xref: /openbmc/qemu/block/throttle.c (revision 2b74dd91)
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  */
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 
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 
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
113 throttle_co_getlength(BlockDriverState *bs)
114 {
115     return bdrv_co_getlength(bs->file->bs);
116 }
117 
118 static int coroutine_fn GRAPH_RDLOCK
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
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
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
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
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 
166 static int coroutine_fn GRAPH_RDLOCK throttle_co_flush(BlockDriverState *bs)
167 {
168     return bdrv_co_flush(bs->file->bs);
169 }
170 
171 static void throttle_detach_aio_context(BlockDriverState *bs)
172 {
173     ThrottleGroupMember *tgm = bs->opaque;
174     throttle_group_detach_aio_context(tgm);
175 }
176 
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 
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 
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 
214 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
215 {
216     g_free(reopen_state->opaque);
217     reopen_state->opaque = NULL;
218 }
219 
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 
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 
274 static void bdrv_throttle_init(void)
275 {
276     bdrv_register(&bdrv_throttle);
277 }
278 
279 block_init(bdrv_throttle_init);
280