]> git.proxmox.com Git - mirror_zfs.git/blobdiff - module/zfs/dsl_pool.c
Use boot_ncpus in place of max_ncpus in taskq_create
[mirror_zfs.git] / module / zfs / dsl_pool.c
index 700cc962865da79b18a5876e86725715144502d9..4dd86a9fe481509e5589f842a9c14cb3710fbe2e 100644 (file)
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2019 by Delphix. All rights reserved.
+ * Copyright (c) 2013 Steven Hartland. All rights reserved.
+ * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
+ * Copyright 2016 Nexenta Systems, Inc.  All rights reserved.
  */
 
 #include <sys/dsl_pool.h>
 #include <sys/fs/zfs.h>
 #include <sys/zfs_znode.h>
 #include <sys/spa_impl.h>
-#include <sys/dsl_deadlist.h>
+#include <sys/vdev_impl.h>
+#include <sys/metaslab_impl.h>
+#include <sys/bptree.h>
+#include <sys/zfeature.h>
+#include <sys/zil_impl.h>
+#include <sys/dsl_userhold.h>
+#include <sys/trace_zfs.h>
+#include <sys/mmp.h>
 
-int zfs_no_write_throttle = 0;
-int zfs_write_limit_shift = 3;                 /* 1/8th of physical memory */
-int zfs_txg_synctime_ms = 1000;                /* target millisecs to sync a txg */
+/*
+ * ZFS Write Throttle
+ * ------------------
+ *
+ * ZFS must limit the rate of incoming writes to the rate at which it is able
+ * to sync data modifications to the backend storage. Throttling by too much
+ * creates an artificial limit; throttling by too little can only be sustained
+ * for short periods and would lead to highly lumpy performance. On a per-pool
+ * basis, ZFS tracks the amount of modified (dirty) data. As operations change
+ * data, the amount of dirty data increases; as ZFS syncs out data, the amount
+ * of dirty data decreases. When the amount of dirty data exceeds a
+ * predetermined threshold further modifications are blocked until the amount
+ * of dirty data decreases (as data is synced out).
+ *
+ * The limit on dirty data is tunable, and should be adjusted according to
+ * both the IO capacity and available memory of the system. The larger the
+ * window, the more ZFS is able to aggregate and amortize metadata (and data)
+ * changes. However, memory is a limited resource, and allowing for more dirty
+ * data comes at the cost of keeping other useful data in memory (for example
+ * ZFS data cached by the ARC).
+ *
+ * Implementation
+ *
+ * As buffers are modified dsl_pool_willuse_space() increments both the per-
+ * txg (dp_dirty_pertxg[]) and poolwide (dp_dirty_total) accounting of
+ * dirty space used; dsl_pool_dirty_space() decrements those values as data
+ * is synced out from dsl_pool_sync(). While only the poolwide value is
+ * relevant, the per-txg value is useful for debugging. The tunable
+ * zfs_dirty_data_max determines the dirty space limit. Once that value is
+ * exceeded, new writes are halted until space frees up.
+ *
+ * The zfs_dirty_data_sync_percent tunable dictates the threshold at which we
+ * ensure that there is a txg syncing (see the comment in txg.c for a full
+ * description of transaction group stages).
+ *
+ * The IO scheduler uses both the dirty space limit and current amount of
+ * dirty data as inputs. Those values affect the number of concurrent IOs ZFS
+ * issues. See the comment in vdev_queue.c for details of the IO scheduler.
+ *
+ * The delay is also calculated based on the amount of dirty data.  See the
+ * comment above dmu_tx_delay() for details.
+ */
+
+/*
+ * zfs_dirty_data_max will be set to zfs_dirty_data_max_percent% of all memory,
+ * capped at zfs_dirty_data_max_max.  It can also be overridden with a module
+ * parameter.
+ */
+unsigned long zfs_dirty_data_max = 0;
+unsigned long zfs_dirty_data_max_max = 0;
+int zfs_dirty_data_max_percent = 10;
+int zfs_dirty_data_max_max_percent = 25;
+
+/*
+ * If there's at least this much dirty data (as a percentage of
+ * zfs_dirty_data_max), push out a txg.  This should be less than
+ * zfs_vdev_async_write_active_min_dirty_percent.
+ */
+int zfs_dirty_data_sync_percent = 20;
+
+/*
+ * Once there is this amount of dirty data, the dmu_tx_delay() will kick in
+ * and delay each transaction.
+ * This value should be >= zfs_vdev_async_write_active_max_dirty_percent.
+ */
+int zfs_delay_min_dirty_percent = 60;
 
-uint64_t zfs_write_limit_min = 32 << 20;       /* min write limit is 32MB */
-uint64_t zfs_write_limit_max = 0;              /* max data payload per txg */
-uint64_t zfs_write_limit_inflated = 0;
-uint64_t zfs_write_limit_override = 0;
+/*
+ * This controls how quickly the delay approaches infinity.
+ * Larger values cause it to delay more for a given amount of dirty data.
+ * Therefore larger values will cause there to be less dirty data for a
+ * given throughput.
+ *
+ * For the smoothest delay, this value should be about 1 billion divided
+ * by the maximum number of operations per second.  This will smoothly
+ * handle between 10x and 1/10th this number.
+ *
+ * Note: zfs_delay_scale * zfs_dirty_data_max must be < 2^64, due to the
+ * multiply in dmu_tx_delay().
+ */
+unsigned long zfs_delay_scale = 1000 * 1000 * 1000 / 2000;
 
-kmutex_t zfs_write_limit_lock;
+/*
+ * This determines the number of threads used by the dp_sync_taskq.
+ */
+int zfs_sync_taskq_batch_pct = 75;
 
-static pgcnt_t old_physmem = 0;
+/*
+ * These tunables determine the behavior of how zil_itxg_clean() is
+ * called via zil_clean() in the context of spa_sync(). When an itxg
+ * list needs to be cleaned, TQ_NOSLEEP will be used when dispatching.
+ * If the dispatch fails, the call to zil_itxg_clean() will occur
+ * synchronously in the context of spa_sync(), which can negatively
+ * impact the performance of spa_sync() (e.g. in the case of the itxg
+ * list having a large number of itxs that needs to be cleaned).
+ *
+ * Thus, these tunables can be used to manipulate the behavior of the
+ * taskq used by zil_clean(); they determine the number of taskq entries
+ * that are pre-populated when the taskq is first created (via the
+ * "zfs_zil_clean_taskq_minalloc" tunable) and the maximum number of
+ * taskq entries that are cached after an on-demand allocation (via the
+ * "zfs_zil_clean_taskq_maxalloc").
+ *
+ * The idea being, we want to try reasonably hard to ensure there will
+ * already be a taskq entry pre-allocated by the time that it is needed
+ * by zil_clean(). This way, we can avoid the possibility of an
+ * on-demand allocation of a new taskq entry from failing, which would
+ * result in zil_itxg_clean() being called synchronously from zil_clean()
+ * (which can adversely affect performance of spa_sync()).
+ *
+ * Additionally, the number of threads used by the taskq can be
+ * configured via the "zfs_zil_clean_taskq_nthr_pct" tunable.
+ */
+int zfs_zil_clean_taskq_nthr_pct = 100;
+int zfs_zil_clean_taskq_minalloc = 1024;
+int zfs_zil_clean_taskq_maxalloc = 1024 * 1024;
 
 int
 dsl_pool_open_special_dir(dsl_pool_t *dp, const char *name, dsl_dir_t **ddp)
@@ -60,12 +175,12 @@ dsl_pool_open_special_dir(dsl_pool_t *dp, const char *name, dsl_dir_t **ddp)
        int err;
 
        err = zap_lookup(dp->dp_meta_objset,
-           dp->dp_root_dir->dd_phys->dd_child_dir_zapobj,
+           dsl_dir_phys(dp->dp_root_dir)->dd_child_dir_zapobj,
            name, sizeof (obj), 1, &obj);
        if (err)
                return (err);
 
-       return (dsl_dir_open_obj(dp, obj, name, dp, ddp));
+       return (dsl_dir_hold_obj(dp, obj, name, dp, ddp));
 }
 
 static dsl_pool_t *
@@ -77,49 +192,83 @@ dsl_pool_open_impl(spa_t *spa, uint64_t txg)
        dp = kmem_zalloc(sizeof (dsl_pool_t), KM_SLEEP);
        dp->dp_spa = spa;
        dp->dp_meta_rootbp = *bp;
-       rw_init(&dp->dp_config_rwlock, NULL, RW_DEFAULT, NULL);
-       dp->dp_write_limit = zfs_write_limit_min;
+       rrw_init(&dp->dp_config_rwlock, B_TRUE);
        txg_init(dp, txg);
+       mmp_init(spa);
 
