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