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/throttle-groups.h"
22#include "qemu/module.h"
23#include "qemu/option.h"
24#include "qemu/throttle-options.h"
25#include "qapi/error.h"
26
27static QemuOptsList throttle_opts = {
28 .name = "throttle",
29 .head = QTAILQ_HEAD_INITIALIZER(throttle_opts.head),
30 .desc = {
31 {
32 .name = QEMU_OPT_THROTTLE_GROUP_NAME,
33 .type = QEMU_OPT_STRING,
34 .help = "Name of the throttle group",
35 },
36 { /* end of list */ }
37 },
38};
39
40/*
41 * If this function succeeds then the throttle group name is stored in
42 * @group and must be freed by the caller.
43 * If there's an error then @group remains unmodified.
44 */
45static int throttle_parse_options(QDict *options, char **group, Error **errp)
46{
47 int ret;
48 const char *group_name;
49 Error *local_err = NULL;
50 QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort);
51
52 qemu_opts_absorb_qdict(opts, options, &local_err);
53 if (local_err) {
54 error_propagate(errp, local_err);
55 ret = -EINVAL;
56 goto fin;
57 }
58
59 group_name = qemu_opt_get(opts, QEMU_OPT_THROTTLE_GROUP_NAME);
60 if (!group_name) {
61 error_setg(errp, "Please specify a throttle group");
62 ret = -EINVAL;
63 goto fin;
64 } else if (!throttle_group_exists(group_name)) {
65 error_setg(errp, "Throttle group '%s' does not exist", group_name);
66 ret = -EINVAL;
67 goto fin;
68 }
69
70 *group = g_strdup(group_name);
71 ret = 0;
72fin:
73 qemu_opts_del(opts);
74 return ret;
75}
76
77static int throttle_open(BlockDriverState *bs, QDict *options,
78 int flags, Error **errp)
79{
80 ThrottleGroupMember *tgm = bs->opaque;
81 char *group;
82 int ret;
83
84 bs->file = bdrv_open_child(NULL, options, "file", bs,
85 &child_file, false, errp);
86 if (!bs->file) {
87 return -EINVAL;
88 }
89 bs->supported_write_flags = bs->file->bs->supported_write_flags |
90 BDRV_REQ_WRITE_UNCHANGED;
91 bs->supported_zero_flags = bs->file->bs->supported_zero_flags |
92 BDRV_REQ_WRITE_UNCHANGED;
93
94 ret = throttle_parse_options(options, &group, errp);
95 if (ret == 0) {
96 /* Register membership to group with name group_name */
97 throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
98 g_free(group);
99 }
100
101 return ret;
102}
103
104static void throttle_close(BlockDriverState *bs)
105{
106 ThrottleGroupMember *tgm = bs->opaque;
107 throttle_group_unregister_tgm(tgm);
108}
109
110
111static int64_t throttle_getlength(BlockDriverState *bs)
112{
113 return bdrv_getlength(bs->file->bs);
114}
115
116static int coroutine_fn throttle_co_preadv(BlockDriverState *bs,
117 uint64_t offset, uint64_t bytes,
118 QEMUIOVector *qiov, int flags)
119{
120
121 ThrottleGroupMember *tgm = bs->opaque;
122 throttle_group_co_io_limits_intercept(tgm, bytes, false);
123
124 return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
125}
126
127static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs,
128 uint64_t offset, uint64_t bytes,
129 QEMUIOVector *qiov, int flags)
130{
131 ThrottleGroupMember *tgm = bs->opaque;
132 throttle_group_co_io_limits_intercept(tgm, bytes, true);
133
134 return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
135}
136
137static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs,
138 int64_t offset, int bytes,
139 BdrvRequestFlags flags)
140{
141 ThrottleGroupMember *tgm = bs->opaque;
142 throttle_group_co_io_limits_intercept(tgm, bytes, true);
143
144 return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
145}
146
147static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs,
148 int64_t offset, int bytes)
149{
150 ThrottleGroupMember *tgm = bs->opaque;
