| 1 | /* |
| 2 | * Present a block device as a raw image through FUSE |
| 3 | * |
| 4 | * Copyright (c) 2020, 2025 Hanna Czenczek <hreitz@redhat.com> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License as published by |
| 8 | * the Free Software Foundation; under version 2 or later of the License. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, see <http://www.gnu.org/licenses/>. |
| 17 | */ |
| 18 | |
| 19 | #define FUSE_USE_VERSION 31 |
| 20 | |
| 21 | #include "qemu/osdep.h" |
| 22 | #include "qemu/memalign.h" |
| 23 | #include "qemu/aio.h" |
| 24 | #include "block/block_int-common.h" |
| 25 | #include "block/export.h" |
| 26 | #include "block/fuse.h" |
| 27 | #include "block/qapi.h" |
| 28 | #include "qapi/error.h" |
| 29 | #include "qapi/qapi-commands-block.h" |
| 30 | #include "qemu/coroutine.h" |
| 31 | #include "qemu/error-report.h" |
| 32 | #include "qemu/main-loop.h" |
| 33 | #include "system/block-backend.h" |
| 34 | #include "system/iothread.h" |
| 35 | |
| 36 | #include <fuse.h> |
| 37 | #include <fuse_lowlevel.h> |
| 38 | |
| 39 | #include "standard-headers/linux/fuse.h" |
| 40 | #include <sys/ioctl.h> |
| 41 | |
| 42 | #if defined(CONFIG_FALLOCATE_ZERO_RANGE) |
| 43 | #include <linux/falloc.h> |
| 44 | #endif |
| 45 | |
| 46 | #ifdef __linux__ |
| 47 | #include <linux/fs.h> |
| 48 | #endif |
| 49 | |
| 50 | /* Prevent overly long bounce buffer allocations */ |
| 51 | #define FUSE_MAX_READ_BYTES (MIN(BDRV_REQUEST_MAX_BYTES, 1 * 1024 * 1024)) |
| 52 | #define FUSE_MAX_WRITE_BYTES (64 * 1024) |
| 53 | |
| 54 | typedef struct FuseRequestInHeader { |
| 55 | struct fuse_in_header common; |
| 56 | /* All supported requests */ |
| 57 | union { |
| 58 | /* |
| 59 | * When using_old_fuse_init_in() is true, then the smaller older struct |
| 60 | * is used by the kernel. The flags2 member and other new members must |
| 61 | * be treated as absent then. |
| 62 | */ |
| 63 | struct fuse_init_in init; |
| 64 | struct fuse_open_in open; |
| 65 | struct fuse_setattr_in setattr; |
| 66 | struct fuse_read_in read; |
| 67 | struct fuse_write_in write; |
| 68 | struct fuse_fallocate_in fallocate; |
| 69 | #ifdef CONFIG_FUSE_LSEEK |
| 70 | struct fuse_lseek_in lseek; |
| 71 | #endif |
| 72 | }; |
| 73 | } FuseRequestInHeader; |
| 74 | |
| 75 | typedef struct FuseRequestOutHeader { |
| 76 | struct fuse_out_header common; |
| 77 | /* All supported requests */ |
| 78 | union { |
| 79 | struct fuse_init_out init; |
| 80 | struct fuse_statfs_out statfs; |
| 81 | struct fuse_open_out open; |
| 82 | struct fuse_attr_out attr; |
| 83 | struct fuse_write_out write; |
| 84 | #ifdef CONFIG_FUSE_LSEEK |
| 85 | struct fuse_lseek_out lseek; |
| 86 | #endif |
| 87 | }; |
| 88 | } FuseRequestOutHeader; |
| 89 | |
| 90 | typedef union FuseRequestInHeaderBuf { |
| 91 | struct FuseRequestInHeader structured; |
| 92 | struct { |
| 93 | /* |
| 94 | * Part of the request header that is filled for write requests |
| 95 | * (Needed because we want the data to go into a different buffer, to |
| 96 | * avoid having to use a bounce buffer) |
| 97 | */ |
| 98 | char head[sizeof(struct fuse_in_header) + |
| 99 | sizeof(struct fuse_write_in)]; |
| 100 | /* |
| 101 | * Rest of the request header for requests that have a longer header |
| 102 | * than write requests |
| 103 | */ |
| 104 | char tail[sizeof(FuseRequestInHeader) - |
| 105 | (sizeof(struct fuse_in_header) + |
| 106 | sizeof(struct fuse_write_in))]; |
| 107 | }; |
| 108 | } FuseRequestInHeaderBuf; |
| 109 | |
| 110 | QEMU_BUILD_BUG_ON(sizeof(FuseRequestInHeaderBuf) != |
| 111 | sizeof(FuseRequestInHeader)); |
| 112 | QEMU_BUILD_BUG_ON(sizeof(((FuseRequestInHeaderBuf *)0)->head) + |
| 113 | sizeof(((FuseRequestInHeaderBuf *)0)->tail) != |
| 114 | sizeof(FuseRequestInHeader)); |
| 115 | |
| 116 | typedef struct FuseExport FuseExport; |
| 117 | |
| 118 | /* |
| 119 | * One FUSE "queue", representing one FUSE FD from which requests are fetched |
| 120 | * and processed. Each queue is tied to an AioContext. |
| 121 | */ |
| 122 | typedef struct FuseQueue { |
| 123 | FuseExport *exp; |
| 124 | |
| 125 | AioContext *ctx; |
| 126 | int fuse_fd; |
| 127 | |
| 128 | /* |
| 129 | * Cached buffer to receive the data of WRITE requests. Cached because: |
| 130 | * To read requests, we put a FuseRequestInHeaderBuf (FRIHB) object on the |
| 131 | * stack, and a (WRITE data) buffer on the heap. We pass FRIHB.head and the |
| 132 | * data buffer to readv(). This way, for WRITE requests, we get exactly |
| 133 | * their data in the data buffer and can avoid bounce buffering. |
| 134 | * However, for non-WRITE requests, some of the header may end up in the |
| 135 | * data buffer, so we will need to copy that back into the FRIHB object, and |
| 136 | * then we don't need the heap buffer anymore. That is why we cache it, so |
| 137 | * we can trivially reuse it between non-WRITE requests. |
| 138 | * |
| 139 | * Note that these data buffers and thus req_write_data_cached are allocated |
| 140 | * via blk_blockalign() and thus need to be freed via qemu_vfree(). |
| 141 | */ |
| 142 | void *req_write_data_cached; |
| 143 | } FuseQueue; |
| 144 | |
| 145 | struct FuseExport { |
| 146 | BlockExport common; |
| 147 | |
| 148 | struct fuse_session *fuse_session; |
| 149 | unsigned int in_flight; /* atomic */ |
| 150 | bool mounted, fd_handler_set_up; |
| 151 | |
| 152 | /* |
| 153 | * Set when there was an unrecoverable error and no requests should be read |
| 154 | * from the device anymore (basically only in case of something we would |
| 155 | * consider a kernel bug). Access atomically. |
| 156 | */ |
| 157 | bool halted; |
| 158 | |
| 159 | int num_queues; |
| 160 | FuseQueue *queues; |
| 161 | /* |
| 162 | * True if this export should follow the generic export's AioContext. |
| 163 | * Will be false if the queues' AioContexts have been explicitly set by the |
| 164 | * user, i.e. are expected to stay in those contexts. |
| 165 | * (I.e. is always false if there is more than one queue.) |
| 166 | */ |
| 167 | bool follow_aio_context; |
| 168 | |
| 169 | char *mountpoint; |
| 170 | bool writable; |
| 171 | bool growable; |
| 172 | /* Whether allow_other was used as a mount option or not */ |
| 173 | bool allow_other; |
| 174 | |
| 175 | /* All atomic */ |
| 176 | mode_t st_mode; |
| 177 | uid_t st_uid; |
| 178 | gid_t st_gid; |
| 179 | }; |
| 180 | |
| 181 | /* |
| 182 | * Verify that the size of FuseRequestInHeaderBuf.head plus the data |
| 183 | * buffer are big enough to be accepted by the FUSE kernel driver. |
| 184 | */ |
| 185 | QEMU_BUILD_BUG_ON(sizeof(((FuseRequestInHeaderBuf *)0)->head) + |
| 186 | FUSE_MAX_WRITE_BYTES < |
| 187 | FUSE_MIN_READ_BUFFER); |
| 188 | |
| 189 | static GHashTable *exports; |
| 190 | |
| 191 | static void fuse_export_shutdown(BlockExport *exp); |
| 192 | static void fuse_export_delete(BlockExport *exp); |
| 193 | static void fuse_export_halt(FuseExport *exp); |
| 194 | |
| 195 | static void init_exports_table(void); |
| 196 | |
| 197 | static int mount_fuse_export(FuseExport *exp, Error **errp); |
| 198 | static int clone_fuse_fd(int fd, Error **errp); |
