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, &child_of_bds,
  85                                BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
  86                                false, errp);
  87     if (!bs->file) {
  88         return -EINVAL;
  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 throttle_getlength(BlockDriverState *bs)
 113 {
 114     return bdrv_getlength(bs->file->bs);
 115 }
 116
 117 static int coroutine_fn throttle_co_preadv(BlockDriverState *bs,
 118                                            uint64_t offset, uint64_t bytes,
 119                                            QEMUIOVector *qiov, int flags)
 120 {
 121
 122     ThrottleGroupMember *tgm = bs->opaque;
 123     throttle_group_co_io_limits_intercept(tgm, bytes, false);
 124
 125     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
 126 }
 127
 128 static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs,
 129                                             uint64_t offset, uint64_t bytes,
 130                                             QEMUIOVector *qiov, int flags)
 131 {
 132     ThrottleGroupMember *tgm = bs->opaque;
 133     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 134
 135     return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
 136 }
 137
 138 static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs,
 139                                                   int64_t offset, int bytes,
 140                                                   BdrvRequestFlags flags)
 141 {
 142     ThrottleGroupMember *tgm = bs->opaque;
 143     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 144
 145     return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
 146 }
 147
 148 static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs,
 149                                              int64_t offset, int bytes)
 150 {
 151     ThrottleGroupMember *tgm = bs->opaque;
 152     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 153
 154     return bdrv_co_pdiscard(bs->file, offset, bytes);
 155 }
 156
 157 static int throttle_co_flush(BlockDriverState *bs)
 158 {
 159     return bdrv_co_flush(bs->file->bs);
 160 }
 161
 162 static void throttle_detach_aio_context(BlockDriverState *bs)
 163 {
 164     ThrottleGroupMember *tgm = bs->opaque;
 165     throttle_group_detach_aio_context(tgm);
 166 }
 167
 168 static void throttle_attach_aio_context(BlockDriverState *bs,
 169                                         AioContext *new_context)
 170 {
 171     ThrottleGroupMember *tgm = bs->opaque;
 172     throttle_group_attach_aio_context(tgm, new_context);
 173 }
 174
 175 static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
 176                                    BlockReopenQueue *queue, Error **errp)
 177 {
 178     int ret;
 179     char *group = NULL;
 180
 181     assert(reopen_state != NULL);
 182     assert(reopen_state->bs != NULL);
 183
 184     ret = throttle_parse_options(reopen_state->options, &group, errp);
 185     reopen_state->opaque = group;
 186     return ret;
 187 }
 188
 189 static void throttle_reopen_commit(BDRVReopenState *reopen_state)
 190 {
 191     BlockDriverState *bs = reopen_state->bs;
 192     ThrottleGroupMember *tgm = bs->opaque;
 193     char *group = reopen_state->opaque;
 194
 195     assert(group);
 196
 197     if (strcmp(group, throttle_group_get_name(tgm))) {
 198         throttle_group_unregister_tgm(tgm);
 199         throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
 200     }
 201     g_free(reopen_state->opaque);
 202     reopen_state->opaque = NULL;
 203 }
 204
 205 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
 206 {
 207     g_free(reopen_state->opaque);
 208     reopen_state->opaque = NULL;
 209 }
 210
 211 static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs)
 212 {
 213     ThrottleGroupMember *tgm = bs->opaque;
 214     if (atomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
 215         throttle_group_restart_tgm(tgm);
 216     }
 217 }
 218
 219 static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs)
 220 {
 221     ThrottleGroupMember *tgm = bs->opaque;
 222     assert(tgm->io_limits_disabled);
 223     atomic_dec(&tgm->io_limits_disabled);
 224 }
 225
 226 static const char *const throttle_strong_runtime_opts[] = {
 227     QEMU_OPT_THROTTLE_GROUP_NAME,
 228
 229     NULL
 230 };
 231
 232 static BlockDriver bdrv_throttle = {
 233     .format_name                        =   "throttle",
 234     .instance_size                      =   sizeof(ThrottleGroupMember),
 235
 236     .bdrv_open                          =   throttle_open,
 237     .bdrv_close                         =   throttle_close,
 238     .bdrv_co_flush                      =   throttle_co_flush,
 239
 240     .bdrv_child_perm                    =   bdrv_default_perms,
 241
 242     .bdrv_getlength                     =   throttle_getlength,
 243
 244     .bdrv_co_preadv                     =   throttle_co_preadv,
 245     .bdrv_co_pwritev                    =   throttle_co_pwritev,
 246
 247     .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,
 248     .bdrv_co_pdiscard                   =   throttle_co_pdiscard,
 249
 250     .bdrv_attach_aio_context            =   throttle_attach_aio_context,
 251     .bdrv_detach_aio_context            =   throttle_detach_aio_context,
 252
 253     .bdrv_reopen_prepare                =   throttle_reopen_prepare,
 254     .bdrv_reopen_commit                 =   throttle_reopen_commit,
 255     .bdrv_reopen_abort                  =   throttle_reopen_abort,
 256     .bdrv_co_block_status               =   bdrv_co_block_status_from_file,
 257
 258     .bdrv_co_drain_begin                =   throttle_co_drain_begin,
 259     .bdrv_co_drain_end                  =   throttle_co_drain_end,
 260
 261     .is_filter                          =   true,
 262     .strong_runtime_opts                =   throttle_strong_runtime_opts,
 263 };
 264
 265 static void bdrv_throttle_init(void)
 266 {
 267     bdrv_register(&bdrv_throttle);
 268 }
 269
 270 block_init(bdrv_throttle_init);