1 /*
2 * QEMU block throttling filter driver infrastructure
3 *
4 * Copyright (c) 2017 Manos Pitsidianakis
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation; either version 2 or
9 * (at your option) version 3 of the License.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, see <http://www.gnu.org/licenses/>.
18 */
19
20 #include "qemu/osdep.h"
21 #include "block/block-io.h"
22 #include "block/block_int.h"
23 #include "block/throttle-groups.h"
24 #include "qemu/module.h"
25 #include "qemu/option.h"
26 #include "qemu/throttle-options.h"
27 #include "qapi/error.h"
28
29 static QemuOptsList throttle_opts = {
30 .name = "throttle",
31 .head = QTAILQ_HEAD_INITIALIZER(throttle_opts.head),
32 .desc = {
33 {
34 .name = QEMU_OPT_THROTTLE_GROUP_NAME,
35 .type = QEMU_OPT_STRING,
36 .help = "Name of the throttle group",
37 },
38 { /* end of list */ }
39 },
40 };
41
42 /*
43 * If this function succeeds then the throttle group name is stored in
44 * @group and must be freed by the caller.
45 * If there's an error then @group remains unmodified.
46 */
throttle_parse_options(QDict * options,char ** group,Error ** errp)47 static int throttle_parse_options(QDict *options, char **group, Error **errp)
48 {
49 int ret;
50 const char *group_name;
51 QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort);
52
53 if (!qemu_opts_absorb_qdict(opts, options, errp)) {
54 ret = -EINVAL;
55 goto fin;
56 }
57
58 group_name = qemu_opt_get(opts, QEMU_OPT_THROTTLE_GROUP_NAME);
59 if (!group_name) {
60 error_setg(errp, "Please specify a throttle group");
61 ret = -EINVAL;
62 goto fin;
63 } else if (!throttle_group_exists(group_name)) {
64 error_setg(errp, "Throttle group '%s' does not exist", group_name);
65 ret = -EINVAL;
66 goto fin;
67 }
68
69 *group = g_strdup(group_name);
70 ret = 0;
71 fin:
72 qemu_opts_del(opts);
73 return ret;
74 }
75
throttle_open(BlockDriverState * bs,QDict * options,int flags,Error ** errp)76 static int throttle_open(BlockDriverState *bs, QDict *options,
77 int flags, Error **errp)
78 {
79 ThrottleGroupMember *tgm = bs->opaque;
80 char *group;
81 int ret;
82
83 ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
84 if (ret < 0) {
85 return ret;
86 }
87
88 GRAPH_RDLOCK_GUARD_MAINLOOP();
89
90 bs->supported_write_flags = bs->file->bs->supported_write_flags |
91 BDRV_REQ_WRITE_UNCHANGED;
92 bs->supported_zero_flags = bs->file->bs->supported_zero_flags |
93 BDRV_REQ_WRITE_UNCHANGED;
94
95 ret = throttle_parse_options(options, &group, errp);
96 if (ret == 0) {
97 /* Register membership to group with name group_name */
98 throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
99 g_free(group);
100 }
101
102 return ret;
103 }
104
throttle_close(BlockDriverState * bs)105 static void throttle_close(BlockDriverState *bs)
106 {
107 ThrottleGroupMember *tgm = bs->opaque;
108 throttle_group_unregister_tgm(tgm);
109 }
110
111
112 static int64_t coroutine_fn GRAPH_RDLOCK
throttle_co_getlength(BlockDriverState * bs)113 throttle_co_getlength(BlockDriverState *bs)
114 {
115 return bdrv_co_getlength(bs->file->bs);
116 }
117
118 static int coroutine_fn GRAPH_RDLOCK
throttle_co_preadv(BlockDriverState * bs,int64_t offset,int64_t bytes,QEMUIOVector * qiov,BdrvRequestFlags flags)119 throttle_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
120 QEMUIOVector *qiov, BdrvRequestFlags flags)
121 {
122
123 ThrottleGroupMember *tgm = bs->opaque;
124 throttle_group_co_io_limits_intercept(tgm, bytes, THROTTLE_READ);
125
126 return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
127 }
128
129 static int coroutine_fn GRAPH_RDLOCK
throttle_co_pwritev(BlockDriverState * bs,int64_t offset,int64_t bytes,QEMUIOVector * qiov,BdrvRequestFlags flags)130 throttle_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
131 QEMUIOVector *qiov, BdrvRequestFlags flags)
132 {
133 ThrottleGroupMember *tgm = bs->opaque;
134 throttle_group_co_io_limits_intercept(tgm, bytes, THROTTLE_WRITE);
135
136 return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
137 }
138
139 static int coroutine_fn GRAPH_RDLOCK
throttle_co_pwrite_zeroes(BlockDriverState * bs,int64_t offset,int64_t bytes,BdrvRequestFlags flags)140 throttle_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int64_t bytes,
141 BdrvRequestFlags flags)
142 {
143 ThrottleGroupMember *tgm = bs->opaque;
144 throttle_group_co_io_limits_intercept(tgm, bytes, THROTTLE_WRITE);
145
146 return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
