diff options
Diffstat (limited to 'module/zfs/dsl_pool.c')
| -rw-r--r-- | module/zfs/dsl_pool.c | 1384 |
1 files changed, 1384 insertions, 0 deletions
diff --git a/module/zfs/dsl_pool.c b/module/zfs/dsl_pool.c new file mode 100644 index 000000000000..3a2028625e8b --- /dev/null +++ b/module/zfs/dsl_pool.c @@ -0,0 +1,1384 @@ +/* + * CDDL HEADER START + * + * The contents of this file are subject to the terms of the + * Common Development and Distribution License (the "License"). + * You may not use this file except in compliance with the License. + * + * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE + * or http://www.opensolaris.org/os/licensing. + * See the License for the specific language governing permissions + * and limitations under the License. + * + * When distributing Covered Code, include this CDDL HEADER in each + * file and include the License file at usr/src/OPENSOLARIS.LICENSE. + * If applicable, add the following below this CDDL HEADER, with the + * fields enclosed by brackets "[]" replaced with your own identifying + * information: Portions Copyright [yyyy] [name of copyright owner] + * + * CDDL HEADER END + */ +/* + * Copyright (c) 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/dsl_dataset.h> +#include <sys/dsl_prop.h> +#include <sys/dsl_dir.h> +#include <sys/dsl_synctask.h> +#include <sys/dsl_scan.h> +#include <sys/dnode.h> +#include <sys/dmu_tx.h> +#include <sys/dmu_objset.h> +#include <sys/arc.h> +#include <sys/zap.h> +#include <sys/zio.h> +#include <sys/zfs_context.h> +#include <sys/fs/zfs.h> +#include <sys/zfs_znode.h> +#include <sys/spa_impl.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> + +/* + * 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; + +/* + * 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; + +/* + * This determines the number of threads used by the dp_sync_taskq. + */ +int zfs_sync_taskq_batch_pct = 75; + +/* + * 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) +{ + uint64_t obj; + int err; + + err = zap_lookup(dp->dp_meta_objset, + dsl_dir_phys(dp->dp_root_dir)->dd_child_dir_zapobj, + name, sizeof (obj), 1, &obj); + if (err) + return (err); + + return (dsl_dir_hold_obj(dp, obj, name, dp, ddp)); +} + +static dsl_pool_t * +dsl_pool_open_impl(spa_t *spa, uint64_t txg) +{ + dsl_pool_t *dp; + blkptr_t *bp = spa_get_rootblkptr(spa); + + dp = kmem_zalloc(sizeof (dsl_pool_t), KM_SLEEP); + dp->dp_spa = spa; + dp->dp_meta_rootbp = *bp; + rrw_init(&dp->dp_config_rwlock, B_TRUE); + txg_init(dp, txg); + mmp_init(spa); + + txg_list_create(&dp->dp_dirty_datasets, spa, + offsetof(dsl_dataset_t, ds_dirty_link)); + 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, 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_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_init(spa_t *spa, uint64_t txg, dsl_pool_t **dpp) +{ + int err; + dsl_pool_t *dp = dsl_pool_open_impl(spa, txg); + + /* + * 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 != 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_hold_obj(dp, dp->dp_root_dir_obj, + NULL, dp, &dp->dp_root_dir); + if (err) + goto out; + + err = dsl_pool_open_special_dir(dp, MOS_DIR_NAME, &dp->dp_mos_dir); + if (err) + goto out; + + 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, + dsl_dir_phys(dd)->dd_head_dataset_obj, FTAG, &ds); + if (err == 0) { + err = dsl_dataset_hold_obj(dp, + dsl_dataset_phys(ds)->ds_prev_snap_obj, dp, + &dp->dp_origin_snap); + dsl_dataset_rele(ds, FTAG); + } + dsl_dir_rele(dd, dp); + if (err) + goto out; + } + + 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) + goto out; + + err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT, + DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj); + if (err) + goto out; + 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); + if (err == ENOENT) + err = 0; + if (err) + goto out; + + err = dsl_scan_init(dp, dp->dp_tx.tx_open_txg); + +out: + rrw_exit(&dp->dp_config_rwlock, FTAG); + return (err); +} + +void +dsl_pool_close(dsl_pool_t *dp) +{ + /* + * 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 != 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 != 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); + + 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); + dmu_buf_user_evict_wait(); + + rrw_destroy(&dp->dp_config_rwlock); + mutex_destroy(&dp->dp_lock); + 