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 Error *local_err = NULL; 50 QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort); 51 52 qemu_opts_absorb_qdict(opts, options, &local_err); 53 if (local_err) { 54 error_propagate(errp, local_err); 55 ret = -EINVAL; 56 goto fin; 57 } 58 59 group_name = qemu_opt_get(opts, QEMU_OPT_THROTTLE_GROUP_NAME); 60 if (!group_name) { 61 error_setg(errp, "Please specify a throttle group"); 62 ret = -EINVAL; 63 goto fin; 64 } else if (!throttle_group_exists(group_name)) { 65 error_setg(errp, "Throttle group '%s' does not exist", group_name); 66 ret = -EINVAL; 67 goto fin; 68 } 69 70 *group = g_strdup(group_name); 71 ret = 0; 72 fin: 73 qemu_opts_del(opts); 74 return ret; 75 } 76 77 static int throttle_open(BlockDriverState *bs, QDict *options, 78 int flags, Error **errp) 79 { 80 ThrottleGroupMember *tgm = bs->opaque; 81 char *group; 82 int ret; 83 84 bs->file = bdrv_open_child(NULL, options, "file", bs, 85 &child_file, false, errp); 86 if (!bs->file) { 87 return -EINVAL; 88 } 89 bs->supported_write_flags = bs->file->bs->supported_write_flags | 90 BDRV_REQ_WRITE_UNCHANGED; 91 bs->supported_zero_flags = bs->file->bs->supported_zero_flags | 92 BDRV_REQ_WRITE_UNCHANGED; 93 94 ret = throttle_parse_options(options, &group, errp); 95 if (ret == 0) { 96 /* Register membership to group with name group_name */ 97 throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs)); 98 g_free(group); 99 } 100 101 return ret; 102 } 103 104 static void throttle_close(BlockDriverState *bs) 105 { 106 ThrottleGroupMember *tgm = bs->opaque; 107 throttle_group_unregister_tgm(tgm); 108 } 109 110 111 static int64_t throttle_getlength(BlockDriverState *bs) 112 { 113 return bdrv_getlength(bs->file->bs); 114 } 115 116 static int coroutine_fn throttle_co_preadv(BlockDriverState *bs, 117 uint64_t offset, uint64_t bytes, 118 QEMUIOVector *qiov, int flags) 119 { 120 121 ThrottleGroupMember *tgm = bs->opaque; 122 throttle_group_co_io_limits_intercept(tgm, bytes, false); 123 124 return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags); 125 } 126 127 static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs, 128 uint64_t offset, uint64_t bytes, 129 QEMUIOVector *qiov, int 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, int 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, int 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 throttle_co_flush(BlockDriverState *bs) 157 { 158 return bdrv_co_flush(bs->file->bs); 159 } 160 161 static void throttle_detach_aio_context(BlockDriverState *bs) 162 { 163 ThrottleGroupMember *tgm = bs->opaque; 164 throttle_group_detach_aio_context(tgm); 165 } 166 167 static void throttle_attach_aio_context(BlockDriverState *bs, 168 AioContext *new_context) 169 { 170 ThrottleGroupMember *tgm = bs->opaque; 171 throttle_group_attach_aio_context(tgm, new_context); 172 } 173 174 static int throttle_reopen_prepare(BDRVReopenState *reopen_state, 175 BlockReopenQueue *queue, Error **errp) 176 { 177 int ret; 178 char *group = NULL; 179 180 assert(reopen_state != NULL); 181 assert(reopen_state->bs != NULL); 182 183 ret = throttle_parse_options(reopen_state->options, &group, errp); 184 reopen_state->opaque = group; 185 return ret; 186 } 187 188 static void throttle_reopen_commit(BDRVReopenState *reopen_state) 189 { 190 BlockDriverState *bs = reopen_state->bs; 191 ThrottleGroupMember *tgm = bs->opaque; 192 char *group = reopen_state->opaque; 193 194 assert(group); 195 196 if (strcmp(group, throttle_group_get_name(tgm))) { 197 throttle_group_unregister_tgm(tgm); 198 throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs)); 199 } 200 g_free(reopen_state->opaque); 201 reopen_state->opaque = NULL; 202 } 203 204 static void throttle_reopen_abort(BDRVReopenState *reopen_state) 205 { 206 g_free(reopen_state->opaque); 207 reopen_state->opaque = NULL; 208 } 209 210 static bool throttle_recurse_is_first_non_filter(BlockDriverState *bs, 211 BlockDriverState *candidate) 212 { 213 return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate); 214 } 215 216 static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs) 217 { 218 ThrottleGroupMember *tgm = bs->opaque; 219 if (atomic_fetch_inc(&tgm->io_limits_disabled) == 0) { 220 throttle_group_restart_tgm(tgm); 221 } 222 } 223 224 static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs) 225 { 226 ThrottleGroupMember *tgm = bs->opaque; 227 assert(tgm->io_limits_disabled); 228 atomic_dec(&tgm->io_limits_disabled); 229 } 230 231 static const char *const throttle_strong_runtime_opts[] = { 232 QEMU_OPT_THROTTLE_GROUP_NAME, 233 234 NULL 235 }; 236 237 static BlockDriver bdrv_throttle = { 238 .format_name = "throttle", 239 .instance_size = sizeof(ThrottleGroupMember), 240 241 .bdrv_open = throttle_open, 242 .bdrv_close = throttle_close, 243 .bdrv_co_flush = throttle_co_flush, 244 245 .bdrv_child_perm = bdrv_filter_default_perms, 246 247 .bdrv_getlength = throttle_getlength, 248 249 .bdrv_co_preadv = throttle_co_preadv, 250 .bdrv_co_pwritev = throttle_co_pwritev, 251 252 .bdrv_co_pwrite_zeroes = throttle_co_pwrite_zeroes, 253 .bdrv_co_pdiscard = throttle_co_pdiscard, 254 255 .bdrv_recurse_is_first_non_filter = throttle_recurse_is_first_non_filter, 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 .bdrv_co_block_status = bdrv_co_block_status_from_file, 264 265 .bdrv_co_drain_begin = throttle_co_drain_begin, 266 .bdrv_co_drain_end = throttle_co_drain_end, 267 268 .is_filter = true, 269 .strong_runtime_opts = throttle_strong_runtime_opts, 270 }; 271 272 static void bdrv_throttle_init(void) 273 { 274 bdrv_register(&bdrv_throttle); 275 } 276 277 block_init(bdrv_throttle_init); 278