| 199 | |
| 200 | static bool is_regular_file(const char *path, Error **errp); |
| 201 | |
| 202 | static void read_from_fuse_fd(void *opaque); |
| 203 | static void coroutine_fn |
| 204 | fuse_co_process_request(FuseQueue *q, const FuseRequestInHeader *in_hdr, |
| 205 | const void *data_buffer); |
| 206 | static int fuse_write_err(int fd, const struct fuse_in_header *in_hdr, int err); |
| 207 | |
| 208 | static void fuse_inc_in_flight(FuseExport *exp) |
| 209 | { |
| 210 | if (qatomic_fetch_inc(&exp->in_flight) == 0) { |
| 211 | /* Prevent export from being deleted */ |
| 212 | blk_exp_ref(&exp->common); |
| 213 | } |
| 214 | } |
| 215 | |
| 216 | static void fuse_dec_in_flight(FuseExport *exp) |
| 217 | { |
| 218 | if (qatomic_fetch_dec(&exp->in_flight) == 1) { |
| 219 | /* Wake AIO_WAIT_WHILE() */ |
| 220 | aio_wait_kick(); |
| 221 | |
| 222 | /* Now the export can be deleted */ |
| 223 | blk_exp_unref(&exp->common); |
| 224 | } |
| 225 | } |
| 226 | |
| 227 | /** |
| 228 | * Attach FUSE FD read handler. |
| 229 | */ |
| 230 | static void fuse_attach_handlers(FuseExport *exp) |
| 231 | { |
| 232 | if (qatomic_read(&exp->halted)) { |
| 233 | return; |
| 234 | } |
| 235 | |
| 236 | for (int i = 0; i < exp->num_queues; i++) { |
| 237 | aio_set_fd_handler(exp->queues[i].ctx, exp->queues[i].fuse_fd, |
| 238 | read_from_fuse_fd, NULL, NULL, NULL, |
| 239 | &exp->queues[i]); |
| 240 | } |
| 241 | exp->fd_handler_set_up = true; |
| 242 | } |
| 243 | |
| 244 | /** |
| 245 | * Detach FUSE FD read handler. |
| 246 | */ |
| 247 | static void fuse_detach_handlers(FuseExport *exp) |
| 248 | { |
| 249 | for (int i = 0; i < exp->num_queues; i++) { |
| 250 | aio_set_fd_handler(exp->queues[i].ctx, exp->queues[i].fuse_fd, |
| 251 | NULL, NULL, NULL, NULL, NULL); |
| 252 | } |
| 253 | exp->fd_handler_set_up = false; |
| 254 | } |
| 255 | |
| 256 | static void fuse_export_drained_begin(void *opaque) |
| 257 | { |
| 258 | fuse_detach_handlers(opaque); |
| 259 | } |
| 260 | |
| 261 | static void fuse_export_drained_end(void *opaque) |
| 262 | { |
| 263 | FuseExport *exp = opaque; |
| 264 | |
| 265 | /* Refresh AioContext in case it changed */ |
| 266 | exp->common.ctx = blk_get_aio_context(exp->common.blk); |
| 267 | if (exp->follow_aio_context) { |
| 268 | assert(exp->num_queues == 1); |
| 269 | exp->queues[0].ctx = exp->common.ctx; |
| 270 | } |
| 271 | |
| 272 | fuse_attach_handlers(exp); |
| 273 | } |
| 274 | |
| 275 | static bool fuse_export_drained_poll(void *opaque) |
| 276 | { |
| 277 | FuseExport *exp = opaque; |
| 278 | |
| 279 | return qatomic_read(&exp->in_flight) > 0; |
| 280 | } |
| 281 | |
| 282 | static const BlockDevOps fuse_export_blk_dev_ops = { |
| 283 | .drained_begin = fuse_export_drained_begin, |
| 284 | .drained_end = fuse_export_drained_end, |
| 285 | .drained_poll = fuse_export_drained_poll, |
| 286 | }; |
| 287 | |
| 288 | static int fuse_export_create(BlockExport *blk_exp, |
| 289 | BlockExportOptions *blk_exp_args, |
| 290 | AioContext *const *multithread, |
| 291 | size_t mt_count, |
| 292 | Error **errp) |
| 293 | { |
| 294 | ERRP_GUARD(); /* ensure clean-up even with error_fatal */ |
| 295 | FuseExport *exp = container_of(blk_exp, FuseExport, common); |
| 296 | BlockExportOptionsFuse *args = &blk_exp_args->u.fuse; |
| 297 | uint32_t st_mode; |
| 298 | int ret; |
| 299 | |
| 300 | assert(blk_exp_args->type == BLOCK_EXPORT_TYPE_FUSE); |
| 301 | |
| 302 | if (multithread) { |
| 303 | /* Guaranteed by common export code */ |
| 304 | assert(mt_count >= 1); |
| 305 | |
| 306 | exp->follow_aio_context = false; |
| 307 | exp->num_queues = mt_count; |
| 308 | exp->queues = g_new(FuseQueue, mt_count); |
| 309 | |
| 310 | for (size_t i = 0; i < mt_count; i++) { |
| 311 | exp->queues[i] = (FuseQueue) { |
| 312 | .exp = exp, |
| 313 | .ctx = multithread[i], |
| 314 | .fuse_fd = -1, |
| 315 | }; |
| 316 | } |
| 317 | } else { |
| 318 | /* Guaranteed by common export code */ |
| 319 | assert(mt_count == 0); |
| 320 | |
| 321 | exp->follow_aio_context = true; |
| 322 | exp->num_queues = 1; |
| 323 | exp->queues = g_new(FuseQueue, 1); |
| 324 | exp->queues[0] = (FuseQueue) { |
| 325 | .exp = exp, |
| 326 | .ctx = exp->common.ctx, |
| 327 | .fuse_fd = -1, |
| 328 | }; |
| 329 | } |
| 330 | |
| 331 | /* For growable and writable exports, take the RESIZE permission */ |
| 332 | if (args->growable || blk_exp_args->writable) { |
| 333 | uint64_t blk_perm, blk_shared_perm; |
| 334 | |
| 335 | blk_get_perm(exp->common.blk, &blk_perm, &blk_shared_perm); |
| 336 | |
| 337 | ret = blk_set_perm(exp->common.blk, blk_perm | BLK_PERM_RESIZE, |
| 338 | blk_shared_perm, errp); |
| 339 | if (ret < 0) { |
| 340 | goto fail; |
| 341 | } |
| 342 | } |
| 343 | |
| 344 | blk_set_dev_ops(exp->common.blk, &fuse_export_blk_dev_ops, exp); |
| 345 | |
| 346 | /* |
| 347 | * We handle draining ourselves using an in-flight counter and by disabling |
| 348 | * the FUSE fd handler. Do not queue BlockBackend requests, they need to |
| 349 | * complete so the in-flight counter reaches zero. |
| 350 | */ |
| 351 | blk_set_disable_request_queuing(exp->common.blk, true); |
| 352 | |
| 353 | init_exports_table(); |
| 354 | |
| 355 | /* |
| 356 | * It is important to do this check before calling is_regular_file() -- |
| 357 | * that function will do a stat(), which we would have to handle if we |
| 358 | * already exported something on @mountpoint. But we cannot, because |
| 359 | * we are currently caught up here. |
| 360 | * (Note that ideally we would want to resolve relative paths here, |
| 361 | * but bdrv_make_absolute_filename() might do the wrong thing for |
| 362 | * paths that contain colons, and realpath() would resolve symlinks, |
| 363 | * which we do not want: The mount point is not going to be the |
| 364 | * symlink's destination, but the link itself.) |
| 365 | * So this will not catch all potential clashes, but hopefully at |
| 366 | * least the most common one of specifying exactly the same path |
| 367 | * string twice. |
| 368 | */ |
| 369 | if (g_hash_table_contains(exports, args->mountpoint)) { |
| 370 | error_setg(errp, "There already is a FUSE export on '%s'", |
| 371 | args->mountpoint); |
| 372 | ret = -EEXIST; |
| 373 | goto fail; |
| 374 | } |
| 375 | |
| 376 | if (!is_regular_file(args->mountpoint, errp)) { |
| 377 | ret = -EINVAL; |
| 378 | goto fail; |
| 379 | } |
| 380 | |
| 381 | exp->mountpoint = g_strdup(args->mountpoint); |
| 382 | exp->writable = blk_exp_args->writable; |
| 383 | exp->growable = args->growable; |
| 384 | |
| 385 | /* set default */ |
| 386 | if (!args->has_allow_other) { |
| 387 | args->allow_other = FUSE_EXPORT_ALLOW_OTHER_AUTO; |
| 388 | } |
| 389 | |
| 390 | st_mode = S_IFREG | S_IRUSR; |
| 391 | if (exp->writable) { |
| 392 | st_mode |= S_IWUSR; |
| 393 | } |
| 394 | qatomic_set(&exp->st_mode, st_mode); |
| 395 | qatomic_set(&exp->st_uid, getuid()); |
| 396 | qatomic_set(&exp->st_gid, getgid()); |
| 397 | |
| 398 | if (args->allow_other == FUSE_EXPORT_ALLOW_OTHER_AUTO) { |
| 399 | /* Try allow_other == true first, ignore errors */ |
| 400 | exp->allow_other = true; |
| 401 | ret = mount_fuse_export(exp, NULL); |