147 }
148
149 static int coroutine_fn GRAPH_RDLOCK
throttle_co_pdiscard(BlockDriverState * bs,int64_t offset,int64_t bytes)150 throttle_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
151 {
152 ThrottleGroupMember *tgm = bs->opaque;
153 throttle_group_co_io_limits_intercept(tgm, bytes, THROTTLE_WRITE);
154
155 return bdrv_co_pdiscard(bs->file, offset, bytes);
156 }
157
158 static int coroutine_fn GRAPH_RDLOCK
throttle_co_pwritev_compressed(BlockDriverState * bs,int64_t offset,int64_t bytes,QEMUIOVector * qiov)159 throttle_co_pwritev_compressed(BlockDriverState *bs, int64_t offset,
160 int64_t bytes, QEMUIOVector *qiov)
161 {
162 return throttle_co_pwritev(bs, offset, bytes, qiov,
163 BDRV_REQ_WRITE_COMPRESSED);
164 }
165
throttle_co_flush(BlockDriverState * bs)166 static int coroutine_fn GRAPH_RDLOCK throttle_co_flush(BlockDriverState *bs)
167 {
168 return bdrv_co_flush(bs->file->bs);
169 }
170
throttle_detach_aio_context(BlockDriverState * bs)171 static void throttle_detach_aio_context(BlockDriverState *bs)
172 {
173 ThrottleGroupMember *tgm = bs->opaque;
174 throttle_group_detach_aio_context(tgm);
175 }
176
throttle_attach_aio_context(BlockDriverState * bs,AioContext * new_context)177 static void throttle_attach_aio_context(BlockDriverState *bs,
178 AioContext *new_context)
179 {
180 ThrottleGroupMember *tgm = bs->opaque;
181 throttle_group_attach_aio_context(tgm, new_context);
182 }
183
throttle_reopen_prepare(BDRVReopenState * reopen_state,BlockReopenQueue * queue,Error ** errp)184 static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
185 BlockReopenQueue *queue, Error **errp)
186 {
187 int ret;
188 char *group = NULL;
189
190 assert(reopen_state != NULL);
191 assert(reopen_state->bs != NULL);
192
193 ret = throttle_parse_options(reopen_state->options, &group, errp);
194 reopen_state->opaque = group;
195 return ret;
196 }
197
throttle_reopen_commit(BDRVReopenState * reopen_state)198 static void throttle_reopen_commit(BDRVReopenState *reopen_state)
199 {
200 BlockDriverState *bs = reopen_state->bs;
201 ThrottleGroupMember *tgm = bs->opaque;
202 char *group = reopen_state->opaque;
203
204 assert(group);
205
206 if (strcmp(group, throttle_group_get_name(tgm))) {
207 throttle_group_unregister_tgm(tgm);
208 throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
209 }
210 g_free(reopen_state->opaque);
211 reopen_state->opaque = NULL;
212 }
213
throttle_reopen_abort(BDRVReopenState * reopen_state)214 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
215 {
216 g_free(reopen_state->opaque);
217 reopen_state->opaque = NULL;
218 }
219
throttle_drain_begin(BlockDriverState * bs)220 static void throttle_drain_begin(BlockDriverState *bs)
221 {
222 ThrottleGroupMember *tgm = bs->opaque;
223 if (qatomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
224 throttle_group_restart_tgm(tgm);
225 }
226 }
227
throttle_drain_end(BlockDriverState * bs)228 static void throttle_drain_end(BlockDriverState *bs)
229 {
230 ThrottleGroupMember *tgm = bs->opaque;
231 assert(tgm->io_limits_disabled);
232 qatomic_dec(&tgm->io_limits_disabled);
233 }
234
235 static const char *const throttle_strong_runtime_opts[] = {
236 QEMU_OPT_THROTTLE_GROUP_NAME,
237
238 NULL
239 };
240
241 static BlockDriver bdrv_throttle = {
242 .format_name = "throttle",
243 .instance_size = sizeof(ThrottleGroupMember),
244
245 .bdrv_open = throttle_open,
246 .bdrv_close = throttle_close,
247 .bdrv_co_flush = throttle_co_flush,
248
249 .bdrv_child_perm = bdrv_default_perms,
250
251 .bdrv_co_getlength = throttle_co_getlength,
252
253 .bdrv_co_preadv = throttle_co_preadv,
254 .bdrv_co_pwritev = throttle_co_pwritev,
255
256 .bdrv_co_pwrite_zeroes = throttle_co_pwrite_zeroes,
257 .bdrv_co_pdiscard = throttle_co_pdiscard,
258 .bdrv_co_pwritev_compressed = throttle_co_pwritev_compressed,
259
260 .bdrv_attach_aio_context = throttle_attach_aio_context,
261 .bdrv_detach_aio_context = throttle_detach_aio_context,
262
263 .bdrv_reopen_prepare = throttle_reopen_prepare,
264 .bdrv_reopen_commit = throttle_reopen_commit,
265 .bdrv_reopen_abort = throttle_reopen_abort,
266
267 .bdrv_drain_begin = throttle_drain_begin,
268 .bdrv_drain_end = throttle_drain_end,
269
270 .is_filter = true,
271 .strong_runtime_opts = throttle_strong_runtime_opts,
272 };
273
bdrv_throttle_init(void)274 static void bdrv_throttle_init(void)
275 {
276 bdrv_register(&bdrv_throttle);
277 }
278
279 block_init(bdrv_throttle_init);
280