| 1 | /* |
| 2 | * Common block export infrastructure |
| 3 | * |
| 4 | * Copyright (c) 2012, 2020 Red Hat, Inc. |
| 5 | * |
| 6 | * Authors: |
| 7 | * Paolo Bonzini <pbonzini@redhat.com> |
| 8 | * Kevin Wolf <kwolf@redhat.com> |
| 9 | * |
| 10 | * This work is licensed under the terms of the GNU GPL, version 2 or |
| 11 | * later. See the COPYING file in the top-level directory. |
| 12 | */ |
| 13 | |
| 14 | #include "qemu/osdep.h" |
| 15 | |
| 16 | #include "block/block.h" |
| 17 | #include "system/block-backend.h" |
| 18 | #include "system/iothread.h" |
| 19 | #include "block/export.h" |
| 20 | #include "block/fuse.h" |
| 21 | #include "block/nbd.h" |
| 22 | #include "qapi/error.h" |
| 23 | #include "qapi/qapi-commands-block-export.h" |
| 24 | #include "qapi/qapi-events-block-export.h" |
| 25 | #include "qemu/id.h" |
| 26 | #ifdef CONFIG_VHOST_USER_BLK_SERVER |
| 27 | #include "vhost-user-blk-server.h" |
| 28 | #endif |
| 29 | #ifdef CONFIG_VDUSE_BLK_EXPORT |
| 30 | #include "vduse-blk.h" |
| 31 | #endif |
| 32 | |
| 33 | static const BlockExportDriver *blk_exp_drivers[] = { |
| 34 | &blk_exp_nbd, |
| 35 | #ifdef CONFIG_VHOST_USER_BLK_SERVER |
| 36 | &blk_exp_vhost_user_blk, |
| 37 | #endif |
| 38 | #ifdef CONFIG_FUSE |
| 39 | &blk_exp_fuse, |
| 40 | #endif |
| 41 | #ifdef CONFIG_VDUSE_BLK_EXPORT |
| 42 | &blk_exp_vduse_blk, |
| 43 | #endif |
| 44 | }; |
| 45 | |
| 46 | /* Only accessed from the main thread */ |
| 47 | static QLIST_HEAD(, BlockExport) block_exports = |
| 48 | QLIST_HEAD_INITIALIZER(block_exports); |
| 49 | |
| 50 | BlockExport *blk_exp_find(const char *id) |
| 51 | { |
| 52 | BlockExport *exp; |
| 53 | |
| 54 | QLIST_FOREACH(exp, &block_exports, next) { |
| 55 | if (strcmp(id, exp->id) == 0) { |
| 56 | return exp; |
| 57 | } |
| 58 | } |
| 59 | |
| 60 | return NULL; |
| 61 | } |
| 62 | |
| 63 | static const BlockExportDriver *blk_exp_find_driver(BlockExportType type) |
| 64 | { |
| 65 | int i; |
| 66 | |
| 67 | for (i = 0; i < ARRAY_SIZE(blk_exp_drivers); i++) { |
| 68 | if (blk_exp_drivers[i]->type == type) { |
| 69 | return blk_exp_drivers[i]; |
| 70 | } |
| 71 | } |
| 72 | return NULL; |
| 73 | } |
| 74 | |
| 75 | BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp) |
| 76 | { |
| 77 | bool fixed_iothread = export->has_fixed_iothread && export->fixed_iothread; |
| 78 | bool allow_inactive = export->has_allow_inactive && export->allow_inactive; |
| 79 | bool multithread = export->iothread && |
| 80 | export->iothread->type == QTYPE_QLIST; |
| 81 | const BlockExportDriver *drv; |
| 82 | BlockExport *exp = NULL; |
| 83 | BlockDriverState *bs; |
| 84 | BlockBackend *blk = NULL; |
| 85 | AioContext *ctx; |
| 86 | AioContext **multithread_ctxs = NULL; |
| 87 | size_t multithread_count = 0; |
| 88 | uint64_t perm; |
| 89 | int ret; |
| 90 | |
| 91 | GLOBAL_STATE_CODE(); |
| 92 | |
| 93 | if (fixed_iothread && multithread) { |
| 94 | error_setg(errp, |
| 95 | "Cannot use fixed-iothread for a multi-threaded export"); |
| 96 | return NULL; |
| 97 | } |
| 98 | |
| 99 | if (!id_wellformed(export->id)) { |
| 100 | error_setg(errp, "Invalid block export id"); |
| 101 | return NULL; |
| 102 | } |
| 103 | if (blk_exp_find(export->id)) { |
| 104 | error_setg(errp, "Block export id '%s' is already in use", export->id); |
