block/throttle.c

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