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 void *callback; 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 int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file, 75 int cmd, struct file_lock *fl) 76 { 77 struct dlm_ls *ls; 78 struct plock_op *op; 79 struct plock_xop *xop; 80 int rv; 81 82 ls = dlm_find_lockspace_local(lockspace); 83 if (!ls) 84 return -EINVAL; 85 86 xop = kzalloc(sizeof(*xop), GFP_NOFS); 87 if (!xop) { 88 rv = -ENOMEM; 89 goto out; 90 } 91 92 op = &xop->xop; 93 op->info.optype = DLM_PLOCK_OP_LOCK; 94 op->info.pid = fl->fl_pid; 95 op->info.ex = (fl->fl_type == F_WRLCK); 96 op->info.wait = IS_SETLKW(cmd); 97 op->info.fsid = ls->ls_global_id; 98 op->info.number = number; 99 op->info.start = fl->fl_start; 100 op->info.end = fl->fl_end; 101 if (fl->fl_lmops && fl->fl_lmops->fl_grant) { 102 /* fl_owner is lockd which doesn't distinguish 103 processes on the nfs client */ 104 op->info.owner = (__u64) fl->fl_pid; 105 xop->callback = fl->fl_lmops->fl_grant; 106 locks_init_lock(&xop->flc); 107 locks_copy_lock(&xop->flc, fl); 108 xop->fl = fl; 109 xop->file = file; 110 } else { 111 op->info.owner = (__u64)(long) fl->fl_owner; 112 xop->callback = NULL; 113 } 114 115 send_op(op); 116 117 if (xop->callback == NULL) 118 wait_event(recv_wq, (op->done != 0)); 119 else { 120 rv = FILE_LOCK_DEFERRED; 121 goto out; 122 } 123 124 spin_lock(&ops_lock); 125 if (!list_empty(&op->list)) { 126 log_error(ls, "dlm_posix_lock: op on list %llx", 127 (unsigned long long)number); 128 list_del(&op->list); 129 } 130 spin_unlock(&ops_lock); 131 132 rv = op->info.rv; 133 134 if (!rv) { 135 if (posix_lock_file_wait(file, fl) < 0) 136 log_error(ls, "dlm_posix_lock: vfs lock error %llx", 137 (unsigned long long)number); 138 } 139 140 kfree(xop); 141 out: 142 dlm_put_lockspace(ls); 143 return rv; 144 } 145 EXPORT_SYMBOL_GPL(dlm_posix_lock); 146 147 /* Returns failure iff a successful lock operation should be canceled */ 148 static int dlm_plock_callback(struct plock_op *op) 149 { 150 struct file *file; 151 struct file_lock *fl; 152 struct file_lock *flc; 153 int (*notify)(void *, void *, int) = NULL; 154 struct plock_xop *xop = (struct plock_xop *)op; 155 int rv = 0; 156 157 spin_lock(&ops_lock); 158 if (!list_empty(&op->list)) { 159 log_print("dlm_plock_callback: op on list %llx", 160 (unsigned long long)op->info.number); 161 list_del(&op->list); 162 } 163 spin_unlock(&ops_lock); 164 165 /* check if the following 2 are still valid or make a copy */ 166 file = xop->file; 167 flc = &xop->flc; 168 fl = xop->fl; 169 notify = xop->callback; 170 171 if (op->info.rv) { 172 notify(fl, NULL, op->info.rv); 173 goto out; 174 } 175 176 /* got fs lock; bookkeep locally as well: */ 177 flc->fl_flags &= ~FL_SLEEP; 178 if (posix_lock_file(file, flc, NULL)) { 179 /* 180 * This can only happen in the case of kmalloc() failure. 181 * The filesystem's own lock is the authoritative lock, 182 * so a failure to get the lock locally is not a disaster. 183 * As long as the fs cannot reliably cancel locks (especially 184 * in a low-memory situation), we're better off ignoring 185 * this failure than trying to recover. 