1 /* 2 * Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved. 3 * 4 * This copyrighted material is made available to anyone wishing to use, 5 * modify, copy, or redistribute it subject to the terms and conditions 6 * of the GNU General Public License version 2. 7 */ 8 9 #include <linux/fs.h> 10 #include <linux/miscdevice.h> 11 #include <linux/poll.h> 12 #include <linux/dlm.h> 13 #include <linux/dlm_plock.h> 14 #include <linux/slab.h> 15 16 #include "dlm_internal.h" 17 #include "lockspace.h" 18 19 static spinlock_t ops_lock; 20 static struct list_head send_list; 21 static struct list_head recv_list; 22 static wait_queue_head_t send_wq; 23 static wait_queue_head_t recv_wq; 24 25 struct plock_op { 26 struct list_head list; 27 int done; 28 struct dlm_plock_info info; 29 }; 30 31 struct plock_xop { 32 struct plock_op xop; 33 int (*callback)(struct file_lock *fl, int result); 34 void *fl; 35 void *file; 36 struct file_lock flc; 37 }; 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 int check_version(struct dlm_plock_info *info) 48 { 49 if ((DLM_PLOCK_VERSION_MAJOR != info->version[0]) || 50 (DLM_PLOCK_VERSION_MINOR < info->version[1])) { 51 log_print("plock device version mismatch: " 52 "kernel (%u.%u.%u), user (%u.%u.%u)", 53 DLM_PLOCK_VERSION_MAJOR, 54 DLM_PLOCK_VERSION_MINOR, 55 DLM_PLOCK_VERSION_PATCH, 56 info->version[0], 57 info->version[1], 58 info->version[2]); 59 return -EINVAL; 60 } 61 return 0; 62 } 63 64 static void send_op(struct plock_op *op) 65 { 66 set_version(&op->info); 67 INIT_LIST_HEAD(&op->list); 68 spin_lock(&ops_lock); 69 list_add_tail(&op->list, &send_list); 70 spin_unlock(&ops_lock); 71 wake_up(&send_wq); 72 } 73 74 /* If a process was killed while waiting for the only plock on a file, 75 locks_remove_posix will not see any lock on the file so it won't 76 send an unlock-close to us to pass on to userspace to clean up the 77 abandoned waiter. So, we have to insert the unlock-close when the 78 lock call is interrupted. */ 79 80 static void do_unlock_close(struct dlm_ls *ls, u64 number, 81 struct file *file, struct file_lock *fl) 82 { 83 struct plock_op *op; 84 85 op = kzalloc(sizeof(*op), GFP_NOFS); 86 if (!op) 87 return; 88 89 op->info.optype = DLM_PLOCK_OP_UNLOCK; 90 op->info.pid = fl->fl_pid; 91 op->info.fsid = ls->ls_global_id; 92 op->info.number = number; 93 op->info.start = 0; 94 op->info.end = OFFSET_MAX; 95 if (fl->fl_lmops && fl->fl_lmops->lm_grant) 96 op->info.owner = (__u64) fl->fl_pid; 97 else 98 op->info.owner = (__u64)(long) fl->fl_owner; 99 100 op->info.flags |= DLM_PLOCK_FL_CLOSE; 101 send_op(op); 102 } 103 104 int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file, 105 int cmd, struct file_lock *fl) 106 { 107 struct dlm_ls *ls; 108 struct plock_op *op; 109 struct plock_xop *xop; 110 int rv; 111 112 ls = dlm_find_lockspace_local(lockspace); 113 if (!ls) 114 return -EINVAL; 115 116 xop = kzalloc(sizeof(*xop), GFP_NOFS); 117 if (!xop) { 118 rv = -ENOMEM; 119 goto out; 120 } 121 122 op = &xop->xop; 123 op->info.optype = DLM_PLOCK_OP_LOCK; 124 op->info.pid = fl->fl_pid; 125 op->info.ex = (fl->fl_type == F_WRLCK); 126 op->info.wait = IS_SETLKW(cmd); 127 op->info.fsid = ls->ls_global_id; 128 op->info.number = number; 129 