dsl_synctask.c

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/*
 * 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.
 */

#include <sys/dmu.h>
#include <sys/dmu_tx.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_synctask.h>
#include <sys/metaslab.h>

#define DST_AVG_BLKSHIFT 14

/* ARGSUSED */
static int
dsl_null_checkfunc(void *arg1, void *arg2, dmu_tx_t *tx)
{
        return (0);
}

dsl_sync_task_group_t *
dsl_sync_task_group_create(dsl_pool_t *dp)
{
        dsl_sync_task_group_t *dstg;

        dstg = kmem_zalloc(sizeof (dsl_sync_task_group_t), KM_SLEEP);
        list_create(&dstg->dstg_tasks, sizeof (dsl_sync_task_t),
            offsetof(dsl_sync_task_t, dst_node));
        dstg->dstg_pool = dp;

        return (dstg);
}

void
dsl_sync_task_create(dsl_sync_task_group_t *dstg,
    dsl_checkfunc_t *checkfunc, dsl_syncfunc_t *syncfunc,
    void *arg1, void *arg2, int blocks_modified)
{
        dsl_sync_task_t *dst;

        if (checkfunc == NULL)
                checkfunc = dsl_null_checkfunc;
        dst = kmem_zalloc(sizeof (dsl_sync_task_t), KM_SLEEP);
        dst->dst_checkfunc = checkfunc;
        dst->dst_syncfunc = syncfunc;
        dst->dst_arg1 = arg1;
        dst->dst_arg2 = arg2;
        list_insert_tail(&dstg->dstg_tasks, dst);

        dstg->dstg_space += blocks_modified << DST_AVG_BLKSHIFT;
}

int
dsl_sync_task_group_wait(dsl_sync_task_group_t *dstg)
{
        dmu_tx_t *tx;
        uint64_t txg;
        dsl_sync_task_t *dst;

top:
        tx = dmu_tx_create_dd(dstg->dstg_pool->dp_mos_dir);
        VERIFY(0 == dmu_tx_assign(tx, TXG_WAIT));

        txg = dmu_tx_get_txg(tx);

        /* Do a preliminary error check. */
        dstg->dstg_err = 0;
        rw_enter(&dstg->dstg_pool->dp_config_rwlock, RW_READER);
        for (dst = list_head(&dstg->dstg_tasks); dst;
            dst = list_next(&dstg->dstg_tasks, dst)) {
#ifdef ZFS_DEBUG
                /*
                 * Only check half the time, otherwise, the sync-context
                 * check will almost never fail.
                 */
                if (spa_get_random(2) == 0)
                        continue;
#endif
                dst->dst_err =
                    dst->dst_checkfunc(dst->dst_arg1, dst->dst_arg2, tx);
                if (dst->dst_err)
                        dstg->dstg_err = dst->dst_err;
        }
        rw_exit(&dstg->dstg_pool->dp_config_rwlock);

        if (dstg->dstg_err) {
                dmu_tx_commit(tx);
                return (dstg->dstg_err);
        }

        /*
         * We don't generally have many sync tasks, so pay the price of
         * add_tail to get the tasks executed in the right order.
         */
        VERIFY(0 == txg_list_add_tail(&dstg->dstg_pool->dp_sync_tasks,
            dstg, txg));

        dmu_tx_commit(tx);

        txg_wait_synced(dstg->dstg_pool, txg);

        if (dstg->dstg_err == EAGAIN) {
                txg_wait_synced(dstg->dstg_pool, txg + TXG_DEFER_SIZE);
                goto top;
        }

        return (dstg->dstg_err);
}

void
dsl_sync_task_group_nowait(dsl_sync_task_group_t *dstg, dmu_tx_t *tx)
{
        uint64_t txg;

        dstg->dstg_nowaiter = B_TRUE;
        txg = dmu_tx_get_txg(tx);
        /*
         * We don't generally have many sync tasks, so pay the price of
         * add_tail to get the tasks executed in the right order.
         */
        VERIFY(0 == txg_list_add_tail(&dstg->dstg_pool->dp_sync_tasks,
            dstg, txg));
}

void
dsl_sync_task_group_destroy(dsl_sync_task_group_t *dstg)
{
        dsl_sync_task_t *dst;

        while (dst = list_head(&dstg->dstg_tasks)) {
                list_remove(&dstg->dstg_tasks, dst);
                kmem_free(dst, sizeof (dsl_sync_task_t));
        }
        kmem_free(dstg, sizeof (dsl_sync_task_group_t));
}

void
dsl_sync_task_group_sync(dsl_sync_task_group_t *dstg, dmu_tx_t *tx)
{
        dsl_sync_task_t *dst;
        dsl_pool_t *dp = dstg->dstg_pool;
        uint64_t quota, used;

        ASSERT0(dstg->dstg_err);

        /*
         * Check for sufficient space.  We just check against what's
         * on-disk; we don't want any in-flight accounting to get in our
         * way, because open context may have already used up various
         * in-core limits (arc_tempreserve, dsl_pool_tempreserve).
         */
        quota = dsl_pool_adjustedsize(dp, B_FALSE) -
            metaslab_class_get_deferred(spa_normal_class(dp->dp_spa));
        used = dp->dp_root_dir->dd_phys->dd_used_bytes;
        /* MOS space is triple-dittoed, so we multiply by 3. */
        if (dstg->dstg_space > 0 && used + dstg->dstg_space * 3 > quota) {
                dstg->dstg_err = ENOSPC;
                return;
        }

        /*
         * Check for errors by calling checkfuncs.
         */
        rw_enter(&dp->dp_config_rwlock, RW_WRITER);
        for (dst = list_head(&dstg->dstg_tasks); dst;
            dst = list_next(&dstg->dstg_tasks, dst)) {
                dst->dst_err =
                    dst->dst_checkfunc(dst->dst_arg1, dst->dst_arg2, tx);
                if (dst->dst_err)
                        dstg->dstg_err = dst->dst_err;
        }

        if (dstg->dstg_err == 0) {
                /*
                 * Execute sync tasks.
                 */
                for (dst = list_head(&dstg->dstg_tasks); dst;
                    dst = list_next(&dstg->dstg_tasks, dst)) {
                        dst->dst_syncfunc(dst->dst_arg1, dst->dst_arg2, tx);
                }
        }
        rw_exit(&dp->dp_config_rwlock);

        if (dstg->dstg_nowaiter)
                dsl_sync_task_group_destroy(dstg);
}

int
dsl_sync_task_do(dsl_pool_t *dp,
    dsl_checkfunc_t *checkfunc, dsl_syncfunc_t *syncfunc,
    void *arg1, void *arg2, int blocks_modified)
{
        dsl_sync_task_group_t *dstg;
        int err;

        ASSERT(spa_writeable(dp->dp_spa));

        dstg = dsl_sync_task_group_create(dp);
        dsl_sync_task_create(dstg, checkfunc, syncfunc,
            arg1, arg2, blocks_modified);
        err = dsl_sync_task_group_wait(dstg);
        dsl_sync_task_group_destroy(dstg);
        return (err);
}

void
dsl_sync_task_do_nowait(dsl_pool_t *dp,
    dsl_checkfunc_t *checkfunc, dsl_syncfunc_t *syncfunc,
    void *arg1, void *arg2, int blocks_modified, dmu_tx_t *tx)
{
        dsl_sync_task_group_t *dstg = dsl_sync_task_group_create(dp);
        dsl_sync_task_create(dstg, checkfunc, syncfunc,
            arg1, arg2, blocks_modified);
        dsl_sync_task_group_nowait(dstg, tx);
}