-       txg_list_create(&dp->dp_dirty_datasets,
+       txg_list_create(&dp->dp_dirty_datasets, spa,
            offsetof(dsl_dataset_t, ds_dirty_link));
-       txg_list_create(&dp->dp_dirty_dirs,
+       txg_list_create(&dp->dp_dirty_zilogs, spa,
+           offsetof(zilog_t, zl_dirty_link));
+       txg_list_create(&dp->dp_dirty_dirs, spa,
            offsetof(dsl_dir_t, dd_dirty_link));
-       txg_list_create(&dp->dp_sync_tasks,
-           offsetof(dsl_sync_task_group_t, dstg_node));
-       list_create(&dp->dp_synced_datasets, sizeof (dsl_dataset_t),
-           offsetof(dsl_dataset_t, ds_synced_link));
+       txg_list_create(&dp->dp_sync_tasks, spa,
+           offsetof(dsl_sync_task_t, dst_node));
+       txg_list_create(&dp->dp_early_sync_tasks, spa,
+           offsetof(dsl_sync_task_t, dst_node));
+
+       dp->dp_sync_taskq = taskq_create("dp_sync_taskq",
+           zfs_sync_taskq_batch_pct, minclsyspri, 1, INT_MAX,
+           TASKQ_THREADS_CPU_PCT);
+
+       dp->dp_zil_clean_taskq = taskq_create("dp_zil_clean_taskq",
+           zfs_zil_clean_taskq_nthr_pct, minclsyspri,
+           zfs_zil_clean_taskq_minalloc,
+           zfs_zil_clean_taskq_maxalloc,
+           TASKQ_PREPOPULATE | TASKQ_THREADS_CPU_PCT);
 
        mutex_init(&dp->dp_lock, NULL, MUTEX_DEFAULT, NULL);
+       cv_init(&dp->dp_spaceavail_cv, NULL, CV_DEFAULT, NULL);
 
-       dp->dp_vnrele_taskq = taskq_create("zfs_vn_rele_taskq", 1, minclsyspri,
-           1, 4, 0);
+       dp->dp_zrele_taskq = taskq_create("z_zrele", boot_ncpus, defclsyspri,
+           boot_ncpus * 8, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
+       dp->dp_unlinked_drain_taskq = taskq_create("z_unlinked_drain",
+           boot_ncpus, defclsyspri, boot_ncpus, INT_MAX,
+           TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 
        return (dp);
 }
 
 int
-dsl_pool_open(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
+dsl_pool_init(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
 {
        int err;
        dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
-       dsl_dir_t *dd;
-       dsl_dataset_t *ds;
-       uint64_t obj;
 
-       rw_enter(&dp->dp_config_rwlock, RW_WRITER);
+       /*
+        * Initialize the caller's dsl_pool_t structure before we actually open
+        * the meta objset.  This is done because a self-healing write zio may
+        * be issued as part of dmu_objset_open_impl() and the spa needs its
+        * dsl_pool_t initialized in order to handle the write.
+        */
+       *dpp = dp;
+
        err = dmu_objset_open_impl(spa, NULL, &dp->dp_meta_rootbp,
            &dp->dp_meta_objset);
-       if (err)
-               goto out;
+       if (err != 0) {
+               dsl_pool_close(dp);
+               *dpp = NULL;
+       }
+
+       return (err);
+}
 
+int
+dsl_pool_open(dsl_pool_t *dp)
+{
+       int err;
+       dsl_dir_t *dd;
+       dsl_dataset_t *ds;
+       uint64_t obj;
+
+       rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
        err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
            DMU_POOL_ROOT_DATASET, sizeof (uint64_t), 1,
            &dp->dp_root_dir_obj);
        if (err)
                goto out;
 
-       err = dsl_dir_open_obj(dp, dp->dp_root_dir_obj,
+       err = dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
            NULL, dp, &dp->dp_root_dir);
        if (err)
                goto out;
@@ -128,24 +277,24 @@ dsl_pool_open(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
        if (err)
                goto out;
 
-       if (spa_version(spa) >= SPA_VERSION_ORIGIN) {
+       if (spa_version(dp->dp_spa) >= SPA_VERSION_ORIGIN) {
                err = dsl_pool_open_special_dir(dp, ORIGIN_DIR_NAME, &dd);
                if (err)
                        goto out;
-               err = dsl_dataset_hold_obj(dp, dd->dd_phys->dd_head_dataset_obj,
-                   FTAG, &ds);
+               err = dsl_dataset_hold_obj(dp,
+                   dsl_dir_phys(dd)->dd_head_dataset_obj, FTAG, &ds);
                if (err == 0) {
                        err = dsl_dataset_hold_obj(dp,
-                           ds->ds_phys->ds_prev_snap_obj, dp,
+                           dsl_dataset_phys(ds)->ds_prev_snap_obj, dp,
                            &dp->dp_origin_snap);
                        dsl_dataset_rele(ds, FTAG);
                }
-               dsl_dir_close(dd, dp);
+               dsl_dir_rele(dd, dp);
                if (err)
                        goto out;
        }
 
-       if (spa_version(spa) >= SPA_VERSION_DEADLISTS) {
+       if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
                err = dsl_pool_open_special_dir(dp, FREE_DIR_NAME,
                    &dp->dp_free_dir);
                if (err)
@@ -155,10 +304,49 @@ dsl_pool_open(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
                    DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj);
                if (err)
                        goto out;
-               VERIFY3U(0, ==, bpobj_open(&dp->dp_free_bpobj,
+               VERIFY0(bpobj_open(&dp->dp_free_bpobj,
                    dp->dp_meta_objset, obj));
        }
 
+       if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_OBSOLETE_COUNTS)) {
+               err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+                   DMU_POOL_OBSOLETE_BPOBJ, sizeof (uint64_t), 1, &obj);
+               if (err == 0) {
+                       VERIFY0(bpobj_open(&dp->dp_obsolete_bpobj,
+                           dp->dp_meta_objset, obj));
+               } else if (err == ENOENT) {
+                       /*
+                        * We might not have created the remap bpobj yet.
+                        */
+                       err = 0;
+               } else {
+                       goto out;
+               }
+       }
+
+       /*
+        * Note: errors ignored, because the these special dirs, used for
+        * space accounting, are only created on demand.
+        */
+       (void) dsl_pool_open_special_dir(dp, LEAK_DIR_NAME,
+           &dp->dp_leak_dir);
+
+       if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_ASYNC_DESTROY)) {
+               err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+                   DMU_POOL_BPTREE_OBJ, sizeof (uint64_t), 1,
+                   &dp->dp_bptree_obj);
+               if (err != 0)
+                       goto out;
+       }
+
+       if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_EMPTY_BPOBJ)) {
+               err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+                   DMU_POOL_EMPTY_BPOBJ, sizeof (uint64_t), 1,
+                   &dp->dp_empty_bpobj);
+               if (err != 0)
+                       goto out;
+       }
+
        err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
            DMU_POOL_TMP_USERREFS, sizeof (uint64_t), 1,
            &dp->dp_tmp_userrefs_obj);
@@ -167,134 +355,261 @@ dsl_pool_open(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
        if (err)
                goto out;
 
-       err = dsl_scan_init(dp, txg);
+       err = dsl_scan_init(dp, dp->dp_tx.tx_open_txg);
 
 out:
-       rw_exit(&dp->dp_config_rwlock);
-       if (err)
-               dsl_pool_close(dp);
-       else
-               *dpp = dp;
-
+       rrw_exit(&dp->dp_config_rwlock, FTAG);
        return (err);
 }
 
 void
 dsl_pool_close(dsl_pool_t *dp)
 {
-       /* drop our references from dsl_pool_open() */
-
        /*
+        * Drop our references from dsl_pool_open().
+        *
         * Since we held the origin_snap from "syncing" context (which
         * includes pool-opening context), it actually only got a "ref"
         * and not a hold, so just drop that here.
         */
-       if (dp->dp_origin_snap)
-               dsl_dataset_drop_ref(dp->dp_origin_snap, dp);
-       if (dp->dp_mos_dir)
-               dsl_dir_close(dp->dp_mos_dir, dp);
-       if (dp->dp_free_dir)
-               dsl_dir_close(dp->dp_free_dir, dp);
-       if (dp->dp_root_dir)
-               dsl_dir_close(dp->dp_root_dir, dp);
+       if (dp->dp_origin_snap != NULL)
+               dsl_dataset_rele(dp->dp_origin_snap, dp);
+       if (dp->dp_mos_dir != NULL)
+               dsl_dir_rele(dp->dp_mos_dir, dp);
+       if (dp->dp_free_dir != NULL)
+               dsl_dir_rele(dp->dp_free_dir, dp);
+       if (dp->dp_leak_dir != NULL)
+               dsl_dir_rele(dp->dp_leak_dir, dp);
+       if (dp->dp_root_dir != NULL)
+               dsl_dir_rele(dp->dp_root_dir, dp);
 
        bpobj_close(&dp->dp_free_bpobj);
+       bpobj_close(&dp->dp_obsolete_bpobj);
 
