1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
24 * Copyright 2015 Nexenta Systems, Inc. All rights reserved.
25 */
26
27 #include <sys/dmu.h>
28 #include <sys/dmu_tx.h>
29 #include <sys/dsl_pool.h>
30 #include <sys/dsl_dir.h>
31 #include <sys/dsl_synctask.h>
32 #include <sys/metaslab.h>
33
34 /* ARGSUSED */
35 static int
36 dsl_null_checkfunc(void *arg, dmu_tx_t *tx)
37 {
38 return (0);
39 }
40
41 /*
42 * Called from open context to perform a callback in syncing context. Waits
43 * for the operation to complete.
44 *
45 * The checkfunc will be called from open context as a preliminary check
46 * which can quickly fail. If it succeeds, it will be called again from
47 * syncing context. The checkfunc should generally be designed to work
48 * properly in either context, but if necessary it can check
49 * dmu_tx_is_syncing(tx).
50 *
51 * The synctask infrastructure enforces proper locking strategy with respect
52 * to the dp_config_rwlock -- the lock will always be held when the callbacks
53 * are called. It will be held for read during the open-context (preliminary)
54 * call to the checkfunc, and then held for write from syncing context during
55 * the calls to the check and sync funcs.
56 *
57 * A dataset or pool name can be passed as the first argument. Typically,
58 * the check func will hold, check the return value of the hold, and then
59 * release the dataset. The sync func will VERIFYO(hold()) the dataset.
60 * This is safe because no changes can be made between the check and sync funcs,
61 * and the sync func will only be called if the check func successfully opened
62 * the dataset.
63 */
64 int
65 dsl_sync_task(const char *pool, dsl_checkfunc_t *checkfunc,
66 dsl_syncfunc_t *syncfunc, void *arg,
67 int blocks_modified, zfs_space_check_t space_check)
68 {
69 spa_t *spa;
70 dmu_tx_t *tx;
71 int err;
72 dsl_sync_task_t dst = { 0 };
73 dsl_pool_t *dp;
74
75 err = spa_open(pool, &spa, FTAG);
76 if (err != 0)
77 return (err);
78 dp = spa_get_dsl(spa);
79
80 top:
81 tx = dmu_tx_create_dd(dp->dp_mos_dir);
82 VERIFY0(dmu_tx_assign(tx, TXG_WAIT));
83
84 dst.dst_pool = dp;
85 dst.dst_txg = dmu_tx_get_txg(tx);
86 dst.dst_space = blocks_modified << DST_AVG_BLKSHIFT;
87 dst.dst_space_check = space_check;
88 dst.dst_checkfunc = checkfunc != NULL ? checkfunc : dsl_null_checkfunc;
89 dst.dst_syncfunc = syncfunc;
90 dst.dst_arg = arg;
91 dst.dst_error = 0;
92 dst.dst_nowaiter = B_FALSE;
93
94 dsl_pool_config_enter(dp, FTAG);
95 err = dst.dst_checkfunc(arg, tx);
96 dsl_pool_config_exit(dp, FTAG);
97
98 if (err != 0) {
99 dmu_tx_commit(tx);
100 spa_close(spa, FTAG);
101 return (err);
102 }
103
104 VERIFY(txg_list_add_tail(&dp->dp_sync_tasks, &dst, dst.dst_txg));
105
106 dmu_tx_commit(tx);
107
108 txg_wait_synced(dp, dst.dst_txg);
109
110 if (dst.dst_error == EAGAIN) {
111 txg_wait_synced(dp, dst.dst_txg + TXG_DEFER_SIZE);
112 goto top;
113 }
114 spa_close(spa, FTAG);
115 return (dst.dst_error);
116 }
117
118 void
119 dsl_sync_task_nowait(dsl_pool_t *dp, dsl_syncfunc_t *syncfunc, void *arg,
120 int blocks_modified, zfs_space_check_t space_check, dmu_tx_t *tx)
121 {
122 dsl_sync_task_t *dst = kmem_zalloc(sizeof (*dst), KM_SLEEP);
123
124 dst->dst_pool = dp;
125 dst->dst_txg = dmu_tx_get_txg(tx);
126 dst->dst_space = blocks_modified << DST_AVG_BLKSHIFT;
127 dst->dst_space_check = space_check;
128 dst->dst_checkfunc = dsl_null_checkfunc;
129 dst->dst_syncfunc = syncfunc;
130 dst->dst_arg = arg;
131 dst->dst_error = 0;
132 dst->dst_nowaiter = B_TRUE;
133
134 VERIFY(txg_list_add_tail(&dp->dp_sync_tasks, dst, dst->dst_txg));
135 }
136
137 /*
138 * Called in syncing context to execute the synctask.
139 */
140 void
141 dsl_sync_task_sync(dsl_sync_task_t *dst, dmu_tx_t *tx)
142 {
143 dsl_pool_t *dp = dst->dst_pool;
144
145 ASSERT0(dst->dst_error);
146
147 /*
148 * Check for sufficient space.
149 *
150 * When the sync task was created, the caller specified the
151 * type of space checking required. See the comment in
152 * zfs_space_check_t for details on the semantics of each
153 * type of space checking.
154 *
155 * We just check against what's on-disk; we don't want any
156 * in-flight accounting to get in our way, because open context
157 * may have already used up various in-core limits
158 * (arc_tempreserve, dsl_pool_tempreserve).
159 */
160 if (dst->dst_space_check != ZFS_SPACE_CHECK_NONE) {
161 uint64_t quota = dsl_pool_adjustedsize(dp,
162 dst->dst_space_check == ZFS_SPACE_CHECK_RESERVED) -
163 metaslab_class_get_deferred(spa_normal_class(dp->dp_spa));
164 uint64_t used = dsl_dir_phys(dp->dp_root_dir)->dd_used_bytes;
165 /* MOS space is triple-dittoed, so we multiply by 3. */
166 if (dst->dst_space > 0 && used + dst->dst_space * 3 > quota) {
167 dst->dst_error = SET_ERROR(ENOSPC);
168 if (dst->dst_nowaiter)
169 kmem_free(dst, sizeof (*dst));
170 return;
171 }
172 }
173
174 /*
175 * Check for errors by calling checkfunc.
176 */
177 rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
178 dst->dst_error = dst->dst_checkfunc(dst->dst_arg, tx);
179 if (dst->dst_error == 0)
180 dst->dst_syncfunc(dst->dst_arg, tx);
181 rrw_exit(&dp->dp_config_rwlock, FTAG);
182 if (dst->dst_nowaiter)
183 kmem_free(dst, sizeof (*dst));
184 }