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
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_killable(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 (posix_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)(void *, void *, int) = 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, NULL, 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, NULL, 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
251 ls = dlm_find_lockspace_local(lockspace);
252 if (!ls)
253 return -EINVAL;
254
255 op = kzalloc(sizeof(*op), GFP_NOFS);
256 if (!op) {
257 rv = -ENOMEM;
258 goto out;
259 }
260
261 if (posix_lock_file_wait(file, fl) < 0)
262 log_error(ls, "dlm_posix_unlock: vfs unlock error %llx",
263 (unsigned long long)number);
264
265 op->info.optype = DLM_PLOCK_OP_UNLOCK;
266 op->info.pid = fl->fl_pid;
267 op->info.fsid = ls->ls_global_id;
268 op->info.number = number;
269 op->info.start = fl->fl_start;
270 op->info.end = fl->fl_end;
271 if (fl->fl_lmops && fl->fl_lmops->lm_grant)
272 op->info.owner = (__u64) fl->fl_pid;
273 else
274 op->info.owner = (__u64)(long) fl->fl_owner;
275
276 if (fl->fl_flags & FL_CLOSE) {
277 op->info.flags |= DLM_PLOCK_FL_CLOSE;
278 send_op(op);
279 rv = 0;
280 goto out;
281 }
282
283 send_op(op);
284 wait_event(recv_wq, (op->done != 0));
285
286 spin_lock(&ops_lock);
287 if (!list_empty(&op->list)) {
288 log_error(ls, "dlm_posix_unlock: op on list %llx",
289 (unsigned long long)number);
290 list_del(&op->list);
291 }
292 spin_unlock(&ops_lock);
293
294 rv = op->info.rv;
295
296 if (rv == -ENOENT)
297 rv = 0;
298
299 kfree(op);
300 out:
301 dlm_put_lockspace(ls);
302 return rv;
303 }
304 EXPORT_SYMBOL_GPL(dlm_posix_unlock);
305
dlm_posix_get(dlm_lockspace_t * lockspace,u64 number,struct file * file,struct file_lock * fl)306 int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file,
307 struct file_lock *fl)
308 {
309 struct dlm_ls *ls;
310 struct plock_op *op;
311 int rv;
312
313 ls = dlm_find_lockspace_local(lockspace);
314 if (!ls)
315 return -EINVAL;
316
317 op = kzalloc(sizeof(*op), GFP_NOFS);
318 if (!op) {
319 rv = -ENOMEM;
320 goto out;
321 }
322
323 op->info.optype = DLM_PLOCK_OP_GET;
324 op->info.pid = fl->fl_pid;
325 op->info.ex = (fl->fl_type == F_WRLCK);
326 op->info.fsid = ls->ls_global_id;
327 op->info.number = number;
328 op->info.start = fl->fl_start;
329 op->info.end = fl->fl_end;
330 if (fl->fl_lmops && fl->fl_lmops->lm_grant)
331 op->info.owner = (__u64) fl->fl_pid;
332 else
333 op->info.owner = (__u64)(long) fl->fl_owner;
334
335 send_op(op);
336 wait_event(recv_wq, (op->done != 0));
337
338 spin_lock(&ops_lock);
339 if (!list_empty(&op->list)) {
340 log_error(ls, "dlm_posix_get: op on list %llx",
341 (unsigned long long)number);
342 list_del(&op->list);
343 }
344 spin_unlock(&ops_lock);
345
346 /* info.rv from userspace is 1 for conflict, 0 for no-conflict,
347 -ENOENT if there are no locks on the file */
348
349 rv = op->info.rv;
350
351 fl->fl_type = F_UNLCK;
352 if (rv == -ENOENT)
353 rv = 0;
354 else if (rv > 0) {
355 locks_init_lock(fl);
356 fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK;
357 fl->fl_flags = FL_POSIX;
358 fl->fl_pid = op->info.pid;
359 fl->fl_start = op->info.start;
360 fl->fl_end = op->info.end;
361 rv = 0;
362 }
363
364 kfree(op);
365 out:
366 dlm_put_lockspace(ls);
367 return rv;
368 }
369 EXPORT_SYMBOL_GPL(dlm_posix_get);
370
