1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved. 4 */ 5 6 #include <linux/fs.h> 7 #include <linux/filelock.h> 8 #include <linux/miscdevice.h> 9 #include <linux/poll.h> 10 #include <linux/dlm.h> 11 #include <linux/dlm_plock.h> 12 #include <linux/slab.h> 13 14 #include <trace/events/dlm.h> 15 16 #include "dlm_internal.h" 17 #include "lockspace.h" 18 19 static DEFINE_SPINLOCK(ops_lock); 20 static LIST_HEAD(send_list); 21 static LIST_HEAD(recv_list); 22 static DECLARE_WAIT_QUEUE_HEAD(send_wq); 23 static DECLARE_WAIT_QUEUE_HEAD(recv_wq); 24 25 struct plock_async_data { 26 void *fl; 27 void *file; 28 struct file_lock flc; 29 int (*callback)(struct file_lock *fl, int result); 30 }; 31 32 struct plock_op { 33 struct list_head list; 34 int done; 35 struct dlm_plock_info info; 36 /* if set indicates async handling */ 37 struct plock_async_data *data; 38 }; 39 40 static inline void set_version(struct dlm_plock_info *info) 41 { 42 info->version[0] = DLM_PLOCK_VERSION_MAJOR; 43 info->version[1] = DLM_PLOCK_VERSION_MINOR; 44 info->version[2] = DLM_PLOCK_VERSION_PATCH; 45 } 46 47 static struct plock_op *plock_lookup_waiter(const struct dlm_plock_info *info) 48 { 49 struct plock_op *op = NULL, *iter; 50 51 list_for_each_entry(iter, &recv_list, list) { 52 if (iter->info.fsid == info->fsid && 53 iter->info.number == info->number && 54 iter->info.owner == info->owner && 55 iter->info.pid == info->pid && 56 iter->info.start == info->start && 57 iter->info.end == info->end && 58 iter->info.ex == info->ex && 59 iter->info.wait) { 60 op = iter; 61 break; 62 } 63 } 64 65 return op; 66 } 67 68 static int check_version(struct dlm_plock_info *info) 69 { 70 if ((DLM_PLOCK_VERSION_MAJOR != info->version[0]) || 71 (DLM_PLOCK_VERSION_MINOR < info->version[1])) { 72 log_print("plock device version mismatch: " 73 "kernel (%u.%u.%u), user (%u.%u.%u)", 74 DLM_PLOCK_VERSION_MAJOR, 75 DLM_PLOCK_VERSION_MINOR, 76 DLM_PLOCK_VERSION_PATCH, 77 info->version[0], 78 info->version[1], 79 info->version[2]); 80 return -EINVAL; 81 } 82 return 0; 83 } 84 85 static void dlm_release_plock_op(struct plock_op *op) 86 { 87 kfree(op->data); 88 kfree(op); 89 } 90 91 static void send_op(struct plock_op *op) 92 { 93 set_version(&op->info); 94 spin_lock(&ops_lock); 95 list_add_tail(&op->list, &send_list); 96 spin_unlock(&ops_lock); 97 wake_up(&send_wq); 98 } 99 100 static int do_lock_cancel(const struct dlm_plock_info *orig_info) 101 { 102 struct plock_op *op; 103 int rv; 104 105 op = kzalloc(sizeof(*op), GFP_NOFS); 106 if (!op) 107 return -ENOMEM; 108 109 op->info = *orig_info; 110 op->info.optype = DLM_PLOCK_OP_CANCEL; 111 op->info.wait = 0; 112 113 send_op(op); 114 wait_event(recv_wq, (op->done != 0)); 115 116 rv = op->info.rv; 117 118 dlm_release_plock_op(op); 119 return rv; 120 } 121 122 int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file, 123 int cmd, struct file_lock *fl) 124 { 125 struct plock_async_data *op_data; 126 struct dlm_ls *ls; 127 struct plock_op *op; 128 int rv; 129 130 ls = dlm_find_lockspace_local(lockspace); 131 if (!ls) 132 return -EINVAL; 133 134 op = kzalloc(sizeof(*op), GFP_NOFS); 135 if (!op) { 136 rv = -ENOMEM; 137 goto out; 138 } 139 140 op->info.optype = DLM_PLOCK_OP_LOCK; 141 op->info.pid = fl->c.flc_pid; 142 op->info.ex = lock_is_write(fl); 143 op->info.wait = !!