186 */ 187 log_print("dlm_plock_callback: vfs lock error %llx file %p fl %p", 188 (unsigned long long)op->info.number, file, fl); 189 } 190 191 rv = notify(fl, NULL, 0); 192 if (rv) { 193 /* XXX: We need to cancel the fs lock here: */ 194 log_print("dlm_plock_callback: lock granted after lock request " 195 "failed; dangling lock!\n"); 196 goto out; 197 } 198 199 out: 200 kfree(xop); 201 return rv; 202 } 203 204 int dlm_posix_unlock(dlm_lockspace_t *lockspace, u64 number, struct file *file, 205 struct file_lock *fl) 206 { 207 struct dlm_ls *ls; 208 struct plock_op *op; 209 int rv; 210 211 ls = dlm_find_lockspace_local(lockspace); 212 if (!ls) 213 return -EINVAL; 214 215 op = kzalloc(sizeof(*op), GFP_NOFS); 216 if (!op) { 217 rv = -ENOMEM; 218 goto out; 219 } 220 221 if (posix_lock_file_wait(file, fl) < 0) 222 log_error(ls, "dlm_posix_unlock: vfs unlock error %llx", 223 (unsigned long long)number); 224 225 op->info.optype = DLM_PLOCK_OP_UNLOCK; 226 op->info.pid = fl->fl_pid; 227 op->info.fsid = ls->ls_global_id; 228 op->info.number = number; 229 op->info.start = fl->fl_start; 230 op->info.end = fl->fl_end; 231 if (fl->fl_lmops && fl->fl_lmops->fl_grant) 232 op->info.owner = (__u64) fl->fl_pid; 233 else 234 op->info.owner = (__u64)(long) fl->fl_owner; 235 236 send_op(op); 237 wait_event(recv_wq, (op->done != 0)); 238 239 spin_lock(&ops_lock); 240 if (!list_empty(&op->list)) { 241 log_error(ls, "dlm_posix_unlock: op on list %llx", 242 (unsigned long long)number); 243 list_del(&op->list); 244 } 245 spin_unlock(&ops_lock); 246 247 rv = op->info.rv; 248 249 if (rv == -ENOENT) 250 rv = 0; 251 252 kfree(op); 253 out: 254 dlm_put_lockspace(ls); 255 return rv; 256 } 257 EXPORT_SYMBOL_GPL(dlm_posix_unlock); 258 259 int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file, 260 struct file_lock *fl) 261 { 262 struct dlm_ls *ls; 263 struct plock_op *op; 264 int rv; 265 266 ls = dlm_find_lockspace_local(lockspace); 267 if (!ls) 268 return -EINVAL; 269 270 op = kzalloc(sizeof(*op), GFP_NOFS); 271 if (!op) { 272 rv = -ENOMEM; 273 goto out; 274 } 275 276 op->info.optype = DLM_PLOCK_OP_GET; 277 op->info.pid = fl->fl_pid; 278 op->info.ex = (fl->fl_type == F_WRLCK); 279 op->info.fsid = ls->ls_global_id; 280 op->info.number = number; 281 op->info.start = fl->fl_start; 282 op->info.end = fl->fl_end; 283 if (fl->fl_lmops && fl->fl_lmops->fl_grant) 284 op->info.owner = (__u64) fl->fl_pid; 285 else 286 op->info.owner = (__u64)(long) fl->fl_owner; 287 288 send_op(op); 289 wait_event(recv_wq, (op->done != 0)); 290 291 spin_lock(&ops_lock); 292 if (!list_empty(&op->list)) { 293 log_error(ls, "dlm_posix_get: op on list %llx", 294 (unsigned long long)number); 295 list_del(&op->list); 296 } 297 spin_unlock(&ops_lock); 298 299 /* info.rv from userspace is 1 for conflict, 0 for no-conflict, 300 -ENOENT if there are no locks on the file */ 301 302 rv = op->info.rv; 303 304 fl->fl_type = F_UNLCK; 305 if (rv == -ENOENT) 306 rv = 0; 307 else if (rv > 0) { 308 locks_init_lock(fl); 309 fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK; 310 fl->fl_flags = FL_POSIX; 311 fl->fl_pid = op->info.pid; 312 