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     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;
  72 fin:
  73     qemu_opts_del(opts);
  74     return ret;
  75 }
  76
  77 static 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
 104 static void throttle_close(BlockDriverState *bs)
 105 {
 106     ThrottleGroupMember *tgm = bs->opaque;
 107     throttle_group_unregister_tgm(tgm);
 108 }
 109
 110
 111 static int64_t throttle_getlength(BlockDriverState *bs)
 112 {
 113     return bdrv_getlength(bs->file->bs);
 114 }
 115
 116 static 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
 127 static 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
 137 static 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
 147 static 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
 156 static int throttle_co_flush(BlockDriverState *bs)
 157 {
 158     return bdrv_co_flush(bs->file->bs);
 159 }
 160
 161 static void throttle_detach_aio_context(BlockDriverState *bs)
 162 {
 163     ThrottleGroupMember *tgm = bs->opaque;
 164     throttle_group_detach_aio_context(tgm);
 165 }
 166
 167 static 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
 174 static 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
 188 static 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
 204 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
 205 {
 206     g_free(reopen_state->opaque);
 207     reopen_state->opaque = NULL;
 208 }
 209
 210 static 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
 216 static 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
 224 static 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
 231 static const char *const throttle_strong_runtime_opts[] = {
 232     QEMU_OPT_THROTTLE_GROUP_NAME,
 233
 234     NULL
 235 };
 236
 237 static 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
 272 static void bdrv_throttle_init(void)
 273 {
 274     bdrv_register(&bdrv_throttle);
 275 }
 276
 277 block_init(bdrv_throttle_init);