(fl->c.flc_flags & FL_SLEEP); 144 op->info.fsid = ls->ls_global_id; 145 op->info.number = number; 146 op->info.start = fl->fl_start; 147 op->info.end = fl->fl_end; 148 op->info.owner = (__u64)(long) fl->c.flc_owner; 149 /* async handling */ 150 if (fl->fl_lmops && fl->fl_lmops->lm_grant) { 151 op_data = kzalloc(sizeof(*op_data), GFP_NOFS); 152 if (!op_data) { 153 dlm_release_plock_op(op); 154 rv = -ENOMEM; 155 goto out; 156 } 157 158 op_data->callback = fl->fl_lmops->lm_grant; 159 locks_init_lock(&op_data->flc); 160 locks_copy_lock(&op_data->flc, fl); 161 op_data->fl = fl; 162 op_data->file = file; 163 164 op->data = op_data; 165 166 send_op(op); 167 rv = FILE_LOCK_DEFERRED; 168 goto out; 169 } 170 171 send_op(op); 172 173 if (op->info.wait) { 174 rv = wait_event_interruptible(recv_wq, (op->done != 0)); 175 if (rv == -ERESTARTSYS) { 176 spin_lock(&ops_lock); 177 /* recheck under ops_lock if we got a done != 0, 178 * if so this interrupt case should be ignored 179 */ 180 if (op->done != 0) { 181 spin_unlock(&ops_lock); 182 goto do_lock_wait; 183 } 184 spin_unlock(&ops_lock); 185 186 rv = do_lock_cancel(&op->info); 187 switch (rv) { 188 case 0: 189 /* waiter was deleted in user space, answer will never come 190 * remove original request. The original request must be 191 * on recv_list because the answer of do_lock_cancel() 192 * synchronized it. 193 */ 194 spin_lock(&ops_lock); 195 list_del(&op->list); 196 spin_unlock(&ops_lock); 197 rv = -EINTR; 198 break; 199 case -ENOENT: 200 /* cancellation wasn't successful but op should be done */ 201 fallthrough; 202 default: 203 /* internal error doing cancel we need to wait */ 204 goto wait; 205 } 206 207 log_debug(ls, "%s: wait interrupted %x %llx pid %d", 208 __func__, ls->ls_global_id, 209 (unsigned long long)number, op->info.pid); 210 dlm_release_plock_op(op); 211 goto out; 212 } 213 } else { 214 wait: 215 wait_event(recv_wq, (op->done != 0)); 216 } 217 218 do_lock_wait: 219 220 WARN_ON(!list_empty(&op->list)); 221 222 rv = op->info.rv; 223 224 if (!rv) { 225 if (locks_lock_file_wait(file, fl) < 0) 226 log_error(ls, "dlm_posix_lock: vfs lock error %llx", 227 (unsigned long long)number); 228 } 229 230 dlm_release_plock_op(op); 231 out: 232 dlm_put_lockspace(ls); 233 return rv; 234 } 235 EXPORT_SYMBOL_GPL(dlm_posix_lock); 236 237 /* Returns failure iff a successful lock operation should be canceled */ 238 static int dlm_plock_callback(struct plock_op *op) 239 { 240 struct plock_async_data *op_data = op->data; 241 struct file *file; 242 struct file_lock *fl; 243 struct file_lock *flc; 244 int (*notify)(struct file_lock *fl, int result) = NULL; 245 int rv = 0; 246 247 WARN_ON(!list_empty(&op->list)); 248 249 /* check if the following 2 are still valid or make a copy */ 250 file = op_data->file; 251 flc = &op_data->flc; 252 fl = op_data->fl; 253 notify = op_data->callback; 254 255 if (op->info.rv) { 256 notify(fl, op->info.rv); 257 goto out; 258 } 259 260 /* got fs lock; bookkeep locally as well: */ 261 flc->c.flc_flags &= ~FL_SLEEP; 262 if (posix_lock_file(file, flc, NULL)) { 263 /* 264 * This can only happen in the case of kmalloc() failure. 