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/miscdevice.h> 8 #include <linux/poll.h> 9 #include <linux/dlm.h> 10 #include <linux/dlm_plock.h> 11 #include <linux/slab.h> 12 13 #include "dlm_internal.h" 14 #include "lockspace.h" 15 16 static DEFINE_SPINLOCK(ops_lock); 17 static LIST_HEAD(send_list); 18 static LIST_HEAD(recv_list); 19 static DECLARE_WAIT_QUEUE_HEAD(send_wq); 20 static DECLARE_WAIT_QUEUE_HEAD(recv_wq); 21 22 struct plock_async_data { 23 void *fl; 24 void *file; 25 struct file_lock flc; 26 int (*callback)(struct file_lock *fl, int result); 27 }; 28 29 struct plock_op { 30 struct list_head list; 31 int done; 32 struct dlm_plock_info info; 33 /* if set indicates async handling */ 34 struct plock_async_data *data; 35 }; 36 37 static inline void set_version(struct dlm_plock_info *info) 38 { 39 info->version[0] = DLM_PLOCK_VERSION_MAJOR; 40 info->version[1] = DLM_PLOCK_VERSION_MINOR; 41 info->version[2] = DLM_PLOCK_VERSION_PATCH; 42 } 43 44 static int check_version(struct dlm_plock_info *info) 45 { 46 if ((DLM_PLOCK_VERSION_MAJOR != info->version[0]) || 47 (DLM_PLOCK_VERSION_MINOR < info->version[1])) { 48 log_print("plock device version mismatch: " 49 "kernel (%u.%u.%u), user (%u.%u.%u)", 50 DLM_PLOCK_VERSION_MAJOR, 51 DLM_PLOCK_VERSION_MINOR, 52 DLM_PLOCK_VERSION_PATCH, 53 info->version[0], 54 info->version[1], 55 info->version[2]); 56 return -EINVAL; 57 } 58 return 0; 59 } 60 61 static void dlm_release_plock_op(struct plock_op *op) 62 { 63 kfree(op->data); 64 kfree(op); 65 } 66 67 static void send_op(struct plock_op *op) 68 { 69 set_version(&op->info); 70 spin_lock(&ops_lock); 71 list_add_tail(&op->list, &send_list); 72 spin_unlock(&ops_lock); 73 wake_up(&send_wq); 74 } 75 76 /* If a process was killed while waiting for the only plock on a file, 77 locks_remove_posix will not see any lock on the file so it won't 78 send an unlock-close to us to pass on to userspace to clean up the 79 abandoned waiter. So, we have to insert the unlock-close when the 80 lock call is interrupted. */ 81 82 static void do_unlock_close(struct dlm_ls *ls, u64 number, 83 struct file *file, struct file_lock *fl) 84 { 85 struct plock_op *op; 86 87 op = kzalloc(sizeof(*op), GFP_NOFS); 88 if (!op) 89 return; 90 91 op->info.optype = DLM_PLOCK_OP_UNLOCK; 92 op->info.pid = fl->fl_pid; 93 op->info.fsid = ls->ls_global_id; 94 op->info.number = number; 95 op->info.start = 0; 96 op->info.end = OFFSET_MAX; 97 if (fl->fl_lmops && fl->fl_lmops->lm_grant) 98 op->info.owner = (__u64) fl->fl_pid; 99 else 100 op->info.owner = (__u64)(long) fl->fl_owner; 101 102 op->info.flags |= DLM_PLOCK_FL_CLOSE; 103 send_op(op); 104 } 105 106 int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file, 107 int cmd, struct file_lock *fl) 108 { 109 struct plock_async_data *op_data; 110 struct dlm_ls *ls; 111 struct plock_op *op; 112 int rv; 113 114 ls = dlm_find_lockspace_local(lockspace); 115 if (!ls) 116 return -EINVAL; 117 118 op = kzalloc(sizeof(*op), GFP_NOFS); 119 if (!op) { 120 rv = -ENOMEM; 121 goto out; 122 } 123 124 op->info.optype = DLM_PLOCK_OP_LOCK; 125 op->info.pid = fl->fl_pid; 126 op->info.ex = (fl->fl_type == F_WRLCK); 127 op->info.wait = IS_SETLKW(cmd); 128 op->info.fsid = ls->ls_global_id; 129 op->info.number = number; 130 op->info.start = fl->fl_start; 131 op->info.end = fl->fl_end; 132 /* async handling */ 133 if (fl->fl_lmops && fl->fl_lmops->lm_grant) { 134 op_data = kzalloc(sizeof(*op_data), GFP_NOFS); 135 if (!op_data) { 136 dlm_release_plock_op(op); 137 rv = -ENOMEM; 138 goto out; 139 } 140 141 /* fl_owner is lockd which doesn't distinguish 142 processes on the nfs client */ 143 op->info.owner = (__u64) fl->fl_pid; 144 op_data->callback = fl->fl_lmops->lm_grant; 145 locks_init_lock(&op_data->flc); 146 locks_copy_lock(&op_data->flc, fl); 147 op_data->fl = fl; 148 op_data->file = file; 149 150 op->data = op_data; 151 152 send_op(op); 153 rv = FILE_LOCK_DEFERRED; 154 goto out; 155 } else { 156 op->info.owner = (__u64)(long) fl->fl_owner; 157 } 158 159 send_op(op); 160 161 rv = wait_event_interruptible(recv_wq, (op->done != 0)); 162 if (rv == -ERESTARTSYS) { 163 spin_lock(&ops_lock); 164 list_del(&op->list); 165 spin_unlock(&ops_lock); 166 log_print("%s: wait interrupted %x %llx, op removed", 167 __func__, ls->ls_global_id, 168 (unsigned long long)number); 169 dlm_release_plock_op(op); 170 do_unlock_close(ls, number, file, fl); 171 goto out; 172 } 173 174 WARN_ON(!list_empty(&op->list)); 175 176 rv = op->info.rv; 177 178 if (!rv) { 179 if (locks_lock_file_wait(file, fl) < 0) 180 log_error(ls, "dlm_posix_lock: vfs lock error %llx", 181 (unsigned long long)number); 182 } 183 184 dlm_release_plock_op(op); 185 out: 186 dlm_put_lockspace(ls); 187 return rv; 188 } 189 EXPORT_SYMBOL_GPL(dlm_posix_lock); 190 191 /* Returns failure iff a successful lock operation should be canceled */ 192 static int dlm_plock_callback(struct plock_op *op) 193 { 194 struct plock_async_data *op_data = op->data; 195 struct file *file; 196 struct file_lock *fl; 197 struct file_lock *flc; 198 int (*notify)(struct file_lock *fl, int result) = NULL; 199 int rv = 0; 200 201 WARN_ON(!list_empty(&op->list)); 202 203 /* check if the following 2 are still valid or make a copy */ 204 file = op_data->file; 205 flc = &op_data->flc; 206 fl = op_data->fl; 207 notify = op_data->callback; 208 209 if (op->info.rv) { 210 notify(fl, op->info.rv); 211 goto out; 212 } 213 214 /* got fs lock; bookkeep locally as well: */ 215 flc->fl_flags &= ~FL_SLEEP; 216 if (posix_lock_file(file, flc, NULL)) { 217 /* 218 * This can only happen in the case of kmalloc() failure. 219 * The filesystem's own lock is the authoritative lock, 220 * so a failure to get the lock locally is not a disaster. 221 * As long as the fs cannot reliably cancel locks (especially 222 * in a low-memory situation), we're better off ignoring 223 * this failure than trying to recover. 224 */ 225 log_print("dlm_plock_callback: vfs lock error %llx file %p fl %p", 226 (unsigned long long)op->info.number, file, fl); 227 } 228 229 rv = notify(fl, 0); 230 if (rv) { 231 /* XXX: We need to cancel the fs lock here: */ 232 log_print("dlm_plock_callback: lock granted after lock request " 233 "failed; dangling lock!