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 throttle_co_getlength(BlockDriverState *bs)
 110 {
 111     return bdrv_co_getlength(bs->file->bs);
 112 }
 113
 114 static int coroutine_fn GRAPH_RDLOCK
 115 throttle_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
 116                    QEMUIOVector *qiov, BdrvRequestFlags flags)
 117 {
 118
 119     ThrottleGroupMember *tgm = bs->opaque;
 120     throttle_group_co_io_limits_intercept(tgm, bytes, false);
 121
 122     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
 123 }
 124
 125 static int coroutine_fn GRAPH_RDLOCK
 126 throttle_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
 127                     QEMUIOVector *qiov, BdrvRequestFlags flags)
 128 {
 129     ThrottleGroupMember *tgm = bs->opaque;
 130     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 131
 132     return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
 133 }
 134
 135 static int coroutine_fn GRAPH_RDLOCK
 136 throttle_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int64_t bytes,
 137                           BdrvRequestFlags flags)
 138 {
 139     ThrottleGroupMember *tgm = bs->opaque;
 140     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 141
 142     return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
 143 }
 144
 145 static int coroutine_fn GRAPH_RDLOCK
 146 throttle_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
 147 {
 148     ThrottleGroupMember *tgm = bs->opaque;
 149     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 150
 151     return bdrv_co_pdiscard(bs->file, offset, bytes);
 152 }
 153
 154 static int coroutine_fn GRAPH_RDLOCK
 155 throttle_co_pwritev_compressed(BlockDriverState *bs, int64_t offset,
 156                                int64_t bytes, QEMUIOVector *qiov)
 157 {
 158     return throttle_co_pwritev(bs, offset, bytes, qiov,
 159                                BDRV_REQ_WRITE_COMPRESSED);
 160 }
 161
 162 static int coroutine_fn GRAPH_RDLOCK throttle_co_flush(BlockDriverState *bs)
 163 {
 164     return bdrv_co_flush(bs->file->bs);
 165 }
 166
 167 static void throttle_detach_aio_context(BlockDriverState *bs)
 168 {
 169     ThrottleGroupMember *tgm = bs->opaque;
 170     throttle_group_detach_aio_context(tgm);
 171 }
 172
 173 static void throttle_attach_aio_context(BlockDriverState *bs,
 174                                         AioContext *new_context)
 175 {
 176     ThrottleGroupMember *tgm = bs->opaque;
 177     throttle_group_attach_aio_context(tgm, new_context);
 178 }
 179
 180 static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
 181                                    BlockReopenQueue *queue, Error **errp)
 182 {
 183     int ret;
 184     char *group = NULL;
 185
 186     assert(reopen_state != NULL);
 187     assert(reopen_state->bs != NULL);
 188
 189     ret = throttle_parse_options(reopen_state->options, &group, errp);
 190     reopen_state->opaque = group;
 191     return ret;
 192 }
 193
 194 static void throttle_reopen_commit(BDRVReopenState *reopen_state)
 195 {
 196     BlockDriverState *bs = reopen_state->bs;
 197     ThrottleGroupMember *tgm = bs->opaque;
 198     char *group = reopen_state->opaque;
 199
 200     assert(group);
 201
 202     if (strcmp(group, throttle_group_get_name(tgm))) {
 203         throttle_group_unregister_tgm(tgm);
 204         throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
 205     }
 206     g_free(reopen_state->opaque);
 207     reopen_state->opaque = NULL;
 208 }
 209
 210 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
 211 {
 212     g_free(reopen_state->opaque);
 213     reopen_state->opaque = NULL;
 214 }
 215
 216 static void throttle_drain_begin(BlockDriverState *bs)
 217 {
 218     ThrottleGroupMember *tgm = bs->opaque;
 219     if (qatomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
 220         throttle_group_restart_tgm(tgm);
 221     }
 222 }
 223
 224 static void throttle_drain_end(BlockDriverState *bs)
 225 {
 226     ThrottleGroupMember *tgm = bs->opaque;
 227     assert(tgm->io_limits_disabled);
 228     qatomic_dec(&tgm->io_limits_disabled);
 229 }
 230
 231 static const char *const throttle_strong_runtime_opts[] = {
 232     QEMU_OPT_THROTTLE_GROUP_NAME,
 233
 234     NULL
 235 };
 236
 237 static BlockDriver bdrv_throttle = {
 238     .format_name                        =   "throttle",
 239     .instance_size                      =   sizeof(ThrottleGroupMember),
 240
 241     .bdrv_open                          =   throttle_open,
 242     .bdrv_close                         =   throttle_close,
 243     .bdrv_co_flush                      =   throttle_co_flush,
 244
 245     .bdrv_child_perm                    =   bdrv_default_perms,
 246
 247     .bdrv_co_getlength                  =   throttle_co_getlength,
 248
 249     .bdrv_co_preadv                     =   throttle_co_preadv,
 250     .bdrv_co_pwritev                    =   throttle_co_pwritev,
 251
 252     .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,
 253     .bdrv_co_pdiscard                   =   throttle_co_pdiscard,
 254     .bdrv_co_pwritev_compressed         =   throttle_co_pwritev_compressed,
 255
 256     .bdrv_attach_aio_context            =   throttle_attach_aio_context,
 257     .bdrv_detach_aio_context            =   throttle_detach_aio_context,
 258
 259     .bdrv_reopen_prepare                =   throttle_reopen_prepare,
 260     .bdrv_reopen_commit                 =   throttle_reopen_commit,
 261     .bdrv_reopen_abort                  =   throttle_reopen_abort,
 262
 263     .bdrv_drain_begin                   =   throttle_drain_begin,
 264     .bdrv_drain_end                     =   throttle_drain_end,
 265
 266     .is_filter                          =   true,
 267     .strong_runtime_opts                =   throttle_strong_runtime_opts,
 268 };
 269
 270 static void bdrv_throttle_init(void)
 271 {
 272     bdrv_register(&bdrv_throttle);
 273 }
 274
 275 block_init(bdrv_throttle_init);