265 * The filesystem's own lock is the authoritative lock, 266 * so a failure to get the lock locally is not a disaster. 267 * As long as the fs cannot reliably cancel locks (especially 268 * in a low-memory situation), we're better off ignoring 269 * this failure than trying to recover. 270 */ 271 log_print("dlm_plock_callback: vfs lock error %llx file %p fl %p", 272 (unsigned long long)op->info.number, file, fl); 273 } 274 275 rv = notify(fl, 0); 276 if (rv) { 277 /* XXX: We need to cancel the fs lock here: */ 278 log_print("%s: lock granted after lock request failed; dangling lock!", 279 __func__); 280 goto out; 281 } 282 283 out: 284 dlm_release_plock_op(op); 285 return rv; 286 } 287 288 int dlm_posix_unlock(dlm_lockspace_t *lockspace, u64 number, struct file *file, 289 struct file_lock *fl) 290 { 291 struct dlm_ls *ls; 292 struct plock_op *op; 293 int rv; 294 unsigned char saved_flags = fl->c.flc_flags; 295 296 ls = dlm_find_lockspace_local(lockspace); 297 if (!ls) 298 return -EINVAL; 299 300 op = kzalloc(sizeof(*op), GFP_NOFS); 301 if (!op) { 302 rv = -ENOMEM; 303 goto out; 304 } 305 306 /* cause the vfs unlock to return ENOENT if lock is not found */ 307 fl->c.flc_flags |= FL_EXISTS; 308 309 rv = locks_lock_file_wait(file, fl); 310 if (rv == -ENOENT) { 311 rv = 0; 312 goto out_free; 313 } 314 if (rv < 0) { 315 log_error(ls, "dlm_posix_unlock: vfs unlock error %d %llx", 316 rv, (unsigned long long)number); 317 } 318 319 op->info.optype = DLM_PLOCK_OP_UNLOCK; 320 op->info.pid = fl->c.flc_pid; 321 op->info.fsid = ls->ls_global_id; 322 op->info.number = number; 323 op->info.start = fl->fl_start; 324 op->info.end = fl->fl_end; 325 op->info.owner = (__u64)(long) fl->c.flc_owner; 326 327 if (fl->c.flc_flags & FL_CLOSE) { 328 op->info.flags |= DLM_PLOCK_FL_CLOSE; 329 send_op(op); 330 rv = 0; 331 goto out; 332 } 333 334 send_op(op); 335 wait_event(recv_wq, (op->done != 0)); 336 337 WARN_ON(!list_empty(&op->list)); 338 339 rv = op->info.rv; 340 341 if (rv == -ENOENT) 342 rv = 0; 343 344 out_free: 345 dlm_release_plock_op(op); 346 out: 347 dlm_put_lockspace(ls); 348 fl->c.flc_flags = saved_flags; 349 return rv; 350 } 351 EXPORT_SYMBOL_GPL(dlm_posix_unlock); 352 353 /* 354 * NOTE: This implementation can only handle async lock requests as nfs 355 * do it. It cannot handle cancellation of a pending lock request sitting 356 * in wait_event(), but for now only nfs is the only user local kernel 357 * user. 358 */ 359 int dlm_posix_cancel(dlm_lockspace_t *lockspace, u64 number, struct file *file, 360 struct file_lock *fl) 361 { 362 struct dlm_plock_info info; 363 struct plock_op *op; 364 struct dlm_ls *ls; 365 int rv; 366 367 /* this only works for async request for now and nfs is the only 368 * kernel user right now. 369 */ 370 if (WARN_ON_ONCE(!fl->fl_lmops || !fl->fl_lmops->lm_grant)) 371 return -EOPNOTSUPP; 372 373 ls = dlm_find_lockspace_local(lockspace); 374 if (!ls) 375 return -EINVAL; 376 377 memset(&info, 0, sizeof(info)); 378 