feature: large_microzap

include/sys/fs/zfs.h

@@ -30,6 +30,7 @@
  * Portions Copyright 2010 Robert Milkowski
  * Copyright (c) 2021, Colm Buckley <[email protected]>
  * Copyright (c) 2022 Hewlett Packard Enterprise Development LP.
+ * Copyright (c) 2024, Klara, Inc.
  */
 
 #ifndef	_SYS_FS_ZFS_H
@@ -1631,6 +1632,7 @@ typedef enum {
 	ZFS_ERR_CRYPTO_NOTSUP,
 	ZFS_ERR_RAIDZ_EXPAND_IN_PROGRESS,
 	ZFS_ERR_ASHIFT_MISMATCH,
+	ZFS_ERR_STREAM_LARGE_MICROZAP,
 } zfs_errno_t;
 
 /*

include/sys/zap_impl.h

@@ -24,6 +24,7 @@
  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
  * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
  * Copyright 2017 Nexenta Systems, Inc.
+ * Copyright (c) 2024, Klara, Inc.
  */
 
 #ifndef	_SYS_ZAP_IMPL_H
@@ -45,7 +46,6 @@ extern int fzap_default_block_shift;
 
 #define	MZAP_ENT_LEN		64
 #define	MZAP_NAME_LEN		(MZAP_ENT_LEN - 8 - 4 - 2)
-#define	MZAP_MAX_BLKSZ		SPA_OLD_MAXBLOCKSIZE
 
 #define	ZAP_NEED_CD		(-1U)
 
@@ -210,6 +210,8 @@ int zap_hashbits(zap_t *zap);
 uint32_t zap_maxcd(zap_t *zap);
 uint64_t zap_getflags(zap_t *zap);
 
+uint64_t zap_get_micro_max_size(spa_t *spa);
+
 #define	ZAP_HASH_IDX(hash, n) (((n) == 0) ? 0 : ((hash) >> (64 - (n))))
 
 void fzap_byteswap(void *buf, size_t size);

include/sys/zfs_ioctl.h

@@ -23,6 +23,7 @@
  * Copyright (c) 2012, 2024 by Delphix. All rights reserved.
  * Copyright 2016 RackTop Systems.
  * Copyright (c) 2017, Intel Corporation.
+ * Copyright (c) 2024, Klara, Inc.
  */
 
 #ifndef	_SYS_ZFS_IOCTL_H
@@ -145,6 +146,7 @@ typedef enum drr_headertype {
  */
 #define	DMU_BACKUP_FEATURE_SWITCH_TO_LARGE_BLOCKS (1 << 27)
 #define	DMU_BACKUP_FEATURE_LONGNAME		(1 << 28)
+#define	DMU_BACKUP_FEATURE_LARGE_MICROZAP	(1 << 29)
 
 /*
  * Mask of all supported backup features
@@ -155,7 +157,8 @@ typedef enum drr_headertype {
     DMU_BACKUP_FEATURE_COMPRESSED | DMU_BACKUP_FEATURE_LARGE_DNODE | \
     DMU_BACKUP_FEATURE_RAW | DMU_BACKUP_FEATURE_HOLDS | \
     DMU_BACKUP_FEATURE_REDACTED | DMU_BACKUP_FEATURE_SWITCH_TO_LARGE_BLOCKS | \
-    DMU_BACKUP_FEATURE_ZSTD | DMU_BACKUP_FEATURE_LONGNAME)
+    DMU_BACKUP_FEATURE_ZSTD | DMU_BACKUP_FEATURE_LONGNAME | \
+    DMU_BACKUP_FEATURE_LARGE_MICROZAP)
 
 /* Are all features in the given flag word currently supported? */
 #define	DMU_STREAM_SUPPORTED(x)	(!((x) & ~DMU_BACKUP_FEATURE_MASK))

include/zfeature_common.h

@@ -24,6 +24,7 @@
  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
  * Copyright (c) 2017, Intel Corporation.
+ * Copyright (c) 2024, Klara, Inc.
  */
 