| 105 | return NULL; |
| 106 | } |
| 107 | |
| 108 | drv = blk_exp_find_driver(export->type); |
| 109 | if (!drv) { |
| 110 | error_setg(errp, "No driver found for the requested export type"); |
| 111 | return NULL; |
| 112 | } |
| 113 | |
| 114 | bs = bdrv_lookup_bs(NULL, export->node_name, errp); |
| 115 | if (!bs) { |
| 116 | return NULL; |
| 117 | } |
| 118 | |
| 119 | if (!export->has_writable) { |
| 120 | export->writable = false; |
| 121 | } |
| 122 | if (bdrv_is_read_only(bs) && export->writable) { |
| 123 | error_setg(errp, "Cannot export read-only node as writable"); |
| 124 | return NULL; |
| 125 | } |
| 126 | |
| 127 | ctx = bdrv_get_aio_context(bs); |
| 128 | |
| 129 | /* Move the BDS to the target I/O thread, if it is a single one */ |
| 130 | if (export->iothread && !multithread) { |
| 131 | const char *iothread_id = export->iothread->u.single; |
| 132 | IOThread *iothread; |
| 133 | AioContext *new_ctx; |
| 134 | Error **set_context_errp; |
| 135 | |
| 136 | iothread = iothread_by_id(iothread_id); |
| 137 | if (!iothread) { |
| 138 | error_setg(errp, "iothread \"%s\" not found", iothread_id); |
| 139 | goto fail; |
| 140 | } |
| 141 | |
| 142 | new_ctx = iothread_get_aio_context(iothread); |
| 143 | |
| 144 | /* Ignore errors with fixed-iothread=false */ |
| 145 | set_context_errp = fixed_iothread ? errp : NULL; |
| 146 | ret = bdrv_try_change_aio_context(bs, new_ctx, NULL, set_context_errp); |
| 147 | if (ret == 0) { |
| 148 | ctx = new_ctx; |
| 149 | } else if (fixed_iothread) { |
| 150 | goto fail; |
| 151 | } |
| 152 | } else if (multithread) { |
| 153 | strList *iothread_list = export->iothread->u.multi; |
| 154 | size_t i; |
| 155 | |
| 156 | multithread_count = 0; |
| 157 | for (strList *e = iothread_list; e; e = e->next) { |
| 158 | multithread_count++; |
| 159 | } |
| 160 | |
| 161 | if (multithread_count == 0) { |
| 162 | error_setg(errp, "The set of I/O threads must not be empty"); |
| 163 | return NULL; |
| 164 | } |
| 165 | |
| 166 | multithread_ctxs = g_new(AioContext *, multithread_count); |
| 167 | i = 0; |
| 168 | for (strList *e = iothread_list; e; e = e->next) { |
| 169 | IOThread *iothread = iothread_by_id(e->value); |
| 170 | |
| 171 | if (!iothread) { |
| 172 | error_setg(errp, "iothread \"%s\" not found", e->value); |
| 173 | goto fail; |
| 174 | } |
| 175 | multithread_ctxs[i++] = iothread_get_aio_context(iothread); |
| 176 | } |
| 177 | assert(i == multithread_count); |
| 178 | } |
| 179 | |
| 180 | bdrv_graph_rdlock_main_loop(); |
| 181 | if (allow_inactive) { |
| 182 | if (!drv->supports_inactive) { |
| 183 | error_setg(errp, "Export type does not support inactive exports"); |
| 184 | bdrv_graph_rdunlock_main_loop(); |
| 185 | goto fail; |
| 186 | } |
| 187 | } else { |
| 188 | /* |
| 189 | * Block exports are used for non-shared storage migration. Make sure |
| 190 | * that BDRV_O_INACTIVE is cleared and the image is ready for write |
| 191 | * access since the export could be available before migration handover. |
| 192 | */ |
| 193 | ret = bdrv_activate(bs, errp); |
| 194 | if (ret < 0) { |
| 195 | bdrv_graph_rdunlock_main_loop(); |
| 196 | goto fail; |
| 197 | } |
| 198 | } |
| 199 | bdrv_graph_rdunlock_main_loop(); |
