llseek: automatically add .llseek fop
[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 int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
75                    int cmd, struct file_lock *fl)
76 {
77         struct dlm_ls *ls;
78         struct plock_op *op;
79         struct plock_xop *xop;
80         int rv;
81
82         ls = dlm_find_lockspace_local(lockspace);
83         if (!ls)
84                 return -EINVAL;
85
86         xop = kzalloc(sizeof(*xop), GFP_NOFS);
87         if (!xop) {
88                 rv = -ENOMEM;
89                 goto out;
90         }
91
92         op = &xop->xop;
93         op->info.optype         = DLM_PLOCK_OP_LOCK;
94         op->info.pid            = fl->fl_pid;
95         op->info.ex             = (fl->fl_type == F_WRLCK);
96         op->info.wait           = IS_SETLKW(cmd);
97         op->info.fsid           = ls->ls_global_id;
98         op->info.number         = number;
99         op->info.start          = fl->fl_start;
100         op->info.end            = fl->fl_end;
101         if (fl->fl_lmops && fl->fl_lmops->fl_grant) {
102                 /* fl_owner is lockd which doesn't distinguish
103                    processes on the nfs client */
104                 op->info.owner  = (__u64) fl->fl_pid;
105                 xop->callback   = fl->fl_lmops->fl_grant;
106                 locks_init_lock(&xop->flc);
107                 locks_copy_lock(&xop->flc, fl);
108                 xop->fl         = fl;
109                 xop->file       = file;
110         } else {
111                 op->info.owner  = (__u64)(long) fl->fl_owner;
112                 xop->callback   = NULL;
113         }
114
115         send_op(op);
116
117         if (xop->callback == NULL)
118                 wait_event(recv_wq, (op->done != 0));
119         else {
120                 rv = FILE_LOCK_DEFERRED;
121                 goto out;
122         }
123
124         spin_lock(&ops_lock);
125         if (!list_empty(&op->list)) {
126                 log_error(ls, "dlm_posix_lock: op on list %llx",
127                           (unsigned long long)number);
128                 list_del(&op->list);
129         }
130         spin_unlock(&ops_lock);
131
132         rv = op->info.rv;
133
134         if (!rv) {
135                 if (posix_lock_file_wait(file, fl) < 0)
136                         log_error(ls, "dlm_posix_lock: vfs lock error %llx",
137                                   (unsigned long long)number);
138         }
139
140         kfree(xop);
141 out:
142         dlm_put_lockspace(ls);
143         return rv;
144 }
145 EXPORT_SYMBOL_GPL(dlm_posix_lock);
146
147 /* Returns failure iff a successful lock operation should be canceled */
148 static int dlm_plock_callback(struct plock_op *op)
149 {
150         struct file *file;
151         struct file_lock *fl;
152         struct file_lock *flc;
153         int (*notify)(void *, void *, int) = NULL;
154         struct plock_xop *xop = (struct plock_xop *)op;
155         int rv = 0;
156
157         spin_lock(&ops_lock);
158         if (!list_empty(&op->list)) {
159                 log_print("dlm_plock_callback: op on list %llx",
160                           (unsigned long long)op->info.number);
161                 list_del(&op->list);
162         }
163         spin_unlock(&ops_lock);
164
165         /* check if the following 2 are still valid or make a copy */
166         file = xop->file;
167         flc = &xop->flc;
168         fl = xop->fl;
169         notify = xop->callback;
170
171         if (op->info.rv) {
172                 notify(fl, NULL, op->info.rv);
173                 goto out;
174         }
175
176         /* got fs lock; bookkeep locally as well: */
177         flc->fl_flags &= ~FL_SLEEP;
178         if (posix_lock_file(file, flc, NULL)) {
179                 /*
180                  * This can only happen in the case of kmalloc() failure.
181                  * The filesystem's own lock is the authoritative lock,
182                  * so a failure to get the lock locally is not a disaster.
183                  * As long as the fs cannot reliably cancel locks (especially
184                  * in a low-memory situation), we're better off ignoring
185                  * this failure than trying to recover.
