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/block-io.h"
  22 #include "block/block_int.h"
  23 #include "block/throttle-groups.h"
  24 #include "qemu/module.h"
  25 #include "qemu/option.h"
  26 #include "qemu/throttle-options.h"
  27 #include "qapi/error.h"
  28
  29 static QemuOptsList throttle_opts = {
  30     .name = "throttle",
  31     .head = QTAILQ_HEAD_INITIALIZER(throttle_opts.head),
  32     .desc = {
  33         {
  34             .name = QEMU_OPT_THROTTLE_GROUP_NAME,
  35             .type = QEMU_OPT_STRING,
  36             .help = "Name of the throttle group",
  37         },
  38         { /* end of list */ }
  39     },
  40 };
  41
  42 /*
  43  * If this function succeeds then the throttle group name is stored in
  44  * @group and must be freed by the caller.
  45  * If there's an error then @group remains unmodified.
  46  */
  47 static int throttle_parse_options(QDict *options, char **group, Error **errp)
  48 {
  49     int ret;
  50     const char *group_name;
  51     QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort);
  52
  53     if (!qemu_opts_absorb_qdict(opts, options, errp)) {
  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     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
  84     if (ret < 0) {
  85         return ret;
  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 coroutine_fn GRAPH_RDLOCK
 110 throttle_co_getlength(BlockDriverState *bs)
 111 {
 112     return bdrv_co_getlength(bs->file->bs);
 113 }
 114
 115 static int coroutine_fn GRAPH_RDLOCK
 116 throttle_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
 117                    QEMUIOVector *qiov, 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 GRAPH_RDLOCK
 127 throttle_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
 128                     QEMUIOVector *qiov, BdrvRequestFlags 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 GRAPH_RDLOCK
 137 throttle_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int64_t 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 GRAPH_RDLOCK
 147 throttle_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t 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 coroutine_fn GRAPH_RDLOCK
 156 throttle_co_pwritev_compressed(BlockDriverState *bs, int64_t offset,
 157                                int64_t bytes, QEMUIOVector *qiov)
 158 {
 159     return throttle_co_pwritev(bs, offset, bytes, qiov,
 160                                BDRV_REQ_WRITE_COMPRESSED);
 161 }
 162
 163 static int coroutine_fn GRAPH_RDLOCK throttle_co_flush(BlockDriverState *bs)
 164 {
 165     return bdrv_co_flush(bs->file->bs);
 166 }
 167
 168 static void throttle_detach_aio_context(BlockDriverState *bs)
 169 {
 170     ThrottleGroupMember *tgm = bs->opaque;
 171     throttle_group_detach_aio_context(tgm);
 172 }
 173
 174 static void throttle_attach_aio_context(BlockDriverState *bs,
 175                                         AioContext *new_context)
 176 {
 177     ThrottleGroupMember *tgm = bs->opaque;
 178     throttle_group_attach_aio_context(tgm, new_context);
 179 }
 180
 181 static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
 182                                    BlockReopenQueue *queue, Error **errp)
 183 {
 184     int ret;
 185     char *group = NULL;
 186
 187     assert(reopen_state != NULL);
 188     assert(reopen_state->bs != NULL);
 189
 190     ret = throttle_parse_options(reopen_state->options, &group, errp);
 191     reopen_state->opaque = group;
 192     return ret;
 193 }
 194
 195 static void throttle_reopen_commit(BDRVReopenState *reopen_state)
 196 {
 197     BlockDriverState *bs = reopen_state->bs;
 198     ThrottleGroupMember *tgm = bs->opaque;
 199     char *group = reopen_state->opaque;
 200
 201     assert(group);
 202
 203     if (strcmp(group, throttle_group_get_name(tgm))) {
 204         throttle_group_unregister_tgm(tgm);
 205         throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
 206     }
 207     g_free(reopen_state->opaque);
 208     reopen_state->opaque = NULL;
 209 }
 210
 211 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
 212 {
 213     g_free(reopen_state->opaque);
 214     reopen_state->opaque = NULL;
 215 }
 216
 217 static void throttle_drain_begin(BlockDriverState *bs)
 218 {
 219     ThrottleGroupMember *tgm = bs->opaque;
 220     if (qatomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
 221         throttle_group_restart_tgm(tgm);
 222     }
 223 }
 224
 225 static void throttle_drain_end(BlockDriverState *bs)
 226 {
 227     ThrottleGroupMember *tgm = bs->opaque;
 228     assert(tgm->io_limits_disabled);
 229     qatomic_dec(&tgm->io_limits_disabled);
 230 }
 231
 232 static const char *const throttle_strong_runtime_opts[] = {
 233     QEMU_OPT_THROTTLE_GROUP_NAME,
 234
 235     NULL
 236 };
 237
 238 static BlockDriver bdrv_throttle = {
 239     .format_name                        =   "throttle",
 240     .instance_size                      =   sizeof(ThrottleGroupMember),
 241
 242     .bdrv_open                          =   throttle_open,
 243     .bdrv_close                         =   throttle_close,
 244     .bdrv_co_flush                      =   throttle_co_flush,
 245
 246     .bdrv_child_perm                    =   bdrv_default_perms,
 247
 248     .bdrv_co_getlength                  =   throttle_co_getlength,
 249
 250     .bdrv_co_preadv                     =   throttle_co_preadv,
 251     .bdrv_co_pwritev                    =   throttle_co_pwritev,
 252
 253     .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,
 254     .bdrv_co_pdiscard                   =   throttle_co_pdiscard,
 255     .bdrv_co_pwritev_compressed         =   throttle_co_pwritev_compressed,
 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
 264     .bdrv_drain_begin                   =   throttle_drain_begin,
 265     .bdrv_drain_end                     =   throttle_drain_end,
 266
 267     .is_filter                          =   true,
 268     .strong_runtime_opts                =   throttle_strong_runtime_opts,
 269 };
 270
 271 static void bdrv_throttle_init(void)
 272 {
 273     bdrv_register(&bdrv_throttle);
 274 }
 275
 276 block_init(bdrv_throttle_init);