aboutsummaryrefslogtreecommitdiffstats
path: root/uts/common/fs/zfs/dsl_synctask.c
blob: 7014581d0e47f10aec8067334ba52945ad24b0dc (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
/*
 * 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) 2012, 2017 by Delphix. 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 *arg, dmu_tx_t *tx)
{
	return (0);
}

static int
dsl_sync_task_common(const char *pool, dsl_checkfunc_t *checkfunc,
    dsl_syncfunc_t *syncfunc, void *arg,
    int blocks_modified, zfs_space_check_t space_check, boolean_t early)
{
	spa_t *spa;
	dmu_tx_t *tx;
	int err;
	dsl_sync_task_t dst = { 0 };
	dsl_pool_t *dp;

	err = spa_open(pool, &spa, FTAG);
	if (err != 0)
		return (err);
	dp = spa_get_dsl(spa);

top:
	tx = dmu_tx_create_dd(dp->dp_mos_dir);
	VERIFY0(dmu_tx_assign(tx, TXG_WAIT));

	dst.dst_pool = dp;
	dst.dst_txg = dmu_tx_get_txg(tx);
	dst.dst_space = blocks_modified << DST_AVG_BLKSHIFT;
	dst.dst_space_check = space_check;
	dst.dst_checkfunc = checkfunc != NULL ? checkfunc : dsl_null_checkfunc;
	dst.dst_syncfunc = syncfunc;
	dst.dst_arg = arg;
	dst.dst_error = 0;
	dst.dst_nowaiter = B_FALSE;

	dsl_pool_config_enter(dp, FTAG);
	err = dst.dst_checkfunc(arg, tx);
	dsl_pool_config_exit(dp, FTAG);

	if (err != 0) {
		dmu_tx_commit(tx);
		spa_close(spa, FTAG);
		return (err);
	}

	txg_list_t *task_list = (early) ?
	    &dp->dp_early_sync_tasks : &dp->dp_sync_tasks;
	VERIFY(txg_list_add_tail(task_list, &dst, dst.dst_txg));

	dmu_tx_commit(tx);

	txg_wait_synced(dp, dst.dst_txg);

	if (dst.dst_error == EAGAIN) {
		txg_wait_synced(dp, dst.dst_txg + TXG_DEFER_SIZE);
		goto top;
	}

	spa_close(spa, FTAG);
	return (dst.dst_error);
}

/*
 * Called from open context to perform a callback in syncing context.  Waits
 * for the operation to complete.
 *
 * The checkfunc will be called from open context as a preliminary check
 * which can quickly fail.  If it succeeds, it will be called again from
 * syncing context.  The checkfunc should generally be designed to work
 * properly in either context, but if necessary it can check
 * dmu_tx_is_syncing(tx).
 *
 * The synctask infrastructure enforces proper locking strategy with respect
 * to the dp_config_rwlock -- the lock will always be held when the callbacks
 * are called.  It will be held for read during the open-context (preliminary)
 * call to the checkfunc, and then held for write from syncing context during
 * the calls to the check and sync funcs.
 *
 * A dataset or pool name can be passed as the first argument.  Typically,
 * the check func will hold, check the return value of the hold, and then
 * release the dataset.  The sync func will VERIFYO(hold()) the dataset.
 * This is safe because no changes can be made between the check and sync funcs,
 * and the sync func will only be called if the check func successfully opened
 * the dataset.
 */
int
dsl_sync_task(const char *pool, dsl_checkfunc_t *checkfunc,
    dsl_syncfunc_t *syncfunc, void *arg,
    int blocks_modified, zfs_space_check_t space_check)
{
	return (dsl_sync_task_common(pool, checkfunc, syncfunc, arg,
	    blocks_modified, space_check, B_FALSE));
}