| 402 | if (ret < 0) { |
| 403 | exp->allow_other = false; |
| 404 | ret = mount_fuse_export(exp, errp); |
| 405 | } |
| 406 | } else { |
| 407 | exp->allow_other = args->allow_other == FUSE_EXPORT_ALLOW_OTHER_ON; |
| 408 | ret = mount_fuse_export(exp, errp); |
| 409 | } |
| 410 | if (ret < 0) { |
| 411 | goto fail; |
| 412 | } |
| 413 | |
| 414 | g_hash_table_insert(exports, g_strdup(exp->mountpoint), NULL); |
| 415 | |
| 416 | assert(exp->num_queues >= 1); |
| 417 | exp->queues[0].fuse_fd = fuse_session_fd(exp->fuse_session); |
| 418 | ret = qemu_fcntl_addfl(exp->queues[0].fuse_fd, O_NONBLOCK); |
| 419 | if (ret < 0) { |
| 420 | error_setg_errno(errp, -ret, "Failed to make FUSE FD non-blocking"); |
| 421 | goto fail; |
| 422 | } |
| 423 | |
| 424 | for (int i = 1; i < exp->num_queues; i++) { |
| 425 | int fd = clone_fuse_fd(exp->queues[0].fuse_fd, errp); |
| 426 | if (fd < 0) { |
| 427 | ret = fd; |
| 428 | goto fail; |
| 429 | } |
| 430 | exp->queues[i].fuse_fd = fd; |
| 431 | } |
| 432 | |
| 433 | fuse_attach_handlers(exp); |
| 434 | return 0; |
| 435 | |
| 436 | fail: |
| 437 | fuse_export_shutdown(blk_exp); |
| 438 | fuse_export_delete(blk_exp); |
| 439 | return ret; |
| 440 | } |
| 441 | |
| 442 | /** |
| 443 | * Allocates the global @exports hash table. |
| 444 | */ |
| 445 | static void init_exports_table(void) |
| 446 | { |
| 447 | if (exports) { |
| 448 | return; |
| 449 | } |
| 450 | |
| 451 | exports = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL); |
| 452 | } |
| 453 | |
| 454 | /** |
| 455 | * Create exp->fuse_session and mount it. Expects exp->mountpoint, |
| 456 | * exp->writable, and exp->allow_other to be set as intended for the mount. |
| 457 | */ |
| 458 | static int mount_fuse_export(FuseExport *exp, Error **errp) |
| 459 | { |
| 460 | const char *fuse_argv[4]; |
| 461 | char *mount_opts; |
| 462 | struct fuse_args fuse_args; |
| 463 | int ret; |
| 464 | /* |
| 465 | * We just create the session for mounting/unmounting, no need to provide |
| 466 | * any operations. However, since libfuse commit 52a633a5d, we have to |
| 467 | * provide some op struct and cannot just pass NULL (even though the commit |
| 468 | * message ("allow passing ops as NULL") seems to imply the exact opposite, |
| 469 | * as does the comment added to fuse_session_new_fn() ("To create a no-op |
| 470 | * session just for mounting pass op as NULL."). |
| 471 | * This is how said libfuse commit implements a no-op session internally, so |
| 472 | * do it the same way. |
| 473 | */ |
| 474 | static const struct fuse_lowlevel_ops null_ops = { 0 }; |
| 475 | |
| 476 | /* |
| 477 | * Note that these mount options differ from what we would pass to a direct |
| 478 | * mount() call: |
| 479 | * - nosuid, nodev, and noatime are not understood by the kernel; libfuse |
| 480 | * uses those options to construct the mount flags (MS_*) |
| 481 | * - The FUSE kernel driver requires additional options (fd, rootmode, |
| 482 | * user_id, group_id); these will be set by libfuse. |
| 483 | * Note that max_read is set here, while max_write is set via the FUSE INIT |
| 484 | * operation. |
| 485 | */ |
| 486 | mount_opts = g_strdup_printf("%s,nosuid,nodev,noatime,max_read=%zu," |
| 487 | "default_permissions%s", |
| 488 | exp->writable ? "rw" : "ro", |
| 489 | FUSE_MAX_READ_BYTES, |
| 490 | exp->allow_other ? ",allow_other" : ""); |
| 491 | |
| 492 | fuse_argv[0] = ""; /* Dummy program name */ |
| 493 | fuse_argv[1] = "-o"; |
| 494 | fuse_argv[2] = mount_opts; |
| 495 | fuse_argv[3] = NULL; |
| 496 | fuse_args = (struct fuse_args)FUSE_ARGS_INIT(3, (char **)fuse_argv); |
| 497 | |
| 498 | exp->fuse_session = fuse_session_new(&fuse_args, &null_ops, |
| 499 | sizeof(null_ops), NULL); |
| 500 | g_free(mount_opts); |
| 501 | if (!exp->fuse_session) { |
| 502 | error_setg(errp, "Failed to set up FUSE session"); |
| 503 | return -EIO; |
| 504 | } |
| 505 | |
| 506 | ret = fuse_session_mount(exp->fuse_session, exp->mountpoint); |
| 507 | if (ret < 0) { |
| 508 | error_setg(errp, "Failed to mount FUSE session to export"); |
| 509 | ret = -EIO; |
| 510 | goto fail; |
| 511 | } |
| 512 | exp->mounted = true; |
| 513 | |
| 514 | return 0; |
| 515 | |
| 516 | fail: |
| 517 | fuse_session_destroy(exp->fuse_session); |
| 518 | exp->fuse_session = NULL; |
| 519 | return ret; |
| 520 | } |
| 521 | |
| 522 | /** |
| 523 | * Allocate a buffer to receive WRITE data, or take the cached one. |
| 524 | */ |
| 525 | static void *get_write_data_buffer(FuseQueue *q) |
| 526 | { |
| 527 | if (q->req_write_data_cached) { |
| 528 | void *cached = q->req_write_data_cached; |
| 529 | q->req_write_data_cached = NULL; |
| 530 | return cached; |
| 531 | } else { |
| 532 | return blk_blockalign(q->exp->common.blk, FUSE_MAX_WRITE_BYTES); |
| 533 | } |
| 534 | } |
| 535 | |
| 536 | /** |
| 537 | * Release a WRITE data buffer, possibly reusing it for a subsequent request. |
| 538 | */ |
| 539 | static void release_write_data_buffer(FuseQueue *q, void **buffer) |
| 540 | { |
| 541 | if (!*buffer) { |
| 542 | return; |
| 543 | } |
| 544 | |
| 545 | if (!q->req_write_data_cached) { |
| 546 | q->req_write_data_cached = *buffer; |
| 547 | } else { |
| 548 | qemu_vfree(*buffer); |
| 549 | } |
| 550 | *buffer = NULL; |
| 551 | } |
| 552 | |
| 553 | /** |
| 554 | * Return the length of the specific operation's own in_header. |
| 555 | * Return -ENOSYS if the operation is not supported. |
| 556 | */ |
| 557 | static ssize_t req_op_hdr_len(const FuseRequestInHeader *in_hdr) |
| 558 | { |
| 559 | switch (in_hdr->common.opcode) { |
| 560 | case FUSE_INIT: |
| 561 | return sizeof(in_hdr->init); |
| 562 | case FUSE_OPEN: |
| 563 | return sizeof(in_hdr->open); |
| 564 | case FUSE_SETATTR: |
| 565 | return sizeof(in_hdr->setattr); |
| 566 | case FUSE_READ: |
| 567 | return sizeof(in_hdr->read); |
| 568 | case FUSE_WRITE: |
| 569 | return sizeof(in_hdr->write); |
| 570 | case FUSE_FALLOCATE: |
| 571 | return sizeof(in_hdr->fallocate); |
| 572 | #ifdef CONFIG_FUSE_LSEEK |
| 573 | case FUSE_LSEEK: |
| 574 | return sizeof(in_hdr->lseek); |
| 575 | #endif |
| 576 | case FUSE_DESTROY: |
| 577 | case FUSE_STATFS: |
| 578 | case FUSE_RELEASE: |
| 579 | case FUSE_LOOKUP: |
| 580 | case FUSE_FORGET: |
| 581 | case FUSE_BATCH_FORGET: |
| 582 | case FUSE_GETATTR: |
| 583 | case FUSE_FSYNC: |
| 584 | case FUSE_FLUSH: |
| 585 | /* These requests don't have their own header or we don't care */ |
| 586 | return 0; |
| 587 | default: |
| 588 | return -ENOSYS; |
| 589 | } |
| 590 | } |
| 591 | |
| 592 | /** |
| 593 | * Clone the given /dev/fuse file descriptor, yielding a second FD from which |
| 594 | * requests can be pulled for the associated filesystem. Returns an FD on |
| 595 | * success, and -errno on error. |
| 596 | */ |
| 597 | static int clone_fuse_fd(int fd, Error **errp) |
| 598 | { |
| 599 | uint32_t src_fd = fd; |
| 600 | int new_fd; |
| 601 | int ret; |
| 602 | |
| 603 | /* |
| 604 | * The name "/dev/fuse" is fixed, see libfuse's lib/fuse_loop_mt.c |
| 605 | * (fuse_clone_chan()). |
| 606 | */ |
| 607 | new_fd = open("/dev/fuse", O_RDWR | O_CLOEXEC | O_NONBLOCK); |