\n"); 234 goto out; 235 } 236 237 out: 238 dlm_release_plock_op(op); 239 return rv; 240 } 241 242 int dlm_posix_unlock(dlm_lockspace_t *lockspace, u64 number, struct file *file, 243 struct file_lock *fl) 244 { 245 struct dlm_ls *ls; 246 struct plock_op *op; 247 int rv; 248 unsigned char fl_flags = fl->fl_flags; 249 250 ls = dlm_find_lockspace_local(lockspace); 251 if (!ls) 252 return -EINVAL; 253 254 op = kzalloc(sizeof(*op), GFP_NOFS); 255 if (!op) { 256 rv = -ENOMEM; 257 goto out; 258 } 259 260 /* cause the vfs unlock to return ENOENT if lock is not found */ 261 fl->fl_flags |= FL_EXISTS; 262 263 rv = locks_lock_file_wait(file, fl); 264 if (rv == -ENOENT) { 265 rv = 0; 266 goto out_free; 267 } 268 if (rv < 0) { 269 log_error(ls, "dlm_posix_unlock: vfs unlock error %d %llx", 270 rv, (unsigned long long)number); 271 } 272 273 op->info.optype = DLM_PLOCK_OP_UNLOCK; 274 op->info.pid = fl->fl_pid; 275 op->info.fsid = ls->ls_global_id; 276 op->info.number = number; 277 op->info.start = fl->fl_start; 278 op->info.end = fl->fl_end; 279 if (fl->fl_lmops && fl->fl_lmops->lm_grant) 280 op->info.owner = (__u64) fl->fl_pid; 281 else 282 op->info.owner = (__u64)(long) fl->fl_owner; 283 284 if (fl->fl_flags & FL_CLOSE) { 285 op->info.flags |= DLM_PLOCK_FL_CLOSE; 286 send_op(op); 287 rv = 0; 288 goto out; 289 } 290 291 send_op(op); 292 wait_event(recv_wq, (op->done != 0)); 293 294 WARN_ON(!list_empty(&op->list)); 295 296 rv = op->info.rv; 297 298 if (rv == -ENOENT) 299 rv = 0; 300 301 out_free: 302 dlm_release_plock_op(op); 303 out: 304 dlm_put_lockspace(ls); 305 fl->fl_flags = fl_flags; 306 return rv; 307 } 308 EXPORT_SYMBOL_GPL(dlm_posix_unlock); 309 310 int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file, 311 struct file_lock *fl) 312 { 313 struct dlm_ls *ls; 314 struct plock_op *op; 315 int rv; 316 317 ls = dlm_find_lockspace_local(lockspace); 318 if (!ls) 319 return -EINVAL; 320 321 op = kzalloc(sizeof(*op), GFP_NOFS); 322 if (!op) { 323 rv = -ENOMEM; 324 goto out; 325 } 326 327 op->info.optype = DLM_PLOCK_OP_GET; 328 op->info.pid = fl->fl_pid; 329 op->info.ex = (fl->fl_type == F_WRLCK); 330 op->info.fsid = ls->ls_global_id; 331 op->info.number = number; 332 op->info.start = fl->fl_start; 333 op->info.end = fl->fl_end; 334 if (fl->fl_lmops && fl->fl_lmops->lm_grant) 335 op->info.owner = (__u64) fl->fl_pid; 336 else 337 op->info.owner = (__u64)(long) fl->fl_owner; 338 339 send_op(op); 340 wait_event(recv_wq, (op->done != 0)); 341 342 WARN_ON(!list_empty(&op->list)); 343 344 /* info.rv from userspace is 1 for conflict, 0 for no-conflict, 345 -ENOENT if there are no locks on the file */ 346 347 rv = op->info.rv; 348 349 fl->fl_type = F_UNLCK; 350 if (rv == -ENOENT) 351 rv = 0; 352 else if (rv > 0) { 353 locks_init_lock(fl); 354 fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK; 355 fl->fl_flags = FL_POSIX; 356 fl->fl_pid = -op->info.pid; 357 fl->fl_start = op->info.start; 358 fl->fl_end = op->info.end; 359 rv = 0; 360 } 361 362 dlm_release_plock_op(op); 363 out: 364 dlm_put_lockspace(ls); 365 return rv; 366 } 