Fast Clone Deletion

Deleting a clone requires finding blocks are clone-only, not shared
with the snapshot. This was done by traversing the entire block tree
which results in a large performance penalty for sparsely
written clones.

This is new method keeps track of clone blocks when they are
modified in a "Livelist" so that, when it’s time to delete,
the clone-specific blocks are already at hand.

We see performance improvements because now deletion work is
proportional to the number of clone-modified blocks, not the size
of the original dataset.

Reviewed-by: Sean Eric Fagan <[email protected]>
Reviewed-by: Matt Ahrens <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Serapheim Dimitropoulos <[email protected]>
Signed-off-by: Sara Hartse <[email protected]>
Closes #8416

include/sys/bplist.h

@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018 by Delphix. All rights reserved.
  */
 
 #ifndef	_SYS_BPLIST_H
@@ -49,6 +50,7 @@ void bplist_destroy(bplist_t *bpl);
 void bplist_append(bplist_t *bpl, const blkptr_t *bp);
 void bplist_iterate(bplist_t *bpl, bplist_itor_t *func,
     void *arg, dmu_tx_t *tx);
+void bplist_clear(bplist_t *bpl);
 
 #ifdef	__cplusplus
 }

include/sys/bpobj.h

@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2015, 2019 by Delphix. All rights reserved.
  */
 
 #ifndef	_SYS_BPOBJ_H
@@ -31,6 +31,7 @@
 #include <sys/txg.h>
 #include <sys/zio.h>
 #include <sys/zfs_context.h>
+#include <sys/bplist.h>
 
 #ifdef	__cplusplus
 extern "C" {
@@ -48,10 +49,12 @@ typedef struct bpobj_phys {
 	uint64_t	bpo_uncomp;
 	uint64_t	bpo_subobjs;
 	uint64_t	bpo_num_subobjs;
+	uint64_t	bpo_num_freed;
 } bpobj_phys_t;
 
 #define	BPOBJ_SIZE_V0	(2 * sizeof (uint64_t))
 #define	BPOBJ_SIZE_V1	(4 * sizeof (uint64_t))
+#define	BPOBJ_SIZE_V2	(6 * sizeof (uint64_t))
 
 typedef struct bpobj {
 	kmutex_t	bpo_lock;
@@ -60,12 +63,14 @@ typedef struct bpobj {
 	int		bpo_epb;
 	uint8_t		bpo_havecomp;
 	uint8_t		bpo_havesubobj;
+	uint8_t		bpo_havefreed;
 	bpobj_phys_t	*bpo_phys;
 	dmu_buf_t	*bpo_dbuf;
 	dmu_buf_t	*bpo_cached_dbuf;
 } bpobj_t;
 
-typedef int bpobj_itor_t(void *arg, const blkptr_t *bp, dmu_tx_t *tx);
+typedef int bpobj_itor_t(void *arg, const blkptr_t *bp, boolean_t bp_freed,
+    dmu_tx_t *tx);
 
 uint64_t bpobj_alloc(objset_t *mos, int blocksize, dmu_tx_t *tx);
 uint64_t bpobj_alloc_empty(objset_t *os, int blocksize, dmu_tx_t *tx);
@@ -77,17 +82,23 @@ void bpobj_close(bpobj_t *bpo);
 boolean_t bpobj_is_open(const bpobj_t *bpo);
 
 int bpobj_iterate(bpobj_t *bpo, bpobj_itor_t func, void *arg, dmu_tx_t *tx);
-int bpobj_iterate_nofree(bpobj_t *bpo, bpobj_itor_t func, void *, dmu_tx_t *);
+int bpobj_iterate_nofree(bpobj_t *bpo, bpobj_itor_t func, void *, uint64_t *);
+int livelist_bpobj_iterate_from_nofree(bpobj_t *bpo, bpobj_itor_t func,
+    void *arg, int64_t start);
 
 void bpobj_enqueue_subobj(bpobj_t *bpo, uint64_t subobj, dmu_tx_t *tx);
-void bpobj_enqueue(bpobj_t *bpo, const blkptr_t *bp, dmu_tx_t *tx);
+void bpobj_enqueue(bpobj_t *bpo, const blkptr_t *bp, boolean_t bp_freed,
+    dmu_tx_t *tx);
 
 int bpobj_space(bpobj_t *bpo,
     uint64_t *usedp, uint64_t *compp, uint64_t *uncompp);
 int bpobj_space_range(bpobj_t *bpo, uint64_t mintxg, uint64_t maxtxg,
     uint64_t *usedp, uint64_t *compp, uint64_t *uncompp);
 boolean_t bpobj_is_empty(bpobj_t *bpo);
 