info.pid = fl->c.flc_pid; 379 info.ex = lock_is_write(fl); 380 info.fsid = ls->ls_global_id; 381 dlm_put_lockspace(ls); 382 info.number = number; 383 info.start = fl->fl_start; 384 info.end = fl->fl_end; 385 info.owner = (__u64)(long) fl->c.flc_owner; 386 387 rv = do_lock_cancel(&info); 388 switch (rv) { 389 case 0: 390 spin_lock(&ops_lock); 391 /* lock request to cancel must be on recv_list because 392 * do_lock_cancel() synchronizes it. 393 */ 394 op = plock_lookup_waiter(&info); 395 if (WARN_ON_ONCE(!op)) { 396 spin_unlock(&ops_lock); 397 rv = -ENOLCK; 398 break; 399 } 400 401 list_del(&op->list); 402 spin_unlock(&ops_lock); 403 WARN_ON(op->info.optype != DLM_PLOCK_OP_LOCK); 404 op->data->callback(op->data->fl, -EINTR); 405 dlm_release_plock_op(op); 406 rv = -EINTR; 407 break; 408 case -ENOENT: 409 /* if cancel wasn't successful we probably were to late 410 * or it was a non-blocking lock request, so just unlock it. 411 */ 412 rv = dlm_posix_unlock(lockspace, number, file, fl); 413 break; 414 default: 415 break; 416 } 417 418 return rv; 419 } 420 EXPORT_SYMBOL_GPL(dlm_posix_cancel); 421 422 int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file, 423 struct file_lock *fl) 424 { 425 struct dlm_ls *ls; 426 struct plock_op *op; 427 int rv; 428 429 ls = dlm_find_lockspace_local(lockspace); 430 if (!ls) 431 return -EINVAL; 432 433 op = kzalloc(sizeof(*op), GFP_NOFS); 434 if (!op) { 435 rv = -ENOMEM; 436 goto out; 437 } 438 439 op->info.optype = DLM_PLOCK_OP_GET; 440 op->info.pid = fl->c.flc_pid; 441 op->info.ex = lock_is_write(fl); 442 op->info.fsid = ls->ls_global_id; 443 op->info.number = number; 444 op->info.start = fl->fl_start; 445 op->info.end = fl->fl_end; 446 op->info.owner = (__u64)(long) fl->c.flc_owner; 447 448 send_op(op); 449 wait_event(recv_wq, (op->done != 0)); 450 451 WARN_ON(!list_empty(&op->list)); 452 453 /* info.rv from userspace is 1 for conflict, 0 for no-conflict, 454 -ENOENT if there are no locks on the file */ 455 456 rv = op->info.rv; 457 458 fl->c.flc_type = F_UNLCK; 459 if (rv == -ENOENT) 460 rv = 0; 461 else if (rv > 0) { 462 locks_init_lock(fl); 463 fl->c.flc_type = (op->info.ex) ? F_WRLCK : F_RDLCK; 464 fl->c.flc_flags = FL_POSIX; 465 fl->c.flc_pid = op->info.pid; 466 if (op->info.nodeid != dlm_our_nodeid()) 467 fl->c.flc_pid = -fl->c.flc_pid; 468 fl->fl_start = op->info.start; 469 fl->fl_end = op->info.end; 470 rv = 0; 471 } 472 473 dlm_release_plock_op(op); 474 out: 475 dlm_put_lockspace(ls); 476 return rv; 477 } 478 EXPORT_SYMBOL_GPL(dlm_posix_get); 479 480 /* a read copies out one plock request from the send list */ 481 static ssize_t dev_read(struct file *file, char __user *u, size_t count, 482 loff_t *ppos) 483 { 484 struct dlm_plock_info info; 485 struct plock_op *op = NULL; 486 487 if (count < sizeof(info)) 488 return -EINVAL; 489 490 spin_lock(&ops_lock); 491 if (!list_empty(&send_list)) { 492 op = list_first_entry(&send_list, struct plock_op, list); 493 if (op->info.flags & DLM_PLOCK_FL_CLOSE) 494 list_del(&op->list); 495 else 496 list_move_tail(&op->list, &recv_list); 497 memcpy(&info, &op->info, sizeof(info)); 498 } 499 spin_unlock(&ops_lock); 