fat: Remove FAT Directory Bread message
[linux-2.6.git] / fs / dlm / plock.c
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 /* 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
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
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 */
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
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
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 */
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 */
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
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
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
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