| 200 | |
| 201 | perm = BLK_PERM_CONSISTENT_READ; |
| 202 | if (export->writable) { |
| 203 | perm |= BLK_PERM_WRITE; |
| 204 | } |
| 205 | |
| 206 | blk = blk_new(ctx, perm, BLK_PERM_ALL); |
| 207 | |
| 208 | if (!fixed_iothread) { |
| 209 | blk_set_allow_aio_context_change(blk, true); |
| 210 | } |
| 211 | if (allow_inactive) { |
| 212 | blk_set_force_allow_inactivate(blk); |
| 213 | } |
| 214 | |
| 215 | ret = blk_insert_bs(blk, bs, errp); |
| 216 | if (ret < 0) { |
| 217 | goto fail; |
| 218 | } |
| 219 | |
| 220 | if (!export->has_writethrough) { |
| 221 | export->writethrough = false; |
| 222 | } |
| 223 | blk_set_enable_write_cache(blk, !export->writethrough); |
| 224 | |
| 225 | assert(drv->instance_size >= sizeof(BlockExport)); |
| 226 | exp = g_malloc0(drv->instance_size); |
| 227 | *exp = (BlockExport) { |
| 228 | .drv = drv, |
| 229 | .refcount = 1, |
| 230 | .user_owned = true, |
| 231 | .id = g_strdup(export->id), |
| 232 | .ctx = ctx, |
| 233 | .blk = blk, |
| 234 | }; |
| 235 | |
| 236 | ret = drv->create(exp, export, multithread_ctxs, multithread_count, errp); |
| 237 | if (ret < 0) { |
| 238 | goto fail; |
| 239 | } |
| 240 | |
| 241 | assert(exp->blk != NULL); |
| 242 | |
| 243 | QLIST_INSERT_HEAD(&block_exports, exp, next); |
| 244 | g_free(multithread_ctxs); |
| 245 | return exp; |
| 246 | |
| 247 | fail: |
| 248 | if (blk) { |
| 249 | blk_set_dev_ops(blk, NULL, NULL); |
| 250 | blk_unref(blk); |
| 251 | } |
| 252 | if (exp) { |
| 253 | g_free(exp->id); |
| 254 | g_free(exp); |
| 255 | } |
| 256 | g_free(multithread_ctxs); |
| 257 | return NULL; |
| 258 | } |
| 259 | |
| 260 | void blk_exp_ref(BlockExport *exp) |
| 261 | { |
| 262 | assert(qatomic_read(&exp->refcount) > 0); |
| 263 | qatomic_inc(&exp->refcount); |
| 264 | } |
| 265 | |
| 266 | /* Runs in the main thread */ |
| 267 | static void blk_exp_delete_bh(void *opaque) |
| 268 | { |
| 269 | BlockExport *exp = opaque; |
| 270 | |
| 271 | assert(exp->refcount == 0); |
| 272 | QLIST_REMOVE(exp, next); |
| 273 | exp->drv->delete(exp); |
| 274 | blk_set_dev_ops(exp->blk, NULL, NULL); |
| 275 | blk_unref(exp->blk); |
| 276 | qapi_event_send_block_export_deleted(exp->id); |
| 277 | g_free(exp->id); |
| 278 | g_free(exp); |
| 279 | } |
| 280 | |
| 281 | void blk_exp_unref(BlockExport *exp) |
| 282 | { |
| 283 | assert(qatomic_read(&exp->refcount) > 0); |
| 284 | if (qatomic_fetch_dec(&exp->refcount) == 1) { |
| 285 | /* Touch the block_exports list only in the main thread */ |
| 286 | aio_bh_schedule_oneshot(qemu_get_aio_context(), blk_exp_delete_bh, |
| 287 | exp); |
| 288 | } |
| 289 | } |
| 290 | |
| 291 | /* |
| 292 | * Drops the user reference to the export and requests that all client |
| 293 | * connections and other internally held references start to shut down. When |
| 294 | * the function returns, there may still be active references while the export |
| 295 | * is in the process of shutting down. |
| 296 | */ |
| 297 | void blk_exp_request_shutdown(BlockExport *exp) |
| 298 | { |
| 299 | /* |
| 300 | * If the user doesn't own the export any more, it is already shutting |
| 301 | * down. We must not call .request_shutdown and decrease the refcount a |
| 302 | * second time. |
| 303 | */ |
| 304 | if (!exp->user_owned) { |
