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