500 501 if (!op) 502 return -EAGAIN; 503 504 trace_dlm_plock_read(&info); 505 506 /* there is no need to get a reply from userspace for unlocks 507 that were generated by the vfs cleaning up for a close 508 (the process did not make an unlock call). */ 509 510 if (op->info.flags & DLM_PLOCK_FL_CLOSE) 511 dlm_release_plock_op(op); 512 513 if (copy_to_user(u, &info, sizeof(info))) 514 return -EFAULT; 515 return sizeof(info); 516 } 517 518 /* a write copies in one plock result that should match a plock_op 519 on the recv list */ 520 static ssize_t dev_write(struct file *file, const char __user *u, size_t count, 521 loff_t *ppos) 522 { 523 struct plock_op *op = NULL, *iter; 524 struct dlm_plock_info info; 525 int do_callback = 0; 526 527 if (count != sizeof(info)) 528 return -EINVAL; 529 530 if (copy_from_user(&info, u, sizeof(info))) 531 return -EFAULT; 532 533 trace_dlm_plock_write(&info); 534 535 if (check_version(&info)) 536 return -EINVAL; 537 538 /* 539 * The results for waiting ops (SETLKW) can be returned in any 540 * order, so match all fields to find the op. The results for 541 * non-waiting ops are returned in the order that they were sent 542 * to userspace, so match the result with the first non-waiting op. 543 */ 544 spin_lock(&ops_lock); 545 if (info.wait) { 546 op = plock_lookup_waiter(&info); 547 } else { 548 list_for_each_entry(iter, &recv_list, list) { 549 if (!iter->info.wait && 550 iter->info.fsid == info.fsid) { 551 op = iter; 552 break; 553 } 554 } 555 } 556 557 if (op) { 558 /* Sanity check that op and info match. */ 559 if (info.wait) 560 WARN_ON(op->info.optype != DLM_PLOCK_OP_LOCK); 561 else 562 WARN_ON(op->info.number != info.number || 563 op->info.owner != info.owner || 564 op->info.optype != info.optype); 565 566 list_del_init(&op->list); 567 memcpy(&op->info, &info, sizeof(info)); 568 if (op->data) 569 do_callback = 1; 570 else 571 op->done = 1; 572 } 573 spin_unlock(&ops_lock); 574 575 if (op) { 576 if (do_callback) 577 dlm_plock_callback(op); 578 else 579 wake_up(&recv_wq); 580 } else 581 pr_debug("%s: no op %x %llx", __func__, 582 info.fsid, (unsigned long long)info.number); 583 return count; 584 } 585 586 static __poll_t dev_poll(struct file *file, poll_table *wait) 587 { 588 __poll_t mask = 0; 589 590 poll_wait(file, &send_wq, wait); 591 592 spin_lock(&ops_lock); 593 if (!list_empty(&send_list)) 594 mask = EPOLLIN | EPOLLRDNORM; 595 spin_unlock(&ops_lock); 596 597 return mask; 598 } 599 600 static const struct file_operations dev_fops = { 601 .read = dev_read, 602 .write = dev_write, 603 .poll = dev_poll, 604 .owner = THIS_MODULE, 605 .llseek = noop_llseek, 606 }; 607 608 static struct miscdevice plock_dev_misc = { 609 .minor = MISC_DYNAMIC_MINOR, 610 .name = DLM_PLOCK_MISC_NAME, 611 .fops = &dev_fops 612 }; 613 614 int dlm_plock_init(void) 615 { 616 int rv; 617 618 rv = misc_register(&plock_dev_misc); 619 if (rv) 620 log_print("dlm_plock_init: misc_register failed %d", rv); 621 return rv; 622 } 623 624 void dlm_plock_exit(void) 625 { 626 misc_deregister(&plock_dev_misc); 627 WARN_ON(!list_empty(&send_list)); 628 WARN_ON(!list_empty(&recv_list)); 629 } 630 631