        /* undo the dmu_objset_open_impl(mos) from dsl_pool_open() */
-       if (dp->dp_meta_objset)
+       if (dp->dp_meta_objset != NULL)
                dmu_objset_evict(dp->dp_meta_objset);
 
        txg_list_destroy(&dp->dp_dirty_datasets);
+       txg_list_destroy(&dp->dp_dirty_zilogs);
        txg_list_destroy(&dp->dp_sync_tasks);
+       txg_list_destroy(&dp->dp_early_sync_tasks);
        txg_list_destroy(&dp->dp_dirty_dirs);
-       list_destroy(&dp->dp_synced_datasets);
 
-       arc_flush(dp->dp_spa);
+       taskq_destroy(dp->dp_zil_clean_taskq);
+       taskq_destroy(dp->dp_sync_taskq);
+
+       /*
+        * We can't set retry to TRUE since we're explicitly specifying
+        * a spa to flush. This is good enough; any missed buffers for
+        * this spa won't cause trouble, and they'll eventually fall
+        * out of the ARC just like any other unused buffer.
+        */
+       arc_flush(dp->dp_spa, FALSE);
+
+       mmp_fini(dp->dp_spa);
        txg_fini(dp);
        dsl_scan_fini(dp);
-       rw_destroy(&dp->dp_config_rwlock);
+       dmu_buf_user_evict_wait();
+
+       rrw_destroy(&dp->dp_config_rwlock);
        mutex_destroy(&dp->dp_lock);
-       taskq_destroy(dp->dp_vnrele_taskq);
-       if (dp->dp_blkstats)
-               kmem_free(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
+       cv_destroy(&dp->dp_spaceavail_cv);
+       taskq_destroy(dp->dp_unlinked_drain_taskq);
+       taskq_destroy(dp->dp_zrele_taskq);
+       if (dp->dp_blkstats != NULL) {
+               mutex_destroy(&dp->dp_blkstats->zab_lock);
+               vmem_free(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
+       }
        kmem_free(dp, sizeof (dsl_pool_t));
 }
 
+void
+dsl_pool_create_obsolete_bpobj(dsl_pool_t *dp, dmu_tx_t *tx)
+{
+       uint64_t obj;
+       /*
+        * Currently, we only create the obsolete_bpobj where there are
+        * indirect vdevs with referenced mappings.
+        */
+       ASSERT(spa_feature_is_active(dp->dp_spa, SPA_FEATURE_DEVICE_REMOVAL));
+       /* create and open the obsolete_bpobj */
+       obj = bpobj_alloc(dp->dp_meta_objset, SPA_OLD_MAXBLOCKSIZE, tx);
+       VERIFY0(bpobj_open(&dp->dp_obsolete_bpobj, dp->dp_meta_objset, obj));
+       VERIFY0(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+           DMU_POOL_OBSOLETE_BPOBJ, sizeof (uint64_t), 1, &obj, tx));
+       spa_feature_incr(dp->dp_spa, SPA_FEATURE_OBSOLETE_COUNTS, tx);
+}
+
+void
+dsl_pool_destroy_obsolete_bpobj(dsl_pool_t *dp, dmu_tx_t *tx)
+{
+       spa_feature_decr(dp->dp_spa, SPA_FEATURE_OBSOLETE_COUNTS, tx);
+       VERIFY0(zap_remove(dp->dp_meta_objset,
+           DMU_POOL_DIRECTORY_OBJECT,
+           DMU_POOL_OBSOLETE_BPOBJ, tx));
+       bpobj_free(dp->dp_meta_objset,
+           dp->dp_obsolete_bpobj.bpo_object, tx);
+       bpobj_close(&dp->dp_obsolete_bpobj);
+}
+
 dsl_pool_t *
-dsl_pool_create(spa_t *spa, nvlist_t *zplprops, uint64_t txg)
+dsl_pool_create(spa_t *spa, nvlist_t *zplprops, dsl_crypto_params_t *dcp,
+    uint64_t txg)
 {
        int err;
        dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
        dmu_tx_t *tx = dmu_tx_create_assigned(dp, txg);
+#ifdef _KERNEL
        objset_t *os;
+#else
+       objset_t *os __attribute__((unused));
+#endif
        dsl_dataset_t *ds;
        uint64_t obj;
 
+       rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
+
        /* create and open the MOS (meta-objset) */
        dp->dp_meta_objset = dmu_objset_create_impl(spa,
            NULL, &dp->dp_meta_rootbp, DMU_OST_META, tx);
+       spa->spa_meta_objset = dp->dp_meta_objset;
 
        /* create the pool directory */
        err = zap_create_claim(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
            DMU_OT_OBJECT_DIRECTORY, DMU_OT_NONE, 0, tx);
-       ASSERT3U(err, ==, 0);
+       ASSERT0(err);
 
        /* Initialize scan structures */
-       VERIFY3U(0, ==, dsl_scan_init(dp, txg));
+       VERIFY0(dsl_scan_init(dp, txg));
 
        /* create and open the root dir */
        dp->dp_root_dir_obj = dsl_dir_create_sync(dp, NULL, NULL, tx);
-       VERIFY(0 == dsl_dir_open_obj(dp, dp->dp_root_dir_obj,
+       VERIFY0(dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
            NULL, dp, &dp->dp_root_dir));
 
        /* create and open the meta-objset dir */
        (void) dsl_dir_create_sync(dp, dp->dp_root_dir, MOS_DIR_NAME, tx);
-       VERIFY(0 == dsl_pool_open_special_dir(dp,
+       VERIFY0(dsl_pool_open_special_dir(dp,
            MOS_DIR_NAME, &dp->dp_mos_dir));
 
        if (spa_version(spa) >= SPA_VERSION_DEADLISTS) {
                /* create and open the free dir */
                (void) dsl_dir_create_sync(dp, dp->dp_root_dir,
                    FREE_DIR_NAME, tx);
-               VERIFY(0 == dsl_pool_open_special_dir(dp,
+               VERIFY0(dsl_pool_open_special_dir(dp,
                    FREE_DIR_NAME, &dp->dp_free_dir));
 
                /* create and open the free_bplist */
-               obj = bpobj_alloc(dp->dp_meta_objset, SPA_MAXBLOCKSIZE, tx);
+               obj = bpobj_alloc(dp->dp_meta_objset, SPA_OLD_MAXBLOCKSIZE, tx);
                VERIFY(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
                    DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx) == 0);
-               VERIFY3U(0, ==, bpobj_open(&dp->dp_free_bpobj,
+               VERIFY0(bpobj_open(&dp->dp_free_bpobj,
                    dp->dp_meta_objset, obj));
        }
 
        if (spa_version(spa) >= SPA_VERSION_DSL_SCRUB)
                dsl_pool_create_origin(dp, tx);
 
+       /*
+        * Some features may be needed when creating the root dataset, so we
+        * create the feature objects here.
+        */
+       if (spa_version(spa) >= SPA_VERSION_FEATURES)
+               spa_feature_create_zap_objects(spa, tx);
+
+       if (dcp != NULL && dcp->cp_crypt != ZIO_CRYPT_OFF &&
+           dcp->cp_crypt != ZIO_CRYPT_INHERIT)
+               spa_feature_enable(spa, SPA_FEATURE_ENCRYPTION, tx);
+
        /* create the root dataset */
-       obj = dsl_dataset_create_sync_dd(dp->dp_root_dir, NULL, 0, tx);
+       obj = dsl_dataset_create_sync_dd(dp->dp_root_dir, NULL, dcp, 0, tx);
 
        /* create the root objset */
-       VERIFY(0 == dsl_dataset_hold_obj(dp, obj, FTAG, &ds));
+       VERIFY0(dsl_dataset_hold_obj_flags(dp, obj,
+           DS_HOLD_FLAG_DECRYPT, FTAG, &ds));
+       rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
        os = dmu_objset_create_impl(dp->dp_spa, ds,
            dsl_dataset_get_blkptr(ds), DMU_OST_ZFS, tx);
+       rrw_exit(&ds->ds_bp_rwlock, FTAG);
 #ifdef _KERNEL
        zfs_create_fs(os, kcred, zplprops, tx);
 #endif
-       dsl_dataset_rele(ds, FTAG);
+       dsl_dataset_rele_flags(ds, DS_HOLD_FLAG_DECRYPT, FTAG);
 
        dmu_tx_commit(tx);
 
