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                                            int64_t offset, int64_t bytes,
 116                                            QEMUIOVector *qiov,
 117                                            BdrvRequestFlags flags)
 118 {
 119
 120     ThrottleGroupMember *tgm = bs->opaque;
 121     throttle_group_co_io_limits_intercept(tgm, bytes, false);
 122
 123     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
 124 }
 125
 126 static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs,
 127                                             int64_t offset, int64_t bytes,
 128                                             QEMUIOVector *qiov,
 129                                             BdrvRequestFlags 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, int64_t 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, int64_t 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 coroutine_fn throttle_co_pwritev_compressed(BlockDriverState *bs,
 157                                                        int64_t offset,
 158                                                        int64_t bytes,
 159                                                        QEMUIOVector *qiov)
 160 {
 161     return throttle_co_pwritev(bs, offset, bytes, qiov,
 162                                BDRV_REQ_WRITE_COMPRESSED);
 163 }
 164
 165 static int throttle_co_flush(BlockDriverState *bs)
 166 {
 167     return bdrv_co_flush(bs->file->bs);
 168 }
 169
 170 static void throttle_detach_aio_context(BlockDriverState *bs)
 171 {
 172     ThrottleGroupMember *tgm = bs->opaque;
 173     throttle_group_detach_aio_context(tgm);
 174 }
 175
 176 static void throttle_attach_aio_context(BlockDriverState *bs,
 177                                         AioContext *new_context)
 178 {
 179     ThrottleGroupMember *tgm = bs->opaque;
 180     throttle_group_attach_aio_context(tgm, new_context);
 181 }
 182
 183 static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
 184                                    BlockReopenQueue *queue, Error **errp)
 185 {
 186     int ret;
 187     char *group = NULL;
 188
 189     assert(reopen_state != NULL);
 190     assert(reopen_state->bs != NULL);
 191
 192     ret = throttle_parse_options(reopen_state->options, &group, errp);
 193     reopen_state->opaque = group;
 194     return ret;
 195 }
 196
 197 static void throttle_reopen_commit(BDRVReopenState *reopen_state)
 198 {
 199     BlockDriverState *bs = reopen_state->bs;
 200     ThrottleGroupMember *tgm = bs->opaque;
 201     char *group = reopen_state->opaque;
 202
 203     assert(group);
 204
 205     if (strcmp(group, throttle_group_get_name(tgm))) {
 206         throttle_group_unregister_tgm(tgm);
 207         throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
 208     }
 209     g_free(reopen_state->opaque);
 210     reopen_state->opaque = NULL;
 211 }
 212
 213 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
 214 {
 215     g_free(reopen_state->opaque);
 216     reopen_state->opaque = NULL;
 217 }
 218
 219 static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs)
 220 {
 221     ThrottleGroupMember *tgm = bs->opaque;
 222     if (qatomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
 223         throttle_group_restart_tgm(tgm);
 224     }
 225 }
 226
 227 static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs)
 228 {
 229     ThrottleGroupMember *tgm = bs->opaque;
 230     assert(tgm->io_limits_disabled);
 231     qatomic_dec(&tgm->io_limits_disabled);
 232 }
 233
 234 static const char *const throttle_strong_runtime_opts[] = {
 235     QEMU_OPT_THROTTLE_GROUP_NAME,
 236
 237     NULL
 238 };
 239
 240 static BlockDriver bdrv_throttle = {
 241     .format_name                        =   "throttle",
 242     .instance_size                      =   sizeof(ThrottleGroupMember),
 243
 244     .bdrv_open                          =   throttle_open,
 245     .bdrv_close                         =   throttle_close,
 246     .bdrv_co_flush                      =   throttle_co_flush,
 247
 248     .bdrv_child_perm                    =   bdrv_default_perms,
 249
 250     .bdrv_getlength                     =   throttle_getlength,
 251
 252     .bdrv_co_preadv                     =   throttle_co_preadv,
 253     .bdrv_co_pwritev                    =   throttle_co_pwritev,
 254
 255     .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,
 256     .bdrv_co_pdiscard                   =   throttle_co_pdiscard,
 257     .bdrv_co_pwritev_compressed         =   throttle_co_pwritev_compressed,
 258
 259     .bdrv_attach_aio_context            =   throttle_attach_aio_context,
 260     .bdrv_detach_aio_context            =   throttle_detach_aio_context,
 261
 262     .bdrv_reopen_prepare                =   throttle_reopen_prepare,
 263     .bdrv_reopen_commit                 =   throttle_reopen_commit,
 264     .bdrv_reopen_abort                  =   throttle_reopen_abort,
 265
 266     .bdrv_co_drain_begin                =   throttle_co_drain_begin,
 267     .bdrv_co_drain_end                  =   throttle_co_drain_end,
 268
 269     .is_filter                          =   true,
 270     .strong_runtime_opts                =   throttle_strong_runtime_opts,
 271 };
 272
 273 static void bdrv_throttle_init(void)
 274 {
 275     bdrv_register(&bdrv_throttle);
 276 }
 277
 278 block_init(bdrv_throttle_init);