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dsl_pool.c

/*
 * 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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/dsl_pool.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_synctask.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>

int zfs_no_write_throttle = 0;
int zfs_write_limit_shift = 3;                  /* 1/8th of physical memory */
int zfs_txg_synctime = 5;                 /* target secs to sync a txg */

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;
extern uint64_t zfs_write_limit_min;

kmutex_t zfs_write_limit_lock;

static pgcnt_t old_physmem = 0;

static 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,
          dp->dp_root_dir->dd_phys->dd_child_dir_zapobj,
          name, sizeof (obj), 1, &obj);
      if (err)
            return (err);

      return (dsl_dir_open_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;
      rw_init(&dp->dp_config_rwlock, NULL, RW_DEFAULT, NULL);
      dp->dp_write_limit = zfs_write_limit_min;
      txg_init(dp, txg);

      txg_list_create(&dp->dp_dirty_datasets,
          offsetof(dsl_dataset_t, ds_dirty_link));
      txg_list_create(&dp->dp_dirty_dirs,
          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));

      mutex_init(&dp->dp_lock, NULL, MUTEX_DEFAULT, NULL);
      mutex_init(&dp->dp_scrub_cancel_lock, NULL, MUTEX_DEFAULT, NULL);

      dp->dp_vnrele_taskq = taskq_create("zfs_vn_rele_taskq", 1, minclsyspri,
          1, 4, 0);

      return (dp);
}

int
dsl_pool_open(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;
      objset_impl_t *osi;

      rw_enter(&dp->dp_config_rwlock, RW_WRITER);
      err = dmu_objset_open_impl(spa, NULL, &dp->dp_meta_rootbp, &osi);
      if (err)
            goto out;
      dp->dp_meta_objset = &osi->os;

      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,
          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(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);
            if (err)
                  goto out;
            err = dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
                dp, &dp->dp_origin_snap);
            if (err)
                  goto out;
            dsl_dataset_rele(ds, FTAG);
            dsl_dir_close(dd, dp);
      }

      /* get scrub status */
      err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
          DMU_POOL_SCRUB_FUNC, sizeof (uint32_t), 1,
          &dp->dp_scrub_func);
      if (err == 0) {
            err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
                DMU_POOL_SCRUB_QUEUE, sizeof (uint64_t), 1,
                &dp->dp_scrub_queue_obj);
            if (err)
                  goto out;
            err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
                DMU_POOL_SCRUB_MIN_TXG, sizeof (uint64_t), 1,
                &dp->dp_scrub_min_txg);
            if (err)
                  goto out;
            err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
                DMU_POOL_SCRUB_MAX_TXG, sizeof (uint64_t), 1,
                &dp->dp_scrub_max_txg);
            if (err)
                  goto out;
            err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
                DMU_POOL_SCRUB_BOOKMARK, sizeof (uint64_t), 4,
                &dp->dp_scrub_bookmark);
            if (err)
                  goto out;
            err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
                DMU_POOL_SCRUB_ERRORS, sizeof (uint64_t), 1,
                &spa->spa_scrub_errors);
            if (err)
                  goto out;
            if (spa_version(spa) < SPA_VERSION_DSL_SCRUB) {
                  /*
                   * A new-type scrub was in progress on an old
                   * pool.  Restart from the beginning, since the
                   * old software may have changed the pool in the
                   * meantime.
                   */
                  dsl_pool_scrub_restart(dp);
            }
      } else {
            /*
             * It's OK if there is no scrub in progress (and if
             * there was an I/O error, ignore it).
             */
            err = 0;
      }

out:
      rw_exit(&dp->dp_config_rwlock);
      if (err)
            dsl_pool_close(dp);
      else
            *dpp = dp;

      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)
            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_root_dir)
            dsl_dir_close(dp->dp_root_dir, dp);

      /* undo the dmu_objset_open_impl(mos) from dsl_pool_open() */
      if (dp->dp_meta_objset)
            dmu_objset_evict(NULL, dp->dp_meta_objset->os);

      txg_list_destroy(&dp->dp_dirty_datasets);
      txg_list_destroy(&dp->dp_dirty_dirs);
      txg_list_destroy(&dp->dp_sync_tasks);
      list_destroy(&dp->dp_synced_datasets);

      arc_flush(dp->dp_spa);
      txg_fini(dp);
      rw_destroy(&dp->dp_config_rwlock);
      mutex_destroy(&dp->dp_lock);
      mutex_destroy(&dp->dp_scrub_cancel_lock);
      taskq_destroy(dp->dp_vnrele_taskq);
      if (dp->dp_blkstats)
            kmem_free(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
      kmem_free(dp, sizeof (dsl_pool_t));
}

dsl_pool_t *
dsl_pool_create(spa_t *spa, nvlist_t *zplprops, 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);
      objset_impl_t *osip;
      dsl_dataset_t *ds;
      uint64_t dsobj;

      /* 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)->os;

      /* 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);

      /* 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,
          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,
          MOS_DIR_NAME, &dp->dp_mos_dir));

      if (spa_version(spa) >= SPA_VERSION_DSL_SCRUB)
            dsl_pool_create_origin(dp, tx);

      /* create the root dataset */
      dsobj = dsl_dataset_create_sync_dd(dp->dp_root_dir, NULL, 0, tx);