367 EXPORT_SYMBOL_GPL(dlm_posix_get); 368 369 /* a read copies out one plock request from the send list */ 370 static ssize_t dev_read(struct file *file, char __user *u, size_t count, 371 loff_t *ppos) 372 { 373 struct dlm_plock_info info; 374 struct plock_op *op = NULL; 375 376 if (count < sizeof(info)) 377 return -EINVAL; 378 379 spin_lock(&ops_lock); 380 if (!list_empty(&send_list)) { 381 op = list_entry(send_list.next, struct plock_op, list); 382 if (op->info.flags & DLM_PLOCK_FL_CLOSE) 383 list_del(&op->list); 384 else 385 list_move(&op->list, &recv_list); 386 memcpy(&info, &op->info, sizeof(info)); 387 } 388 spin_unlock(&ops_lock); 389 390 if (!op) 391 return -EAGAIN; 392 393 /* there is no need to get a reply from userspace for unlocks 394 that were generated by the vfs cleaning up for a close 395 (the process did not make an unlock call). */ 396 397 if (op->info.flags & DLM_PLOCK_FL_CLOSE) 398 dlm_release_plock_op(op); 399 400 if (copy_to_user(u, &info, sizeof(info))) 401 return -EFAULT; 402 return sizeof(info); 403 } 404 405 /* a write copies in one plock result that should match a plock_op 406 on the recv list */ 407 static ssize_t dev_write(struct file *file, const char __user *u, size_t count, 408 loff_t *ppos) 409 { 410 struct plock_op *op = NULL, *iter; 411 struct dlm_plock_info info; 412 int do_callback = 0; 413 414 if (count != sizeof(info)) 415 return -EINVAL; 416 417 if (copy_from_user(&info, u, sizeof(info))) 418 return -EFAULT; 419 420 if (check_version(&info)) 421 return -EINVAL; 422 423 spin_lock(&ops_lock); 424 list_for_each_entry(iter, &recv_list, list) { 425 if (iter->info.fsid == info.fsid && 426 iter->info.number == info.number && 427 iter->info.owner == info.owner) { 428 list_del_init(&iter->list); 429 memcpy(&iter->info, &info, sizeof(info)); 430 if (iter->data) 431 do_callback = 1; 432 else 433 iter->done = 1; 434 op = iter; 435 break; 436 } 437 } 438 spin_unlock(&ops_lock); 439 440 if (op) { 441 if (do_callback) 442 dlm_plock_callback(op); 443 else 444 wake_up(&recv_wq); 445 } else 446 log_print("%s: no op %x %llx - may got interrupted?", __func__, 447 info.fsid, (unsigned long long)info.number); 448 return count; 449 } 450 451 static __poll_t dev_poll(struct file *file, poll_table *wait) 452 { 453 __poll_t mask = 0; 454 455 poll_wait(file, &send_wq, wait); 456 457 spin_lock(&ops_lock); 458 if (!list_empty(&send_list)) 459 mask = EPOLLIN | EPOLLRDNORM; 460 spin_unlock(&ops_lock); 461 462 return mask; 463 } 464 465 static const struct file_operations dev_fops = { 466 .read = dev_read, 467 .write = dev_write, 468 .poll = dev_poll, 469 .owner = THIS_MODULE, 470 .llseek = noop_llseek, 471 }; 472 473 static struct miscdevice plock_dev_misc = { 474 .minor = MISC_DYNAMIC_MINOR, 475 .name = DLM_PLOCK_MISC_NAME, 476 .fops = &dev_fops 477 }; 478 479 int dlm_plock_init(void) 480 { 481 int rv; 482 483 rv = misc_register(&plock_dev_misc); 484 if (rv) 485 log_print("dlm_plock_init: misc_register failed %d", rv); 486 return rv; 487 } 488 489 void dlm_plock_exit(void) 490 { 491 misc_deregister(&plock_dev_misc); 492 } 493 494