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/throttle-options.h"
  23 #include "qapi/error.h"
  24
  25 static QemuOptsList throttle_opts = {
  26     .name = "throttle",
  27     .head = QTAILQ_HEAD_INITIALIZER(throttle_opts.head),
  28     .desc = {
  29         {
  30             .name = QEMU_OPT_THROTTLE_GROUP_NAME,
  31             .type = QEMU_OPT_STRING,
  32             .help = "Name of the throttle group",
  33         },
  34         { /* end of list */ }
  35     },
  36 };
  37
  38 static int throttle_configure_tgm(BlockDriverState *bs,
  39                                   ThrottleGroupMember *tgm,
  40                                   QDict *options, Error **errp)
  41 {
  42     int ret;
  43     const char *group_name;
  44     Error *local_err = NULL;
  45     QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort);
  46
  47     qemu_opts_absorb_qdict(opts, options, &local_err);
  48     if (local_err) {
  49         error_propagate(errp, local_err);
  50         ret = -EINVAL;
  51         goto fin;
  52     }
  53
  54     group_name = qemu_opt_get(opts, QEMU_OPT_THROTTLE_GROUP_NAME);
  55     if (!group_name) {
  56         error_setg(errp, "Please specify a throttle group");
  57         ret = -EINVAL;
  58         goto fin;
  59     } else if (!throttle_group_exists(group_name)) {
  60         error_setg(errp, "Throttle group '%s' does not exist", group_name);
  61         ret = -EINVAL;
  62         goto fin;
  63     }
  64
  65     /* Register membership to group with name group_name */
  66     throttle_group_register_tgm(tgm, group_name, bdrv_get_aio_context(bs));
  67     ret = 0;
  68 fin:
  69     qemu_opts_del(opts);
  70     return ret;
  71 }
  72
  73 static int throttle_open(BlockDriverState *bs, QDict *options,
  74                          int flags, Error **errp)
  75 {
  76     ThrottleGroupMember *tgm = bs->opaque;
  77
  78     bs->file = bdrv_open_child(NULL, options, "file", bs,
  79                                &child_file, false, errp);
  80     if (!bs->file) {
  81         return -EINVAL;
  82     }
  83     bs->supported_write_flags = bs->file->bs->supported_write_flags;
  84     bs->supported_zero_flags = bs->file->bs->supported_zero_flags;
  85
  86     return throttle_configure_tgm(bs, tgm, options, errp);
  87 }
  88
  89 static void throttle_close(BlockDriverState *bs)
  90 {
  91     ThrottleGroupMember *tgm = bs->opaque;
  92     throttle_group_unregister_tgm(tgm);
  93 }
  94
  95
  96 static int64_t throttle_getlength(BlockDriverState *bs)
  97 {
  98     return bdrv_getlength(bs->file->bs);
  99 }
 100
 101 static int coroutine_fn throttle_co_preadv(BlockDriverState *bs,
 102                                            uint64_t offset, uint64_t bytes,
 103                                            QEMUIOVector *qiov, int flags)
 104 {
 105
 106     ThrottleGroupMember *tgm = bs->opaque;
 107     throttle_group_co_io_limits_intercept(tgm, bytes, false);
 108
 109     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
 110 }
 111
 112 static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs,
 113                                             uint64_t offset, uint64_t bytes,
 114                                             QEMUIOVector *qiov, int flags)
 115 {
 116     ThrottleGroupMember *tgm = bs->opaque;
 117     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 118
 119     return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
 120 }
 121
 122 static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs,
 123                                                   int64_t offset, int bytes,
 124                                                   BdrvRequestFlags flags)
 125 {
 126     ThrottleGroupMember *tgm = bs->opaque;
 127     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 128
 129     return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
 130 }
 131
 132 static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs,
 133                                              int64_t offset, int bytes)
 134 {
 135     ThrottleGroupMember *tgm = bs->opaque;
 136     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 137
 138     return bdrv_co_pdiscard(bs->file->bs, offset, bytes);
 139 }
 140
 141 static int throttle_co_flush(BlockDriverState *bs)
 142 {
 143     return bdrv_co_flush(bs->file->bs);
 144 }
 145
 146 static void throttle_detach_aio_context(BlockDriverState *bs)
 147 {
 148     ThrottleGroupMember *tgm = bs->opaque;
 149     throttle_group_detach_aio_context(tgm);
 150 }
 151
 152 static void throttle_attach_aio_context(BlockDriverState *bs,
 153                                         AioContext *new_context)
 154 {
 155     ThrottleGroupMember *tgm = bs->opaque;
 156     throttle_group_attach_aio_context(tgm, new_context);
 157 }
 158
 159 static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
 160                                    BlockReopenQueue *queue, Error **errp)
 161 {
 162     ThrottleGroupMember *tgm;
 163
 164     assert(reopen_state != NULL);
 165     assert(reopen_state->bs != NULL);
 166
 167     reopen_state->opaque = g_new0(ThrottleGroupMember, 1);
 168     tgm = reopen_state->opaque;
 169
 170     return throttle_configure_tgm(reopen_state->bs, tgm, reopen_state->options,
 171             errp);
 172 }
 173
 174 static void throttle_reopen_commit(BDRVReopenState *reopen_state)
 175 {
 176     ThrottleGroupMember *old_tgm = reopen_state->bs->opaque;
 177     ThrottleGroupMember *new_tgm = reopen_state->opaque;
 178
 179     throttle_group_unregister_tgm(old_tgm);
 180     g_free(old_tgm);
 181     reopen_state->bs->opaque = new_tgm;
 182     reopen_state->opaque = NULL;
 183 }
 184
 185 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
 186 {
 187     ThrottleGroupMember *tgm = reopen_state->opaque;
 188
 189     throttle_group_unregister_tgm(tgm);
 190     g_free(tgm);
 191     reopen_state->opaque = NULL;
 192 }
 193
 194 static bool throttle_recurse_is_first_non_filter(BlockDriverState *bs,
 195                                                  BlockDriverState *candidate)
 196 {
 197     return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
 198 }
 199
 200 static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs)
 201 {
 202     ThrottleGroupMember *tgm = bs->opaque;
 203     if (atomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
 204         throttle_group_restart_tgm(tgm);
 205     }
 206 }
 207
 208 static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs)
 209 {
 210     ThrottleGroupMember *tgm = bs->opaque;
 211     assert(tgm->io_limits_disabled);
 212     atomic_dec(&tgm->io_limits_disabled);
 213 }
 214
 215 static BlockDriver bdrv_throttle = {
 216     .format_name                        =   "throttle",
 217     .protocol_name                      =   "throttle",
 218     .instance_size                      =   sizeof(ThrottleGroupMember),
 219
 220     .bdrv_file_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_get_block_status           =   bdrv_co_get_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);