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); 280