+       rrw_exit(&dp->dp_config_rwlock, FTAG);
+
        return (dp);
 }
 
-static int
-deadlist_enqueue_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
+/*
+ * Account for the meta-objset space in its placeholder dsl_dir.
+ */
+void
+dsl_pool_mos_diduse_space(dsl_pool_t *dp,
+    int64_t used, int64_t comp, int64_t uncomp)
 {
-       dsl_deadlist_t *dl = arg;
-       dsl_deadlist_insert(dl, bp, tx);
-       return (0);
+       ASSERT3U(comp, ==, uncomp); /* it's all metadata */
+       mutex_enter(&dp->dp_lock);
+       dp->dp_mos_used_delta += used;
+       dp->dp_mos_compressed_delta += comp;
+       dp->dp_mos_uncompressed_delta += uncomp;
+       mutex_exit(&dp->dp_lock);
+}
+
+static void
+dsl_pool_sync_mos(dsl_pool_t *dp, dmu_tx_t *tx)
+{
+       zio_t *zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
+       dmu_objset_sync(dp->dp_meta_objset, zio, tx);
+       VERIFY0(zio_wait(zio));
+       dprintf_bp(&dp->dp_meta_rootbp, "meta objset rootbp is %s", "");
+       spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
+}
+
+static void
+dsl_pool_dirty_delta(dsl_pool_t *dp, int64_t delta)
+{
+       ASSERT(MUTEX_HELD(&dp->dp_lock));
+
+       if (delta < 0)
+               ASSERT3U(-delta, <=, dp->dp_dirty_total);
+
+       dp->dp_dirty_total += delta;
+
+       /*
+        * Note: we signal even when increasing dp_dirty_total.
+        * This ensures forward progress -- each thread wakes the next waiter.
+        */
+       if (dp->dp_dirty_total < zfs_dirty_data_max)
+               cv_signal(&dp->dp_spaceavail_cv);
 }
 
+#ifdef ZFS_DEBUG
+static boolean_t
+dsl_early_sync_task_verify(dsl_pool_t *dp, uint64_t txg)
+{
+       spa_t *spa = dp->dp_spa;
+       vdev_t *rvd = spa->spa_root_vdev;
+
+       for (uint64_t c = 0; c < rvd->vdev_children; c++) {
+               vdev_t *vd = rvd->vdev_child[c];
+               txg_list_t *tl = &vd->vdev_ms_list;
+               metaslab_t *ms;
+
+               for (ms = txg_list_head(tl, TXG_CLEAN(txg)); ms;
+                   ms = txg_list_next(tl, ms, TXG_CLEAN(txg))) {
+                       VERIFY(range_tree_is_empty(ms->ms_freeing));
+                       VERIFY(range_tree_is_empty(ms->ms_checkpointing));
+               }
+       }
+
+       return (B_TRUE);
+}
+#endif
+
 void
 dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
 {
@@ -302,158 +617,199 @@ dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
        dmu_tx_t *tx;
        dsl_dir_t *dd;
        dsl_dataset_t *ds;
-       dsl_sync_task_group_t *dstg;
        objset_t *mos = dp->dp_meta_objset;
-       hrtime_t start, write_time;
-       uint64_t data_written;
-       int err;
+       list_t synced_datasets;
 
-       /*
-        * We need to copy dp_space_towrite() before doing
-        * dsl_sync_task_group_sync(), because
-        * dsl_dataset_snapshot_reserve_space() will increase
-        * dp_space_towrite but not actually write anything.
-        */
-       data_written = dp->dp_space_towrite[txg & TXG_MASK];
+       list_create(&synced_datasets, sizeof (dsl_dataset_t),
+           offsetof(dsl_dataset_t, ds_synced_link));
 
        tx = dmu_tx_create_assigned(dp, txg);
 
-       dp->dp_read_overhead = 0;
-       start = gethrtime();
+       /*
+        * Run all early sync tasks before writing out any dirty blocks.
+        * For more info on early sync tasks see block comment in
+        * dsl_early_sync_task().
+        */
+       if (!txg_list_empty(&dp->dp_early_sync_tasks, txg)) {
+               dsl_sync_task_t *dst;
+
+               ASSERT3U(spa_sync_pass(dp->dp_spa), ==, 1);
+               while ((dst =
+                   txg_list_remove(&dp->dp_early_sync_tasks, txg)) != NULL) {
+                       ASSERT(dsl_early_sync_task_verify(dp, txg));
+                       dsl_sync_task_sync(dst, tx);
+               }
+               ASSERT(dsl_early_sync_task_verify(dp, txg));
+       }
 
+       /*
+        * Write out all dirty blocks of dirty datasets.
+        */
        zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
-       while (ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) {
+       while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
                /*
                 * We must not sync any non-MOS datasets twice, because
                 * we may have taken a snapshot of them.  However, we
                 * may sync newly-created datasets on pass 2.
                 */
                ASSERT(!list_link_active(&ds->ds_synced_link));
-               list_insert_tail(&dp->dp_synced_datasets, ds);
+               list_insert_tail(&synced_datasets, ds);
                dsl_dataset_sync(ds, zio, tx);
        }
-       DTRACE_PROBE(pool_sync__1setup);
-       err = zio_wait(zio);
+       VERIFY0(zio_wait(zio));
 
-       write_time = gethrtime() - start;
-       ASSERT(err == 0);
-       DTRACE_PROBE(pool_sync__2rootzio);
+       /*
+        * Update the long range free counter after
+        * we're done syncing user data
+        */
+       mutex_enter(&dp->dp_lock);
+       ASSERT(spa_sync_pass(dp->dp_spa) == 1 ||
+           dp->dp_long_free_dirty_pertxg[txg & TXG_MASK] == 0);
+       dp->dp_long_free_dirty_pertxg[txg & TXG_MASK] = 0;
+       mutex_exit(&dp->dp_lock);
 
-       for (ds = list_head(&dp->dp_synced_datasets); ds;
-           ds = list_next(&dp->dp_synced_datasets, ds))
+       /*
+        * After the data blocks have been written (ensured by the zio_wait()
+        * above), update the user/group/project space accounting.  This happens
+        * in tasks dispatched to dp_sync_taskq, so wait for them before
+        * continuing.
+        */
+       for (ds = list_head(&synced_datasets); ds != NULL;
+           ds = list_next(&synced_datasets, ds)) {
                dmu_objset_do_userquota_updates(ds->ds_objset, tx);
+       }
+       taskq_wait(dp->dp_sync_taskq);
 
        /*
         * Sync the datasets again to push out the changes due to
         * userspace updates.  This must be done before we process the
-        * sync tasks, because that could cause a snapshot of a dataset
-        * whose ds_bp will be rewritten when we do this 2nd sync.
+        * sync tasks, so that any snapshots will have the correct
+        * user accounting information (and we won't get confused
+        * about which blocks are part of the snapshot).
         */
        zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
-       while (ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) {
+       while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
+               objset_t *os = ds->ds_objset;
+
                ASSERT(list_link_active(&ds->ds_synced_link));
                dmu_buf_rele(ds->ds_dbuf, ds);
                dsl_dataset_sync(ds, zio, tx);
+
+               /*
+                * Release any key mappings created by calls to
+                * dsl_dataset_dirty() from the userquota accounting
+                * code paths.
+                */
+               if (os->os_encrypted && !os->os_raw_receive &&
+                   !os->os_next_write_raw[txg & TXG_MASK]) {
+                       ASSERT3P(ds->ds_key_mapping, !=, NULL);
+                       key_mapping_rele(dp->dp_spa, ds->ds_key_mapping, ds);
+               }
        }
-       err = zio_wait(zio);
+       VERIFY0(zio_wait(zio));
 
        /*
-        * Move dead blocks from the pending deadlist to the on-disk
-        * deadlist.
+        * Now that the datasets have been completely synced, we can
+        * clean up our in-memory structures accumulated while syncing:
+        *
+        *  - move dead blocks from the pending deadlist and livelists
+        *    to the on-disk versions
+        *  - release hold from dsl_dataset_dirty()
+        *  - release key mapping hold from dsl_dataset_dirty()
         */
-       for (ds = list_head(&dp->dp_synced_datasets); ds;
-           ds = list_next(&dp->dp_synced_datasets, ds)) {
-               bplist_iterate(&ds->ds_pending_deadlist,
-                   deadlist_enqueue_cb, &ds->ds_deadlist, tx);
-       }
+       while ((ds = list_remove_head(&synced_datasets)) != NULL) {
+               objset_t *os = ds->ds_objset;
 
-       while (dstg = txg_list_remove(&dp->dp_sync_tasks, txg)) {
-               /*
-                * No more sync tasks should have been added while we
-                * were syncing.
-                */
-               ASSERT(spa_sync_pass(dp->dp_spa) == 1);
-               dsl_sync_task_group_sync(dstg, tx);
+               if (os->os_encrypted && !os->os_raw_receive &&
+                   !os->os_next_write_raw[txg & TXG_MASK]) {
+                       ASSERT3P(ds->ds_key_mapping, !=, NULL);
+                       key_mapping_rele(dp->dp_spa, ds->ds_key_mapping, ds);
+               }
+
+               dsl_dataset_sync_done(ds, tx);
        }
-       DTRACE_PROBE(pool_sync__3task);
 