 #ifndef _ZFEATURE_COMMON_H
@@ -84,6 +85,7 @@ typedef enum spa_feature {
 	SPA_FEATURE_RAIDZ_EXPANSION,
 	SPA_FEATURE_FAST_DEDUP,
 	SPA_FEATURE_LONGNAME,
+	SPA_FEATURE_LARGE_MICROZAP,
 	SPA_FEATURES
 } spa_feature_t;
 

lib/libzfs/libzfs.abi

@@ -629,7 +629,7 @@
     <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='2408' type='object-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
+    <elf-symbol name='spa_feature_table' size='2464' 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'/>
@@ -6194,7 +6194,8 @@
       <enumerator name='SPA_FEATURE_RAIDZ_EXPANSION' value='40'/>
       <enumerator name='SPA_FEATURE_FAST_DEDUP' value='41'/>
       <enumerator name='SPA_FEATURE_LONGNAME' value='42'/>
-      <enumerator name='SPA_FEATURES' value='43'/>
+      <enumerator name='SPA_FEATURE_LARGE_MICROZAP' value='43'/>
+      <enumerator name='SPA_FEATURES' value='44'/>
     </enum-decl>
     <typedef-decl name='spa_feature_t' type-id='33ecb627' id='d6618c78'/>
     <qualified-type-def type-id='80f4b756' const='yes' id='b99c00c9'/>
@@ -9373,8 +9374,8 @@
     </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='19264' id='bd39d632'>
-      <subrange length='43' type-id='7359adad' id='8f7e73a2'/>
+    <array-type-def dimensions='1' type-id='83f29ca2' size-in-bits='19712' id='fd4573e5'>
+      <subrange length='44' type-id='7359adad' id='cf8ba455'/>
     </array-type-def>
     <enum-decl name='zfeature_flags' id='6db816a4'>
       <underlying-type type-id='9cac1fee'/>
@@ -9451,7 +9452,7 @@
     <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='bd39d632' mangled-name='spa_feature_table' visibility='default' elf-symbol-id='spa_feature_table'/>
+    <var-decl name='spa_feature_table' type-id='fd4573e5' 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'/>

lib/libzfs/libzfs_sendrecv.c

@@ -30,6 +30,7 @@
  * Copyright 2016 Igor Kozhukhov <[email protected]>
  * Copyright (c) 2018, loli10K <[email protected]>. All rights reserved.
  * Copyright (c) 2019 Datto Inc.
+ * Copyright (c) 2024, Klara, Inc.
  */
 
 #include <assert.h>
@@ -2828,7 +2829,12 @@ zfs_send_one_cb_impl(zfs_handle_t *zhp, const char *from, int fd,
 		case EROFS:
 			zfs_error_aux(hdl, "%s", zfs_strerror(errno));
 			return (zfs_error(hdl, EZFS_BADBACKUP, errbuf));
-
+		case ZFS_ERR_STREAM_LARGE_MICROZAP:
+			zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
+			    "source snapshot contains large microzaps, "
+			    "need -L (--large-block) or -w (--raw) to "
+			    "generate stream"));
+			return (zfs_error(hdl, EZFS_BADBACKUP, errbuf));
 		default:
 			return (zfs_standard_error(hdl, errno, errbuf));
 		}

man/man4/zfs.4

@@ -16,7 +16,9 @@
 .\" own identifying information:
 .\" Portions Copyright [yyyy] [name of copyright owner]
 .\"
-.Dd June 27, 2024
+.\" Copyright (c) 2024, Klara, Inc.
+.\"
+.Dd October 2, 2024
 .Dt ZFS 4
 .Os
 .
@@ -614,7 +616,11 @@ However, this is limited by
 .
 .It Sy zap_micro_max_size Ns = Ns Sy 131072 Ns B Po 128 KiB Pc Pq int
 Maximum micro ZAP size.
-A micro ZAP is upgraded to a fat ZAP, once it grows beyond the specified size.
+A "micro" ZAP is upgraded to a "fat" ZAP once it grows beyond the specified
+size.
+Sizes higher than 128KiB will be clamped to 128KiB unless the
+.Sy large_microzap
+feature is enabled.
 .
 .It Sy zap_shrink_enabled Ns = Ns Sy 1 Ns | Ns 0 Pq int
 If set, adjacent empty ZAP blocks will be collapsed, reducing disk space.

