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/option.h"
  23 #include "qemu/throttle-options.h"
  24 #include "qapi/error.h"
  25
  26 static QemuOptsList throttle_opts = {
  27     .name = "throttle",
  28     .head = QTAILQ_HEAD_INITIALIZER(throttle_opts.head),
  29     .desc = {
  30         {
  31             .name = QEMU_OPT_THROTTLE_GROUP_NAME,
  32             .type = QEMU_OPT_STRING,
  33             .help = "Name of the throttle group",
  34         },
  35         { /* end of list */ }
  36     },
  37 };
  38
  39 /*
  40  * If this function succeeds then the throttle group name is stored in
  41  * @group and must be freed by the caller.
  42  * If there's an error then @group remains unmodified.
  43  */
  44 static int throttle_parse_options(QDict *options, char **group, Error **errp)
  45 {
  46     int ret;
  47     const char *group_name;
  48     Error *local_err = NULL;
  49     QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort);
  50
  51     qemu_opts_absorb_qdict(opts, options, &local_err);
  52     if (local_err) {
  53         error_propagate(errp, local_err);
  54         ret = -EINVAL;
  55         goto fin;
  56     }
  57
  58     group_name = qemu_opt_get(opts, QEMU_OPT_THROTTLE_GROUP_NAME);
  59     if (!group_name) {
  60         error_setg(errp, "Please specify a throttle group");
  61         ret = -EINVAL;
  62         goto fin;
  63     } else if (!throttle_group_exists(group_name)) {
  64         error_setg(errp, "Throttle group '%s' does not exist", group_name);
  65         ret = -EINVAL;
  66         goto fin;
  67     }
  68
  69     *group = g_strdup(group_name);
  70     ret = 0;
  71 fin:
  72     qemu_opts_del(opts);
  73     return ret;
  74 }
  75
  76 static int throttle_open(BlockDriverState *bs, QDict *options,
  77                          int flags, Error **errp)
  78 {
  79     ThrottleGroupMember *tgm = bs->opaque;
  80     char *group;
  81     int ret;
  82
  83     bs->file = bdrv_open_child(NULL, options, "file", bs,
  84                                &child_file, false, errp);
  85     if (!bs->file) {
  86         return -EINVAL;
  87     }
  88     bs->supported_write_flags = bs->file->bs->supported_write_flags |
  89                                 BDRV_REQ_WRITE_UNCHANGED;
  90     bs->supported_zero_flags = bs->file->bs->supported_zero_flags |
  91                                BDRV_REQ_WRITE_UNCHANGED;
  92
  93     ret = throttle_parse_options(options, &group, errp);
  94     if (ret == 0) {
  95         /* Register membership to group with name group_name */
  96         throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
  97         g_free(group);
  98     }
  99
 100     return ret;
 101 }
 102
 103 static void throttle_close(BlockDriverState *bs)
 104 {
 105     ThrottleGroupMember *tgm = bs->opaque;
 106     throttle_group_unregister_tgm(tgm);
 107 }
 108
 109
 110 static int64_t throttle_getlength(BlockDriverState *bs)
 111 {
 112     return bdrv_getlength(bs->file->bs);
 113 }
 114
 115 static int coroutine_fn throttle_co_preadv(BlockDriverState *bs,
 116                                            uint64_t offset, uint64_t bytes,
 117                                            QEMUIOVector *qiov, int 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                                             uint64_t offset, uint64_t bytes,
 128                                             QEMUIOVector *qiov, int flags)
 129 {
 130     ThrottleGroupMember *tgm = bs->opaque;
 131     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 132
 133     return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
 134 }
 135
 136 static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs,
 137                                                   int64_t offset, int bytes,
 138                                                   BdrvRequestFlags flags)
 139 {
 140     ThrottleGroupMember *tgm = bs->opaque;
 141     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 142
 143     return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
 144 }
 145
 146 static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs,
 147                                              int64_t offset, int bytes)
 148 {
 149     ThrottleGroupMember *tgm = bs->opaque;
 150     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 151
 152     return bdrv_co_pdiscard(bs->file, offset, bytes);
 153 }
 154
 155 static int throttle_co_flush(BlockDriverState *bs)
 156 {
 157     return bdrv_co_flush(bs->file->bs);
 158 }
 159
 160 static void throttle_detach_aio_context(BlockDriverState *bs)
 161 {
 162     ThrottleGroupMember *tgm = bs->opaque;
 163     throttle_group_detach_aio_context(tgm);
 164 }
 165
 166 static void throttle_attach_aio_context(BlockDriverState *bs,
 167                                         AioContext *new_context)
 168 {
 169     ThrottleGroupMember *tgm = bs->opaque;
 170     throttle_group_attach_aio_context(tgm, new_context);
 171 }
 172
 173 static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
 174                                    BlockReopenQueue *queue, Error **errp)
 175 {
 176     int ret;
 177     char *group = NULL;
 178
 179     assert(reopen_state != NULL);
 180     assert(reopen_state->bs != NULL);
 181
 182     ret = throttle_parse_options(reopen_state->options, &group, errp);
 183     reopen_state->opaque = group;
 184     return ret;
 185 }
 186
 187 static void throttle_reopen_commit(BDRVReopenState *reopen_state)
 188 {
 189     BlockDriverState *bs = reopen_state->bs;
 190     ThrottleGroupMember *tgm = bs->opaque;
 191     char *group = reopen_state->opaque;
 192
 193     assert(group);
 194
 195     if (strcmp(group, throttle_group_get_name(tgm))) {
 196         throttle_group_unregister_tgm(tgm);
 197         throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
 198     }
 199     g_free(reopen_state->opaque);
 200     reopen_state->opaque = NULL;
 201 }
 202
 203 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
 204 {
 205     g_free(reopen_state->opaque);
 206     reopen_state->opaque = NULL;
 207 }
 208
 209 static bool throttle_recurse_is_first_non_filter(BlockDriverState *bs,
 210                                                  BlockDriverState *candidate)
 211 {
 212     return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
 213 }
 214
 215 static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs)
 216 {
 217     ThrottleGroupMember *tgm = bs->opaque;
 218     if (atomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
 219         throttle_group_restart_tgm(tgm);
 220     }
 221 }
 222
 223 static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs)
 224 {
 225     ThrottleGroupMember *tgm = bs->opaque;
 226     assert(tgm->io_limits_disabled);
 227     atomic_dec(&tgm->io_limits_disabled);
 228 }
 229
 230 static BlockDriver bdrv_throttle = {
 231     .format_name                        =   "throttle",
 232     .instance_size                      =   sizeof(ThrottleGroupMember),
 233
 234     .bdrv_open                          =   throttle_open,
 235     .bdrv_close                         =   throttle_close,
 236     .bdrv_co_flush                      =   throttle_co_flush,
 237
 238     .bdrv_child_perm                    =   bdrv_filter_default_perms,
 239
 240     .bdrv_getlength                     =   throttle_getlength,
 241
 242     .bdrv_co_preadv                     =   throttle_co_preadv,
 243     .bdrv_co_pwritev                    =   throttle_co_pwritev,
 244
 245     .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,
 246     .bdrv_co_pdiscard                   =   throttle_co_pdiscard,
 247
 248     .bdrv_recurse_is_first_non_filter   =   throttle_recurse_is_first_non_filter,
 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 };
 263
 264 static void bdrv_throttle_init(void)
 265 {
 266     bdrv_register(&bdrv_throttle);
 267 }
 268
 269 block_init(bdrv_throttle_init);