-       start = gethrtime();
-       while (dd = txg_list_remove(&dp->dp_dirty_dirs, txg))
+       while ((dd = txg_list_remove(&dp->dp_dirty_dirs, txg)) != NULL) {
                dsl_dir_sync(dd, tx);
-       write_time += gethrtime() - start;
-
-       start = gethrtime();
-       if (list_head(&mos->os_dirty_dnodes[txg & TXG_MASK]) != NULL ||
-           list_head(&mos->os_free_dnodes[txg & TXG_MASK]) != NULL) {
-               zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
-               dmu_objset_sync(mos, zio, tx);
-               err = zio_wait(zio);
-               ASSERT(err == 0);
-               dprintf_bp(&dp->dp_meta_rootbp, "meta objset rootbp is %s", "");
-               spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
        }
-       write_time += gethrtime() - start;
-       DTRACE_PROBE2(pool_sync__4io, hrtime_t, write_time,
-           hrtime_t, dp->dp_read_overhead);
-       write_time -= dp->dp_read_overhead;
-
-       dmu_tx_commit(tx);
-
-       dp->dp_space_towrite[txg & TXG_MASK] = 0;
-       ASSERT(dp->dp_tempreserved[txg & TXG_MASK] == 0);
 
        /*
-        * If the write limit max has not been explicitly set, set it
-        * to a fraction of available physical memory (default 1/8th).
-        * Note that we must inflate the limit because the spa
-        * inflates write sizes to account for data replication.
-        * Check this each sync phase to catch changing memory size.
+        * The MOS's space is accounted for in the pool/$MOS
+        * (dp_mos_dir).  We can't modify the mos while we're syncing
+        * it, so we remember the deltas and apply them here.
         */
-       if (physmem != old_physmem && zfs_write_limit_shift) {
-               mutex_enter(&zfs_write_limit_lock);
-               old_physmem = physmem;
-               zfs_write_limit_max = ptob(physmem) >> zfs_write_limit_shift;
-               zfs_write_limit_inflated = MAX(zfs_write_limit_min,
-                   spa_get_asize(dp->dp_spa, zfs_write_limit_max));
-               mutex_exit(&zfs_write_limit_lock);
+       if (dp->dp_mos_used_delta != 0 || dp->dp_mos_compressed_delta != 0 ||
+           dp->dp_mos_uncompressed_delta != 0) {
+               dsl_dir_diduse_space(dp->dp_mos_dir, DD_USED_HEAD,
+                   dp->dp_mos_used_delta,
+                   dp->dp_mos_compressed_delta,
+                   dp->dp_mos_uncompressed_delta, tx);
+               dp->dp_mos_used_delta = 0;
+               dp->dp_mos_compressed_delta = 0;
+               dp->dp_mos_uncompressed_delta = 0;
+       }
+
+       if (dmu_objset_is_dirty(mos, txg)) {
+               dsl_pool_sync_mos(dp, tx);
        }
 
        /*
-        * Attempt to keep the sync time consistent by adjusting the
-        * amount of write traffic allowed into each transaction group.
-        * Weight the throughput calculation towards the current value:
-        *      thru = 3/4 old_thru + 1/4 new_thru
+        * We have written all of the accounted dirty data, so our
+        * dp_space_towrite should now be zero. However, some seldom-used
+        * code paths do not adhere to this (e.g. dbuf_undirty()). Shore up
+        * the accounting of any dirtied space now.
         *
-        * Note: write_time is in nanosecs, so write_time/MICROSEC
-        * yields millisecs
+        * Note that, besides any dirty data from datasets, the amount of
+        * dirty data in the MOS is also accounted by the pool. Therefore,
+        * we want to do this cleanup after dsl_pool_sync_mos() so we don't
+        * attempt to update the accounting for the same dirty data twice.
+        * (i.e. at this point we only update the accounting for the space
+        * that we know that we "leaked").
+        */
+       dsl_pool_undirty_space(dp, dp->dp_dirty_pertxg[txg & TXG_MASK], txg);
+
+       /*
+        * If we modify a dataset in the same txg that we want to destroy it,
+        * its dsl_dir's dd_dbuf will be dirty, and thus have a hold on it.
+        * dsl_dir_destroy_check() will fail if there are unexpected holds.
+        * Therefore, we want to sync the MOS (thus syncing the dd_dbuf
+        * and clearing the hold on it) before we process the sync_tasks.
+        * The MOS data dirtied by the sync_tasks will be synced on the next
+        * pass.
         */
-       ASSERT(zfs_write_limit_min > 0);
-       if (data_written > zfs_write_limit_min / 8 && write_time > MICROSEC) {
-               uint64_t throughput = data_written / (write_time / MICROSEC);
-
-               if (dp->dp_throughput)
-                       dp->dp_throughput = throughput / 4 +
-                           3 * dp->dp_throughput / 4;
-               else
-                       dp->dp_throughput = throughput;
-               dp->dp_write_limit = MIN(zfs_write_limit_inflated,
-                   MAX(zfs_write_limit_min,
-                   dp->dp_throughput * zfs_txg_synctime_ms));
+       if (!txg_list_empty(&dp->dp_sync_tasks, txg)) {
+               dsl_sync_task_t *dst;
+               /*
+                * No more sync tasks should have been added while we
+                * were syncing.
+                */
+               ASSERT3U(spa_sync_pass(dp->dp_spa), ==, 1);
+               while ((dst = txg_list_remove(&dp->dp_sync_tasks, txg)) != NULL)
+                       dsl_sync_task_sync(dst, tx);
        }
+
+       dmu_tx_commit(tx);
+
+       DTRACE_PROBE2(dsl_pool_sync__done, dsl_pool_t *dp, dp, uint64_t, txg);
 }
 
 void
 dsl_pool_sync_done(dsl_pool_t *dp, uint64_t txg)
 {
-       dsl_dataset_t *ds;
-       objset_t *os;
+       zilog_t *zilog;
 
-       while (ds = list_head(&dp->dp_synced_datasets)) {
-               list_remove(&dp->dp_synced_datasets, ds);
-               os = ds->ds_objset;
-               zil_clean(os->os_zil, txg);
-               ASSERT(!dmu_objset_is_dirty(os, txg));
-               dmu_buf_rele(ds->ds_dbuf, ds);
+       while ((zilog = txg_list_head(&dp->dp_dirty_zilogs, txg))) {
+               dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os);
+               /*
+                * We don't remove the zilog from the dp_dirty_zilogs
+                * list until after we've cleaned it. This ensures that
+                * callers of zilog_is_dirty() receive an accurate
+                * answer when they are racing with the spa sync thread.
+                */
+               zil_clean(zilog, txg);
+               (void) txg_list_remove_this(&dp->dp_dirty_zilogs, zilog, txg);
+               ASSERT(!dmu_objset_is_dirty(zilog->zl_os, txg));
+               dmu_buf_rele(ds->ds_dbuf, zilog);
        }
        ASSERT(!dmu_objset_is_dirty(dp->dp_meta_objset, txg));
 }
@@ -466,130 +822,140 @@ int
 dsl_pool_sync_context(dsl_pool_t *dp)
 {
        return (curthread == dp->dp_tx.tx_sync_thread ||
-           spa_get_dsl(dp->dp_spa) == NULL);
+           spa_is_initializing(dp->dp_spa) ||
+           taskq_member(dp->dp_sync_taskq, curthread));
 }
 
+/*
+ * This function returns the amount of allocatable space in the pool
+ * minus whatever space is currently reserved by ZFS for specific
+ * purposes. Specifically:
+ *
+ * 1] Any reserved SLOP space
+ * 2] Any space used by the checkpoint
+ * 3] Any space used for deferred frees
+ *
+ * The latter 2 are especially important because they are needed to
+ * rectify the SPA's and DMU's different understanding of how much space
+ * is used. Now the DMU is aware of that extra space tracked by the SPA
+ * without having to maintain a separate special dir (e.g similar to
+ * $MOS, $FREEING, and $LEAKED).
+ *
+ * Note: By deferred frees here, we mean the frees that were deferred
+ * in spa_sync() after sync pass 1 (spa_deferred_bpobj), and not the
+ * segments placed in ms_defer trees during metaslab_sync_done().
+ */
 uint64_t
-dsl_pool_adjustedsize(dsl_pool_t *dp, boolean_t netfree)
+dsl_pool_adjustedsize(dsl_pool_t *dp, zfs_space_check_t slop_policy)
 {
-       uint64_t space, resv;
-
-       /*
-        * Reserve about 1.6% (1/64), or at least 32MB, for allocation
-        * efficiency.
-        * XXX The intent log is not accounted for, so it must fit
-        * within this slop.
-        *
-        * If we're trying to assess whether it's OK to do a free,
-        * cut the reservation in half to allow forward progress
-        * (e.g. make it possible to rm(1) files from a full pool).
-        */
-       space = spa_get_dspace(dp->dp_spa);
-       resv = MAX(space >> 6, SPA_MINDEVSIZE >> 1);
-       if (netfree)
+       spa_t *spa = dp->dp_spa;
+       uint64_t space, resv, adjustedsize;
+       uint64_t spa_deferred_frees =
+           spa->spa_deferred_bpobj.bpo_phys->bpo_bytes;
+
+       space = spa_get_dspace(spa)
+           - spa_get_checkpoint_space(spa) - spa_deferred_frees;
+       resv = spa_get_slop_space(spa);
+
+       switch (slop_policy) {
+       case ZFS_SPACE_CHECK_NORMAL:
+               break;
+       case ZFS_SPACE_CHECK_RESERVED:
                resv >>= 1;
+               break;
+       case ZFS_SPACE_CHECK_EXTRA_RESERVED:
+               resv >>= 2;
+               break;
+       case ZFS_SPACE_CHECK_NONE:
+               resv = 0;
+               break;
+       default:
+               panic("invalid slop policy value: %d", slop_policy);
+               break;
+       }
+       adjustedsize = (space >= resv) ? (space - resv) : 0;
 