op->info.start = fl->fl_start; 130 op->info.end = fl->fl_end; 131 if (fl->fl_lmops && fl->fl_lmops->lm_grant) { 132 /* fl_owner is lockd which doesn't distinguish 133 processes on the nfs client */ 134 op->info.owner = (__u64) fl->fl_pid; 135 xop->callback = fl->fl_lmops->lm_grant; 136 locks_init_lock(&xop->flc); 137 locks_copy_lock(&xop->flc, fl); 138 xop->fl = fl; 139 xop->file = file; 140 } else { 141 op->info.owner = (__u64)(long) fl->fl_owner; 142 xop->callback = NULL; 143 } 144 145 send_op(op); 146 147 if (xop->callback == NULL) { 148 rv = wait_event_interruptible(recv_wq, (op->done != 0)); 149 if (rv == -ERESTARTSYS) { 150 log_debug(ls, "dlm_posix_lock: wait killed %llx", 151 (unsigned long long)number); 152 spin_lock(&ops_lock); 153 list_del(&op->list); 154 spin_unlock(&ops_lock); 155 kfree(xop); 156 do_unlock_close(ls, number, file, fl); 157 goto out; 158 } 159 } else { 160 rv = FILE_LOCK_DEFERRED; 161 goto out; 162 } 163 164 spin_lock(&ops_lock); 165 if (!list_empty(&op->list)) { 166 log_error(ls, "dlm_posix_lock: op on list %llx", 167 (unsigned long long)number); 168 list_del(&op->list); 169 } 170 spin_unlock(&ops_lock); 171 172 rv = op->info.rv; 173 174 if (!rv) { 175 if (locks_lock_file_wait(file, fl) < 0) 176 log_error(ls, "dlm_posix_lock: vfs lock error %llx", 177 (unsigned long long)number); 178 } 179 180 kfree(xop); 181 out: 182 dlm_put_lockspace(ls); 183 return rv; 184 } 185 EXPORT_SYMBOL_GPL(dlm_posix_lock); 186 187 /* Returns failure iff a successful lock operation should be canceled */ 188 static int dlm_plock_callback(struct plock_op *op) 189 { 190 struct file *file; 191 struct file_lock *fl; 192 struct file_lock *flc; 193 int (*notify)(struct file_lock *fl, int result) = NULL; 194 struct plock_xop *xop = (struct plock_xop *)op; 195 int rv = 0; 196 197 spin_lock(&ops_lock); 198 if (!list_empty(&op->list)) { 199 log_print("dlm_plock_callback: op on list %llx", 200 (unsigned long long)op->info.number); 201 list_del(&op->list); 202 } 203 spin_unlock(&ops_lock); 204 205 /* check if the following 2 are still valid or make a copy */ 206 file = xop->file; 207 flc = &xop->flc; 208 fl = xop->fl; 209 notify = xop->callback; 210 211 if (op->info.rv) { 212 notify(fl, op->info.rv); 213 goto out; 214 } 215 216 /* got fs lock; bookkeep locally as well: */ 217 flc->fl_flags &= ~FL_SLEEP; 218 if (posix_lock_file(file, flc, NULL)) { 219 /* 220 * This can only happen in the case of kmalloc() failure. 221 * The filesystem's own lock is the authoritative lock, 222 * so a failure to get the lock locally is not a disaster. 223 * As long as the fs cannot reliably cancel locks (especially 224 * in a low-memory situation), we're better off ignoring 225 * this failure than trying to recover. 226 */ 227 log_print("dlm_plock_callback: vfs lock error %llx file %p fl %p", 228 (unsigned long long)op->info.number, file, fl); 229 } 230 231 rv = notify(fl, 0); 232 if (rv) { 233 /* XXX: We need to cancel the fs lock here: */ 234 log_print("dlm_plock_callback: lock granted after lock request " 235 "failed; dangling lock!