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, &child_of_bds, 85 BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, 86 false, errp); 87 if (!bs->file) { 88 return -EINVAL; 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 throttle_getlength(BlockDriverState *bs) 113 { 114 return bdrv_getlength(bs->file->bs); 115 } 116 117 static int coroutine_fn throttle_co_preadv(BlockDriverState *bs, 118 uint64_t offset, uint64_t bytes, 119 QEMUIOVector *qiov, int flags) 120 { 121 122 ThrottleGroupMember *tgm = bs->opaque; 123 throttle_group_co_io_limits_intercept(tgm, bytes, false); 124 125 return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags); 126 } 127 128 static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs, 129 uint64_t offset, uint64_t bytes, 130 QEMUIOVector *qiov, int flags) 131 { 132 ThrottleGroupMember *tgm = bs->opaque; 133 throttle_group_co_io_limits_intercept(tgm, bytes, true); 134 135 return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags); 136 } 137 138 static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs, 139 int64_t offset, int bytes, 140 BdrvRequestFlags flags) 141 { 142 ThrottleGroupMember *tgm = bs->opaque; 143 throttle_group_co_io_limits_intercept(tgm, bytes, true); 144 145 return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags); 146 } 147 148 static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs, 149 int64_t offset, int bytes) 150 { 151 ThrottleGroupMember *tgm = bs->opaque; 152 throttle_group_co_io_limits_intercept(tgm, bytes, true); 153 154 return bdrv_co_pdiscard(bs->file, offset, bytes); 155 } 156 157 static int throttle_co_flush(BlockDriverState *bs) 158 { 159 return bdrv_co_flush(bs->file->bs); 160 } 161 162 static void throttle_detach_aio_context(BlockDriverState *bs) 163 { 164 ThrottleGroupMember *tgm = bs->opaque; 165 throttle_group_detach_aio_context(tgm); 166 } 167 168 static void throttle_attach_aio_context(BlockDriverState *bs, 169 AioContext *new_context) 170 { 171 ThrottleGroupMember *tgm = bs->opaque; 172 throttle_group_attach_aio_context(tgm, new_context); 173 } 174 175 static int throttle_reopen_prepare(BDRVReopenState *reopen_state, 176 BlockReopenQueue *queue, Error **errp) 177 { 178 int ret; 179 char *group = NULL; 180 181 assert(reopen_state != NULL); 182 assert(reopen_state->bs != NULL); 183 184 ret = throttle_parse_options(reopen_state->options, &group, errp); 185 reopen_state->opaque = group; 186 return ret; 187 } 188 189 static void throttle_reopen_commit(BDRVReopenState *reopen_state) 190 { 191 BlockDriverState *bs = reopen_state->bs; 192 ThrottleGroupMember *tgm = bs->opaque; 193 char *group = reopen_state->opaque; 194 195 assert(group); 196 197 if (strcmp(group, throttle_group_get_name(tgm))) { 198 throttle_group_unregister_tgm(tgm); 199 throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs)); 200 } 201 g_free(reopen_state->opaque); 202 reopen_state->opaque = NULL; 203 } 204 205 static void throttle_reopen_abort(BDRVReopenState *reopen_state) 206 { 207 g_free(reopen_state->opaque); 208 reopen_state->opaque = NULL; 209 } 210 211 static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs) 212 { 213 ThrottleGroupMember *tgm = bs->opaque; 214 if (atomic_fetch_inc(&tgm->io_limits_disabled) == 0) { 215 throttle_group_restart_tgm(tgm); 216 } 217 } 218 219 static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs) 220 { 221 ThrottleGroupMember *tgm = bs->opaque; 222 assert(tgm->io_limits_disabled); 223 atomic_dec(&tgm->io_limits_disabled); 224 } 225 226 static const char *const throttle_strong_runtime_opts[] = { 227 QEMU_OPT_THROTTLE_GROUP_NAME, 228 229 NULL 230 }; 231 232 static BlockDriver bdrv_throttle = { 233 .format_name = "throttle", 234 .instance_size = sizeof(ThrottleGroupMember), 235 236 .bdrv_open = throttle_open, 237 .bdrv_close = throttle_close, 238 .bdrv_co_flush = throttle_co_flush, 239 240 .bdrv_child_perm = bdrv_default_perms, 241 242 .bdrv_getlength = throttle_getlength, 243 244 .bdrv_co_preadv = throttle_co_preadv, 245 .bdrv_co_pwritev = throttle_co_pwritev, 246 247 .bdrv_co_pwrite_zeroes = throttle_co_pwrite_zeroes, 248 .bdrv_co_pdiscard = throttle_co_pdiscard, 249 250 .bdrv_attach_aio_context = throttle_attach_aio_context, 251 .bdrv_detach_aio_context = throttle_detach_aio_context, 252 253 .bdrv_reopen_prepare = throttle_reopen_prepare, 254 .bdrv_reopen_commit = throttle_reopen_commit, 255 .bdrv_reopen_abort = throttle_reopen_abort, 256 .bdrv_co_block_status = bdrv_co_block_status_from_file, 257 258 .bdrv_co_drain_begin = throttle_co_drain_begin, 259 .bdrv_co_drain_end = throttle_co_drain_end, 260 261 .is_filter = true, 262 .strong_runtime_opts = throttle_strong_runtime_opts, 263 }; 264 265 static void bdrv_throttle_init(void) 266 { 267 bdrv_register(&bdrv_throttle); 268 } 269 270 block_init(bdrv_throttle_init); 271