man/man7/zpool-features.7

@@ -14,12 +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, 2023, 2024, Klara, Inc.
 .\" Copyright (c) 2019, Allan Jude
 .\" Copyright (c) 2021, Colm Buckley <[email protected]>
-.\" Copyright (c) 2023, Klara Inc.
 .\"
-.Dd February 14, 2024
+.Dd October 2, 2024
 .Dt ZPOOL-FEATURES 7
 .Os
 .
@@ -706,6 +705,24 @@ are destroyed.
 Large dnodes allow more data to be stored in the bonus buffer,
 thus potentially improving performance by avoiding the use of spill blocks.
 .
+.feature com.klarasystems large_microzap yes extensible_dataset large_blocks
+This feature allows "micro" ZAPs to grow larger than 128 KiB without being
+upgraded to "fat" ZAPs.
+.Pp
+This feature becomes
+.Sy active
+the first time a micro ZAP grows larger than 128KiB.
+It will only be returned to the
+.Sy enabled
+state when all datasets that ever had a large micro ZAP are destroyed.
+.Pp
+Note that even when this feature is enabled, micro ZAPs cannot grow larger
+than 128 KiB without also changing the
+.Sy zap_micro_max_size
+module parameter.
+See
+.Xr zfs 4 .
+.
 .feature com.delphix livelist yes extensible_dataset
 This feature allows clones to be deleted faster than the traditional method
 when a large number of random/sparse writes have been made to the clone.

man/man8/zfs-send.8

@@ -28,8 +28,9 @@
 .\" Copyright 2019 Richard Laager. All rights reserved.
 .\" Copyright 2018 Nexenta Systems, Inc.
 .\" Copyright 2019 Joyent, Inc.
+.\" Copyright (c) 2024, Klara, Inc.
 .\"
-.Dd July 27, 2023
+.Dd October 2, 2024
 .Dt ZFS-SEND 8
 .Os
 .
@@ -111,6 +112,9 @@ property of this filesystem has never been set above 128 KiB.
 The receiving system must have the
 .Sy large_blocks
 pool feature enabled as well.
+This flag is required if the
+.Sy large_microzap
+pool feature is active.
 See
 .Xr zpool-features 7
 for details on ZFS feature flags and the

module/zcommon/zfeature_common.c

@@ -25,7 +25,7 @@
  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
  * Copyright (c) 2014, Nexenta Systems, Inc. All rights reserved.
  * Copyright (c) 2017, Intel Corporation.
- * Copyright (c) 2019, Klara Inc.
+ * Copyright (c) 2019, 2024, Klara, Inc.
  * Copyright (c) 2019, Allan Jude
  */
 
@@ -772,6 +772,19 @@ zpool_feature_init(void)
 		    longname_deps, sfeatures);
 	}
 
+	{
+		static const spa_feature_t large_microzap_deps[] = {
+			SPA_FEATURE_EXTENSIBLE_DATASET,
+			SPA_FEATURE_LARGE_BLOCKS,
+			SPA_FEATURE_NONE
+		};
+		zfeature_register(SPA_FEATURE_LARGE_MICROZAP,
+		    "com.klarasystems:large_microzap", "large_microzap",
+		    "Support for microzaps larger than 128KB.",
+		    ZFEATURE_FLAG_PER_DATASET | ZFEATURE_FLAG_READONLY_COMPAT,
+		    ZFEATURE_TYPE_BOOLEAN, large_microzap_deps, sfeatures);
+	}
+
 	zfs_mod_list_supported_free(sfeatures);
 }
 

module/zfs/dmu_recv.c

@@ -25,7 +25,7 @@
  * Copyright (c) 2014, Joyent, Inc. All rights reserved.
  * Copyright 2014 HybridCluster. All rights reserved.
  * Copyright (c) 2018, loli10K <[email protected]>. All rights reserved.
- * Copyright (c) 2019, Klara Inc.
+ * Copyright (c) 2019, 2024, Klara, Inc.
  * Copyright (c) 2019, Allan Jude
  * Copyright (c) 2019 Datto Inc.
  * Copyright (c) 2022 Axcient.
@@ -593,6 +593,9 @@ recv_begin_check_feature_flags_impl(uint64_t featureflags, spa_t *spa)
 	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_DNODE) &&
 	    !spa_feature_is_enabled(spa, SPA_FEATURE_LARGE_DNODE))
 		return (SET_ERROR(ENOTSUP));
+	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_MICROZAP) &&
+	    !spa_feature_is_enabled(spa, SPA_FEATURE_LARGE_MICROZAP))
+		return (SET_ERROR(ENOTSUP));
 