\n"); 236 goto out; 237 } 238 239 out: 240 kfree(xop); 241 return rv; 242 } 243 244 int dlm_posix_unlock(dlm_lockspace_t *lockspace, u64 number, struct file *file, 245 struct file_lock *fl) 246 { 247 struct dlm_ls *ls; 248 struct plock_op *op; 249 int rv; 250 unsigned char fl_flags = fl->fl_flags; 251 252 ls = dlm_find_lockspace_local(lockspace); 253 if (!ls) 254 return -EINVAL; 255 256 op = kzalloc(sizeof(*op), GFP_NOFS); 257 if (!op) { 258 rv = -ENOMEM; 259 goto out; 260 } 261 262 /* cause the vfs unlock to return ENOENT if lock is not found */ 263 fl->fl_flags |= FL_EXISTS; 264 265 rv = locks_lock_file_wait(file, fl); 266 if (rv == -ENOENT) { 267 rv = 0; 268 goto out_free; 269 } 270 if (rv < 0) { 271 log_error(ls, "dlm_posix_unlock: vfs unlock error %d %llx", 272 rv, (unsigned long long)number); 273 } 274 275 op->info.optype = DLM_PLOCK_OP_UNLOCK; 276 op->info.pid = fl->fl_pid; 277 op->info.fsid = ls->ls_global_id; 278 op->info.number = number; 279 op->info.start = fl->fl_start; 280 op->info.end = fl->fl_end; 281 if (fl->fl_lmops && fl->fl_lmops->lm_grant) 282 op->info.owner = (__u64) fl->fl_pid; 283 else 284 op->info.owner = (__u64)(long) fl->fl_owner; 285 286 if (fl->fl_flags & FL_CLOSE) { 287 op->info.flags |= DLM_PLOCK_FL_CLOSE; 288 send_op(op); 289 rv = 0; 290 goto out; 291 } 292 293 send_op(op); 294 wait_event(recv_wq, (op->done != 0)); 295 296 spin_lock(&ops_lock); 297 if (!list_empty(&op->list)) { 298 log_error(ls, "dlm_posix_unlock: op on list %llx", 299 (unsigned long long)number); 300 list_del(&op->list); 301 } 302 spin_unlock(&ops_lock); 303 304 rv = op->info.rv; 305 306 if (rv == -ENOENT) 307 rv = 0; 308 309 out_free: 310 kfree(op); 311 out: 312 dlm_put_lockspace(ls); 313 fl->fl_flags = fl_flags; 314 return rv; 315 } 316 EXPORT_SYMBOL_GPL(dlm_posix_unlock); 317 318 int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file, 319 struct file_lock *fl) 320 { 321 struct dlm_ls *ls; 322 struct plock_op *op; 323 int rv; 324 325 ls = dlm_find_lockspace_local(lockspace); 326 if (!ls) 327 return -EINVAL; 328 329 op = kzalloc(sizeof(*op), GFP_NOFS); 330 if (!op) { 331 rv = -ENOMEM; 332 goto out; 333 } 334 335 op->info.optype = DLM_PLOCK_OP_GET; 336 op->info.pid = fl->fl_pid; 337 op->info.ex = (fl->fl_type == F_WRLCK); 338 op->info.fsid = ls->ls_global_id; 339 op->info.number = number; 340 op->info.start = fl->fl_start; 341 op->info.end = fl->fl_end; 342 if (fl->fl_lmops && fl->fl_lmops->lm_grant) 343 op->info.owner = (__u64) fl->fl_pid; 344 else 345 op->info.owner = (__u64)(long) fl->fl_owner; 346 347 send_op(op); 348 wait_event(recv_wq, (op->done != 0)); 349 350 spin_lock(&ops_lock); 351 if (!list_empty(&op->list)) { 352 log_error(ls, "dlm_posix_get: op on list %llx", 353 (unsigned long long)number); 354 list_del(&op->list); 355 } 356 spin_unlock(&ops_lock); 357 358 /* info.rv from userspace is 1 for conflict, 0 for no-conflict, 359 -ENOENT if there are no locks on the file */ 360 361 rv = op->info.rv; 362 363 fl->fl_type = F_UNLCK; 364 if (rv == -ENOENT) 365 rv = 0; 366 else if (rv > 0) { 367 locks_init_lock(fl); 368 fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK; 369 fl->fl_flags = FL_POSIX; 370 fl->fl_pid = -op->info.pid; 371 fl->fl_start = op->info.start; 372 fl->fl_end = op->info.end; 373 rv = 0; 374 } 375 376 kfree(op); 377 out: 378 dlm_put_lockspace(ls); 379 return rv; 380 } 381 EXPORT_SYMBOL_GPL(dlm_posix_get); 