| 305 | return; |
| 306 | } |
| 307 | |
| 308 | exp->drv->request_shutdown(exp); |
| 309 | |
| 310 | assert(exp->user_owned); |
| 311 | exp->user_owned = false; |
| 312 | blk_exp_unref(exp); |
| 313 | } |
| 314 | |
| 315 | /* |
| 316 | * Returns whether a block export of the given type exists. |
| 317 | * type == BLOCK_EXPORT_TYPE__MAX checks for an export of any type. |
| 318 | */ |
| 319 | static bool blk_exp_has_type(BlockExportType type) |
| 320 | { |
| 321 | BlockExport *exp; |
| 322 | |
| 323 | if (type == BLOCK_EXPORT_TYPE__MAX) { |
| 324 | return !QLIST_EMPTY(&block_exports); |
| 325 | } |
| 326 | |
| 327 | QLIST_FOREACH(exp, &block_exports, next) { |
| 328 | if (exp->drv->type == type) { |
| 329 | return true; |
| 330 | } |
| 331 | } |
| 332 | |
| 333 | return false; |
| 334 | } |
| 335 | |
| 336 | /* type == BLOCK_EXPORT_TYPE__MAX for all types */ |
| 337 | void blk_exp_close_all_type(BlockExportType type) |
| 338 | { |
| 339 | BlockExport *exp, *next; |
| 340 | |
| 341 | assert(in_aio_context_home_thread(qemu_get_aio_context())); |
| 342 | |
| 343 | QLIST_FOREACH_SAFE(exp, &block_exports, next, next) { |
| 344 | if (type != BLOCK_EXPORT_TYPE__MAX && exp->drv->type != type) { |
| 345 | continue; |
| 346 | } |
| 347 | blk_exp_request_shutdown(exp); |
| 348 | } |
| 349 | |
| 350 | AIO_WAIT_WHILE_UNLOCKED(NULL, blk_exp_has_type(type)); |
| 351 | } |
| 352 | |
| 353 | void blk_exp_close_all(void) |
| 354 | { |
| 355 | blk_exp_close_all_type(BLOCK_EXPORT_TYPE__MAX); |
| 356 | } |
| 357 | |
| 358 | void qmp_block_export_add(BlockExportOptions *export, Error **errp) |
| 359 | { |
| 360 | blk_exp_add(export, errp); |
| 361 | } |
| 362 | |
| 363 | void qmp_block_export_del(const char *id, |
| 364 | bool has_mode, BlockExportRemoveMode mode, |
| 365 | Error **errp) |
| 366 | { |
| 367 | ERRP_GUARD(); |
| 368 | BlockExport *exp; |
| 369 | |
| 370 | exp = blk_exp_find(id); |
| 371 | if (exp == NULL) { |
| 372 | error_setg(errp, "Export '%s' is not found", id); |
| 373 | return; |
| 374 | } |
| 375 | if (!exp->user_owned) { |
| 376 | error_setg(errp, "Export '%s' is already shutting down", id); |
| 377 | return; |
| 378 | } |
| 379 | |
| 380 | if (!has_mode) { |
| 381 | mode = BLOCK_EXPORT_REMOVE_MODE_SAFE; |
| 382 | } |
| 383 | if (mode == BLOCK_EXPORT_REMOVE_MODE_SAFE && |
| 384 | qatomic_read(&exp->refcount) > 1) { |
| 385 | error_setg(errp, "export '%s' still in use", exp->id); |
| 386 | error_append_hint(errp, "Use mode='hard' to force client " |
| 387 | "disconnect\n"); |
| 388 | return; |
| 389 | } |
| 390 | |
| 391 | blk_exp_request_shutdown(exp); |
| 392 | } |
| 393 | |
| 394 | BlockExportInfoList *qmp_query_block_exports(Error **errp) |
| 395 | { |
| 396 | BlockExportInfoList *head = NULL, **tail = &head; |
| 397 | BlockExport *exp; |
| 398 | |
| 399 | QLIST_FOREACH(exp, &block_exports, next) { |
| 400 | BlockExportInfo *info = g_new(BlockExportInfo, 1); |
| 401 | *info = (BlockExportInfo) { |
| 402 | .id = g_strdup(exp->id), |
| 403 | .type = exp->drv->type, |
| 404 | .node_name = g_strdup(bdrv_get_node_name(blk_bs(exp->blk))), |
| 405 | .shutting_down = !exp->user_owned, |
| 406 | }; |
| 407 | |
| 408 | QAPI_LIST_APPEND(tail, info); |
| 409 | } |
| 410 | |
| 411 | return head; |
| 412 | } |