-       return (space - resv);
+       return (adjustedsize);
 }
 
-int
-dsl_pool_tempreserve_space(dsl_pool_t *dp, uint64_t space, dmu_tx_t *tx)
+uint64_t
+dsl_pool_unreserved_space(dsl_pool_t *dp, zfs_space_check_t slop_policy)
 {
-       uint64_t reserved = 0;
-       uint64_t write_limit = (zfs_write_limit_override ?
-           zfs_write_limit_override : dp->dp_write_limit);
-
-       if (zfs_no_write_throttle) {
-               atomic_add_64(&dp->dp_tempreserved[tx->tx_txg & TXG_MASK],
-                   space);
-               return (0);
-       }
-
-       /*
-        * Check to see if we have exceeded the maximum allowed IO for
-        * this transaction group.  We can do this without locks since
-        * a little slop here is ok.  Note that we do the reserved check
-        * with only half the requested reserve: this is because the
-        * reserve requests are worst-case, and we really don't want to
-        * throttle based off of worst-case estimates.
-        */
-       if (write_limit > 0) {
-               reserved = dp->dp_space_towrite[tx->tx_txg & TXG_MASK]
-                   + dp->dp_tempreserved[tx->tx_txg & TXG_MASK] / 2;
-
-               if (reserved && reserved > write_limit)
-                       return (ERESTART);
-       }
-
-       atomic_add_64(&dp->dp_tempreserved[tx->tx_txg & TXG_MASK], space);
-
-       /*
-        * If this transaction group is over 7/8ths capacity, delay
-        * the caller 1 clock tick.  This will slow down the "fill"
-        * rate until the sync process can catch up with us.
-        */
-       if (reserved && reserved > (write_limit - (write_limit >> 3)))
-               txg_delay(dp, tx->tx_txg, 1);
-
-       return (0);
+       uint64_t poolsize = dsl_pool_adjustedsize(dp, slop_policy);
+       uint64_t deferred =
+           metaslab_class_get_deferred(spa_normal_class(dp->dp_spa));
+       uint64_t quota = (poolsize >= deferred) ? (poolsize - deferred) : 0;
+       return (quota);
 }
 
-void
-dsl_pool_tempreserve_clear(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx)
+boolean_t
+dsl_pool_need_dirty_delay(dsl_pool_t *dp)
 {
-       ASSERT(dp->dp_tempreserved[tx->tx_txg & TXG_MASK] >= space);
-       atomic_add_64(&dp->dp_tempreserved[tx->tx_txg & TXG_MASK], -space);
+       uint64_t delay_min_bytes =
+           zfs_dirty_data_max * zfs_delay_min_dirty_percent / 100;
+       uint64_t dirty_min_bytes =
+           zfs_dirty_data_max * zfs_dirty_data_sync_percent / 100;
+       uint64_t dirty;
+
+       mutex_enter(&dp->dp_lock);
+       dirty = dp->dp_dirty_total;
+       mutex_exit(&dp->dp_lock);
+       if (dirty > dirty_min_bytes)
+               txg_kick(dp);
+       return (dirty > delay_min_bytes);
 }
 
 void
-dsl_pool_memory_pressure(dsl_pool_t *dp)
+dsl_pool_dirty_space(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx)
 {
-       uint64_t space_inuse = 0;
-       int i;
-
-       if (dp->dp_write_limit == zfs_write_limit_min)
-               return;
-
-       for (i = 0; i < TXG_SIZE; i++) {
-               space_inuse += dp->dp_space_towrite[i];
-               space_inuse += dp->dp_tempreserved[i];
+       if (space > 0) {
+               mutex_enter(&dp->dp_lock);
+               dp->dp_dirty_pertxg[tx->tx_txg & TXG_MASK] += space;
+               dsl_pool_dirty_delta(dp, space);
+               mutex_exit(&dp->dp_lock);
        }
-       dp->dp_write_limit = MAX(zfs_write_limit_min,
-           MIN(dp->dp_write_limit, space_inuse / 4));
 }
 
 void
-dsl_pool_willuse_space(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx)
+dsl_pool_undirty_space(dsl_pool_t *dp, int64_t space, uint64_t txg)
 {
-       if (space > 0) {
-               mutex_enter(&dp->dp_lock);
-               dp->dp_space_towrite[tx->tx_txg & TXG_MASK] += space;
-               mutex_exit(&dp->dp_lock);
+       ASSERT3S(space, >=, 0);
+       if (space == 0)
+               return;
+
+       mutex_enter(&dp->dp_lock);
+       if (dp->dp_dirty_pertxg[txg & TXG_MASK] < space) {
+               /* XXX writing something we didn't dirty? */
+               space = dp->dp_dirty_pertxg[txg & TXG_MASK];
        }
+       ASSERT3U(dp->dp_dirty_pertxg[txg & TXG_MASK], >=, space);
+       dp->dp_dirty_pertxg[txg & TXG_MASK] -= space;
+       ASSERT3U(dp->dp_dirty_total, >=, space);
+       dsl_pool_dirty_delta(dp, -space);
+       mutex_exit(&dp->dp_lock);
 }
 
 /* ARGSUSED */
 static int
-upgrade_clones_cb(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
+upgrade_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
 {
        dmu_tx_t *tx = arg;
        dsl_dataset_t *ds, *prev = NULL;
        int err;
-       dsl_pool_t *dp = spa_get_dsl(spa);
 
-       err = dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds);
+       err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
        if (err)
                return (err);
 
-       while (ds->ds_phys->ds_prev_snap_obj != 0) {
-               err = dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
-                   FTAG, &prev);
+       while (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
+               err = dsl_dataset_hold_obj(dp,
+                   dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &prev);
                if (err) {
                        dsl_dataset_rele(ds, FTAG);
                        return (err);
                }
 
-               if (prev->ds_phys->ds_next_snap_obj != ds->ds_object)
+               if (dsl_dataset_phys(prev)->ds_next_snap_obj != ds->ds_object)
                        break;
                dsl_dataset_rele(ds, FTAG);
                ds = prev;
@@ -603,7 +969,9 @@ upgrade_clones_cb(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
                 * The $ORIGIN can't have any data, or the accounting
                 * will be wrong.
                 */
-               ASSERT(prev->ds_phys->ds_bp.blk_birth == 0);
+               rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
+               ASSERT0(dsl_dataset_phys(prev)->ds_bp.blk_birth);
+               rrw_exit(&ds->ds_bp_rwlock, FTAG);
 
                /* The origin doesn't get attached to itself */
                if (ds->ds_object == prev->ds_object) {
@@ -612,33 +980,35 @@ upgrade_clones_cb(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
                }
 
                dmu_buf_will_dirty(ds->ds_dbuf, tx);
-               ds->ds_phys->ds_prev_snap_obj = prev->ds_object;
-               ds->ds_phys->ds_prev_snap_txg = prev->ds_phys->ds_creation_txg;
+               dsl_dataset_phys(ds)->ds_prev_snap_obj = prev->ds_object;
+               dsl_dataset_phys(ds)->ds_prev_snap_txg =
+                   dsl_dataset_phys(prev)->ds_creation_txg;
 
                dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
-               ds->ds_dir->dd_phys->dd_origin_obj = prev->ds_object;
+               dsl_dir_phys(ds->ds_dir)->dd_origin_obj = prev->ds_object;
 
                dmu_buf_will_dirty(prev->ds_dbuf, tx);
-               prev->ds_phys->ds_num_children++;
+               dsl_dataset_phys(prev)->ds_num_children++;
 
-               if (ds->ds_phys->ds_next_snap_obj == 0) {
+               if (dsl_dataset_phys(ds)->ds_next_snap_obj == 0) {
                        ASSERT(ds->ds_prev == NULL);
-                       VERIFY(0 == dsl_dataset_hold_obj(dp,
-                           ds->ds_phys->ds_prev_snap_obj, ds, &ds->ds_prev));
+                       VERIFY0(dsl_dataset_hold_obj(dp,
+                           dsl_dataset_phys(ds)->ds_prev_snap_obj,
+                           ds, &ds->ds_prev));
                }
        }
 
-       ASSERT(ds->ds_dir->dd_phys->dd_origin_obj == prev->ds_object);
-       ASSERT(ds->ds_phys->ds_prev_snap_obj == prev->ds_object);
+       ASSERT3U(dsl_dir_phys(ds->ds_dir)->dd_origin_obj, ==, prev->ds_object);
+       ASSERT3U(dsl_dataset_phys(ds)->ds_prev_snap_obj, ==, prev->ds_object);
 