| 608 | if (new_fd < 0) { |
| 609 | ret = -errno; |
| 610 | error_setg_errno(errp, errno, "Failed to open /dev/fuse"); |
| 611 | return ret; |
| 612 | } |
| 613 | |
| 614 | ret = ioctl(new_fd, FUSE_DEV_IOC_CLONE, &src_fd); |
| 615 | if (ret < 0) { |
| 616 | ret = -errno; |
| 617 | error_setg_errno(errp, errno, "Failed to clone FUSE FD"); |
| 618 | close(new_fd); |
| 619 | return ret; |
| 620 | } |
| 621 | |
| 622 | return new_fd; |
| 623 | } |
| 624 | |
| 625 | /** |
| 626 | * Check whether the smaller older fuse_init_in structure from before protocol |
| 627 | * version 7.36 is used. The flags2 member and other new members must be treated |
| 628 | * as absent then. |
| 629 | */ |
| 630 | static bool using_old_fuse_init_in(const struct fuse_init_in *in) |
| 631 | { |
| 632 | return in->major < 7 || (in->major == 7 && in->minor < 36); |
| 633 | } |
| 634 | |
| 635 | /** |
| 636 | * Try to read a single request from the FUSE FD. |
| 637 | * Takes a FuseQueue pointer in `opaque`. |
| 638 | * |
| 639 | * Assumes the export's in-flight counter has already been incremented. |
| 640 | * |
| 641 | * If a request is available, process it. |
| 642 | */ |
| 643 | static void coroutine_fn co_read_from_fuse_fd(void *opaque) |
| 644 | { |
| 645 | FuseQueue *q = opaque; |
| 646 | int fuse_fd = q->fuse_fd; |
| 647 | FuseExport *exp = q->exp; |
| 648 | ssize_t ret; |
| 649 | FuseRequestInHeaderBuf in_hdr_buf; |
| 650 | const FuseRequestInHeader *in_hdr; |
| 651 | void *data_buffer = NULL; |
| 652 | struct iovec iov[2]; |
| 653 | ssize_t op_hdr_len; |
| 654 | |
| 655 | if (unlikely(qatomic_read(&exp->halted))) { |
| 656 | goto no_request; |
| 657 | } |
| 658 | |
| 659 | data_buffer = get_write_data_buffer(q); |
| 660 | |
| 661 | /* Construct the I/O vector to hold the FUSE request */ |
| 662 | iov[0] = (struct iovec) { &in_hdr_buf.head, sizeof(in_hdr_buf.head) }; |
| 663 | iov[1] = (struct iovec) { data_buffer, FUSE_MAX_WRITE_BYTES }; |
| 664 | ret = RETRY_ON_EINTR(readv(fuse_fd, iov, ARRAY_SIZE(iov))); |
| 665 | if (ret < 0 && errno == EAGAIN) { |
| 666 | /* No request available */ |
| 667 | goto no_request; |
| 668 | } else if (unlikely(ret < 0)) { |
| 669 | error_report("Failed to read from FUSE device: %s", strerror(errno)); |
| 670 | goto no_request; |
| 671 | } |
| 672 | |
| 673 | if (unlikely(ret < sizeof(in_hdr->common))) { |
| 674 | error_report("Incomplete read from FUSE device, expected at least %zu " |
| 675 | "bytes, read %zi bytes; cannot trust subsequent " |
| 676 | "requests, halting the export", |
| 677 | sizeof(in_hdr->common), ret); |
| 678 | fuse_export_halt(exp); |
| 679 | goto no_request; |
| 680 | } |
| 681 | in_hdr = &in_hdr_buf.structured; |
| 682 | |
| 683 | if (unlikely(ret != in_hdr->common.len)) { |
| 684 | error_report("Number of bytes read from FUSE device does not match " |
| 685 | "request size, expected %" PRIu32 " bytes, read %zi " |
| 686 | "bytes; cannot trust subsequent requests, halting the " |
| 687 | "export", |
| 688 | in_hdr->common.len, ret); |
| 689 | fuse_export_halt(exp); |
| 690 | goto no_request; |
| 691 | } |
| 692 | |
| 693 | op_hdr_len = req_op_hdr_len(in_hdr); |
| 694 | if (op_hdr_len < 0) { |
| 695 | fuse_write_err(fuse_fd, &in_hdr->common, op_hdr_len); |
| 696 | goto no_request; |
| 697 | } |
| 698 | |
| 699 | /* |
| 700 | * If the request is of type FUSE_INIT, need to check the version to |
| 701 | * actually determine the length of the fuse_init_in structure used by the |
| 702 | * kernel. In protocol version 7.36, the structure was extended. |
| 703 | */ |
| 704 | if (in_hdr->common.opcode == FUSE_INIT) { |
| 705 | /* Length of the fuse_init_in structure before 7.36. */ |
| 706 | size_t old_init_hdr_len = 16; |
| 707 | |
| 708 | /* |
| 709 | * Expect at least the size of the smaller older structure to ensure the |
| 710 | * version can be checked. |
| 711 | */ |
| 712 | if (unlikely(ret < sizeof(in_hdr->common) + old_init_hdr_len)) { |
| 713 | error_report("FUSE_INIT request truncated, read only %zi bytes", |
| 714 | ret); |
| 715 | fuse_write_err(fuse_fd, &in_hdr->common, -EINVAL); |
| 716 | goto no_request; |
| 717 | } |
| 718 | |
| 719 | if (using_old_fuse_init_in(&in_hdr->init)) { |
| 720 | op_hdr_len = old_init_hdr_len; |
| 721 | } |
| 722 | } |
| 723 | |
| 724 | if (unlikely(ret < sizeof(in_hdr->common) + op_hdr_len)) { |
| 725 | error_report("FUSE request truncated, expected %zu bytes, read %zi " |
| 726 | "bytes", |
| 727 | sizeof(in_hdr->common) + op_hdr_len, ret); |
| 728 | fuse_write_err(fuse_fd, &in_hdr->common, -EINVAL); |
| 729 | goto no_request; |
| 730 | } |
| 731 | |
| 732 | /* |
| 733 | * Only WRITE uses the write data buffer, so for non-WRITE requests longer |
| 734 | * than .head, we need to copy any data that spilled into data_buffer into |
| 735 | * .tail. Then we can release the write data buffer. |
| 736 | */ |
| 737 | if (in_hdr->common.opcode != FUSE_WRITE) { |
| 738 | if (ret > sizeof(in_hdr_buf.head)) { |
| 739 | size_t len; |
| 740 | /* Limit size to prevent overflow */ |
| 741 | len = MIN(ret - sizeof(in_hdr_buf.head), sizeof(in_hdr_buf.tail)); |
| 742 | memcpy(in_hdr_buf.tail, data_buffer, len); |
| 743 | } |
| 744 | |
| 745 | release_write_data_buffer(q, &data_buffer); |
| 746 | } |
| 747 | |
| 748 | fuse_co_process_request(q, in_hdr, data_buffer); |
| 749 | |
| 750 | no_request: |
| 751 | release_write_data_buffer(q, &data_buffer); |
| 752 | fuse_dec_in_flight(exp); |
| 753 | } |
| 754 | |
| 755 | /** |
| 756 | * Try to read and process a single request from the FUSE FD. |
| 757 | * (To be used as a handler for when the FUSE FD becomes readable.) |
| 758 | * Takes a FuseQueue pointer in `opaque`. |
| 759 | */ |
| 760 | static void read_from_fuse_fd(void *opaque) |
| 761 | { |
| 762 | FuseQueue *q = opaque; |
| 763 | Coroutine *co; |
| 764 | |
| 765 | co = qemu_coroutine_create(co_read_from_fuse_fd, q); |
| 766 | /* Decremented by co_read_from_fuse_fd() */ |
| 767 | fuse_inc_in_flight(q->exp); |
| 768 | qemu_coroutine_enter(co); |
| 769 | } |
| 770 | |
| 771 | static void fuse_export_shutdown(BlockExport *blk_exp) |
| 772 | { |
| 773 | FuseExport *exp = container_of(blk_exp, FuseExport, common); |
| 774 | |
| 775 | if (exp->fd_handler_set_up) { |
| 776 | fuse_detach_handlers(exp); |
| 777 | } |
| 778 | |
| 779 | if (exp->mountpoint) { |
| 780 | /* |
| 781 | * Safe to drop now, because we will not handle any requests for this |
| 782 | * export anymore anyway (at least not from the main thread). |
| 783 | */ |
| 784 | g_hash_table_remove(exports, exp->mountpoint); |
| 785 | } |
| 786 | } |
| 787 | |
| 788 | static void fuse_export_delete(BlockExport *blk_exp) |
| 789 | { |
| 790 | FuseExport *exp = container_of(blk_exp, FuseExport, common); |
| 791 | |
| 792 | for (int i = 0; i < exp->num_queues; i++) { |
| 793 | FuseQueue *q = &exp->queues[i]; |
| 794 | |
| 795 | /* Queue 0's FD belongs to the FUSE session */ |
| 796 | if (i > 0 && q->fuse_fd >= 0) { |
| 797 | close(q->fuse_fd); |
| 798 | } |
| 799 | qemu_vfree(q->req_write_data_cached); |
| 800 | } |
| 801 | g_free(exp->queues); |
| 802 | |
| 803 | if (exp->fuse_session) { |
