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
  88     GRAPH_RDLOCK_GUARD_MAINLOOP();
  89
  90     bs->supported_write_flags = bs->file->bs->supported_write_flags |
  91                                 BDRV_REQ_WRITE_UNCHANGED;
  92     bs->supported_zero_flags = bs->file->bs->supported_zero_flags |
  93                                BDRV_REQ_WRITE_UNCHANGED;
  94
  95     ret = throttle_parse_options(options, &group, errp);
  96     if (ret == 0) {
  97         /* Register membership to group with name group_name */
  98         throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
  99         g_free(group);
 100     }
 101
 102     return ret;
 103 }
 104
 105 static void throttle_close(BlockDriverState *bs)
 106 {
 107     ThrottleGroupMember *tgm = bs->opaque;
 108     throttle_group_unregister_tgm(tgm);
 109 }
 110
 111
 112 static int64_t coroutine_fn GRAPH_RDLOCK
 113 throttle_co_getlength(BlockDriverState *bs)
 114 {
 115     return bdrv_co_getlength(bs->file->bs);
 116 }
 117
 118 static int coroutine_fn GRAPH_RDLOCK
 119 throttle_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
 120                    QEMUIOVector *qiov, BdrvRequestFlags flags)
 121 {
 122
 123     ThrottleGroupMember *tgm = bs->opaque;
 124     throttle_group_co_io_limits_intercept(tgm, bytes, THROTTLE_READ);
 125
 126     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
 127 }
 128
 129 static int coroutine_fn GRAPH_RDLOCK
 130 throttle_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
 131                     QEMUIOVector *qiov, BdrvRequestFlags flags)
 132 {
 133     ThrottleGroupMember *tgm = bs->opaque;
 134     throttle_group_co_io_limits_intercept(tgm, bytes, THROTTLE_WRITE);
 135
 136     return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
 137 }
 138
 139 static int coroutine_fn GRAPH_RDLOCK
 140 throttle_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int64_t bytes,
 141                           BdrvRequestFlags flags)
 142 {
 143     ThrottleGroupMember *tgm = bs->opaque;
 144     throttle_group_co_io_limits_intercept(tgm, bytes, THROTTLE_WRITE);
 145
 146     return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
 147 }
 148
 149 static int coroutine_fn GRAPH_RDLOCK
 150 throttle_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
 151 {
 152     ThrottleGroupMember *tgm = bs->opaque;
 153     throttle_group_co_io_limits_intercept(tgm, bytes, THROTTLE_WRITE);
 154
 155     return bdrv_co_pdiscard(bs->file, offset, bytes);
 156 }
 157
 158 static int coroutine_fn GRAPH_RDLOCK
 159 throttle_co_pwritev_compressed(BlockDriverState *bs, int64_t offset,
 160                                int64_t bytes, QEMUIOVector *qiov)
 161 {
 162     return throttle_co_pwritev(bs, offset, bytes, qiov,
 163                                BDRV_REQ_WRITE_COMPRESSED);
 164 }
 165
 166 static int coroutine_fn GRAPH_RDLOCK throttle_co_flush(BlockDriverState *bs)
 167 {
 168     return bdrv_co_flush(bs->file->bs);
 169 }
 170
 171 static void throttle_detach_aio_context(BlockDriverState *bs)
 172 {
 173     ThrottleGroupMember *tgm = bs->opaque;
 174     throttle_group_detach_aio_context(tgm);
 175 }
 176
 177 static void throttle_attach_aio_context(BlockDriverState *bs,
 178                                         AioContext *new_context)
 179 {
 180     ThrottleGroupMember *tgm = bs->opaque;
 181     throttle_group_attach_aio_context(tgm, new_context);
 182 }
 183
 184 static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
 185                                    BlockReopenQueue *queue, Error **errp)
 186 {
 187     int ret;
 188     char *group = NULL;
 189
 190     assert(reopen_state != NULL);
 191     assert(reopen_state->bs != NULL);
 192
 193     ret = throttle_parse_options(reopen_state->options, &group, errp);
 194     reopen_state->opaque = group;
 195     return ret;
 196 }
 197
 198 static void throttle_reopen_commit(BDRVReopenState *reopen_state)
 199 {
 200     BlockDriverState *bs = reopen_state->bs;
 201     ThrottleGroupMember *tgm = bs->opaque;
 202     char *group = reopen_state->opaque;
 203
 204     assert(group);
 205
 206     if (strcmp(group, throttle_group_get_name(tgm))) {
 207         throttle_group_unregister_tgm(tgm);
 208         throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
 209     }
 210     g_free(reopen_state->opaque);
 211     reopen_state->opaque = NULL;
 212 }
 213
 214 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
 215 {
 216     g_free(reopen_state->opaque);
 217     reopen_state->opaque = NULL;
 218 }
 219
 220 static void throttle_drain_begin(BlockDriverState *bs)
 221 {
 222     ThrottleGroupMember *tgm = bs->opaque;
 223     if (qatomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
 224         throttle_group_restart_tgm(tgm);
 225     }
 226 }
 227
 228 static void throttle_drain_end(BlockDriverState *bs)
 229 {
 230     ThrottleGroupMember *tgm = bs->opaque;
 231     assert(tgm->io_limits_disabled);
 232     qatomic_dec(&tgm->io_limits_disabled);
 233 }
 234
 235 static const char *const throttle_strong_runtime_opts[] = {
 236     QEMU_OPT_THROTTLE_GROUP_NAME,
 237
 238     NULL
 239 };
 240
 241 static BlockDriver bdrv_throttle = {
 242     .format_name                        =   "throttle",
 243     .instance_size                      =   sizeof(ThrottleGroupMember),
 244
 245     .bdrv_open                          =   throttle_open,
 246     .bdrv_close                         =   throttle_close,
 247     .bdrv_co_flush                      =   throttle_co_flush,
 248
 249     .bdrv_child_perm                    =   bdrv_default_perms,
 250
 251     .bdrv_co_getlength                  =   throttle_co_getlength,
 252
 253     .bdrv_co_preadv                     =   throttle_co_preadv,
 254     .bdrv_co_pwritev                    =   throttle_co_pwritev,
 255
 256     .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,
 257     .bdrv_co_pdiscard                   =   throttle_co_pdiscard,
 258     .bdrv_co_pwritev_compressed         =   throttle_co_pwritev_compressed,
 259
 260     .bdrv_attach_aio_context            =   throttle_attach_aio_context,
 261     .bdrv_detach_aio_context            =   throttle_detach_aio_context,
 262
 263     .bdrv_reopen_prepare                =   throttle_reopen_prepare,
 264     .bdrv_reopen_commit                 =   throttle_reopen_commit,
 265     .bdrv_reopen_abort                  =   throttle_reopen_abort,
 266
 267     .bdrv_drain_begin                   =   throttle_drain_begin,
 268     .bdrv_drain_end                     =   throttle_drain_end,
 269
 270     .is_filter                          =   true,
 271     .strong_runtime_opts                =   throttle_strong_runtime_opts,
 272 };
 273
 274 static void bdrv_throttle_init(void)
 275 {
 276     bdrv_register(&bdrv_throttle);
 277 }
 278
 279 block_init(bdrv_throttle_init);