-       if (prev->ds_phys->ds_next_clones_obj == 0) {
+       if (dsl_dataset_phys(prev)->ds_next_clones_obj == 0) {
                dmu_buf_will_dirty(prev->ds_dbuf, tx);
-               prev->ds_phys->ds_next_clones_obj =
+               dsl_dataset_phys(prev)->ds_next_clones_obj =
                    zap_create(dp->dp_meta_objset,
                    DMU_OT_NEXT_CLONES, DMU_OT_NONE, 0, tx);
        }
-       VERIFY(0 == zap_add_int(dp->dp_meta_objset,
-           prev->ds_phys->ds_next_clones_obj, ds->ds_object, tx));
+       VERIFY0(zap_add_int(dp->dp_meta_objset,
+           dsl_dataset_phys(prev)->ds_next_clones_obj, ds->ds_object, tx));
 
        dsl_dataset_rele(ds, FTAG);
        if (prev != dp->dp_origin_snap)
@@ -652,51 +1022,48 @@ dsl_pool_upgrade_clones(dsl_pool_t *dp, dmu_tx_t *tx)
        ASSERT(dmu_tx_is_syncing(tx));
        ASSERT(dp->dp_origin_snap != NULL);
 
-       VERIFY3U(0, ==, dmu_objset_find_spa(dp->dp_spa, NULL, upgrade_clones_cb,
-           tx, DS_FIND_CHILDREN));
+       VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj, upgrade_clones_cb,
+           tx, DS_FIND_CHILDREN | DS_FIND_SERIALIZE));
 }
 
 /* ARGSUSED */
 static int
-upgrade_dir_clones_cb(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
+upgrade_dir_clones_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
 {
        dmu_tx_t *tx = arg;
-       dsl_dataset_t *ds;
-       dsl_pool_t *dp = spa_get_dsl(spa);
        objset_t *mos = dp->dp_meta_objset;
 
-       VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
-
-       if (ds->ds_dir->dd_phys->dd_origin_obj) {
+       if (dsl_dir_phys(ds->ds_dir)->dd_origin_obj != 0) {
                dsl_dataset_t *origin;
 
-               VERIFY3U(0, ==, dsl_dataset_hold_obj(dp,
-                   ds->ds_dir->dd_phys->dd_origin_obj, FTAG, &origin));
+               VERIFY0(dsl_dataset_hold_obj(dp,
+                   dsl_dir_phys(ds->ds_dir)->dd_origin_obj, FTAG, &origin));
 
-               if (origin->ds_dir->dd_phys->dd_clones == 0) {
+               if (dsl_dir_phys(origin->ds_dir)->dd_clones == 0) {
                        dmu_buf_will_dirty(origin->ds_dir->dd_dbuf, tx);
-                       origin->ds_dir->dd_phys->dd_clones = zap_create(mos,
-                           DMU_OT_DSL_CLONES, DMU_OT_NONE, 0, tx);
+                       dsl_dir_phys(origin->ds_dir)->dd_clones =
+                           zap_create(mos, DMU_OT_DSL_CLONES, DMU_OT_NONE,
+                           0, tx);
                }
 
-               VERIFY3U(0, ==, zap_add_int(dp->dp_meta_objset,
-                   origin->ds_dir->dd_phys->dd_clones, dsobj, tx));
+               VERIFY0(zap_add_int(dp->dp_meta_objset,
+                   dsl_dir_phys(origin->ds_dir)->dd_clones,
+                   ds->ds_object, tx));
 
                dsl_dataset_rele(origin, FTAG);
        }
-
-       dsl_dataset_rele(ds, FTAG);
        return (0);
 }
 
 void
 dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx)
 {
-       ASSERT(dmu_tx_is_syncing(tx));
        uint64_t obj;
 
+       ASSERT(dmu_tx_is_syncing(tx));
+
        (void) dsl_dir_create_sync(dp, dp->dp_root_dir, FREE_DIR_NAME, tx);
-       VERIFY(0 == dsl_pool_open_special_dir(dp,
+       VERIFY0(dsl_pool_open_special_dir(dp,
            FREE_DIR_NAME, &dp->dp_free_dir));
 
        /*
@@ -705,14 +1072,13 @@ dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx)
         * subobj support.  So call dmu_object_alloc() directly.
         */
        obj = dmu_object_alloc(dp->dp_meta_objset, DMU_OT_BPOBJ,
-           SPA_MAXBLOCKSIZE, DMU_OT_BPOBJ_HDR, sizeof (bpobj_phys_t), tx);
-       VERIFY3U(0, ==, zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+           SPA_OLD_MAXBLOCKSIZE, DMU_OT_BPOBJ_HDR, sizeof (bpobj_phys_t), tx);
+       VERIFY0(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
            DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx));
-       VERIFY3U(0, ==, bpobj_open(&dp->dp_free_bpobj,
-           dp->dp_meta_objset, obj));
+       VERIFY0(bpobj_open(&dp->dp_free_bpobj, dp->dp_meta_objset, obj));
 
-       VERIFY3U(0, ==, dmu_objset_find_spa(dp->dp_spa, NULL,
-           upgrade_dir_clones_cb, tx, DS_FIND_CHILDREN));
+       VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
+           upgrade_dir_clones_cb, tx, DS_FIND_CHILDREN | DS_FIND_SERIALIZE));
 }
 
 void
@@ -723,23 +1089,28 @@ dsl_pool_create_origin(dsl_pool_t *dp, dmu_tx_t *tx)
 
        ASSERT(dmu_tx_is_syncing(tx));
        ASSERT(dp->dp_origin_snap == NULL);
+       ASSERT(rrw_held(&dp->dp_config_rwlock, RW_WRITER));
 
        /* create the origin dir, ds, & snap-ds */
-       rw_enter(&dp->dp_config_rwlock, RW_WRITER);
        dsobj = dsl_dataset_create_sync(dp->dp_root_dir, ORIGIN_DIR_NAME,
-           NULL, 0, kcred, tx);
-       VERIFY(0 == dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
-       dsl_dataset_snapshot_sync(ds, ORIGIN_DIR_NAME, tx);
-       VERIFY(0 == dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
+           NULL, 0, kcred, NULL, tx);
+       VERIFY0(dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
+       dsl_dataset_snapshot_sync_impl(ds, ORIGIN_DIR_NAME, tx);
+       VERIFY0(dsl_dataset_hold_obj(dp, dsl_dataset_phys(ds)->ds_prev_snap_obj,
            dp, &dp->dp_origin_snap));
        dsl_dataset_rele(ds, FTAG);
-       rw_exit(&dp->dp_config_rwlock);
 }
 
 taskq_t *
-dsl_pool_vnrele_taskq(dsl_pool_t *dp)
+dsl_pool_zrele_taskq(dsl_pool_t *dp)
+{
+       return (dp->dp_zrele_taskq);
+}
+
+taskq_t *
+dsl_pool_unlinked_drain_taskq(dsl_pool_t *dp)
 {
-       return (dp->dp_vnrele_taskq);
+       return (dp->dp_unlinked_drain_taskq);
 }
 
 /*
@@ -753,23 +1124,34 @@ dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp)
        zap_cursor_t zc;
        objset_t *mos = dp->dp_meta_objset;
        uint64_t zapobj = dp->dp_tmp_userrefs_obj;
+       nvlist_t *holds;
 
        if (zapobj == 0)
                return;
        ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
 
+       holds = fnvlist_alloc();
+
        for (zap_cursor_init(&zc, mos, zapobj);
            zap_cursor_retrieve(&zc, &za) == 0;
            zap_cursor_advance(&zc)) {
                char *htag;
-               uint64_t dsobj;
+               nvlist_t *tags;
 
                htag = strchr(za.za_name, '-');
                *htag = '\0';
                ++htag;
-               dsobj = strtonum(za.za_name, NULL);
-               (void) dsl_dataset_user_release_tmp(dp, dsobj, htag, B_FALSE);
+               if (nvlist_lookup_nvlist(holds, za.za_name, &tags) != 0) {
+                       tags = fnvlist_alloc();
+                       fnvlist_add_boolean(tags, htag);
+                       fnvlist_add_nvlist(holds, za.za_name, tags);
+                       fnvlist_free(tags);
+               } else {
+                       fnvlist_add_boolean(tags, htag);
+               }
        }
+       dsl_dataset_user_release_tmp(dp, holds);
+       fnvlist_free(holds);
        zap_cursor_fini(&zc);
 }
 
@@ -784,16 +1166,13 @@ dsl_pool_user_hold_create_obj(dsl_pool_t *dp, dmu_tx_t *tx)
        ASSERT(dp->dp_tmp_userrefs_obj == 0);
        ASSERT(dmu_tx_is_syncing(tx));
 
