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/option.h" 23 #include "qemu/throttle-options.h" 24 #include "qapi/error.h" 25 26 static QemuOptsList throttle_opts = { 27 .name = "throttle", 28 .head = QTAILQ_HEAD_INITIALIZER(throttle_opts.head), 29 .desc = { 30 { 31 .name = QEMU_OPT_THROTTLE_GROUP_NAME, 32 .type = QEMU_OPT_STRING, 33 .help = "Name of the throttle group", 34 }, 35 { /* end of list */ } 36 }, 37 }; 38 39 /* 40 * If this function succeeds then the throttle group name is stored in 41 * @group and must be freed by the caller. 42 * If there's an error then @group remains unmodified. 43 */ 44 static int throttle_parse_options(QDict *options, char **group, Error **errp) 45 { 46 int ret; 47 const char *group_name; 48 Error *local_err = NULL; 49 QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort); 50 51 qemu_opts_absorb_qdict(opts, options, &local_err); 52 if (local_err) { 53 error_propagate(errp, local_err); 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 bs->file = bdrv_open_child(NULL, options, "file", bs, 84 &child_file, false, errp); 85 if (!bs->file) { 86 return -EINVAL; 87 } 88 bs->supported_write_flags = bs->file->bs->supported_write_flags | 89 BDRV_REQ_WRITE_UNCHANGED; 90 bs->supported_zero_flags = bs->file->bs->supported_zero_flags | 91 BDRV_REQ_WRITE_UNCHANGED; 92 93 ret = throttle_parse_options(options, &group, errp); 94 if (ret == 0) { 95 /* Register membership to group with name group_name */ 96 throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs)); 97 g_free(group); 98 } 99 100 return ret; 101 } 102 103 static void throttle_close(BlockDriverState *bs) 104 { 105 ThrottleGroupMember *tgm = bs->opaque; 106 throttle_group_unregister_tgm(tgm); 107 } 108 109 110 static int64_t throttle_getlength(BlockDriverState *bs) 111 { 112 return bdrv_getlength(bs->file->bs); 113 } 114 115 static int coroutine_fn throttle_co_preadv(BlockDriverState *bs, 116 uint64_t offset, uint64_t bytes, 117 QEMUIOVector *qiov, int 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 uint64_t offset, uint64_t bytes, 128 QEMUIOVector *qiov, int flags) 129 { 130 ThrottleGroupMember *tgm = bs->opaque; 131 throttle_group_co_io_limits_intercept(tgm, bytes, true); 132 133 return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags); 134 } 135 136 static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs, 137 int64_t offset, int bytes, 138 BdrvRequestFlags flags) 139 { 140 ThrottleGroupMember *tgm = bs->opaque; 141 throttle_group_co_io_limits_intercept(tgm, bytes, true); 142 143 return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags); 144 } 145 146 static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs, 147 int64_t offset, int bytes) 148 { 149 ThrottleGroupMember *tgm = bs->opaque; 150 throttle_group_co_io_limits_intercept(tgm, bytes, true); 151 152 return bdrv_co_pdiscard(bs->file, offset, bytes); 153 } 154 155 static int throttle_co_flush(BlockDriverState *bs) 156 { 157 return bdrv_co_flush(bs->file->bs); 158 } 159 160 static void throttle_detach_aio_context(BlockDriverState *bs) 161 { 162 ThrottleGroupMember *tgm = bs->opaque; 163 throttle_group_detach_aio_context(tgm); 164 } 165 166 static void throttle_attach_aio_context(BlockDriverState *bs, 167 AioContext *new_context) 168 { 169 ThrottleGroupMember *tgm = bs->opaque; 170 throttle_group_attach_aio_context(tgm, new_context); 171 } 172 173 static int throttle_reopen_prepare(BDRVReopenState *reopen_state, 174 BlockReopenQueue *queue, Error **errp) 175 { 176 int ret; 177 char *group = NULL; 178 179 assert(reopen_state != NULL); 180 assert(reopen_state->bs != NULL); 181 182 ret = throttle_parse_options(reopen_state->options, &group, errp); 183 reopen_state->opaque = group; 184 return ret; 185 } 186 187 static void throttle_reopen_commit(BDRVReopenState *reopen_state) 188 { 189 BlockDriverState *bs = reopen_state->bs; 190 ThrottleGroupMember *tgm = bs->opaque; 191 char *group = reopen_state->opaque; 192 193 assert(group); 194 195 if (strcmp(group, throttle_group_get_name(tgm))) { 196 throttle_group_unregister_tgm(tgm); 197 throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs)); 198 } 199 g_free(reopen_state->opaque); 200 reopen_state->opaque = NULL; 201 } 202 203 static void throttle_reopen_abort(BDRVReopenState *reopen_state) 204 { 205 g_free(reopen_state->opaque); 206 reopen_state->opaque = NULL; 207 } 208 209 static bool throttle_recurse_is_first_non_filter(BlockDriverState *bs, 210 BlockDriverState *candidate) 211 { 212 return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate); 213 } 214 215 static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs) 216 { 217 ThrottleGroupMember *tgm = bs->opaque; 218 if (atomic_fetch_inc(&tgm->io_limits_disabled) == 0) { 219 throttle_group_restart_tgm(tgm); 220 } 221 } 222 223 static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs) 224 { 225 ThrottleGroupMember *tgm = bs->opaque; 226 assert(tgm->io_limits_disabled); 227 atomic_dec(&tgm->io_limits_disabled); 228 } 229 230 static BlockDriver bdrv_throttle = { 231 .format_name = "throttle", 232 .instance_size = sizeof(ThrottleGroupMember), 233 234 .bdrv_open = throttle_open, 235 .bdrv_close = throttle_close, 236 .bdrv_co_flush = throttle_co_flush, 237 238 .bdrv_child_perm = bdrv_filter_default_perms, 239 240 .bdrv_getlength = throttle_getlength, 241 242 .bdrv_co_preadv = throttle_co_preadv, 243 .bdrv_co_pwritev = throttle_co_pwritev, 244 245 .bdrv_co_pwrite_zeroes = throttle_co_pwrite_zeroes, 246 .bdrv_co_pdiscard = throttle_co_pdiscard, 247 248 .bdrv_recurse_is_first_non_filter = throttle_recurse_is_first_non_filter, 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 }; 263 264 static void bdrv_throttle_init(void) 265 { 266 bdrv_register(&bdrv_throttle); 267 } 268 269 block_init(bdrv_throttle_init); 270