186                  */
187                 log_print("dlm_plock_callback: vfs lock error %llx file %p fl %p",
188                           (unsigned long long)op->info.number, file, fl);
189         }
190
191         rv = notify(fl, NULL, 0);
192         if (rv) {
193                 /* XXX: We need to cancel the fs lock here: */
194                 log_print("dlm_plock_callback: lock granted after lock request "
195                           "failed; dangling lock!\n");
196                 goto out;
197         }
198
199 out:
200         kfree(xop);
201         return rv;
202 }
203
204 int dlm_posix_unlock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
205                      struct file_lock *fl)
206 {
207         struct dlm_ls *ls;
208         struct plock_op *op;
209         int rv;
210
211         ls = dlm_find_lockspace_local(lockspace);
212         if (!ls)
213                 return -EINVAL;
214
215         op = kzalloc(sizeof(*op), GFP_NOFS);
216         if (!op) {
217                 rv = -ENOMEM;
218                 goto out;
219         }
220
221         if (posix_lock_file_wait(file, fl) < 0)
222                 log_error(ls, "dlm_posix_unlock: vfs unlock error %llx",
223                           (unsigned long long)number);
224
225         op->info.optype         = DLM_PLOCK_OP_UNLOCK;
226         op->info.pid            = fl->fl_pid;
227         op->info.fsid           = ls->ls_global_id;
228         op->info.number         = number;
229         op->info.start          = fl->fl_start;
230         op->info.end            = fl->fl_end;
231         if (fl->fl_lmops && fl->fl_lmops->fl_grant)
232                 op->info.owner  = (__u64) fl->fl_pid;
233         else
234                 op->info.owner  = (__u64)(long) fl->fl_owner;
235
236         send_op(op);
237         wait_event(recv_wq, (op->done != 0));
238
239         spin_lock(&ops_lock);
240         if (!list_empty(&op->list)) {
241                 log_error(ls, "dlm_posix_unlock: op on list %llx",
242                           (unsigned long long)number);
243                 list_del(&op->list);
244         }
245         spin_unlock(&ops_lock);
246
247         rv = op->info.rv;
248
249         if (rv == -ENOENT)
250                 rv = 0;
251
252         kfree(op);
253 out:
254         dlm_put_lockspace(ls);
255         return rv;
256 }
257 EXPORT_SYMBOL_GPL(dlm_posix_unlock);
258
259 int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file,
260                   struct file_lock *fl)
261 {
262         struct dlm_ls *ls;
263         struct plock_op *op;
264         int rv;
265
266         ls = dlm_find_lockspace_local(lockspace);
267         if (!ls)
268                 return -EINVAL;
269
270         op = kzalloc(sizeof(*op), GFP_NOFS);
271         if (!op) {
272                 rv = -ENOMEM;
273                 goto out;
274         }
275
276         op->info.optype         = DLM_PLOCK_OP_GET;
277         op->info.pid            = fl->fl_pid;
278         op->info.ex             = (fl->fl_type == F_WRLCK);
279         op->info.fsid           = ls->ls_global_id;
280         op->info.number         = number;
281         op->info.start          = fl->fl_start;
282         op->info.end            = fl->fl_end;
283         if (fl->fl_lmops && fl->fl_lmops->fl_grant)
284                 op->info.owner  = (__u64) fl->fl_pid;
285         else
286                 op->info.owner  = (__u64)(long) fl->fl_owner;
287
288         send_op(op);
289         wait_event(recv_wq, (op->done != 0));
290
291         spin_lock(&ops_lock);
292         if (!list_empty(&op->list)) {
293                 log_error(ls, "dlm_posix_get: op on list %llx",
294                           (unsigned long long)number);
295                 list_del(&op->list);
296         }
297         spin_unlock(&ops_lock);
298
299         /* info.rv from userspace is 1 for conflict, 0 for no-conflict,
300            -ENOENT if there are no locks on the file */
301
302         rv = op->info.rv;
303
304         fl->fl_type = F_UNLCK;
305         if (rv == -ENOENT)
306                 rv = 0;
307         else if (rv > 0) {
308                 locks_init_lock(fl);
309                 fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK;
310                 fl->fl_flags = FL_POSIX;
311                 fl->fl_pid = op->info.pid;