+int bplist_append_cb(void *arg, const blkptr_t *bp, boolean_t bp_freed,
+    dmu_tx_t *tx);
+
 #ifdef	__cplusplus
 }
 #endif

include/sys/dmu.h

@@ -383,6 +383,7 @@ typedef struct dmu_buf {
 #define	DMU_POOL_CONDENSING_INDIRECT	"com.delphix:condensing_indirect"
 #define	DMU_POOL_ZPOOL_CHECKPOINT	"com.delphix:zpool_checkpoint"
 #define	DMU_POOL_LOG_SPACEMAP_ZAP	"com.delphix:log_spacemap_zap"
+#define	DMU_POOL_DELETED_CLONES		"com.delphix:deleted_clones"
 
 /*
  * Allocate an object from this objset.  The range of object numbers
@@ -1003,6 +1004,7 @@ extern uint64_t dmu_objset_id(objset_t *os);
 extern uint64_t dmu_objset_dnodesize(objset_t *os);
 extern zfs_sync_type_t dmu_objset_syncprop(objset_t *os);
 extern zfs_logbias_op_t dmu_objset_logbias(objset_t *os);
+extern int dmu_objset_blksize(objset_t *os);
 extern int dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
     uint64_t *id, uint64_t *offp, boolean_t *case_conflict);
 extern int dmu_snapshot_lookup(objset_t *os, const char *name, uint64_t *val);

include/sys/dmu_objset.h

@@ -126,7 +126,7 @@ struct objset {
 	zfs_cache_type_t os_secondary_cache;
 	zfs_sync_type_t os_sync;
 	zfs_redundant_metadata_type_t os_redundant_metadata;
-	int os_recordsize;
+	uint64_t os_recordsize;
 	/*
 	 * The next four values are used as a cache of whatever's on disk, and
 	 * are initialized the first time these properties are queried. Before

include/sys/dsl_deadlist.h

@@ -20,20 +20,22 @@
  */
 /*
  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2018, 2019 by Delphix. All rights reserved.
  */
 
 #ifndef	_SYS_DSL_DEADLIST_H
 #define	_SYS_DSL_DEADLIST_H
 
 #include <sys/bpobj.h>
 #include <sys/zfs_context.h>
+#include <sys/zthr.h>
 
 #ifdef	__cplusplus
 extern "C" {
 #endif
 
 struct dmu_buf;
+struct dsl_pool;
 struct dsl_dataset;
 
 typedef struct dsl_deadlist_phys {
@@ -63,13 +65,34 @@ typedef struct dsl_deadlist_entry {
 	bpobj_t dle_bpobj;
 } dsl_deadlist_entry_t;
 
+typedef struct livelist_condense_entry {
+	struct dsl_dataset *ds;
+	dsl_deadlist_entry_t *first;
+	dsl_deadlist_entry_t *next;
+	boolean_t syncing;
+	boolean_t cancelled;
+} livelist_condense_entry_t;
+
+extern unsigned long zfs_livelist_max_entries;
+extern int zfs_livelist_min_percent_shared;
+
+typedef int deadlist_iter_t(void *args, dsl_deadlist_entry_t *dle);
+
 void dsl_deadlist_open(dsl_deadlist_t *dl, objset_t *os, uint64_t object);
 void dsl_deadlist_close(dsl_deadlist_t *dl);
+void dsl_deadlist_iterate(dsl_deadlist_t *dl, deadlist_iter_t func, void *arg);
 uint64_t dsl_deadlist_alloc(objset_t *os, dmu_tx_t *tx);
 void dsl_deadlist_free(objset_t *os, uint64_t dlobj, dmu_tx_t *tx);
-void dsl_deadlist_insert(dsl_deadlist_t *dl, const blkptr_t *bp, dmu_tx_t *tx);
+void dsl_deadlist_insert(dsl_deadlist_t *dl, const blkptr_t *bp,
+    boolean_t free, dmu_tx_t *tx);
+int dsl_deadlist_insert_alloc_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx);
+int dsl_deadlist_insert_free_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx);
 void dsl_deadlist_add_key(dsl_deadlist_t *dl, uint64_t mintxg, dmu_tx_t *tx);
 void dsl_deadlist_remove_key(dsl_deadlist_t *dl, uint64_t mintxg, dmu_tx_t *tx);
+void dsl_deadlist_remove_entry(dsl_deadlist_t *dl, uint64_t mintxg,
+dmu_tx_t *tx);
+dsl_deadlist_entry_t *dsl_deadlist_first(dsl_deadlist_t *dl);
+dsl_deadlist_entry_t *dsl_deadlist_last(dsl_deadlist_t *dl);
 uint64_t dsl_deadlist_clone(dsl_deadlist_t *dl, uint64_t maxtxg,
     uint64_t mrs_obj, dmu_tx_t *tx);
 void dsl_deadlist_space(dsl_deadlist_t *dl,
@@ -81,6 +104,10 @@ void dsl_deadlist_merge(dsl_deadlist_t *dl, uint64_t obj, dmu_tx_t *tx);
 void dsl_deadlist_move_bpobj(dsl_deadlist_t *dl, bpobj_t *bpo, uint64_t mintxg,
     dmu_tx_t *tx);
 boolean_t dsl_deadlist_is_open(dsl_deadlist_t *dl);
+int dsl_process_sub_livelist(bpobj_t *bpobj, struct bplist *to_free,
+    zthr_t *t, uint64_t *size);
+void dsl_deadlist_clear_entry(dsl_deadlist_entry_t *dle, dsl_deadlist_t *dl,
+    dmu_tx_t *tx);
 