371 /* 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)372 static ssize_t dev_read(struct file *file, char __user *u, size_t count,
373 loff_t *ppos)
374 {
375 struct dlm_plock_info info;
376 struct plock_op *op = NULL;
377
378 if (count < sizeof(info))
379 return -EINVAL;
380
381 spin_lock(&ops_lock);
382 if (!list_empty(&send_list)) {
383 op = list_entry(send_list.next, struct plock_op, list);
384 if (op->info.flags & DLM_PLOCK_FL_CLOSE)
385 list_del(&op->list);
386 else
387 list_move(&op->list, &recv_list);
388 memcpy(&info, &op->info, sizeof(info));
389 }
390 spin_unlock(&ops_lock);
391
392 if (!op)
393 return -EAGAIN;
394
395 /* there is no need to get a reply from userspace for unlocks
396 that were generated by the vfs cleaning up for a close
397 (the process did not make an unlock call). */
398
399 if (op->info.flags & DLM_PLOCK_FL_CLOSE)
400 kfree(op);
401
402 if (copy_to_user(u, &info, sizeof(info)))
403 return -EFAULT;
404 return sizeof(info);
405 }
406
407 /* a write copies in one plock result that should match a plock_op
408 on the recv list */
dev_write(struct file * file,const char __user * u,size_t count,loff_t * ppos)409 static ssize_t dev_write(struct file *file, const char __user *u, size_t count,
410 loff_t *ppos)
411 {
412 struct dlm_plock_info info;
413 struct plock_op *op;
414 int found = 0, do_callback = 0;
415
416 if (count != sizeof(info))
417 return -EINVAL;
418
419 if (copy_from_user(&info, u, sizeof(info)))
420 return -EFAULT;
421
422 if (check_version(&info))
423 return -EINVAL;
424
425 spin_lock(&ops_lock);
426 list_for_each_entry(op, &recv_list, list) {
427 if (op->info.fsid == info.fsid &&
428 op->info.number == info.number &&
429 op->info.owner == info.owner) {
430 struct plock_xop *xop = (struct plock_xop *)op;
431 list_del_init(&op->list);
432 memcpy(&op->info, &info, sizeof(info));
433 if (xop->callback)
434 do_callback = 1;
435 else
436 op->done = 1;
437 found = 1;
438 break;
439 }
440 }
441 spin_unlock(&ops_lock);
442
443 if (found) {
444 if (do_callback)
445 dlm_plock_callback(op);
446 else
447 wake_up(&recv_wq);
448 } else
449 log_print("dev_write no op %x %llx", info.fsid,
450 (unsigned long long)info.number);
451 return count;
452 }
453
dev_poll(struct file * file,poll_table * wait)454 static unsigned int dev_poll(struct file *file, poll_table *wait)
455 {
456 unsigned int mask = 0;
457
458 poll_wait(file, &send_wq, wait);
459
460 spin_lock(&ops_lock);
461 if (!list_empty(&send_list))
462 mask = POLLIN | POLLRDNORM;
463 spin_unlock(&ops_lock);
464
465 return mask;
466 }
467
468 static const struct file_operations dev_fops = {
469 .read = dev_read,
470 .write = dev_write,
471 .poll = dev_poll,
472 .owner = THIS_MODULE,
473 .llseek = noop_llseek,
474 };
475
476 static struct miscdevice plock_dev_misc = {
477 .minor = MISC_DYNAMIC_MINOR,
478 .name = DLM_PLOCK_MISC_NAME,
479 .fops = &dev_fops
480 };
481
dlm_plock_init(void)482 int dlm_plock_init(void)
483 {
484 int rv;
485
486 spin_lock_init(&ops_lock);
487 INIT_LIST_HEAD(&send_list);
488 INIT_LIST_HEAD(&recv_list);
489 init_waitqueue_head(&send_wq);
490 init_waitqueue_head(&recv_wq);
491
492 rv = misc_register(&plock_dev_misc);
493 if (rv)
494 log_print("dlm_plock_init: misc_register failed %d", rv);
495 return rv;
496 }
497
dlm_plock_exit(void)498 void dlm_plock_exit(void)
499 {
500 if (misc_deregister(&plock_dev_misc) < 0)
501 log_print("dlm_plock_exit: misc_deregister failed");
502 }
503
504