      /* create the root objset */
      VERIFY(0 == dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
      osip = dmu_objset_create_impl(dp->dp_spa, ds,
          dsl_dataset_get_blkptr(ds), DMU_OST_ZFS, tx);
#ifdef _KERNEL
      zfs_create_fs(&osip->os, kcred, zplprops, tx);
#endif
      dsl_dataset_rele(ds, FTAG);

      dmu_tx_commit(tx);

      return (dp);
}

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;
      dsl_sync_task_group_t *dstg;
      objset_impl_t *mosi = dp->dp_meta_objset->os;
      hrtime_t start, write_time;
      uint64_t data_written;
      int err;

      tx = dmu_tx_create_assigned(dp, txg);

      dp->dp_read_overhead = 0;
      start = gethrtime();
      zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
      while (ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) {
            if (!list_link_active(&ds->ds_synced_link))
                  list_insert_tail(&dp->dp_synced_datasets, ds);
            else
                  dmu_buf_rele(ds->ds_dbuf, ds);
            dsl_dataset_sync(ds, zio, tx);
      }
      DTRACE_PROBE(pool_sync__1setup);

      err = zio_wait(zio);
      write_time = gethrtime() - start;
      ASSERT(err == 0);
      DTRACE_PROBE(pool_sync__2rootzio);

      while (dstg = txg_list_remove(&dp->dp_sync_tasks, txg))
            dsl_sync_task_group_sync(dstg, tx);
      DTRACE_PROBE(pool_sync__3task);

      start = gethrtime();
      while (dd = txg_list_remove(&dp->dp_dirty_dirs, txg))
            dsl_dir_sync(dd, tx);
      write_time += gethrtime() - start;

      if (spa_sync_pass(dp->dp_spa) == 1)
            dsl_pool_scrub_sync(dp, tx);

      start = gethrtime();
      if (list_head(&mosi->os_dirty_dnodes[txg & TXG_MASK]) != NULL ||
          list_head(&mosi->os_free_dnodes[txg & TXG_MASK]) != NULL) {
            zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
            dmu_objset_sync(mosi, 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);

      data_written = dp->dp_space_towrite[txg & TXG_MASK];
      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.
       */
      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);
      }

      /*
       * 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
       */
      ASSERT(zfs_write_limit_min > 0);
      if (data_written > zfs_write_limit_min / 8 && write_time > 0) {
            uint64_t throughput = (data_written * NANOSEC) / write_time;
            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));
      }
}

void
dsl_pool_zil_clean(dsl_pool_t *dp)
{
      dsl_dataset_t *ds;

      while (ds = list_head(&dp->dp_synced_datasets)) {
            list_remove(&dp->dp_synced_datasets, ds);
            ASSERT(ds->ds_user_ptr != NULL);
            zil_clean(((objset_impl_t *)ds->ds_user_ptr)->os_zil);
            dmu_buf_rele(ds->ds_dbuf, ds);
      }
}

/*
 * 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_get_dsl(dp->dp_spa) == NULL);
}

uint64_t
dsl_pool_adjustedsize(dsl_pool_t *dp, boolean_t netfree)
{
      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)
            resv >>= 1;

      return (space - resv);
}

int
dsl_pool_tempreserve_space(dsl_pool_t *dp, uint64_t space, dmu_tx_t *tx)
{
      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);
}

void
dsl_pool_tempreserve_clear(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx)
{
      ASSERT(dp->dp_tempreserved[tx->tx_txg & TXG_MASK] >= space);
      atomic_add_64(&dp->dp_tempreserved[tx->tx_txg & TXG_MASK], -space);
}

void
dsl_pool_memory_pressure(dsl_pool_t *dp)
{
      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];
      }
      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)
{
      if (space > 0) {
            mutex_enter(&dp->dp_lock);
            dp->dp_space_towrite[tx->tx_txg & TXG_MASK] += space;
            mutex_exit(&dp->dp_lock);
      }
}

/* ARGSUSED */
static int
upgrade_clones_cb(spa_t *spa, uint64_t dsobj, const char *dsname, 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);
      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);
            if (err) {
                  dsl_dataset_rele(ds, FTAG);
                  return (err);
            }

            if (prev->ds_phys->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.
             */
            ASSERT(prev->ds_phys->ds_bp.blk_birth == 0);

            /* 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);
            ds->ds_phys->ds_prev_snap_obj = prev->ds_object;
            ds->ds_phys->ds_prev_snap_txg = prev->ds_phys->ds_creation_txg;

            dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
            ds->ds_dir->dd_phys->dd_origin_obj = prev->ds_object;

            dmu_buf_will_dirty(prev->ds_dbuf, tx);
            prev->ds_phys->ds_num_children++;

            if (ds->ds_phys->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));
            }
      }

      ASSERT(ds->ds_dir->dd_phys->dd_origin_obj == prev->ds_object);
      ASSERT(ds->ds_phys->ds_prev_snap_obj == prev->ds_object);

      if (prev->ds_phys->ds_next_clones_obj == 0) {
            prev->ds_phys->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));

      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);

      (void) dmu_objset_find_spa(dp->dp_spa, NULL, upgrade_clones_cb,
          tx, DS_FIND_CHILDREN);
}

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);

      /* 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, kcred, tx);
      VERIFY(0 == dsl_dataset_hold_obj(dp, ds->ds_phys->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)
{
      return (dp->dp_vnrele_taskq);
}

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