't

tests/zfs-tests/include/properties.shlib

@@ -11,6 +11,7 @@
 
 #
 # Copyright (c) 2012, 2016, Delphix. All rights reserved.
+# Copyright (c) 2022 Hewlett Packard Enterprise Development LP.
 #
 
 . $STF_SUITE/include/libtest.shlib
@@ -27,7 +28,7 @@ typeset -a canmount_prop_vals=('on' 'off' 'noauto')
 typeset -a copies_prop_vals=('1' '2' '3')
 typeset -a logbias_prop_vals=('latency' 'throughput')
 typeset -a primarycache_prop_vals=('all' 'none' 'metadata')
-typeset -a redundant_metadata_prop_vals=('all' 'most')
+typeset -a redundant_metadata_prop_vals=('all' 'most' 'some' 'none')
 typeset -a secondarycache_prop_vals=('all' 'none' 'metadata')
 typeset -a snapdir_prop_vals=('hidden' 'visible')
 typeset -a sync_prop_vals=('standard' 'always' 'disabled')