 #ifdef	__cplusplus
 }

include/sys/dsl_destroy.h

@@ -33,6 +33,7 @@ extern "C" {
 
 struct nvlist;
 struct dsl_dataset;
+struct dsl_pool;
 struct dmu_tx;
 
 int dsl_destroy_snapshots_nvl(struct nvlist *, boolean_t,

include/sys/dsl_dir.h

@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
  * Copyright (c) 2014, Joyent, Inc. All rights reserved.
  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
  */
@@ -29,18 +29,20 @@
 #define	_SYS_DSL_DIR_H
 
 #include <sys/dmu.h>
+#include <sys/dsl_deadlist.h>
 #include <sys/dsl_pool.h>
 #include <sys/dsl_synctask.h>
 #include <sys/refcount.h>
 #include <sys/zfs_context.h>
 #include <sys/dsl_crypt.h>
+#include <sys/bplist.h>
 
 #ifdef	__cplusplus
 extern "C" {
 #endif
 
 struct dsl_dataset;
-
+struct zthr;
 /*
  * DD_FIELD_* are strings that are used in the "extensified" dsl_dir zap object.
  * They should be of the format <reverse-dns>:<field>.
@@ -49,6 +51,7 @@ struct dsl_dataset;
 #define	DD_FIELD_FILESYSTEM_COUNT	"com.joyent:filesystem_count"
 #define	DD_FIELD_SNAPSHOT_COUNT		"com.joyent:snapshot_count"
 #define	DD_FIELD_CRYPTO_KEY_OBJ		"com.datto:crypto_key_obj"
+#define	DD_FIELD_LIVELIST		"com.delphix:livelist"
 
 typedef enum dd_used {
 	DD_USED_HEAD,
@@ -114,6 +117,10 @@ struct dsl_dir {
 	/* amount of space we expect to write; == amount of dirty data */
 	int64_t dd_space_towrite[TXG_SIZE];
 
+	dsl_deadlist_t dd_livelist;
+	bplist_t dd_pending_frees;
+	bplist_t dd_pending_allocs;
+
 	/* protected by dd_lock; keep at end of struct for better locality */
 	char dd_myname[ZFS_MAX_DATASET_NAME_LEN];
 };
@@ -182,6 +189,9 @@ void dsl_dir_set_reservation_sync_impl(dsl_dir_t *dd, uint64_t value,
     dmu_tx_t *tx);
 void dsl_dir_zapify(dsl_dir_t *dd, dmu_tx_t *tx);
 boolean_t dsl_dir_is_zapified(dsl_dir_t *dd);
+void dsl_dir_livelist_open(dsl_dir_t *dd, uint64_t obj);
+void dsl_dir_livelist_close(dsl_dir_t *dd);
+void dsl_dir_remove_livelist(dsl_dir_t *dd, dmu_tx_t *tx, boolean_t total);
 
 /* internal reserved dir name */
 #define	MOS_DIR_NAME "$MOS"

include/sys/dsl_pool.h

@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2013, 2017 by Delphix. All rights reserved.
+ * Copyright (c) 2013, 2018 by Delphix. All rights reserved.
  * Copyright 2016 Nexenta Systems, Inc.  All rights reserved.
  */
 
@@ -54,6 +54,7 @@ struct dsl_pool;
 struct dmu_tx;
 struct dsl_scan;
 struct dsl_crypto_params;
+struct dsl_deadlist;
 
 extern unsigned long zfs_dirty_data_max;
 extern unsigned long zfs_dirty_data_max_max;

include/sys/spa.h

@@ -63,6 +63,8 @@ typedef struct ddt ddt_t;
 typedef struct ddt_entry ddt_entry_t;
 typedef struct zbookmark_phys zbookmark_phys_t;
 
