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
19static spinlock_t ops_lock;
20static struct list_head send_list;
21static struct list_head recv_list;
22static wait_queue_head_t send_wq;
23static wait_queue_head_t recv_wq;
24
25struct plock_op {
26	struct list_head list;
27	int done;
28	struct dlm_plock_info info;
29};
30
31struct 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
40static 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
47static 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
64static 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
80static 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
104int 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);
181out:
182	dlm_put_lockspace(ls);
183	return rv;
184}
185EXPORT_SYMBOL_GPL(dlm_posix_lock);
186
187/* Returns failure iff a successful lock operation should be canceled */
188static 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
239out:
240	kfree(xop);
241	return rv;
242}
243
244int 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 = posix_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
309out_free:
310	kfree(op);
311out:
312	dlm_put_lockspace(ls);
313	fl->fl_flags = fl_flags;
314	return rv;
315}
316EXPORT_SYMBOL_GPL(dlm_posix_unlock);
317
318int 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);
377out:
378	dlm_put_lockspace(ls);
379	return rv;
380}
381EXPORT_SYMBOL_GPL(dlm_posix_get);
382
383/* a read copies out one plock request from the send list */
384static 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 */
421static 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
466static unsigned int dev_poll(struct file *file, poll_table *wait)
467{
468	unsigned int mask = 0;
469
470	poll_wait(file, &send_wq, wait);
471
472	spin_lock(&ops_lock);
473	if (!list_empty(&send_list))
474		mask = POLLIN | POLLRDNORM;
475	spin_unlock(&ops_lock);
476
477	return mask;
478}
479
480static 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
488static struct miscdevice plock_dev_misc = {
489	.minor = MISC_DYNAMIC_MINOR,
490	.name = DLM_PLOCK_MISC_NAME,
491	.fops = &dev_fops
492};
493
494int 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
510void dlm_plock_exit(void)
511{
512	if (misc_deregister(&plock_dev_misc) < 0)
513		log_print("dlm_plock_exit: misc_deregister failed");
514}
515
516