/*
 * An early synctask works exactly as a standard synctask with one important
 * difference on the way it is handled during syncing context. Standard
 * synctasks run after we've written out all the dirty blocks of dirty
 * datasets. Early synctasks are executed before writing out any dirty data,
 * and thus before standard synctasks.
 *
 * For that reason, early synctasks can affect the process of writing dirty
 * changes to disk for the txg that they run and should be used with caution.
 * In addition, early synctasks should not dirty any metaslabs as this would
 * invalidate the precodition/invariant for subsequent early synctasks.
 * [see dsl_pool_sync() and dsl_early_sync_task_verify()]
 */
int
dsl_early_sync_task(const char *pool, dsl_checkfunc_t *checkfunc,
    dsl_syncfunc_t *syncfunc, void *arg,
    int blocks_modified, zfs_space_check_t space_check)
{
	return (dsl_sync_task_common(pool, checkfunc, syncfunc, arg,
	    blocks_modified, space_check, B_TRUE));
}

static void
dsl_sync_task_nowait_common(dsl_pool_t *dp, dsl_syncfunc_t *syncfunc, void *arg,
    int blocks_modified, zfs_space_check_t space_check, dmu_tx_t *tx,
    boolean_t early)
{
	dsl_sync_task_t *dst = kmem_zalloc(sizeof (*dst), KM_SLEEP);

	dst->dst_pool = dp;
	dst->dst_txg = dmu_tx_get_txg(tx);
	dst->dst_space = blocks_modified << DST_AVG_BLKSHIFT;
	dst->dst_space_check = space_check;
	dst->dst_checkfunc = dsl_null_checkfunc;
	dst->dst_syncfunc = syncfunc;
	dst->dst_arg = arg;
	dst->dst_error = 0;
	dst->dst_nowaiter = B_TRUE;

	txg_list_t *task_list = (early) ?
	    &dp->dp_early_sync_tasks : &dp->dp_sync_tasks;
	VERIFY(txg_list_add_tail(task_list, dst, dst->dst_txg));
}

void
dsl_sync_task_nowait(dsl_pool_t *dp, dsl_syncfunc_t *syncfunc, void *arg,
    int blocks_modified, zfs_space_check_t space_check, dmu_tx_t *tx)
{
	dsl_sync_task_nowait_common(dp, syncfunc, arg,
	    blocks_modified, space_check, tx, B_FALSE);
}

void
dsl_early_sync_task_nowait(dsl_pool_t *dp, dsl_syncfunc_t *syncfunc, void *arg,
    int blocks_modified, zfs_space_check_t space_check, dmu_tx_t *tx)
{
	dsl_sync_task_nowait_common(dp, syncfunc, arg,
	    blocks_modified, space_check, tx, B_TRUE);
}

/*
 * Called in syncing context to execute the synctask.
 */
void
dsl_sync_task_sync(dsl_sync_task_t *dst, dmu_tx_t *tx)
{
	dsl_pool_t *dp = dst->dst_pool;

	ASSERT0(dst->dst_error);

	/*
	 * Check for sufficient space.
	 *
	 * When the sync task was created, the caller specified the
	 * type of space checking required.  See the comment in
	 * zfs_space_check_t for details on the semantics of each
	 * type of space checking.
	 *
	 * 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).
	 */
	if (dst->dst_space_check != ZFS_SPACE_CHECK_NONE) {
		uint64_t quota = dsl_pool_unreserved_space(dp,
		    dst->dst_space_check);
		uint64_t used = dsl_dir_phys(dp->dp_root_dir)->dd_used_bytes;

		/* MOS space is triple-dittoed, so we multiply by 3. */
		if (used + dst->dst_space * 3 > quota) {
			dst->dst_error = SET_ERROR(ENOSPC);
			if (dst->dst_nowaiter)
				kmem_free(dst, sizeof (*dst));
			return;
		}
	}

	/*
	 * Check for errors by calling checkfunc.
	 */
	rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
	dst->dst_error = dst->dst_checkfunc(dst->dst_arg, tx);
	if (dst->dst_error == 0)
		dst->dst_syncfunc(dst->dst_arg, tx);
	rrw_exit(&dp->dp_config_rwlock, FTAG);
	if (dst->dst_nowaiter)
		kmem_free(dst, sizeof (*dst));
}