fs/zfs/dsl_pool.c

	dsl_pool.c revision 1ab7f2ded02e7a1bc3c73516eb27efa79bf2a2ff
/*
 * 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.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#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>

int zfs_no_write_throttle = 0;
uint64_t zfs_write_limit_override = 0;

static int
dsl_pool_open_mos_dir(dsl_pool_t *dp, 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,
        MOS_DIR_NAME, sizeof (obj), 1, &obj);
    if (err)
        return (err);

    return (dsl_dir_open_obj(dp, obj, MOS_DIR_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);
    extern uint64_t zfs_write_limit_min;

    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);

    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);
    objset_impl_t *osi;

    rw_enter(&dp->dp_config_rwlock, RW_READER);
    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_mos_dir(dp, &dp->dp_mos_dir);
    if (err)
        goto out;

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 reference from dsl_pool_open() */
    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);
    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);
    kmem_free(dp, sizeof (dsl_pool_t));
}

dsl_pool_t *
dsl_pool_create(spa_t *spa, 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);
    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 */
    dsl_dataset_create_root(dp, &dp->dp_root_dir_obj, 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_root_dir, MOS_DIR_NAME, tx);
    VERIFY(0 == dsl_pool_open_mos_dir(dp, &dp->dp_mos_dir));

    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;
    int err;

    tx = dmu_tx_create_assigned(dp, txg);

    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);
    }
    err = zio_wait(zio);
    ASSERT(err == 0);

    while (dstg = txg_list_remove(&dp->dp_sync_tasks, txg))
        dsl_sync_task_group_sync(dstg, tx);
    while (dd = txg_list_remove(&dp->dp_dirty_dirs, txg))
        dsl_dir_sync(dd, tx);

    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);
    }

    dmu_tx_commit(tx);
}

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) {
        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)
{
    extern uint64_t zfs_write_limit_min;
    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);
    }
}