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 */
25
26 #include <sys/dmu.h>
27 #include <sys/dmu_tx.h>
28 #include <sys/dsl_pool.h>
29 #include <sys/dsl_dir.h>
30 #include <sys/dsl_synctask.h>
31 #include <sys/metaslab.h>
32
33 #define DST_AVG_BLKSHIFT 14
34
35 /* ARGSUSED */
36 static int
37 dsl_null_checkfunc(void *arg, dmu_tx_t *tx)
38 {
39 return (0);
40 }
41
42 /*
43 * Called from open context to perform a callback in syncing context. Waits
44 * for the operation to complete.
45 *
46 * The checkfunc will be called from open context as a preliminary check
47 * which can quickly fail. If it succeeds, it will be called again from
48 * syncing context. The checkfunc should generally be designed to work
49 * properly in either context, but if necessary it can check
50 * dmu_tx_is_syncing(tx).
51 *
52 * The synctask infrastructure enforces proper locking strategy with respect
53 * to the dp_config_rwlock -- the lock will always be held when the callbacks
54 * are called. It will be held for read during the open-context (preliminary)
55 * call to the checkfunc, and then held for write from syncing context during
56 * the calls to the check and sync funcs.
57 *
58 * A dataset or pool name can be passed as the first argument. Typically,
59 * the check func will hold, check the return value of the hold, and then
60 * release the dataset. The sync func will VERIFYO(hold()) the dataset.
61 * This is safe because no changes can be made between the check and sync funcs,
62 * and the sync func will only be called if the check func successfully opened
63 * the dataset.
64 */
65 int
66 dsl_sync_task(const char *pool, dsl_checkfunc_t *checkfunc,
67 dsl_syncfunc_t *syncfunc, void *arg,
68 int blocks_modified, zfs_space_check_t space_check)
69 {
70 spa_t *spa;
71 dmu_tx_t *tx;
72 int err;
73 dsl_sync_task_t dst = { .dst_error = 0 };
74 dsl_pool_t *dp;
75
76 err = spa_open(pool, &spa, FTAG);
77 if (err != 0)
78 return (err);
79 dp = spa_get_dsl(spa);
80
81 top:
82 tx = dmu_tx_create_dd(dp->dp_mos_dir);
83 VERIFY0(dmu_tx_assign(tx, TXG_WAIT));
84
85 dst.dst_pool = dp;
86 dst.dst_txg = dmu_tx_get_txg(tx);
87 dst.dst_space = blocks_modified << DST_AVG_BLKSHIFT;
88 dst.dst_space_check = space_check;
89 dst.dst_checkfunc = checkfunc != NULL ? checkfunc : dsl_null_checkfunc;
90 dst.dst_syncfunc = syncfunc;
91 dst.dst_arg = arg;
92 dst.dst_error = 0;
93 dst.dst_nowaiter = B_FALSE;
94
95 dsl_pool_config_enter(dp, FTAG);
96 err = dst.dst_checkfunc(arg, tx);
97 dsl_pool_config_exit(dp, FTAG);
98
99 if (err != 0) {
100 dmu_tx_commit(tx);
101 spa_close(spa, FTAG);
102 return (err);
103 }
104
105 VERIFY(txg_list_add_tail(&dp->dp_sync_tasks, &dst, dst.dst_txg));
106
107 dmu_tx_commit(tx);
108
109 txg_wait_synced(dp, dst.dst_txg);
110
111 if (dst.dst_error == EAGAIN) {
112 txg_wait_synced(dp, dst.dst_txg + TXG_DEFER_SIZE);
113 goto top;
114 }
115
116 spa_close(spa, FTAG);
117 return (dst.dst_error);
118 }
119
120 void
121 dsl_sync_task_nowait(dsl_pool_t *dp, dsl_syncfunc_t *syncfunc, void *arg,
122 int blocks_modified, zfs_space_check_t space_check, dmu_tx_t *tx)
123 {
124 dsl_sync_task_t *dst = kmem_zalloc(sizeof (*dst), KM_SLEEP);
125
126 dst->dst_pool = dp;
127 dst->dst_txg = dmu_tx_get_txg(tx);
128 dst->dst_space = blocks_modified << DST_AVG_BLKSHIFT;
129 dst->dst_space_check = space_check;
130 dst->dst_checkfunc = dsl_null_checkfunc;
131 dst->dst_syncfunc = syncfunc;
132 dst->dst_arg = arg;
133 dst->dst_error = 0;
134 dst->dst_nowaiter = B_TRUE;
135
136 VERIFY(txg_list_add_tail(&dp->dp_sync_tasks, dst, dst->dst_txg));
137 }
138
139 /*
140 * Called in syncing context to execute the synctask.
141 */
142 void
143 dsl_sync_task_sync(dsl_sync_task_t *dst, dmu_tx_t *tx)
144 {
145 dsl_pool_t *dp = dst->dst_pool;
146
147 ASSERT0(dst->dst_error);
148
149 /*
150 * Check for sufficient space.
151 *
152 * When the sync task was created, the caller specified the
153 * type of space checking required. See the comment in
154 * zfs_space_check_t for details on the semantics of each
155 * type of space checking.
156 *
157 * We just check against what's on-disk; we don't want any
158 * in-flight accounting to get in our way, because open context
159 * may have already used up various in-core limits
160 * (arc_tempreserve, dsl_pool_tempreserve).
161 */
162 if (dst->dst_space_check != ZFS_SPACE_CHECK_NONE) {
163 uint64_t quota = dsl_pool_adjustedsize(dp,
164 dst->dst_space_check == ZFS_SPACE_CHECK_RESERVED) -
165 metaslab_class_get_deferred(spa_normal_class(dp->dp_spa));
166 uint64_t used = dsl_dir_phys(dp->dp_root_dir)->dd_used_bytes;
167 /* MOS space is triple-dittoed, so we multiply by 3. */
168 if (dst->dst_space > 0 && used + dst->dst_space * 3 > quota) {
169 dst->dst_error = SET_ERROR(ENOSPC);
170 if (dst->dst_nowaiter)
171 kmem_free(dst, sizeof (*dst));
172 return;
173 }
174 }
175
176 /*
177 * Check for errors by calling checkfunc.
178 */
179 rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
180 dst->dst_error = dst->dst_checkfunc(dst->dst_arg, tx);
181 if (dst->dst_error == 0)
182 dst->dst_syncfunc(dst->dst_arg, tx);
183 rrw_exit(&dp->dp_config_rwlock, FTAG);
184 if (dst->dst_nowaiter)
185 kmem_free(dst, sizeof (*dst));
186 }