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
set_version(struct dlm_plock_info * info)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
check_version(struct dlm_plock_info * info)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
send_op(struct plock_op * op)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
do_unlock_close(struct dlm_ls * ls,u64 number,struct file * file,struct file_lock * fl)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
dlm_posix_lock(dlm_lockspace_t * lockspace,u64 number,struct file * file,int cmd,struct file_lock * fl)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 */
dlm_plock_callback(struct plock_op * op)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
dlm_posix_unlock(dlm_lockspace_t * lockspace,u64 number,struct file * file,struct file_lock * fl)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
dlm_posix_get(dlm_lockspace_t * lockspace,u64 number,struct file * file,struct file_lock * fl)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 */
dev_read(struct file * file,char __user * u,size_t count,loff_t * ppos)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 */
dev_write(struct file * file,const char __user * u,size_t count,loff_t * ppos)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
dev_poll(struct file * file,poll_table * wait)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
dlm_plock_init(void)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
dlm_plock_exit(void)510 void dlm_plock_exit(void)
511 {
512 misc_deregister(&plock_dev_misc);
513 }
514
515