-       dp->dp_tmp_userrefs_obj = zap_create(mos, DMU_OT_USERREFS,
-           DMU_OT_NONE, 0, tx);
-
-       VERIFY(zap_add(mos, DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_TMP_USERREFS,
-           sizeof (uint64_t), 1, &dp->dp_tmp_userrefs_obj, tx) == 0);
+       dp->dp_tmp_userrefs_obj = zap_create_link(mos, DMU_OT_USERREFS,
+           DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_TMP_USERREFS, tx);
 }
 
 static int
 dsl_pool_user_hold_rele_impl(dsl_pool_t *dp, uint64_t dsobj,
-    const char *tag, uint64_t *now, dmu_tx_t *tx, boolean_t holding)
+    const char *tag, uint64_t now, dmu_tx_t *tx, boolean_t holding)
 {
        objset_t *mos = dp->dp_meta_objset;
        uint64_t zapobj = dp->dp_tmp_userrefs_obj;
@@ -812,16 +1191,16 @@ dsl_pool_user_hold_rele_impl(dsl_pool_t *dp, uint64_t dsobj,
                        dsl_pool_user_hold_create_obj(dp, tx);
                        zapobj = dp->dp_tmp_userrefs_obj;
                } else {
-                       return (ENOENT);
+                       return (SET_ERROR(ENOENT));
                }
        }
 
        name = kmem_asprintf("%llx-%s", (u_longlong_t)dsobj, tag);
        if (holding)
-               error = zap_add(mos, zapobj, name, 8, 1, now, tx);
+               error = zap_add(mos, zapobj, name, 8, 1, &now, tx);
        else
                error = zap_remove(mos, zapobj, name, tx);
-       strfree(name);
+       kmem_strfree(name);
 
        return (error);
 }
@@ -831,7 +1210,7 @@ dsl_pool_user_hold_rele_impl(dsl_pool_t *dp, uint64_t dsobj,
  */
 int
 dsl_pool_user_hold(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
-    uint64_t *now, dmu_tx_t *tx)
+    uint64_t now, dmu_tx_t *tx)
 {
        return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, now, tx, B_TRUE));
 }
@@ -843,6 +1222,163 @@ int
 dsl_pool_user_release(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
     dmu_tx_t *tx)
 {
-       return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, NULL,
+       return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, 0,
            tx, B_FALSE));
 }
+
+/*
+ * DSL Pool Configuration Lock
+ *
+ * The dp_config_rwlock protects against changes to DSL state (e.g. dataset
+ * creation / destruction / rename / property setting).  It must be held for
+ * read to hold a dataset or dsl_dir.  I.e. you must call
+ * dsl_pool_config_enter() or dsl_pool_hold() before calling
+ * dsl_{dataset,dir}_hold{_obj}.  In most circumstances, the dp_config_rwlock
+ * must be held continuously until all datasets and dsl_dirs are released.
+ *
+ * The only exception to this rule is that if a "long hold" is placed on
+ * a dataset, then the dp_config_rwlock may be dropped while the dataset
+ * is still held.  The long hold will prevent the dataset from being
+ * destroyed -- the destroy will fail with EBUSY.  A long hold can be
+ * obtained by calling dsl_dataset_long_hold(), or by "owning" a dataset
+ * (by calling dsl_{dataset,objset}_{try}own{_obj}).
+ *
+ * Legitimate long-holders (including owners) should be long-running, cancelable
+ * tasks that should cause "zfs destroy" to fail.  This includes DMU
+ * consumers (i.e. a ZPL filesystem being mounted or ZVOL being open),
+ * "zfs send", and "zfs diff".  There are several other long-holders whose
+ * uses are suboptimal (e.g. "zfs promote", and zil_suspend()).
+ *
+ * The usual formula for long-holding would be:
+ * dsl_pool_hold()
+ * dsl_dataset_hold()
+ * ... perform checks ...
+ * dsl_dataset_long_hold()
+ * dsl_pool_rele()
+ * ... perform long-running task ...
+ * dsl_dataset_long_rele()
+ * dsl_dataset_rele()
+ *
+ * Note that when the long hold is released, the dataset is still held but
+ * the pool is not held.  The dataset may change arbitrarily during this time
+ * (e.g. it could be destroyed).  Therefore you shouldn't do anything to the
+ * dataset except release it.
+ *
+ * User-initiated operations (e.g. ioctls, zfs_ioc_*()) are either read-only
+ * or modifying operations.
+ *
+ * Modifying operations should generally use dsl_sync_task().  The synctask
+ * infrastructure enforces proper locking strategy with respect to the
+ * dp_config_rwlock.  See the comment above dsl_sync_task() for details.
+ *
+ * Read-only operations will manually hold the pool, then the dataset, obtain
+ * information from the dataset, then release the pool and dataset.
+ * dmu_objset_{hold,rele}() are convenience routines that also do the pool
+ * hold/rele.
+ */
+
+int
+dsl_pool_hold(const char *name, void *tag, dsl_pool_t **dp)
+{
+       spa_t *spa;
+       int error;
+
+       error = spa_open(name, &spa, tag);
+       if (error == 0) {
+               *dp = spa_get_dsl(spa);
+               dsl_pool_config_enter(*dp, tag);
+       }
+       return (error);
+}
+
+void
+dsl_pool_rele(dsl_pool_t *dp, void *tag)
+{
+       dsl_pool_config_exit(dp, tag);
+       spa_close(dp->dp_spa, tag);
+}
+
+void
+dsl_pool_config_enter(dsl_pool_t *dp, void *tag)
+{
+       /*
+        * We use a "reentrant" reader-writer lock, but not reentrantly.
+        *
+        * The rrwlock can (with the track_all flag) track all reading threads,
+        * which is very useful for debugging which code path failed to release
+        * the lock, and for verifying that the *current* thread does hold
+        * the lock.
+        *
+        * (Unlike a rwlock, which knows that N threads hold it for
+        * read, but not *which* threads, so rw_held(RW_READER) returns TRUE
+        * if any thread holds it for read, even if this thread doesn't).
+        */
+       ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
+       rrw_enter(&dp->dp_config_rwlock, RW_READER, tag);
+}
+
+void
+dsl_pool_config_enter_prio(dsl_pool_t *dp, void *tag)
+{
+       ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
+       rrw_enter_read_prio(&dp->dp_config_rwlock, tag);
+}
+
+void
+dsl_pool_config_exit(dsl_pool_t *dp, void *tag)
+{
+       rrw_exit(&dp->dp_config_rwlock, tag);
+}
+
+boolean_t
+dsl_pool_config_held(dsl_pool_t *dp)
+{
+       return (RRW_LOCK_HELD(&dp->dp_config_rwlock));
+}
+
+boolean_t
+dsl_pool_config_held_writer(dsl_pool_t *dp)
+{
+       return (RRW_WRITE_HELD(&dp->dp_config_rwlock));
+}
+
+EXPORT_SYMBOL(dsl_pool_config_enter);
+EXPORT_SYMBOL(dsl_pool_config_exit);
+
+/* BEGIN CSTYLED */
+/* zfs_dirty_data_max_percent only applied at module load in arc_init(). */
+ZFS_MODULE_PARAM(zfs, zfs_, dirty_data_max_percent, INT, ZMOD_RD,
+       "Max percent of RAM allowed to be dirty");
+
+/* zfs_dirty_data_max_max_percent only applied at module load in arc_init(). */
+ZFS_MODULE_PARAM(zfs, zfs_, dirty_data_max_max_percent, INT, ZMOD_RD,
+       "zfs_dirty_data_max upper bound as % of RAM");
+
+ZFS_MODULE_PARAM(zfs, zfs_, delay_min_dirty_percent, INT, ZMOD_RW,
+       "Transaction delay threshold");
+
+ZFS_MODULE_PARAM(zfs, zfs_, dirty_data_max, ULONG, ZMOD_RW,
+       "Determines the dirty space limit");
+
+/* zfs_dirty_data_max_max only applied at module load in arc_init(). */
+ZFS_MODULE_PARAM(zfs, zfs_, dirty_data_max_max, ULONG, ZMOD_RD,
+       "zfs_dirty_data_max upper bound in bytes");
+
+ZFS_MODULE_PARAM(zfs, zfs_, dirty_data_sync_percent, INT, ZMOD_RW,
+       "Dirty data txg sync threshold as a percentage of zfs_dirty_data_max");
+
+ZFS_MODULE_PARAM(zfs, zfs_, delay_scale, ULONG, ZMOD_RW,
+       "How quickly delay approaches infinity");
+
+ZFS_MODULE_PARAM(zfs, zfs_, sync_taskq_batch_pct, INT, ZMOD_RW,
+       "Max percent of CPUs that are used to sync dirty data");
+
+ZFS_MODULE_PARAM(zfs_zil, zfs_zil_, clean_taskq_nthr_pct, INT, ZMOD_RW,
+       "Max percent of CPUs that are used per dp_sync_taskq");
+
+ZFS_MODULE_PARAM(zfs_zil, zfs_zil_, clean_taskq_minalloc, INT, ZMOD_RW,
+       "Number of taskq entries that are pre-populated");
+
+ZFS_MODULE_PARAM(zfs_zil, zfs_zil_, clean_taskq_maxalloc, INT, ZMOD_RW,
+       "Max number of taskq entries that are cached");
+/* END CSTYLED */