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 static int throttle_configure_tgm(BlockDriverState *bs,
  40                                   ThrottleGroupMember *tgm,
  41                                   QDict *options, Error **errp)
  42 {
  43     int ret;
  44     const char *group_name;
  45     Error *local_err = NULL;
  46     QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort);
  47
  48     qemu_opts_absorb_qdict(opts, options, &local_err);
  49     if (local_err) {
  50         error_propagate(errp, local_err);
  51         ret = -EINVAL;
  52         goto fin;
  53     }
  54
  55     group_name = qemu_opt_get(opts, QEMU_OPT_THROTTLE_GROUP_NAME);
  56     if (!group_name) {
  57         error_setg(errp, "Please specify a throttle group");
  58         ret = -EINVAL;
  59         goto fin;
  60     } else if (!throttle_group_exists(group_name)) {
  61         error_setg(errp, "Throttle group '%s' does not exist", group_name);
  62         ret = -EINVAL;
  63         goto fin;
  64     }
  65
  66     /* Register membership to group with name group_name */
  67     throttle_group_register_tgm(tgm, group_name, bdrv_get_aio_context(bs));
  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
  79     bs->file = bdrv_open_child(NULL, options, "file", bs,
  80                                &child_file, false, errp);
  81     if (!bs->file) {
  82         return -EINVAL;
  83     }
  84     bs->supported_write_flags = bs->file->bs->supported_write_flags;
  85     bs->supported_zero_flags = bs->file->bs->supported_zero_flags;
  86
  87     return throttle_configure_tgm(bs, tgm, options, errp);
  88 }
  89
  90 static void throttle_close(BlockDriverState *bs)
  91 {
  92     ThrottleGroupMember *tgm = bs->opaque;
  93     throttle_group_unregister_tgm(tgm);
  94 }
  95
  96
  97 static int64_t throttle_getlength(BlockDriverState *bs)
  98 {
  99     return bdrv_getlength(bs->file->bs);
 100 }
 101
 102 static int coroutine_fn throttle_co_preadv(BlockDriverState *bs,
 103                                            uint64_t offset, uint64_t bytes,
 104                                            QEMUIOVector *qiov, int flags)
 105 {
 106
 107     ThrottleGroupMember *tgm = bs->opaque;
 108     throttle_group_co_io_limits_intercept(tgm, bytes, false);
 109
 110     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
 111 }
 112
 113 static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs,
 114                                             uint64_t offset, uint64_t bytes,
 115                                             QEMUIOVector *qiov, int flags)
 116 {
 117     ThrottleGroupMember *tgm = bs->opaque;
 118     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 119
 120     return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
 121 }
 122
 123 static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs,
 124                                                   int64_t offset, int bytes,
 125                                                   BdrvRequestFlags flags)
 126 {
 127     ThrottleGroupMember *tgm = bs->opaque;
 128     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 129
 130     return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
 131 }
 132
 133 static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs,
 134                                              int64_t offset, int bytes)
 135 {
 136     ThrottleGroupMember *tgm = bs->opaque;
 137     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 138
 139     return bdrv_co_pdiscard(bs->file->bs, offset, bytes);
 140 }
 141
 142 static int throttle_co_flush(BlockDriverState *bs)
 143 {
 144     return bdrv_co_flush(bs->file->bs);
 145 }
 146
 147 static void throttle_detach_aio_context(BlockDriverState *bs)
 148 {
 149     ThrottleGroupMember *tgm = bs->opaque;
 150     throttle_group_detach_aio_context(tgm);
 151 }
 152
 153 static void throttle_attach_aio_context(BlockDriverState *bs,
 154                                         AioContext *new_context)
 155 {
 156     ThrottleGroupMember *tgm = bs->opaque;
 157     throttle_group_attach_aio_context(tgm, new_context);
 158 }
 159
 160 static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
 161                                    BlockReopenQueue *queue, Error **errp)
 162 {
 163     ThrottleGroupMember *tgm;
 164
 165     assert(reopen_state != NULL);
 166     assert(reopen_state->bs != NULL);
 167
 168     reopen_state->opaque = g_new0(ThrottleGroupMember, 1);
 169     tgm = reopen_state->opaque;
 170
 171     return throttle_configure_tgm(reopen_state->bs, tgm, reopen_state->options,
 172             errp);
 173 }
 174
 175 static void throttle_reopen_commit(BDRVReopenState *reopen_state)
 176 {
 177     ThrottleGroupMember *old_tgm = reopen_state->bs->opaque;
 178     ThrottleGroupMember *new_tgm = reopen_state->opaque;
 179
 180     throttle_group_unregister_tgm(old_tgm);
 181     g_free(old_tgm);
 182     reopen_state->bs->opaque = new_tgm;
 183     reopen_state->opaque = NULL;
 184 }
 185
 186 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
 187 {
 188     ThrottleGroupMember *tgm = reopen_state->opaque;
 189
 190     throttle_group_unregister_tgm(tgm);
 191     g_free(tgm);
 192     reopen_state->opaque = NULL;
 193 }
 194
 195 static bool throttle_recurse_is_first_non_filter(BlockDriverState *bs,
 196                                                  BlockDriverState *candidate)
 197 {
 198     return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
 199 }
 200
 201 static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs)
 202 {
 203     ThrottleGroupMember *tgm = bs->opaque;
 204     if (atomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
 205         throttle_group_restart_tgm(tgm);
 206     }
 207 }
 208
 209 static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs)
 210 {
 211     ThrottleGroupMember *tgm = bs->opaque;
 212     assert(tgm->io_limits_disabled);
 213     atomic_dec(&tgm->io_limits_disabled);
 214 }
 215
 216 static BlockDriver bdrv_throttle = {
 217     .format_name                        =   "throttle",
 218     .instance_size                      =   sizeof(ThrottleGroupMember),
 219
 220     .bdrv_open                          =   throttle_open,
 221     .bdrv_close                         =   throttle_close,
 222     .bdrv_co_flush                      =   throttle_co_flush,
 223
 224     .bdrv_child_perm                    =   bdrv_filter_default_perms,
 225
 226     .bdrv_getlength                     =   throttle_getlength,
 227
 228     .bdrv_co_preadv                     =   throttle_co_preadv,
 229     .bdrv_co_pwritev                    =   throttle_co_pwritev,
 230
 231     .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,
 232     .bdrv_co_pdiscard                   =   throttle_co_pdiscard,
 233
 234     .bdrv_recurse_is_first_non_filter   =   throttle_recurse_is_first_non_filter,
 235
 236     .bdrv_attach_aio_context            =   throttle_attach_aio_context,
 237     .bdrv_detach_aio_context            =   throttle_detach_aio_context,
 238
 239     .bdrv_reopen_prepare                =   throttle_reopen_prepare,
 240     .bdrv_reopen_commit                 =   throttle_reopen_commit,
 241     .bdrv_reopen_abort                  =   throttle_reopen_abort,
 242     .bdrv_co_block_status               =   bdrv_co_block_status_from_file,
 243
 244     .bdrv_co_drain_begin                =   throttle_co_drain_begin,
 245     .bdrv_co_drain_end                  =   throttle_co_drain_end,
 246
 247     .is_filter                          =   true,
 248 };
 249
 250 static void bdrv_throttle_init(void)
 251 {
 252     bdrv_register(&bdrv_throttle);
 253 }
 254
 255 block_init(bdrv_throttle_init);