| 804 | if (exp->mounted) { |
| 805 | fuse_session_unmount(exp->fuse_session); |
| 806 | } |
| 807 | |
| 808 | fuse_session_destroy(exp->fuse_session); |
| 809 | } |
| 810 | |
| 811 | g_free(exp->mountpoint); |
| 812 | } |
| 813 | |
| 814 | /** |
| 815 | * Halt the export: Detach FD handlers, and set exp->halted to true, preventing |
| 816 | * fuse_attach_handlers() from re-attaching them, therefore stopping all further |
| 817 | * request processing. |
| 818 | * |
| 819 | * Call this function when an unrecoverable error happens that makes processing |
| 820 | * all future requests unreliable. |
| 821 | */ |
| 822 | static void fuse_export_halt(FuseExport *exp) |
| 823 | { |
| 824 | qatomic_set(&exp->halted, true); |
| 825 | fuse_detach_handlers(exp); |
| 826 | } |
| 827 | |
| 828 | /** |
| 829 | * Check whether @path points to a regular file. If not, put an |
| 830 | * appropriate message into *errp. |
| 831 | */ |
| 832 | static bool is_regular_file(const char *path, Error **errp) |
| 833 | { |
| 834 | struct stat statbuf; |
| 835 | int ret; |
| 836 | |
| 837 | ret = stat(path, &statbuf); |
| 838 | if (ret < 0) { |
| 839 | error_setg_errno(errp, errno, "Failed to stat '%s'", path); |
| 840 | return false; |
| 841 | } |
| 842 | |
| 843 | if (!S_ISREG(statbuf.st_mode)) { |
| 844 | error_setg(errp, "'%s' is not a regular file", path); |
| 845 | return false; |
| 846 | } |
| 847 | |
| 848 | return true; |
| 849 | } |
| 850 | |
| 851 | /** |
| 852 | * Process FUSE INIT. |
| 853 | * Return the number of bytes written to *out on success, and -errno on error. |
| 854 | */ |
| 855 | static ssize_t coroutine_fn GRAPH_RDLOCK |
| 856 | fuse_co_init(FuseExport *exp, struct fuse_init_out *out, |
| 857 | const struct fuse_init_in *in) |
| 858 | { |
| 859 | uint32_t supported_flags = FUSE_ASYNC_READ | FUSE_ASYNC_DIO; |
| 860 | uint32_t flags2 = 0; |
| 861 | |
| 862 | if (!exp->growable) { |
| 863 | /* |
| 864 | * Back when libfuse was used, it would always set this flag and thus |
| 865 | * the kernel did not execute a truncate itself and passed along O_TRUNC |
| 866 | * to user space. Continue setting the flag for backwards compatibility |
| 867 | * when the export is not growable to avoid issues with O_TRUNC, i.e. |
| 868 | * blockdev-based exports running into ENOTSUP and file-based exports |
| 869 | * with growable=off to be truncated and then stuck with size 0. |
| 870 | */ |
| 871 | supported_flags = FUSE_ATOMIC_O_TRUNC; |
| 872 | } |
| 873 | |
| 874 | if (in->major != 7) { |
| 875 | error_report("FUSE major version mismatch: We have 7, but kernel has %" |
| 876 | PRIu32, in->major); |
| 877 | return -EINVAL; |
| 878 | } |
| 879 | |
| 880 | /* 2007's 7.9 added fuse_attr.blksize; working around that would be hard */ |
| 881 | if (in->minor < 9) { |
| 882 | error_report("FUSE minor version too old: 9 required, but kernel has %" |
| 883 | PRIu32, in->minor); |
| 884 | return -EINVAL; |
| 885 | } |
| 886 | |
| 887 | if (!using_old_fuse_init_in(in)) { |
| 888 | /* The flags2 flags must be shifted down by 32 bits. */ |
| 889 | const uint32_t supported_flags2 = FUSE_DIRECT_IO_ALLOW_MMAP >> 32; |
| 890 | /* flags2 is only considered if FUSE_INIT_EXT is set. */ |
| 891 | supported_flags = supported_flags | FUSE_INIT_EXT; |
| 892 | flags2 = in->flags2 & supported_flags2; |
| 893 | } |
| 894 | |
| 895 | *out = (struct fuse_init_out) { |
| 896 | .major = 7, |
| 897 | .minor = MIN(FUSE_KERNEL_MINOR_VERSION, in->minor), |
| 898 | .max_readahead = in->max_readahead, |
| 899 | .max_write = FUSE_MAX_WRITE_BYTES, |
| 900 | .flags = in->flags & supported_flags, |
| 901 | .flags2 = flags2, |
| 902 | |
| 903 | /* libfuse maximum: 2^16 - 1 */ |
| 904 | .max_background = UINT16_MAX, |
| 905 | |
| 906 | /* libfuse default: max_background * 3 / 4 */ |
| 907 | .congestion_threshold = (int)UINT16_MAX * 3 / 4, |
| 908 | |
| 909 | /* libfuse default: 1 */ |
| 910 | .time_gran = 1, |
| 911 | |
| 912 | /* |
| 913 | * probably unneeded without FUSE_MAX_PAGES, but this would be the |
| 914 | * libfuse default |
| 915 | */ |
| 916 | .max_pages = DIV_ROUND_UP(FUSE_MAX_WRITE_BYTES, |
| 917 | qemu_real_host_page_size()), |
| 918 | |
| 919 | /* Only needed for mappings (i.e. DAX) */ |
| 920 | .map_alignment = 0, |
| 921 | }; |
| 922 | |
| 923 | /* |
| 924 | * Before 7.23, fuse_init_out is shorter. |
| 925 | * Drop the tail (time_gran, max_pages, map_alignment). |
| 926 | */ |
| 927 | return out->minor >= 23 ? sizeof(*out) : FUSE_COMPAT_22_INIT_OUT_SIZE; |
| 928 | } |
| 929 | |
| 930 | /** |
| 931 | * Return some filesystem information, just to not break e.g. `df`. |
| 932 | */ |
| 933 | static ssize_t coroutine_fn GRAPH_RDLOCK |
| 934 | fuse_co_statfs(FuseExport *exp, struct fuse_statfs_out *out) |
| 935 | { |
| 936 | BlockDriverState *root_bs; |
| 937 | uint32_t opt_transfer = 512; |
| 938 | |
| 939 | root_bs = blk_bs(exp->common.blk); |
| 940 | if (root_bs) { |
| 941 | opt_transfer = root_bs->bl.opt_transfer; |
| 942 | if (!opt_transfer) { |
| 943 | opt_transfer = root_bs->bl.request_alignment; |
| 944 | } |
| 945 | opt_transfer = MAX(opt_transfer, 512); |
| 946 | } |
| 947 | |
| 948 | *out = (struct fuse_statfs_out) { |
| 949 | /* These are the fields libfuse sets by default */ |
| 950 | .st = { |
| 951 | .namelen = 255, |
| 952 | .bsize = opt_transfer, |
| 953 | }, |
| 954 | }; |
| 955 | return sizeof(*out); |
| 956 | } |
| 957 | |
| 958 | /** |
| 959 | * Let clients get file attributes (i.e., stat() the file). |
| 960 | * Return the number of bytes written to *out on success, and -errno on error. |
| 961 | */ |
| 962 | static ssize_t coroutine_fn GRAPH_RDLOCK |
| 963 | fuse_co_getattr(FuseExport *exp, struct fuse_attr_out *out) |
| 964 | { |
| 965 | int64_t length, allocated_blocks; |
| 966 | time_t now = time(NULL); |
| 967 | |
| 968 | length = blk_co_getlength(exp->common.blk); |
| 969 | if (length < 0) { |
| 970 | return length; |
| 971 | } |
| 972 | |
| 973 | allocated_blocks = bdrv_co_get_allocated_file_size(blk_bs(exp->common.blk)); |
| 974 | if (allocated_blocks <= 0) { |
| 975 | allocated_blocks = DIV_ROUND_UP(length, 512); |
| 976 | } else { |
| 977 | allocated_blocks = DIV_ROUND_UP(allocated_blocks, 512); |
| 978 | } |
| 979 | |
| 980 | *out = (struct fuse_attr_out) { |
| 981 | .attr_valid = 1, |
| 982 | .attr = { |
| 983 | .ino = 1, |
| 984 | .mode = qatomic_read(&exp->st_mode), |
| 985 | .nlink = 1, |
| 986 | .uid = qatomic_read(&exp->st_uid), |
| 987 | .gid = qatomic_read(&exp->st_gid), |
| 988 | .size = length, |
| 989 | .blksize = blk_bs(exp->common.blk)->bl.request_alignment, |
| 990 | .blocks = allocated_blocks, |
| 991 | .atime = now, |
| 992 | .mtime = now, |
| 993 | .ctime = now, |
| 994 | }, |
| 995 | }; |
| 996 | |
| 997 | return sizeof(*out); |
| 998 | } |
| 999 | |
| 1000 | static int coroutine_fn GRAPH_RDLOCK |
| 1001 | fuse_co_do_truncate(const FuseExport *exp, int64_t size, bool req_zero_write, |
| 1002 | PreallocMode prealloc) |
| 1003 | { |
| 1004 | BdrvRequestFlags truncate_flags = 0; |
| 1005 | |
| 1006 | if (req_zero_write) { |
| 1007 | truncate_flags |= BDRV_REQ_ZERO_WRITE; |
| 1008 | } |
| 1009 | |