 	/*
 	 * Receiving redacted streams requires that redacted datasets are
@@ -994,6 +997,24 @@ dmu_recv_begin_sync(void *arg, dmu_tx_t *tx)
 		    numredactsnaps, tx);
 	}
 
+	if (featureflags & DMU_BACKUP_FEATURE_LARGE_MICROZAP) {
+		/*
+		 * The source has seen a large microzap at least once in its
+		 * life, so we activate the feature here to match. It's not
+		 * strictly necessary since a large microzap is usable without
+		 * the feature active, but if that object is sent on from here,
+		 * we need this info to know to add the stream feature.
+		 *
+		 * There may be no large microzap in the incoming stream, or
+		 * ever again, but this is a very niche feature and its very
+		 * difficult to spot a large microzap in the stream, so its
+		 * not worth the effort of trying harder to activate the
+		 * feature at first use.
+		 */
+		dsl_dataset_activate_feature(dsobj, SPA_FEATURE_LARGE_MICROZAP,
+		    (void *)B_TRUE, tx);
+	}
+
 	dmu_buf_will_dirty(newds->ds_dbuf, tx);
 	dsl_dataset_phys(newds)->ds_flags |= DS_FLAG_INCONSISTENT;
 

module/zfs/dmu_send.c

@@ -26,7 +26,7 @@
  * Copyright 2014 HybridCluster. All rights reserved.
  * Copyright 2016 RackTop Systems.
  * Copyright (c) 2016 Actifio, Inc. All rights reserved.
- * Copyright (c) 2019, Klara Inc.
+ * Copyright (c) 2019, 2024, Klara, Inc.
  * Copyright (c) 2019, Allan Jude
  */
 
@@ -2015,6 +2015,17 @@ setup_featureflags(struct dmu_send_params *dspp, objset_t *os,
 	if (dsl_dataset_feature_is_active(to_ds, SPA_FEATURE_LONGNAME)) {
 		*featureflags |= DMU_BACKUP_FEATURE_LONGNAME;
 	}
+
+	if (dsl_dataset_feature_is_active(to_ds, SPA_FEATURE_LARGE_MICROZAP)) {
+		/*
+		 * We must never split a large microzap block, so we can only
+		 * send large microzaps if LARGE_BLOCKS is already enabled.
+		 */
+		if (!(*featureflags & DMU_BACKUP_FEATURE_LARGE_BLOCKS))
+			return (SET_ERROR(ZFS_ERR_STREAM_LARGE_MICROZAP));
+		*featureflags |= DMU_BACKUP_FEATURE_LARGE_MICROZAP;
+	}
+
 	return (0);
 }
 

module/zfs/dmu_tx.c

@@ -22,6 +22,7 @@
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
+ * Copyright (c) 2024, Klara, Inc.
  */
 
 #include <sys/dmu.h>
@@ -575,7 +576,6 @@ dmu_tx_hold_zap_impl(dmu_tx_hold_t *txh, const char *name)
 	dmu_tx_t *tx = txh->txh_tx;
 	dnode_t *dn = txh->txh_dnode;
 	int err;
-	extern int zap_micro_max_size;
 
 	ASSERT(tx->tx_txg == 0);
 
@@ -591,7 +591,7 @@ dmu_tx_hold_zap_impl(dmu_tx_hold_t *txh, const char *name)
 	 *    - 2 grown ptrtbl blocks
 	 */
 	(void) zfs_refcount_add_many(&txh->txh_space_towrite,
-	    zap_micro_max_size, FTAG);
+	    zap_get_micro_max_size(tx->tx_pool->dp_spa), FTAG);
 
 	if (dn == NULL)
 		return;