151 throttle_group_co_io_limits_intercept(tgm, bytes, true);
152
153 return bdrv_co_pdiscard(bs->file, offset, bytes);
154}
155
156static int throttle_co_flush(BlockDriverState *bs)
157{
158 return bdrv_co_flush(bs->file->bs);
159}
160
161static void throttle_detach_aio_context(BlockDriverState *bs)
162{
163 ThrottleGroupMember *tgm = bs->opaque;
164 throttle_group_detach_aio_context(tgm);
165}
166
167static void throttle_attach_aio_context(BlockDriverState *bs,
168 AioContext *new_context)
169{
170 ThrottleGroupMember *tgm = bs->opaque;
171 throttle_group_attach_aio_context(tgm, new_context);
172}
173
174static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
175 BlockReopenQueue *queue, Error **errp)
176{
177 int ret;
178 char *group = NULL;
179
180 assert(reopen_state != NULL);
181 assert(reopen_state->bs != NULL);
182
183 ret = throttle_parse_options(reopen_state->options, &group, errp);
184 reopen_state->opaque = group;
185 return ret;
186}
187
188static void throttle_reopen_commit(BDRVReopenState *reopen_state)
189{
190 BlockDriverState *bs = reopen_state->bs;
191 ThrottleGroupMember *tgm = bs->opaque;
192 char *group = reopen_state->opaque;
193
194 assert(group);
195
196 if (strcmp(group, throttle_group_get_name(tgm))) {
197 throttle_group_unregister_tgm(tgm);
198 throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
199 }
200 g_free(reopen_state->opaque);
201 reopen_state->opaque = NULL;
202}
203
204static void throttle_reopen_abort(BDRVReopenState *reopen_state)
205{
206 g_free(reopen_state->opaque);
207 reopen_state->opaque = NULL;
208}
209
210static bool throttle_recurse_is_first_non_filter(BlockDriverState *bs,
211 BlockDriverState *candidate)
212{
213 return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
214}
215
216static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs)
217{
218 ThrottleGroupMember *tgm = bs->opaque;
219 if (atomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
220 throttle_group_restart_tgm(tgm);
221 }
222}
223
224static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs)
225{
226 ThrottleGroupMember *tgm = bs->opaque;
227 assert(tgm->io_limits_disabled);
228 atomic_dec(&tgm->io_limits_disabled);
229}
230
231static const char *const throttle_strong_runtime_opts[] = {
232 QEMU_OPT_THROTTLE_GROUP_NAME,
233
234 NULL
235};
236
237static BlockDriver bdrv_throttle = {
238 .format_name = "throttle",
239 .instance_size = sizeof(ThrottleGroupMember),
240
241 .bdrv_open = throttle_open,
242 .bdrv_close = throttle_close,
243 .bdrv_co_flush = throttle_co_flush,
244
245 .bdrv_child_perm = bdrv_filter_default_perms,
246
247 .bdrv_getlength = throttle_getlength,
248
249 .bdrv_co_preadv = throttle_co_preadv,
250 .bdrv_co_pwritev = throttle_co_pwritev,
251
252 .bdrv_co_pwrite_zeroes = throttle_co_pwrite_zeroes,
253 .bdrv_co_pdiscard = throttle_co_pdiscard,
254
255 .bdrv_recurse_is_first_non_filter = throttle_recurse_is_first_non_filter,
256
257 .bdrv_attach_aio_context = throttle_attach_aio_context,
258 .bdrv_detach_aio_context = throttle_detach_aio_context,
259
260 .bdrv_reopen_prepare = throttle_reopen_prepare,
261 .bdrv_reopen_commit = throttle_reopen_commit,
262 .bdrv_reopen_abort = throttle_reopen_abort,
263 .bdrv_co_block_status = bdrv_co_block_status_from_file,
264
265 .bdrv_co_drain_begin = throttle_co_drain_begin,
266 .bdrv_co_drain_end = throttle_co_drain_end,
267
268 .is_filter = true,
269 .strong_runtime_opts = throttle_strong_runtime_opts,
270};
271
272static void bdrv_throttle_init(void)
273{
274 bdrv_register(&bdrv_throttle);
275}
276
277block_init(bdrv_throttle_init);
278