| 1010 | return blk_co_truncate(exp->common.blk, size, true, prealloc, |
| 1011 | truncate_flags, NULL); |
| 1012 | } |
| 1013 | |
| 1014 | /** |
| 1015 | * Let clients set file attributes. Only resizing and changing |
| 1016 | * permissions (st_mode, st_uid, st_gid) is allowed. |
| 1017 | * Changing permissions is only allowed as far as it will actually |
| 1018 | * permit access: Read-only exports cannot be given +w, and exports |
| 1019 | * without allow_other cannot be given a different UID or GID, and |
| 1020 | * they cannot be given non-owner access. |
| 1021 | * Return the number of bytes written to *out on success, and -errno on error. |
| 1022 | */ |
| 1023 | static ssize_t coroutine_fn GRAPH_RDLOCK |
| 1024 | fuse_co_setattr(FuseExport *exp, struct fuse_attr_out *out, uint32_t to_set, |
| 1025 | uint64_t size, uint32_t mode, uint32_t uid, uint32_t gid) |
| 1026 | { |
| 1027 | int supported_attrs; |
| 1028 | int ret; |
| 1029 | |
| 1030 | /* SIZE and MODE are actually supported, the others can be safely ignored */ |
| 1031 | supported_attrs = FATTR_SIZE | FATTR_MODE | |
| 1032 | FATTR_FH | FATTR_LOCKOWNER | FATTR_KILL_SUIDGID; |
| 1033 | if (exp->allow_other) { |
| 1034 | supported_attrs |= FATTR_UID | FATTR_GID; |
| 1035 | } |
| 1036 | |
| 1037 | if (to_set & ~supported_attrs) { |
| 1038 | return -ENOTSUP; |
| 1039 | } |
| 1040 | |
| 1041 | /* Do some argument checks first before committing to anything */ |
| 1042 | if (to_set & FATTR_MODE) { |
| 1043 | /* |
| 1044 | * Without allow_other, non-owners can never access the export, so do |
| 1045 | * not allow setting permissions for them |
| 1046 | */ |
| 1047 | if (!exp->allow_other && (mode & (S_IRWXG | S_IRWXO)) != 0) { |
| 1048 | return -EPERM; |
| 1049 | } |
| 1050 | |
| 1051 | /* +w for read-only exports makes no sense, disallow it */ |
| 1052 | if (!exp->writable && (mode & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0) { |
| 1053 | return -EROFS; |
| 1054 | } |
| 1055 | } |
| 1056 | |
| 1057 | if (to_set & FATTR_SIZE) { |
| 1058 | if (!exp->writable) { |
| 1059 | return -EACCES; |
| 1060 | } |
| 1061 | |
| 1062 | ret = fuse_co_do_truncate(exp, size, true, PREALLOC_MODE_OFF); |
| 1063 | if (ret < 0) { |
| 1064 | return ret; |
| 1065 | } |
| 1066 | } |
| 1067 | |
| 1068 | if (to_set & FATTR_MODE) { |
| 1069 | /* Ignore FUSE-supplied file type, only change the mode */ |
| 1070 | qatomic_set(&exp->st_mode, (mode & 07777) | S_IFREG); |
| 1071 | } |
| 1072 | |
| 1073 | if (to_set & FATTR_UID) { |
| 1074 | qatomic_set(&exp->st_uid, uid); |
| 1075 | } |
| 1076 | |
| 1077 | if (to_set & FATTR_GID) { |
| 1078 | qatomic_set(&exp->st_gid, gid); |
| 1079 | } |
| 1080 | |
| 1081 | return fuse_co_getattr(exp, out); |
| 1082 | } |
| 1083 | |
| 1084 | /** |
| 1085 | * Open an inode. We only have a single inode in our exported filesystem, so we |
| 1086 | * just acknowledge the request. |
| 1087 | * Return the number of bytes written to *out on success, and -errno on error. |
| 1088 | */ |
| 1089 | static ssize_t coroutine_fn GRAPH_RDLOCK |
| 1090 | fuse_co_open(FuseExport *exp, struct fuse_open_out *out) |
| 1091 | { |
| 1092 | *out = (struct fuse_open_out) { |
| 1093 | .open_flags = FOPEN_DIRECT_IO | FOPEN_PARALLEL_DIRECT_WRITES, |
| 1094 | }; |
| 1095 | return sizeof(*out); |
| 1096 | } |
| 1097 | |
| 1098 | /** |
| 1099 | * Handle client reads from the exported image. Allocates *bufptr and reads |
| 1100 | * data from the block device into that buffer. |
| 1101 | * Returns the buffer (read) size on success, and -errno on error. |
| 1102 | * Note: If the returned size is 0, *bufptr will be set to NULL. |
| 1103 | * After use, *bufptr must be freed via qemu_vfree(). |
| 1104 | */ |
| 1105 | static ssize_t coroutine_fn GRAPH_RDLOCK |
| 1106 | fuse_co_read(FuseExport *exp, void **bufptr, uint64_t offset, uint32_t size) |
| 1107 | { |
| 1108 | int64_t blk_len; |
| 1109 | void *buf; |
| 1110 | int ret; |
| 1111 | |
| 1112 | /* Limited by max_read, should not happen */ |
| 1113 | if (size > FUSE_MAX_READ_BYTES) { |
| 1114 | return -EINVAL; |
| 1115 | } |
| 1116 | |
| 1117 | /** |
| 1118 | * Clients will expect short reads at EOF, so we have to limit |
| 1119 | * offset+size to the image length. |
| 1120 | */ |
| 1121 | blk_len = blk_co_getlength(exp->common.blk); |
| 1122 | if (blk_len < 0) { |
| 1123 | return blk_len; |
| 1124 | } |
| 1125 | |
| 1126 | if (offset >= blk_len) { |
| 1127 | /* Explicitly set to NULL because we return success here */ |
| 1128 | *bufptr = NULL; |
| 1129 | return 0; |
| 1130 | } |
| 1131 | |
| 1132 | if (offset + size > blk_len) { |
| 1133 | size = blk_len - offset; |
| 1134 | } |
| 1135 | |
| 1136 | buf = qemu_try_blockalign(blk_bs(exp->common.blk), size); |
| 1137 | if (!buf) { |
| 1138 | return -ENOMEM; |
| 1139 | } |
| 1140 | |
| 1141 | ret = blk_co_pread(exp->common.blk, offset, size, buf, 0); |
| 1142 | if (ret < 0) { |
| 1143 | qemu_vfree(buf); |
| 1144 | return ret; |
| 1145 | } |
| 1146 | |
| 1147 | *bufptr = buf; |
| 1148 | return size; |
| 1149 | } |
| 1150 | |
| 1151 | /** |
| 1152 | * Handle client writes to the exported image. @buf has the data to be written. |
| 1153 | * Return the number of bytes written to *out on success, and -errno on error. |
| 1154 | */ |
| 1155 | static ssize_t coroutine_fn GRAPH_RDLOCK |
| 1156 | fuse_co_write(FuseExport *exp, struct fuse_write_out *out, |
| 1157 | uint64_t offset, uint32_t size, const void *buf) |
| 1158 | { |
| 1159 | int64_t blk_len; |
| 1160 | int ret; |
| 1161 | |
| 1162 | QEMU_BUILD_BUG_ON(FUSE_MAX_WRITE_BYTES > BDRV_REQUEST_MAX_BYTES); |
| 1163 | /* Limited by max_write, should not happen */ |
| 1164 | if (size > FUSE_MAX_WRITE_BYTES) { |
| 1165 | return -EINVAL; |
| 1166 | } |
| 1167 | |
| 1168 | if (!exp->writable) { |
| 1169 | return -EACCES; |
| 1170 | } |
| 1171 | |
| 1172 | /** |
| 1173 | * Clients will expect short writes at EOF, so we have to limit |
| 1174 | * offset+size to the image length. |
| 1175 | */ |
| 1176 | blk_len = blk_co_getlength(exp->common.blk); |
| 1177 | if (blk_len < 0) { |
| 1178 | return blk_len; |
| 1179 | } |
| 1180 | |
| 1181 | if (offset >= blk_len && !exp->growable) { |
| 1182 | *out = (struct fuse_write_out) { |
| 1183 | .size = 0, |
| 1184 | }; |
| 1185 | return sizeof(*out); |
| 1186 | } |
| 1187 | |
| 1188 | if (offset + size < offset) { |
| 1189 | return -EINVAL; |
| 1190 | } else if (offset + size > blk_len) { |
| 1191 | if (exp->growable) { |
| 1192 | ret = fuse_co_do_truncate(exp, offset + size, true, |
| 1193 | PREALLOC_MODE_OFF); |
| 1194 | if (ret < 0) { |
| 1195 | return ret; |
| 1196 | } |
| 1197 | } else { |
| 1198 | size = blk_len - offset; |
| 1199 | } |
| 1200 | } |
| 1201 | |
| 1202 | ret = blk_co_pwrite(exp->common.blk, offset, size, buf, 0); |
| 1203 | if (ret < 0) { |
| 1204 | return ret; |
| 1205 | } |
| 1206 | |
| 1207 | *out = (struct fuse_write_out) { |
| 1208 | .size = size, |
| 1209 | }; |
| 1210 | return sizeof(*out); |
| 1211 | } |
| 1212 | |
| 1213 | /** |
| 1214 | * Let clients perform various fallocate() operations. |
| 1215 | * Return 0 on success (no 'out' object), and -errno on error. |
| 1216 | */ |