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, 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); + ASSERT0(err); + + /* Initialize scan structures */ + 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); + 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); + 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); + 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_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); + 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, dcp, 0, tx); + + /* create the root objset */ + 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_flags(ds, DS_HOLD_FLAG_DECRYPT, FTAG); + + dmu_tx_commit(tx); + + rrw_exit(&dp->dp_config_rwlock, FTAG); + + return (dp); +} + +/* + * 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) +{ + 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) +{ + zio_t *zio; + dmu_tx_t *tx; + dsl_dir_t *dd; + dsl_dataset_t *ds; + objset_t *mos = dp->dp_meta_objset; + list_t synced_datasets; + + list_create(&synced_datasets, sizeof (dsl_dataset_t), + offsetof(dsl_dataset_t, ds_synced_link)); + + tx = dmu_tx_create_assigned(dp, txg); + + /* + * 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)) != 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(&synced_datasets, ds); + dsl_dataset_sync(ds, zio, tx); + } + VERIFY0(zio_wait(zio)); + + /* + * 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); + + /* + * 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, 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)) != 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); + } + } + VERIFY0(zio_wait(zio)); + + /* + * 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() + */ + while ((ds = list_remove_head(&synced_datasets)) != NULL) { + objset_t *os = ds->ds_objset; + + 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); + } + + while ((dd = txg_list_remove(&dp->dp_dirty_dirs, txg)) != NULL) { + dsl_dir_sync(dd, tx); + } + + /* + * 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 (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); + } + + /* + * 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 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. + */ + 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) +{ + zilog_t *zilog; + + 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)); +} + +/* + * TRUE if the current thread is the tx_sync_thread or if we + * are being called from SPA context during pool initialization. + */ +int +dsl_pool_sync_context(dsl_pool_t *dp) +{ + return (curthread == dp->dp_tx.tx_sync_thread || + 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, zfs_space_check_t slop_policy) +{ + 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 (adjustedsize); +} + +uint64_t +dsl_pool_unreserved_space(dsl_pool_t *dp, zfs_space_check_t slop_policy) +{ + 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); +} + +boolean_t +dsl_pool_need_dirty_delay(dsl_pool_t *dp) +{ + 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_dirty_space(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx) +{ + 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); + } +} + +void +dsl_pool_undirty_space(dsl_pool_t *dp, int64_t space, uint64_t txg) +{ + 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(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg) +{ + dmu_tx_t *tx = arg; + dsl_dataset_t *ds, *prev = NULL; + int err; + + err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds); + if (err) + return (err); + + 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 (dsl_dataset_phys(prev)->ds_next_snap_obj != ds->ds_object) + break; + dsl_dataset_rele(ds, FTAG); + ds = prev; + prev = NULL; + } + + if (prev == NULL) { + prev = dp->dp_origin_snap; + + /* + * The $ORIGIN can't have any data, or the accounting + * will be wrong. + */ + 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) { + dsl_dataset_rele(ds, FTAG); + return (0); + } + + dmu_buf_will_dirty(ds->ds_dbuf, tx); + 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); + dsl_dir_phys(ds->ds_dir)->dd_origin_obj = prev->ds_object; + + dmu_buf_will_dirty(prev->ds_dbuf, tx); + dsl_dataset_phys(prev)->ds_num_children++; + + if (dsl_dataset_phys(ds)->ds_next_snap_obj == 0) { + ASSERT(ds->ds_prev == NULL); + VERIFY0(dsl_dataset_hold_obj(dp, + dsl_dataset_phys(ds)->ds_prev_snap_obj, + ds, &ds->ds_prev)); + } + } + + 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 (dsl_dataset_phys(prev)->ds_next_clones_obj == 0) { + dmu_buf_will_dirty(prev->ds_dbuf, tx); + dsl_dataset_phys(prev)->ds_next_clones_obj = + zap_create(dp->dp_meta_objset, + DMU_OT_NEXT_CLONES, DMU_OT_NONE, 0, 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) + dsl_dataset_rele(prev, FTAG); + return (0); +} + +void +dsl_pool_upgrade_clones(dsl_pool_t *dp, dmu_tx_t *tx) +{ + ASSERT(dmu_tx_is_syncing(tx)); + ASSERT(dp->dp_origin_snap != NULL); + + 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(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg) +{ + dmu_tx_t *tx = arg; + objset_t *mos = dp->dp_meta_objset; + + if (dsl_dir_phys(ds->ds_dir)->dd_origin_obj != 0) { + dsl_dataset_t *origin; + + VERIFY0(dsl_dataset_hold_obj(dp, + dsl_dir_phys(ds->ds_dir)->dd_origin_obj, FTAG, &origin)); + + if (dsl_dir_phys(origin->ds_dir)->dd_clones == 0) { + dmu_buf_will_dirty(origin->ds_dir->dd_dbuf, tx); + dsl_dir_phys(origin->ds_dir)->dd_clones = + zap_create(mos, DMU_OT_DSL_CLONES, DMU_OT_NONE, + 0, 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); + } + return (0); +} + +void +dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx) +{ + uint64_t obj; + + ASSERT(dmu_tx_is_syncing(tx)); + + (void) dsl_dir_create_sync(dp, dp->dp_root_dir, FREE_DIR_NAME, tx); + VERIFY0(dsl_pool_open_special_dir(dp, + FREE_DIR_NAME, &dp->dp_free_dir)); + + /* + * We can't use bpobj_alloc(), because spa_version() still + * returns the old version, and we need a new-version bpobj with + * subobj support. So call dmu_object_alloc() directly. + */ + obj = dmu_object_alloc(dp->dp_meta_objset, DMU_OT_BPOBJ, + 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)); + VERIFY0(bpobj_open(&dp->dp_free_bpobj, dp->dp_meta_objset, obj)); + + VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj, + upgrade_dir_clones_cb, tx, DS_FIND_CHILDREN | DS_FIND_SERIALIZE)); +} + +void +dsl_pool_create_origin(dsl_pool_t *dp, dmu_tx_t *tx) +{ + uint64_t dsobj; + dsl_dataset_t *ds; + + 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 */ + dsobj = dsl_dataset_create_sync(dp->dp_root_dir, ORIGIN_DIR_NAME, + 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); +} + +taskq_t * +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_unlinked_drain_taskq); +} + +/* + * Walk through the pool-wide zap object of temporary snapshot user holds + * and release them. + */ +void +dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp) +{ + zap_attribute_t za; + 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; + nvlist_t *tags; + + htag = strchr(za.za_name, '-'); + *htag = '\0'; + ++htag; + 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); +} + +/* + * Create the pool-wide zap object for storing temporary snapshot holds. + */ +static void +dsl_pool_user_hold_create_obj(dsl_pool_t *dp, dmu_tx_t *tx) +{ + objset_t *mos = dp->dp_meta_objset; + + ASSERT(dp->dp_tmp_userrefs_obj == 0); + ASSERT(dmu_tx_is_syncing(tx)); + + 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) +{ + objset_t *mos = dp->dp_meta_objset; + uint64_t zapobj = dp->dp_tmp_userrefs_obj; + char *name; + int error; + + ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS); + ASSERT(dmu_tx_is_syncing(tx)); + + /* + * If the pool was created prior to SPA_VERSION_USERREFS, the + * zap object for temporary holds might not exist yet. + */ + if (zapobj == 0) { + if (holding) { + dsl_pool_user_hold_create_obj(dp, tx); + zapobj = dp->dp_tmp_userrefs_obj; + } else { + 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); + else + error = zap_remove(mos, zapobj, name, tx); + kmem_strfree(name); + + return (error); +} + +/* + * Add a temporary hold for the given dataset object and tag. + */ +int +dsl_pool_user_hold(dsl_pool_t *dp, uint64_t dsobj, const char *tag, + uint64_t now, dmu_tx_t *tx) +{ + return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, now, tx, B_TRUE)); +} + +/* + * Release a temporary hold for the given dataset object and tag. + */ +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, 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 */ |