fl->fl_start = op->info.start; 313 fl->fl_end = op->info.end; 314 rv = 0; 315 } 316 317 kfree(op); 318 out: 319 dlm_put_lockspace(ls); 320 return rv; 321 } 322 EXPORT_SYMBOL_GPL(dlm_posix_get); 323 324 /* a read copies out one plock request from the send list */ 325 static ssize_t dev_read(struct file *file, char __user *u, size_t count, 326 loff_t *ppos) 327 { 328 struct dlm_plock_info info; 329 struct plock_op *op = NULL; 330 331 if (count < sizeof(info)) 332 return -EINVAL; 333 334 spin_lock(&ops_lock); 335 if (!list_empty(&send_list)) { 336 op = list_entry(send_list.next, struct plock_op, list); 337 list_move(&op->list, &recv_list); 338 memcpy(&info, &op->info, sizeof(info)); 339 } 340 spin_unlock(&ops_lock); 341 342 if (!op) 343 return -EAGAIN; 344 345 if (copy_to_user(u, &info, sizeof(info))) 346 return -EFAULT; 347 return sizeof(info); 348 } 349 350 /* a write copies in one plock result that should match a plock_op 351 on the recv list */ 352 static ssize_t dev_write(struct file *file, const char __user *u, size_t count, 353 loff_t *ppos) 354 { 355 struct dlm_plock_info info; 356 struct plock_op *op; 357 int found = 0, do_callback = 0; 358 359 if (count != sizeof(info)) 360 return -EINVAL; 361 362 if (copy_from_user(&info, u, sizeof(info))) 363 return -EFAULT; 364 365 if (check_version(&info)) 366 return -EINVAL; 367 368 spin_lock(&ops_lock); 369 list_for_each_entry(op, &recv_list, list) { 370 if (op->info.fsid == info.fsid && 371 op->info.number == info.number && 372 op->info.owner == info.owner) { 373 struct plock_xop *xop = (struct plock_xop *)op; 374 list_del_init(&op->list); 375 memcpy(&op->info, &info, sizeof(info)); 376 if (xop->callback) 377 do_callback = 1; 378 else 379 op->done = 1; 380 found = 1; 381 break; 382 } 383 } 384 spin_unlock(&ops_lock); 385 386 if (found) { 387 if (do_callback) 388 dlm_plock_callback(op); 389 else 390 wake_up(&recv_wq); 391 } else 392 log_print("dev_write no op %x %llx", info.fsid, 393 (unsigned long long)info.number); 394 return count; 395 } 396 397 static unsigned int dev_poll(struct file *file, poll_table *wait) 398 { 399 unsigned int mask = 0; 400 401 poll_wait(file, &send_wq, wait); 402 403 spin_lock(&ops_lock); 404 if (!list_empty(&send_list)) 405 mask = POLLIN | POLLRDNORM; 406 spin_unlock(&ops_lock); 407 408 return mask; 409 } 410 411 static const struct file_operations dev_fops = { 412 .read = dev_read, 413 .write = dev_write, 414 .poll = dev_poll, 415 .owner = THIS_MODULE 416 }; 417 418 static struct miscdevice plock_dev_misc = { 419 .minor = MISC_DYNAMIC_MINOR, 420 .name = DLM_PLOCK_MISC_NAME, 421 .fops = &dev_fops 422 }; 423 424 int dlm_plock_init(void) 425 { 426 int rv; 427 428 spin_lock_init(&ops_lock); 429 INIT_LIST_HEAD(&send_list); 430 INIT_LIST_HEAD(&recv_list); 431 init_waitqueue_head(&send_wq); 432 init_waitqueue_head(&recv_wq); 433 434 rv = misc_register(&plock_dev_misc); 435 if (rv) 436 log_print("dlm_plock_init: misc_register failed %d", rv); 437 return rv; 438 } 439 440 void dlm_plock_exit(void) 441 { 442 if (misc_deregister(&plock_dev_misc) < 0) 443 log_print("dlm_plock_exit: misc_deregister failed"); 444 } 445 446