| 1217 | static ssize_t coroutine_fn GRAPH_RDLOCK |
| 1218 | fuse_co_fallocate(FuseExport *exp, |
| 1219 | uint64_t offset, uint64_t length, uint32_t mode) |
| 1220 | { |
| 1221 | int64_t blk_len; |
| 1222 | int ret; |
| 1223 | |
| 1224 | if (!exp->writable) { |
| 1225 | return -EACCES; |
| 1226 | } |
| 1227 | |
| 1228 | blk_len = blk_co_getlength(exp->common.blk); |
| 1229 | if (blk_len < 0) { |
| 1230 | return blk_len; |
| 1231 | } |
| 1232 | |
| 1233 | #ifdef CONFIG_FALLOCATE_PUNCH_HOLE |
| 1234 | if (mode & FALLOC_FL_KEEP_SIZE) { |
| 1235 | length = MIN(length, blk_len - offset); |
| 1236 | } |
| 1237 | #endif /* CONFIG_FALLOCATE_PUNCH_HOLE */ |
| 1238 | |
| 1239 | if (!mode) { |
| 1240 | /* We can only fallocate at the EOF with a truncate */ |
| 1241 | if (offset < blk_len) { |
| 1242 | return -EOPNOTSUPP; |
| 1243 | } |
| 1244 | |
| 1245 | if (offset > blk_len) { |
| 1246 | /* No preallocation needed here */ |
| 1247 | ret = fuse_co_do_truncate(exp, offset, true, PREALLOC_MODE_OFF); |
| 1248 | if (ret < 0) { |
| 1249 | return ret; |
| 1250 | } |
| 1251 | } |
| 1252 | |
| 1253 | ret = fuse_co_do_truncate(exp, offset + length, true, |
| 1254 | PREALLOC_MODE_FALLOC); |
| 1255 | } |
| 1256 | #ifdef CONFIG_FALLOCATE_PUNCH_HOLE |
| 1257 | else if (mode & FALLOC_FL_PUNCH_HOLE) { |
| 1258 | if (!(mode & FALLOC_FL_KEEP_SIZE)) { |
| 1259 | return -EINVAL; |
| 1260 | } |
| 1261 | |
| 1262 | do { |
| 1263 | int size = MIN(length, BDRV_REQUEST_MAX_BYTES); |
| 1264 | |
| 1265 | ret = blk_co_pwrite_zeroes(exp->common.blk, offset, size, |
| 1266 | BDRV_REQ_MAY_UNMAP | |
| 1267 | BDRV_REQ_NO_FALLBACK); |
| 1268 | if (ret == -ENOTSUP) { |
| 1269 | /* |
| 1270 | * fallocate() specifies to return EOPNOTSUPP for unsupported |
| 1271 | * operations |
| 1272 | */ |
| 1273 | ret = -EOPNOTSUPP; |
| 1274 | } |
| 1275 | |
| 1276 | offset += size; |
| 1277 | length -= size; |
| 1278 | } while (ret == 0 && length > 0); |
| 1279 | } |
| 1280 | #endif /* CONFIG_FALLOCATE_PUNCH_HOLE */ |
| 1281 | #ifdef CONFIG_FALLOCATE_ZERO_RANGE |
| 1282 | else if (mode & FALLOC_FL_ZERO_RANGE) { |
| 1283 | if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + length > blk_len) { |
| 1284 | /* No need for zeroes, we are going to write them ourselves */ |
| 1285 | ret = fuse_co_do_truncate(exp, offset + length, false, |
| 1286 | PREALLOC_MODE_OFF); |
| 1287 | if (ret < 0) { |
| 1288 | return ret; |
| 1289 | } |
| 1290 | } |
| 1291 | |
| 1292 | do { |
| 1293 | int size = MIN(length, BDRV_REQUEST_MAX_BYTES); |
| 1294 | |
| 1295 | ret = blk_co_pwrite_zeroes(exp->common.blk, |
| 1296 | offset, size, 0); |
| 1297 | offset += size; |
| 1298 | length -= size; |
| 1299 | } while (ret == 0 && length > 0); |
| 1300 | } |
| 1301 | #endif /* CONFIG_FALLOCATE_ZERO_RANGE */ |
| 1302 | else { |
| 1303 | ret = -EOPNOTSUPP; |
| 1304 | } |
| 1305 | |
| 1306 | return ret < 0 ? ret : 0; |
| 1307 | } |
| 1308 | |
| 1309 | /** |
| 1310 | * Let clients fsync the exported image. |
| 1311 | * Return 0 on success (no 'out' object), and -errno on error. |
| 1312 | */ |
| 1313 | static ssize_t coroutine_fn GRAPH_RDLOCK fuse_co_fsync(FuseExport *exp) |
| 1314 | { |
| 1315 | return blk_co_flush(exp->common.blk); |
| 1316 | } |
| 1317 | |
| 1318 | /** |
| 1319 | * Called before an FD to the exported image is closed. (libfuse |
| 1320 | * notes this to be a way to return last-minute errors.) |
| 1321 | * Return 0 on success (no 'out' object), and -errno on error. |
| 1322 | */ |
| 1323 | static ssize_t coroutine_fn GRAPH_RDLOCK fuse_co_flush(FuseExport *exp) |
| 1324 | { |
| 1325 | return blk_co_flush(exp->common.blk); |
| 1326 | } |
| 1327 | |
| 1328 | #ifdef CONFIG_FUSE_LSEEK |
| 1329 | /** |
| 1330 | * Let clients inquire allocation status. |
| 1331 | * Return the number of bytes written to *out on success, and -errno on error. |
| 1332 | */ |
| 1333 | static ssize_t coroutine_fn GRAPH_RDLOCK |
| 1334 | fuse_co_lseek(FuseExport *exp, struct fuse_lseek_out *out, |
| 1335 | uint64_t offset, uint32_t whence) |
| 1336 | { |
| 1337 | if (whence != SEEK_HOLE && whence != SEEK_DATA) { |
| 1338 | return -EINVAL; |
| 1339 | } |
| 1340 | |
| 1341 | while (true) { |
| 1342 | int64_t pnum; |
| 1343 | int ret; |
| 1344 | |
| 1345 | ret = bdrv_co_block_status_above(blk_bs(exp->common.blk), NULL, |
| 1346 | offset, INT64_MAX, &pnum, NULL, NULL); |
| 1347 | if (ret < 0) { |
| 1348 | return ret; |
| 1349 | } |
| 1350 | |
| 1351 | if (!pnum && (ret & BDRV_BLOCK_EOF)) { |
| 1352 | int64_t blk_len; |
| 1353 | |
| 1354 | /* |
| 1355 | * If blk_getlength() rounds (e.g. by sectors), then the |
| 1356 | * export length will be rounded, too. However, |
| 1357 | * bdrv_block_status_above() may return EOF at unaligned |
| 1358 | * offsets. We must not let this become visible and thus |
| 1359 | * always simulate a hole between @offset (the real EOF) |
| 1360 | * and @blk_len (the client-visible EOF). |
| 1361 | */ |
| 1362 | |
| 1363 | blk_len = blk_co_getlength(exp->common.blk); |
| 1364 | if (blk_len < 0) { |
| 1365 | return blk_len; |
| 1366 | } |
| 1367 | |
| 1368 | if (offset > blk_len || whence == SEEK_DATA) { |
| 1369 | return -ENXIO; |
| 1370 | } |
| 1371 | |
| 1372 | *out = (struct fuse_lseek_out) { |
| 1373 | .offset = offset, |
| 1374 | }; |
| 1375 | return sizeof(*out); |
| 1376 | } |
| 1377 | |
| 1378 | if (ret & BDRV_BLOCK_DATA) { |
| 1379 | if (whence == SEEK_DATA) { |
| 1380 | *out = (struct fuse_lseek_out) { |
| 1381 | .offset = offset, |
| 1382 | }; |
| 1383 | return sizeof(*out); |
| 1384 | } |
| 1385 | } else { |
| 1386 | if (whence == SEEK_HOLE) { |
| 1387 | *out = (struct fuse_lseek_out) { |
| 1388 | .offset = offset, |
| 1389 | }; |
| 1390 | return sizeof(*out); |
| 1391 | } |
| 1392 | } |
| 1393 | |
| 1394 | /* Safety check against infinite loops */ |
| 1395 | if (!pnum) { |
| 1396 | return -ENXIO; |
| 1397 | } |
| 1398 | |
| 1399 | offset += pnum; |
| 1400 | } |
| 1401 | } |
| 1402 | #endif |
| 1403 | |
| 1404 | /** |
| 1405 | * Write a FUSE response to the given @fd. |
| 1406 | * |
| 1407 | * Effectively, writes out_hdr->common.len bytes of the buffer that is *out_hdr. |
| 1408 | * |
| 1409 | * @fd: FUSE file descriptor |
| 1410 | * @out_hdr: Request response header and request-specific response data |
| 1411 | */ |
| 1412 | static int fuse_write_response(int fd, FuseRequestOutHeader *out_hdr) |
| 1413 | { |
| 1414 | size_t to_write = out_hdr->common.len; |
| 1415 | ssize_t ret; |
| 1416 | |
| 1417 | /* Must at least write fuse_out_header */ |
| 1418 | assert(to_write >= sizeof(out_hdr->common)); |
| 1419 | |
| 1420 | ret = RETRY_ON_EINTR(write(fd, out_hdr, to_write)); |
| 1421 | if (ret < 0) { |
| 1422 | ret = -errno; |
| 1423 | error_report("Failed to write to FUSE device: %s", strerror(-ret)); |
| 1424 | return ret; |
| 1425 | } |
| 1426 | |
| 1427 | /* Short writes are unexpected, treat them as errors */ |
| 1428 | if (ret != to_write) { |
| 1429 | error_report("Short write to FUSE device, wrote %zi of %zu bytes", |
| 1430 | ret, to_write); |
| 1431 | return -EIO; |
| 1432 | } |
| 1433 | |
| 1434 | return 0; |
| 1435 | } |
| 1436 | |
| 1437 | /** |
| 1438 | * Write a FUSE error response to @fd. |
