Convert "translator internals" docs to RST, move to devel manual
[qemu/ar7.git] / block / throttle.c
blob0349f422576eb8009d8e84633b5afaae932a3b3b
1 /*
2 * QEMU block throttling filter driver infrastructure
4 * Copyright (c) 2017 Manos Pitsidianakis
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.
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.
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/>.
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"
27 static QemuOptsList throttle_opts = {
28 .name = "throttle",
29 .head = QTAILQ_HEAD_INITIALIZER(throttle_opts.head),
30 .desc = {
32 .name = QEMU_OPT_THROTTLE_GROUP_NAME,
33 .type = QEMU_OPT_STRING,
34 .help = "Name of the throttle group",
36 { /* end of list */ }
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.
45 static int throttle_parse_options(QDict *options, char **group, Error **errp)
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);
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;
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;
70 *group = g_strdup(group_name);
71 ret = 0;
72 fin:
73 qemu_opts_del(opts);
74 return ret;
77 static int throttle_open(BlockDriverState *bs, QDict *options,
78 int flags, Error **errp)
80 ThrottleGroupMember *tgm = bs->opaque;
81 char *group;
82 int ret;
84 bs->file = bdrv_open_child(NULL, options, "file", bs,
85 &child_file, false, errp);
86 if (!bs->file) {
87 return -EINVAL;
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;
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);
101 return ret;
104 static void throttle_close(BlockDriverState *bs)
106 ThrottleGroupMember *tgm = bs->opaque;
107 throttle_group_unregister_tgm(tgm);
111 static int64_t throttle_getlength(BlockDriverState *bs)
113 return bdrv_getlength(bs->file->bs);
116 static int coroutine_fn throttle_co_preadv(BlockDriverState *bs,
117 uint64_t offset, uint64_t bytes,
118 QEMUIOVector *qiov, int flags)
121 ThrottleGroupMember *tgm = bs->opaque;
122 throttle_group_co_io_limits_intercept(tgm, bytes, false);
124 return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
127 static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs,
128 uint64_t offset, uint64_t bytes,
129 QEMUIOVector *qiov, int flags)
131 ThrottleGroupMember *tgm = bs->opaque;
132 throttle_group_co_io_limits_intercept(tgm, bytes, true);
134 return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
137 static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs,
138 int64_t offset, int bytes,
139 BdrvRequestFlags flags)
141 ThrottleGroupMember *tgm = bs->opaque;
142 throttle_group_co_io_limits_intercept(tgm, bytes, true);
144 return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
147 static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs,
148 int64_t offset, int bytes)
150 ThrottleGroupMember *tgm = bs->opaque;
151 throttle_group_co_io_limits_intercept(tgm, bytes, true);
153 return bdrv_co_pdiscard(bs->file, offset, bytes);
156 static int throttle_co_flush(BlockDriverState *bs)
158 return bdrv_co_flush(bs->file->bs);
161 static void throttle_detach_aio_context(BlockDriverState *bs)
163 ThrottleGroupMember *tgm = bs->opaque;
164 throttle_group_detach_aio_context(tgm);
167 static void throttle_attach_aio_context(BlockDriverState *bs,
168 AioContext *new_context)
170 ThrottleGroupMember *tgm = bs->opaque;
171 throttle_group_attach_aio_context(tgm, new_context);
174 static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
175 BlockReopenQueue *queue, Error **errp)
177 int ret;
178 char *group = NULL;
180 assert(reopen_state != NULL);
181 assert(reopen_state->bs != NULL);
183 ret = throttle_parse_options(reopen_state->options, &group, errp);
184 reopen_state->opaque = group;
185 return ret;
188 static void throttle_reopen_commit(BDRVReopenState *reopen_state)
190 BlockDriverState *bs = reopen_state->bs;
191 ThrottleGroupMember *tgm = bs->opaque;
192 char *group = reopen_state->opaque;
194 assert(group);
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));
200 g_free(reopen_state->opaque);
201 reopen_state->opaque = NULL;
204 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
206 g_free(reopen_state->opaque);
207 reopen_state->opaque = NULL;
210 static bool throttle_recurse_is_first_non_filter(BlockDriverState *bs,
211 BlockDriverState *candidate)
213 return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
216 static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs)
218 ThrottleGroupMember *tgm = bs->opaque;
219 if (atomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
220 throttle_group_restart_tgm(tgm);
224 static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs)
226 ThrottleGroupMember *tgm = bs->opaque;
227 assert(tgm->io_limits_disabled);
228 atomic_dec(&tgm->io_limits_disabled);
231 static const char *const throttle_strong_runtime_opts[] = {
232 QEMU_OPT_THROTTLE_GROUP_NAME,
234 NULL
237 static BlockDriver bdrv_throttle = {
238 .format_name = "throttle",
239 .instance_size = sizeof(ThrottleGroupMember),
241 .bdrv_open = throttle_open,
242 .bdrv_close = throttle_close,
243 .bdrv_co_flush = throttle_co_flush,
245 .bdrv_child_perm = bdrv_filter_default_perms,
247 .bdrv_getlength = throttle_getlength,
249 .bdrv_co_preadv = throttle_co_preadv,
250 .bdrv_co_pwritev = throttle_co_pwritev,
252 .bdrv_co_pwrite_zeroes = throttle_co_pwrite_zeroes,
253 .bdrv_co_pdiscard = throttle_co_pdiscard,
255 .bdrv_recurse_is_first_non_filter = throttle_recurse_is_first_non_filter,
257 .bdrv_attach_aio_context = throttle_attach_aio_context,
258 .bdrv_detach_aio_context = throttle_detach_aio_context,
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,
265 .bdrv_co_drain_begin = throttle_co_drain_begin,
266 .bdrv_co_drain_end = throttle_co_drain_end,
268 .is_filter = true,
269 .strong_runtime_opts = throttle_strong_runtime_opts,
272 static void bdrv_throttle_init(void)
274 bdrv_register(&bdrv_throttle);
277 block_init(bdrv_throttle_init);