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                                 BDRV_REQ_WRITE_UNCHANGED;
  86     bs->supported_zero_flags = bs->file->bs->supported_zero_flags |
  87                                BDRV_REQ_WRITE_UNCHANGED;
  88
  89     return throttle_configure_tgm(bs, tgm, options, errp);
  90 }
  91
  92 static void throttle_close(BlockDriverState *bs)
  93 {
  94     ThrottleGroupMember *tgm = bs->opaque;
  95     throttle_group_unregister_tgm(tgm);
  96 }
  97
  98
  99 static int64_t throttle_getlength(BlockDriverState *bs)
 100 {
 101     return bdrv_getlength(bs->file->bs);
 102 }
 103
 104 static int coroutine_fn throttle_co_preadv(BlockDriverState *bs,
 105                                            uint64_t offset, uint64_t bytes,
 106                                            QEMUIOVector *qiov, int flags)
 107 {
 108
 109     ThrottleGroupMember *tgm = bs->opaque;
 110     throttle_group_co_io_limits_intercept(tgm, bytes, false);
 111
 112     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
 113 }
 114
 115 static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs,
 116                                             uint64_t offset, uint64_t bytes,
 117                                             QEMUIOVector *qiov, int flags)
 118 {
 119     ThrottleGroupMember *tgm = bs->opaque;
 120     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 121
 122     return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
 123 }
 124
 125 static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs,
 126                                                   int64_t offset, int bytes,
 127                                                   BdrvRequestFlags flags)
 128 {
 129     ThrottleGroupMember *tgm = bs->opaque;
 130     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 131
 132     return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
 133 }
 134
 135 static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs,
 136                                              int64_t offset, int bytes)
 137 {
 138     ThrottleGroupMember *tgm = bs->opaque;
 139     throttle_group_co_io_limits_intercept(tgm, bytes, true);
 140
 141     return bdrv_co_pdiscard(bs->file->bs, offset, bytes);
 142 }
 143
 144 static int throttle_co_flush(BlockDriverState *bs)
 145 {
 146     return bdrv_co_flush(bs->file->bs);
 147 }
 148
 149 static void throttle_detach_aio_context(BlockDriverState *bs)
 150 {
 151     ThrottleGroupMember *tgm = bs->opaque;
 152     throttle_group_detach_aio_context(tgm);
 153 }
 154
 155 static void throttle_attach_aio_context(BlockDriverState *bs,
 156                                         AioContext *new_context)
 157 {
 158     ThrottleGroupMember *tgm = bs->opaque;
 159     throttle_group_attach_aio_context(tgm, new_context);
 160 }
 161
 162 static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
 163                                    BlockReopenQueue *queue, Error **errp)
 164 {
 165     ThrottleGroupMember *tgm;
 166
 167     assert(reopen_state != NULL);
 168     assert(reopen_state->bs != NULL);
 169
 170     reopen_state->opaque = g_new0(ThrottleGroupMember, 1);
 171     tgm = reopen_state->opaque;
 172
 173     return throttle_configure_tgm(reopen_state->bs, tgm, reopen_state->options,
 174             errp);
 175 }
 176
 177 static void throttle_reopen_commit(BDRVReopenState *reopen_state)
 178 {
 179     ThrottleGroupMember *old_tgm = reopen_state->bs->opaque;
 180     ThrottleGroupMember *new_tgm = reopen_state->opaque;
 181
 182     throttle_group_unregister_tgm(old_tgm);
 183     g_free(old_tgm);
 184     reopen_state->bs->opaque = new_tgm;
 185     reopen_state->opaque = NULL;
 186 }
 187
 188 static void throttle_reopen_abort(BDRVReopenState *reopen_state)
 189 {
 190     ThrottleGroupMember *tgm = reopen_state->opaque;
 191
 192     throttle_group_unregister_tgm(tgm);
 193     g_free(tgm);
 194     reopen_state->opaque = NULL;
 195 }
 196
 197 static bool throttle_recurse_is_first_non_filter(BlockDriverState *bs,
 198                                                  BlockDriverState *candidate)
 199 {
 200     return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
 201 }
 202
 203 static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs)
 204 {
 205     ThrottleGroupMember *tgm = bs->opaque;
 206     if (atomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
 207         throttle_group_restart_tgm(tgm);
 208     }
 209 }
 210
 211 static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs)
 212 {
 213     ThrottleGroupMember *tgm = bs->opaque;
 214     assert(tgm->io_limits_disabled);
 215     atomic_dec(&tgm->io_limits_disabled);
 216 }
 217
 218 static BlockDriver bdrv_throttle = {
 219     .format_name                        =   "throttle",
 220     .instance_size                      =   sizeof(ThrottleGroupMember),
 221
 222     .bdrv_open                          =   throttle_open,
 223     .bdrv_close                         =   throttle_close,
 224     .bdrv_co_flush                      =   throttle_co_flush,
 225
 226     .bdrv_child_perm                    =   bdrv_filter_default_perms,
 227
 228     .bdrv_getlength                     =   throttle_getlength,
 229
 230     .bdrv_co_preadv                     =   throttle_co_preadv,
 231     .bdrv_co_pwritev                    =   throttle_co_pwritev,
 232
 233     .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,
 234     .bdrv_co_pdiscard                   =   throttle_co_pdiscard,
 235
 236     .bdrv_recurse_is_first_non_filter   =   throttle_recurse_is_first_non_filter,
 237
 238     .bdrv_attach_aio_context            =   throttle_attach_aio_context,
 239     .bdrv_detach_aio_context            =   throttle_detach_aio_context,
 240
 241     .bdrv_reopen_prepare                =   throttle_reopen_prepare,
 242     .bdrv_reopen_commit                 =   throttle_reopen_commit,
 243     .bdrv_reopen_abort                  =   throttle_reopen_abort,
 244     .bdrv_co_block_status               =   bdrv_co_block_status_from_file,
 245
 246     .bdrv_co_drain_begin                =   throttle_co_drain_begin,
 247     .bdrv_co_drain_end                  =   throttle_co_drain_end,
 248
 249     .is_filter                          =   true,
 250 };
 251
 252 static void bdrv_throttle_init(void)
 253 {
 254     bdrv_register(&bdrv_throttle);
 255 }
 256
 257 block_init(bdrv_throttle_init);