+struct bpobj;
+struct bplist;
 struct dsl_pool;
 struct dsl_dataset;
 struct dsl_crypto_params;
@@ -532,6 +534,9 @@ _NOTE(CONSTCOND) } while (0)
 #define	BP_GET_BYTEORDER(bp)		BF64_GET((bp)->blk_prop, 63, 1)
 #define	BP_SET_BYTEORDER(bp, x)		BF64_SET((bp)->blk_prop, 63, 1, x)
 
+#define	BP_GET_FREE(bp)			BF64_GET((bp)->blk_fill, 0, 1)
+#define	BP_SET_FREE(bp, x)		BF64_SET((bp)->blk_fill, 0, 1, x)
+
 #define	BP_PHYSICAL_BIRTH(bp)		\
 	(BP_IS_EMBEDDED(bp) ? 0 : \
 	(bp)->blk_phys_birth ? (bp)->blk_phys_birth : (bp)->blk_birth)
@@ -654,6 +659,7 @@ _NOTE(CONSTCOND) } while (0)
  * 'func' is either snprintf() or mdb_snprintf().
  * 'ws' (whitespace) can be ' ' for single-line format, '\n' for multi-line.
  */
+
 #define	SNPRINTF_BLKPTR(func, ws, buf, size, bp, type, checksum, compress) \
 {									\
 	static const char *copyname[] =					\
@@ -804,6 +810,8 @@ extern spa_t *spa_inject_addref(char *pool);
 extern void spa_inject_delref(spa_t *spa);
 extern void spa_scan_stat_init(spa_t *spa);
 extern int spa_scan_get_stats(spa_t *spa, pool_scan_stat_t *ps);
+extern int bpobj_enqueue_alloc_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx);
+extern int bpobj_enqueue_free_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx);
 
 #define	SPA_ASYNC_CONFIG_UPDATE			0x01
 #define	SPA_ASYNC_REMOVE			0x02
@@ -1131,6 +1139,7 @@ extern uint64_t spa_total_metaslabs(spa_t *spa);
 extern boolean_t spa_multihost(spa_t *spa);
 extern unsigned long spa_get_hostid(void);
 extern void spa_activate_allocation_classes(spa_t *, dmu_tx_t *);
+extern boolean_t spa_livelist_delete_check(spa_t *spa);
 
 extern int spa_mode(spa_t *spa);
 extern uint64_t zfs_strtonum(const char *str, char **nptr);

include/sys/spa_impl.h

@@ -49,6 +49,7 @@
 #include <sys/dsl_crypt.h>
 #include <sys/zfeature.h>
 #include <sys/zthr.h>
+#include <sys/dsl_deadlist.h>
 #include <zfeature_common.h>
 
 #ifdef	__cplusplus
@@ -317,6 +318,11 @@ struct spa {
 	list_t		spa_log_summary;
 	uint64_t	spa_log_flushall_txg;
 
+	zthr_t		*spa_livelist_delete_zthr; /* deleting livelists */
+	zthr_t		*spa_livelist_condense_zthr; /* condensing livelists */
+	uint64_t	spa_livelists_to_delete; /* set of livelists to free */
+	livelist_condense_entry_t	spa_to_condense; /* next to condense */
+
 	char		*spa_root;		/* alternate root directory */
 	uint64_t	spa_ena;		/* spa-wide ereport ENA */
 	int		spa_last_open_failed;	/* error if last open failed */

include/sys/zthr.h

@@ -33,7 +33,9 @@ extern void zthr_destroy(zthr_t *t);
 extern void zthr_wakeup(zthr_t *t);
 extern void zthr_cancel(zthr_t *t);
 extern void zthr_resume(zthr_t *t);
+extern void zthr_wait_cycle_done(zthr_t *t);
 
 extern boolean_t zthr_iscancelled(zthr_t *t);
+extern boolean_t zthr_has_waiters(zthr_t *t);
 
 #endif /* _SYS_ZTHR_H */

include/zfeature_common.h

@@ -71,6 +71,7 @@ typedef enum spa_feature {
 	SPA_FEATURE_REDACTED_DATASETS,
 	SPA_FEATURE_BOOKMARK_WRITTEN,
 	SPA_FEATURE_LOG_SPACEMAP,
+	SPA_FEATURE_LIVELIST,
 	SPA_FEATURES
 } spa_feature_t;