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 bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds, 82 BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, 83 false, errp); 84 if (!bs->file) { 85 return -EINVAL; 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 throttle_getlength(BlockDriverState *bs) 110 { 111 return bdrv_getlength(bs->file->bs); 112 } 113 114 static int coroutine_fn throttle_co_preadv(BlockDriverState *bs, 115 int64_t offset, int64_t bytes, 116 QEMUIOVector *qiov, 117 BdrvRequestFlags flags) 118 { 119 120 ThrottleGroupMember *tgm = bs->opaque; 121 throttle_group_co_io_limits_intercept(tgm, bytes, false); 122 123 return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags); 124 } 125 126 static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs, 127 int64_t offset, int64_t bytes, 128 QEMUIOVector *qiov, 129 BdrvRequestFlags flags) 130 { 131 ThrottleGroupMember *tgm = bs->opaque; 132 throttle_group_co_io_limits_intercept(tgm, bytes, true); 133 134 return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags); 135 } 136 137 static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs, 138 int64_t offset, int64_t bytes, 139 BdrvRequestFlags flags) 140 { 141 ThrottleGroupMember *tgm = bs->opaque; 142 throttle_group_co_io_limits_intercept(tgm, bytes, true); 143 144 return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags); 145 } 146 147 static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs, 148 int64_t offset, int64_t bytes) 149 { 150 ThrottleGroupMember *tgm = bs->opaque; 151 throttle_group_co_io_limits_intercept(tgm, bytes, true); 152 153 return bdrv_co_pdiscard(bs->file, offset, bytes); 154 } 155 156 static int coroutine_fn throttle_co_pwritev_compressed(BlockDriverState *bs, 157 int64_t offset, 158 int64_t bytes, 159 QEMUIOVector *qiov) 160 { 161 return throttle_co_pwritev(bs, offset, bytes, qiov, 162 BDRV_REQ_WRITE_COMPRESSED); 163 } 164 165 static int coroutine_fn throttle_co_flush(BlockDriverState *bs) 166 { 167 return bdrv_co_flush(bs->file->bs); 168 } 169 170 static void throttle_detach_aio_context(BlockDriverState *bs) 171 { 172 ThrottleGroupMember *tgm = bs->opaque; 173 throttle_group_detach_aio_context(tgm); 174 } 175 176 static void throttle_attach_aio_context(BlockDriverState *bs, 177 AioContext *new_context) 178 { 179 ThrottleGroupMember *tgm = bs->opaque; 180 throttle_group_attach_aio_context(tgm, new_context); 181 } 182 183 static int throttle_reopen_prepare(BDRVReopenState *reopen_state, 184 BlockReopenQueue *queue, Error **errp) 185 { 186 int ret; 187 char *group = NULL; 188 189 assert(reopen_state != NULL); 190 assert(reopen_state->bs != NULL); 191 192 ret = throttle_parse_options(reopen_state->options, &group, errp); 193 reopen_state->opaque = group; 194 return ret; 195 } 196 197 static void throttle_reopen_commit(BDRVReopenState *reopen_state) 198 { 199 BlockDriverState *bs = reopen_state->bs; 200 ThrottleGroupMember *tgm = bs->opaque; 201 char *group = reopen_state->opaque; 202 203 assert(group); 204 205 if (strcmp(group, throttle_group_get_name(tgm))) { 206 throttle_group_unregister_tgm(tgm); 207 throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs)); 208 } 209 g_free(reopen_state->opaque); 210 reopen_state->opaque = NULL; 211 } 212 213 static void throttle_reopen_abort(BDRVReopenState *reopen_state) 214 { 215 g_free(reopen_state->opaque); 216 reopen_state->opaque = NULL; 217 } 218 219 static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs) 220 { 221 ThrottleGroupMember *tgm = bs->opaque; 222 if (qatomic_fetch_inc(&tgm->io_limits_disabled) == 0) { 223 throttle_group_restart_tgm(tgm); 224 } 225 } 226 227 static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs) 228 { 229 ThrottleGroupMember *tgm = bs->opaque; 230 assert(tgm->io_limits_disabled); 231 qatomic_dec(&tgm->io_limits_disabled); 232 } 233 234 static const char *const throttle_strong_runtime_opts[] = { 235 QEMU_OPT_THROTTLE_GROUP_NAME, 236 237 NULL 238 }; 239 240 static BlockDriver bdrv_throttle = { 241 .format_name = "throttle", 242 .instance_size = sizeof(ThrottleGroupMember), 243 244 .bdrv_open = throttle_open, 245 .bdrv_close = throttle_close, 246 .bdrv_co_flush = throttle_co_flush, 247 248 .bdrv_child_perm = bdrv_default_perms, 249 250 .bdrv_getlength = throttle_getlength, 251 252 .bdrv_co_preadv = throttle_co_preadv, 253 .bdrv_co_pwritev = throttle_co_pwritev, 254 255 .bdrv_co_pwrite_zeroes = throttle_co_pwrite_zeroes, 256 .bdrv_co_pdiscard = throttle_co_pdiscard, 257 .bdrv_co_pwritev_compressed = throttle_co_pwritev_compressed, 258 259 .bdrv_attach_aio_context = throttle_attach_aio_context, 260 .bdrv_detach_aio_context = throttle_detach_aio_context, 261 262 .bdrv_reopen_prepare = throttle_reopen_prepare, 263 .bdrv_reopen_commit = throttle_reopen_commit, 264 .bdrv_reopen_abort = throttle_reopen_abort, 265 266 .bdrv_co_drain_begin = throttle_co_drain_begin, 267 .bdrv_co_drain_end = throttle_co_drain_end, 268 269 .is_filter = true, 270 .strong_runtime_opts = throttle_strong_runtime_opts, 271 }; 272 273 static void bdrv_throttle_init(void) 274 { 275 bdrv_register(&bdrv_throttle); 276 } 277 278 block_init(bdrv_throttle_init); 279