382 383 /* a read copies out one plock request from the send list */ 384 static ssize_t dev_read(struct file *file, char __user *u, size_t count, 385 loff_t *ppos) 386 { 387 struct dlm_plock_info info; 388 struct plock_op *op = NULL; 389 390 if (count < sizeof(info)) 391 return -EINVAL; 392 393 spin_lock(&ops_lock); 394 if (!list_empty(&send_list)) { 395 op = list_entry(send_list.next, struct plock_op, list); 396 if (op->info.flags & DLM_PLOCK_FL_CLOSE) 397 list_del(&op->list); 398 else 399 list_move(&op->list, &recv_list); 400 memcpy(&info, &op->info, sizeof(info)); 401 } 402 spin_unlock(&ops_lock); 403 404 if (!op) 405 return -EAGAIN; 406 407 /* there is no need to get a reply from userspace for unlocks 408 that were generated by the vfs cleaning up for a close 409 (the process did not make an unlock call). */ 410 411 if (op->info.flags & DLM_PLOCK_FL_CLOSE) 412 kfree(op); 413 414 if (copy_to_user(u, &info, sizeof(info))) 415 return -EFAULT; 416 return sizeof(info); 417 } 418 419 /* a write copies in one plock result that should match a plock_op 420 on the recv list */ 421 static ssize_t dev_write(struct file *file, const char __user *u, size_t count, 422 loff_t *ppos) 423 { 424 struct dlm_plock_info info; 425 struct plock_op *op; 426 int found = 0, do_callback = 0; 427 428 if (count != sizeof(info)) 429 return -EINVAL; 430 431 if (copy_from_user(&info, u, sizeof(info))) 432 return -EFAULT; 433 434 if (check_version(&info)) 435 return -EINVAL; 436 437 spin_lock(&ops_lock); 438 list_for_each_entry(op, &recv_list, list) { 439 if (op->info.fsid == info.fsid && 440 op->info.number == info.number && 441 op->info.owner == info.owner) { 442 struct plock_xop *xop = (struct plock_xop *)op; 443 list_del_init(&op->list); 444 memcpy(&op->info, &info, sizeof(info)); 445 if (xop->callback) 446 do_callback = 1; 447 else 448 op->done = 1; 449 found = 1; 450 break; 451 } 452 } 453 spin_unlock(&ops_lock); 454 455 if (found) { 456 if (do_callback) 457 dlm_plock_callback(op); 458 else 459 wake_up(&recv_wq); 460 } else 461 log_print("dev_write no op %x %llx", info.fsid, 462 (unsigned long long)info.number); 463 return count; 464 } 465 466 static __poll_t dev_poll(struct file *file, poll_table *wait) 467 { 468 __poll_t mask = 0; 469 470 poll_wait(file, &send_wq, wait); 471 472 spin_lock(&ops_lock); 473 if (!list_empty(&send_list)) 474 mask = EPOLLIN | EPOLLRDNORM; 475 spin_unlock(&ops_lock); 476 477 return mask; 478 } 479 480 static const struct file_operations dev_fops = { 481 .read = dev_read, 482 .write = dev_write, 483 .poll = dev_poll, 484 .owner = THIS_MODULE, 485 .llseek = noop_llseek, 486 }; 487 488 static struct miscdevice plock_dev_misc = { 489 .minor = MISC_DYNAMIC_MINOR, 490 .name = DLM_PLOCK_MISC_NAME, 491 .fops = &dev_fops 492 }; 493 494 int dlm_plock_init(void) 495 { 496 int rv; 497 498 spin_lock_init(&ops_lock); 499 INIT_LIST_HEAD(&send_list); 500 INIT_LIST_HEAD(&recv_list); 501 init_waitqueue_head(&send_wq); 502 init_waitqueue_head(&recv_wq); 503 504 rv = misc_register(&plock_dev_misc); 505 if (rv) 506 log_print("dlm_plock_init: misc_register failed %d", rv); 507 return rv; 508 } 509 510 void dlm_plock_exit(void) 511 { 512 misc_deregister(&plock_dev_misc); 513 } 514 515