| 1439 | * |
| 1440 | * @fd: FUSE file descriptor |
| 1441 | * @in_hdr: Incoming request header to which to respond |
| 1442 | * @err: Error code (-errno, must be negative!) |
| 1443 | */ |
| 1444 | static int fuse_write_err(int fd, const struct fuse_in_header *in_hdr, int err) |
| 1445 | { |
| 1446 | FuseRequestOutHeader out_hdr = { |
| 1447 | .common = { |
| 1448 | .len = sizeof(out_hdr.common), |
| 1449 | /* FUSE expects negative error values */ |
| 1450 | .error = err, |
| 1451 | .unique = in_hdr->unique, |
| 1452 | }, |
| 1453 | }; |
| 1454 | |
| 1455 | return fuse_write_response(fd, &out_hdr); |
| 1456 | } |
| 1457 | |
| 1458 | /** |
| 1459 | * Write a FUSE response to the given @fd, using separate buffers for the |
| 1460 | * response header and data. |
| 1461 | * |
| 1462 | * In contrast to fuse_write_response(), this function cannot return a full |
| 1463 | * FuseRequestOutHeader (i.e. including request-specific response structs), |
| 1464 | * but only FuseRequestOutHeader.common. The remaining data must be in |
| 1465 | * *buf. |
| 1466 | * |
| 1467 | * (Total length must be set in out_hdr->len.) |
| 1468 | * |
| 1469 | * @fd: FUSE file descriptor |
| 1470 | * @out_hdr: Request response header |
| 1471 | * @buf: Pointer to response data |
| 1472 | */ |
| 1473 | static int fuse_write_buf_response(int fd, |
| 1474 | const struct fuse_out_header *out_hdr, |
| 1475 | const void *buf) |
| 1476 | { |
| 1477 | size_t to_write = out_hdr->len; |
| 1478 | struct iovec iov[2] = { |
| 1479 | { (void *)out_hdr, sizeof(*out_hdr) }, |
| 1480 | { (void *)buf, to_write - sizeof(*out_hdr) }, |
| 1481 | }; |
| 1482 | ssize_t ret; |
| 1483 | |
| 1484 | /* *buf length must not be negative */ |
| 1485 | assert(to_write >= sizeof(*out_hdr)); |
| 1486 | |
| 1487 | ret = RETRY_ON_EINTR(writev(fd, iov, ARRAY_SIZE(iov))); |
| 1488 | if (ret < 0) { |
| 1489 | ret = -errno; |
| 1490 | error_report("Failed to write to FUSE device: %s", strerror(-ret)); |
| 1491 | return ret; |
| 1492 | } |
| 1493 | |
| 1494 | /* Short writes are unexpected, treat them as errors */ |
| 1495 | if (ret != to_write) { |
| 1496 | error_report("Short write to FUSE device, wrote %zi of %zu bytes", |
| 1497 | ret, to_write); |
| 1498 | return -EIO; |
| 1499 | } |
| 1500 | |
| 1501 | return 0; |
| 1502 | } |
| 1503 | |
| 1504 | /** |
| 1505 | * Process a FUSE request, incl. writing the response. |
| 1506 | */ |
| 1507 | static void coroutine_fn |
| 1508 | fuse_co_process_request(FuseQueue *q, const FuseRequestInHeader *in_hdr, |
| 1509 | const void *data_buffer) |
| 1510 | { |
| 1511 | FuseRequestOutHeader out_hdr; |
| 1512 | FuseExport *exp = q->exp; |
| 1513 | /* For read requests: Data to be returned */ |
| 1514 | void *out_data_buffer = NULL; |
| 1515 | ssize_t ret; |
| 1516 | |
| 1517 | GRAPH_RDLOCK_GUARD(); |
| 1518 | |
| 1519 | switch (in_hdr->common.opcode) { |
| 1520 | case FUSE_INIT: |
| 1521 | ret = fuse_co_init(exp, &out_hdr.init, &in_hdr->init); |
| 1522 | break; |
| 1523 | |
| 1524 | case FUSE_DESTROY: |
| 1525 | ret = 0; |
| 1526 | break; |
| 1527 | |
| 1528 | case FUSE_STATFS: |
| 1529 | ret = fuse_co_statfs(exp, &out_hdr.statfs); |
| 1530 | break; |
| 1531 | |
| 1532 | case FUSE_OPEN: |
| 1533 | ret = fuse_co_open(exp, &out_hdr.open); |
| 1534 | break; |
| 1535 | |
| 1536 | case FUSE_RELEASE: |
| 1537 | ret = 0; |
| 1538 | break; |
| 1539 | |
| 1540 | case FUSE_LOOKUP: |
| 1541 | ret = -ENOENT; /* There is no node but the root node */ |
| 1542 | break; |
| 1543 | |
| 1544 | case FUSE_FORGET: |
| 1545 | case FUSE_BATCH_FORGET: |
| 1546 | /* These have no response, and there is nothing we need to do */ |
| 1547 | return; |
| 1548 | |
| 1549 | case FUSE_GETATTR: |
| 1550 | ret = fuse_co_getattr(exp, &out_hdr.attr); |
| 1551 | break; |
| 1552 | |
| 1553 | case FUSE_SETATTR: { |
| 1554 | const struct fuse_setattr_in *in = &in_hdr->setattr; |
| 1555 | ret = fuse_co_setattr(exp, &out_hdr.attr, |
| 1556 | in->valid, in->size, in->mode, in->uid, in->gid); |
| 1557 | break; |
| 1558 | } |
| 1559 | |
| 1560 | case FUSE_READ: { |
| 1561 | const struct fuse_read_in *in = &in_hdr->read; |
| 1562 | ret = fuse_co_read(exp, &out_data_buffer, in->offset, in->size); |
| 1563 | break; |
| 1564 | } |
| 1565 | |
| 1566 | case FUSE_WRITE: { |
| 1567 | const struct fuse_write_in *in = &in_hdr->write; |
| 1568 | uint32_t req_len = in_hdr->common.len; |
| 1569 | |
| 1570 | if (unlikely(req_len < sizeof(in_hdr->common) + sizeof(*in) + |
| 1571 | in->size)) { |
| 1572 | warn_report("FUSE WRITE truncated; received %zu bytes of %" PRIu32, |
| 1573 | req_len - sizeof(in_hdr->common) - sizeof(*in), |
| 1574 | in->size); |
| 1575 | ret = -EINVAL; |
| 1576 | break; |
| 1577 | } |
| 1578 | |
| 1579 | /* |
| 1580 | * co_read_from_fuse_fd() has checked that in_hdr->len matches the |
| 1581 | * number of bytes read, which cannot exceed the max_write value we set |
| 1582 | * (FUSE_MAX_WRITE_BYTES). So we know that FUSE_MAX_WRITE_BYTES >= |
| 1583 | * in_hdr->len >= in->size + X, so this assertion must hold. |
| 1584 | */ |
| 1585 | assert(in->size <= FUSE_MAX_WRITE_BYTES); |
| 1586 | |
| 1587 | ret = fuse_co_write(exp, &out_hdr.write, |
| 1588 | in->offset, in->size, data_buffer); |
| 1589 | break; |
| 1590 | } |
| 1591 | |
| 1592 | case FUSE_FALLOCATE: { |
| 1593 | const struct fuse_fallocate_in *in = &in_hdr->fallocate; |
| 1594 | ret = fuse_co_fallocate(exp, in->offset, in->length, in->mode); |
| 1595 | break; |
| 1596 | } |
| 1597 | |
| 1598 | case FUSE_FSYNC: |
| 1599 | ret = fuse_co_fsync(exp); |
| 1600 | break; |
| 1601 | |
| 1602 | case FUSE_FLUSH: |
| 1603 | ret = fuse_co_flush(exp); |
| 1604 | break; |
| 1605 | |
| 1606 | #ifdef CONFIG_FUSE_LSEEK |
| 1607 | case FUSE_LSEEK: { |
| 1608 | const struct fuse_lseek_in *in = &in_hdr->lseek; |
| 1609 | ret = fuse_co_lseek(exp, &out_hdr.lseek, in->offset, in->whence); |
| 1610 | break; |
| 1611 | } |
| 1612 | #endif |
| 1613 | |
| 1614 | default: |
| 1615 | ret = -ENOSYS; |
| 1616 | } |
| 1617 | |
| 1618 | if (ret >= 0) { |
| 1619 | out_hdr.common = (struct fuse_out_header) { |
| 1620 | .len = sizeof(out_hdr.common) + ret, |
| 1621 | .unique = in_hdr->common.unique, |
| 1622 | }; |
| 1623 | } else { |
| 1624 | /* fuse_read() must not return a buffer in case of error */ |
| 1625 | assert(out_data_buffer == NULL); |
| 1626 | |
| 1627 | out_hdr.common = (struct fuse_out_header) { |
| 1628 | .len = sizeof(out_hdr.common), |
| 1629 | /* FUSE expects negative errno values */ |
| 1630 | .error = ret, |
| 1631 | .unique = in_hdr->common.unique, |
| 1632 | }; |
| 1633 | } |
| 1634 | |
| 1635 | if (out_data_buffer) { |
| 1636 | fuse_write_buf_response(q->fuse_fd, &out_hdr.common, out_data_buffer); |
| 1637 | qemu_vfree(out_data_buffer); |
| 1638 | } else { |
| 1639 | fuse_write_response(q->fuse_fd, &out_hdr); |
| 1640 | } |
| 1641 | } |
| 1642 | |
| 1643 | const BlockExportDriver blk_exp_fuse = { |
| 1644 | .type = BLOCK_EXPORT_TYPE_FUSE, |
| 1645 | .instance_size = sizeof(FuseExport), |
| 1646 | .create = fuse_export_create, |
| 1647 | .delete = fuse_export_delete, |
| 1648 | .request_shutdown = fuse_export_shutdown, |
| 1649 | }; |