/*

 * 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

 */

/*

 */

#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;

	ASSERT3U(dstg->dstg_err, ==, 0);

	/*

	 * 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)) {

		}

	}

	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;

	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;

	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);

}