312                 fl->fl_start = op->info.start;
313                 fl->fl_end = op->info.end;
314                 rv = 0;
315         }
316
317         kfree(op);
318 out:
319         dlm_put_lockspace(ls);
320         return rv;
321 }
322 EXPORT_SYMBOL_GPL(dlm_posix_get);
323
324 /* a read copies out one plock request from the send list */
325 static ssize_t dev_read(struct file *file, char __user *u, size_t count,
326                         loff_t *ppos)
327 {
328         struct dlm_plock_info info;
329         struct plock_op *op = NULL;
330
331         if (count < sizeof(info))
332                 return -EINVAL;
333
334         spin_lock(&ops_lock);
335         if (!list_empty(&send_list)) {
336                 op = list_entry(send_list.next, struct plock_op, list);
337                 list_move(&op->list, &recv_list);
338                 memcpy(&info, &op->info, sizeof(info));
339         }
340         spin_unlock(&ops_lock);
341
342         if (!op)
343                 return -EAGAIN;
344
345         if (copy_to_user(u, &info, sizeof(info)))
346                 return -EFAULT;
347         return sizeof(info);
348 }
349
350 /* a write copies in one plock result that should match a plock_op
351    on the recv list */
352 static ssize_t dev_write(struct file *file, const char __user *u, size_t count,
353                          loff_t *ppos)
354 {
355         struct dlm_plock_info info;
356         struct plock_op *op;
357         int found = 0, do_callback = 0;
358
359         if (count != sizeof(info))
360                 return -EINVAL;
361
362         if (copy_from_user(&info, u, sizeof(info)))
363                 return -EFAULT;
364
365         if (check_version(&info))
366                 return -EINVAL;
367
368         spin_lock(&ops_lock);
369         list_for_each_entry(op, &recv_list, list) {
370                 if (op->info.fsid == info.fsid &&
371                     op->info.number == info.number &&
372                     op->info.owner == info.owner) {
373                         struct plock_xop *xop = (struct plock_xop *)op;
374                         list_del_init(&op->list);
375                         memcpy(&op->info, &info, sizeof(info));
376                         if (xop->callback)
377                                 do_callback = 1;
378                         else
379                                 op->done = 1;
380                         found = 1;
381                         break;
382                 }
383         }
384         spin_unlock(&ops_lock);
385
386         if (found) {
387                 if (do_callback)
388                         dlm_plock_callback(op);
389                 else
390                         wake_up(&recv_wq);
391         } else
392                 log_print("dev_write no op %x %llx", info.fsid,
393                           (unsigned long long)info.number);
394         return count;
395 }
396
397 static unsigned int dev_poll(struct file *file, poll_table *wait)
398 {
399         unsigned int mask = 0;
400
401         poll_wait(file, &send_wq, wait);
402
403         spin_lock(&ops_lock);
404         if (!list_empty(&send_list))
405                 mask = POLLIN | POLLRDNORM;
406         spin_unlock(&ops_lock);
407
408         return mask;
409 }
410
411 static const struct file_operations dev_fops = {
412         .read    = dev_read,
413         .write   = dev_write,
414         .poll    = dev_poll,
415         .owner   = THIS_MODULE,
416         .llseek  = noop_llseek,
417 };
418
419 static struct miscdevice plock_dev_misc = {
420         .minor = MISC_DYNAMIC_MINOR,
421         .name = DLM_PLOCK_MISC_NAME,
422         .fops = &dev_fops
423 };
424
425 int dlm_plock_init(void)
426 {
427         int rv;
428
429         spin_lock_init(&ops_lock);
430         INIT_LIST_HEAD(&send_list);
431         INIT_LIST_HEAD(&recv_list);
432         init_waitqueue_head(&send_wq);
433         init_waitqueue_head(&recv_wq);
434
435         rv = misc_register(&plock_dev_misc);
436         if (rv)
437                 log_print("dlm_plock_init: misc_register failed %d", rv);
438         return rv;
439 }
440
441 void dlm_plock_exit(void)
442 {
443         if (misc_deregister(&plock_dev_misc) < 0)
444                 log_print("dlm_plock_exit: misc_deregister failed");
445 }
446