throttle.c (8826B)
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/module.h" 23 #include "qemu/option.h" 24 #include "qemu/throttle-options.h" 25 #include "qapi/error.h" 26 27 static QemuOptsList throttle_opts = { 28 .name = "throttle", 29 .head = QTAILQ_HEAD_INITIALIZER(throttle_opts.head), 30 .desc = { 31 { 32 .name = QEMU_OPT_THROTTLE_GROUP_NAME, 33 .type = QEMU_OPT_STRING, 34 .help = "Name of the throttle group", 35 }, 36 { /* end of list */ } 37 }, 38 }; 39 40 /* 41 * If this function succeeds then the throttle group name is stored in 42 * @group and must be freed by the caller. 43 * If there's an error then @group remains unmodified. 44 */ 45 static int throttle_parse_options(QDict *options, char **group, Error **errp) 46 { 47 int ret; 48 const char *group_name; 49 QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort); 50 51 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 52 ret = -EINVAL; 53 goto fin; 54 } 55 56 group_name = qemu_opt_get(opts, QEMU_OPT_THROTTLE_GROUP_NAME); 57 if (!group_name) { 58 error_setg(errp, "Please specify a throttle group"); 59 ret = -EINVAL; 60 goto fin; 61 } else if (!throttle_group_exists(group_name)) { 62 error_setg(errp, "Throttle group '%s' does not exist", group_name); 63 ret = -EINVAL; 64 goto fin; 65 } 66 67 *group = g_strdup(group_name); 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 char *group; 79 int ret; 80 81 ret = bdrv_open_file_child(NULL, options, "file", bs, errp); 82 if (ret < 0) { 83 return ret; 84 } 85 bs->supported_write_flags = bs->file->bs->supported_write_flags | 86 BDRV_REQ_WRITE_UNCHANGED; 87 bs->supported_zero_flags = bs->file->bs->supported_zero_flags | 88 BDRV_REQ_WRITE_UNCHANGED; 89 90 ret = throttle_parse_options(options, &group, errp); 91 if (ret == 0) { 92 /* Register membership to group with name group_name */ 93 throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs)); 94 g_free(group); 95 } 96 97 return ret; 98 } 99 100 static void throttle_close(BlockDriverState *bs) 101 { 102 ThrottleGroupMember *tgm = bs->opaque; 103 throttle_group_unregister_tgm(tgm); 104 } 105 106 107 static int64_t throttle_getlength(BlockDriverState *bs) 108 { 109 return bdrv_getlength(bs->file->bs); 110 } 111 112 static int coroutine_fn throttle_co_preadv(BlockDriverState *bs, 113 int64_t offset, int64_t bytes, 114 QEMUIOVector *qiov, 115 BdrvRequestFlags flags) 116 { 117 118 ThrottleGroupMember *tgm = bs->opaque; 119 throttle_group_co_io_limits_intercept(tgm, bytes, false); 120 121 return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags); 122 } 123 124 static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs, 125 int64_t offset, int64_t bytes, 126 QEMUIOVector *qiov, 127 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 throttle_co_pwrite_zeroes(BlockDriverState *bs, 136 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 throttle_co_pdiscard(BlockDriverState *bs, 146 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 throttle_co_pwritev_compressed(BlockDriverState *bs, 155 int64_t offset, 156 int64_t bytes, 157 QEMUIOVector *qiov) 158 { 159 return throttle_co_pwritev(bs, offset, bytes, qiov, 160 BDRV_REQ_WRITE_COMPRESSED); 161 } 162 163 static int coroutine_fn 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 coroutine_fn throttle_co_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 coroutine_fn throttle_co_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_getlength = throttle_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_co_drain_begin = throttle_co_drain_begin, 265 .bdrv_co_drain_end = throttle_co_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);