cifs: don't allow cifs_reconnect to exit with NULL socket pointer
[linux-2.6.git] / fs / afs / callback.c
1 /*
2  * Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.
3  *
4  * This software may be freely redistributed under the terms of the
5  * GNU General Public License.
6  *
7  * You should have received a copy of the GNU General Public License
8  * along with this program; if not, write to the Free Software
9  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
10  *
11  * Authors: David Woodhouse <dwmw2@infradead.org>
12  *          David Howells <dhowells@redhat.com>
13  *
14  */
15
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/init.h>
19 #include <linux/circ_buf.h>
20 #include <linux/sched.h>
21 #include "internal.h"
22
23 #if 0
24 unsigned afs_vnode_update_timeout = 10;
25 #endif  /*  0  */
26
27 #define afs_breakring_space(server) \
28         CIRC_SPACE((server)->cb_break_head, (server)->cb_break_tail,    \
29                    ARRAY_SIZE((server)->cb_break))
30
31 //static void afs_callback_updater(struct work_struct *);
32
33 static struct workqueue_struct *afs_callback_update_worker;
34
35 /*
36  * allow the fileserver to request callback state (re-)initialisation
37  */
38 void afs_init_callback_state(struct afs_server *server)
39 {
40         struct afs_vnode *vnode;
41
42         _enter("{%p}", server);
43
44         spin_lock(&server->cb_lock);
45
46         /* kill all the promises on record from this server */
47         while (!RB_EMPTY_ROOT(&server->cb_promises)) {
48                 vnode = rb_entry(server->cb_promises.rb_node,
49                                  struct afs_vnode, cb_promise);
50                 _debug("UNPROMISE { vid=%x:%u uq=%u}",
51                        vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
52                 rb_erase(&vnode->cb_promise, &server->cb_promises);
53                 vnode->cb_promised = false;
54         }
55
56         spin_unlock(&server->cb_lock);
57         _leave("");
58 }
59
60 /*
61  * handle the data invalidation side of a callback being broken
62  */
63 void afs_broken_callback_work(struct work_struct *work)
64 {
65         struct afs_vnode *vnode =
66                 container_of(work, struct afs_vnode, cb_broken_work);
67
68         _enter("");
69
70         if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
71                 return;
72
73         /* we're only interested in dealing with a broken callback on *this*
74          * vnode and only if no-one else has dealt with it yet */
75         if (!mutex_trylock(&vnode->validate_lock))
76                 return; /* someone else is dealing with it */
77
78         if (test_bit(AFS_VNODE_CB_BROKEN, &vnode->flags)) {
79                 if (S_ISDIR(vnode->vfs_inode.i_mode))
80                         afs_clear_permits(vnode);
81
82                 if (afs_vnode_fetch_status(vnode, NULL, NULL) < 0)
83                         goto out;
84
85                 if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
86                         goto out;
87
88                 /* if the vnode's data version number changed then its contents
89                  * are different */
90                 if (test_and_clear_bit(AFS_VNODE_ZAP_DATA, &vnode->flags))
91                         afs_zap_data(vnode);
92         }
93
94 out:
95         mutex_unlock(&vnode->validate_lock);
96
97         /* avoid the potential race whereby the mutex_trylock() in this
98          * function happens again between the clear_bit() and the
99          * mutex_unlock() */
100         if (test_bit(AFS_VNODE_CB_BROKEN, &vnode->flags)) {
101                 _debug("requeue");
102                 queue_work(afs_callback_update_worker, &vnode->cb_broken_work);
103         }
104         _leave("");
105 }
106
107 /*
108  * actually break a callback
109  */
110 static void afs_break_callback(struct afs_server *server,
111                                struct afs_vnode *vnode)
112 {
113         _enter("");
114
115         set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
116
117         if (vnode->cb_promised) {
118                 spin_lock(&vnode->lock);
119
120                 _debug("break callback");
121
122                 spin_lock(&server->cb_lock);
123                 if (vnode->cb_promised) {
124                         rb_erase(&vnode->cb_promise, &server->cb_promises);
125                         vnode->cb_promised = false;
126                 }
127                 spin_unlock(&server->cb_lock);
128
129                 queue_work(afs_callback_update_worker, &vnode->cb_broken_work);
130                 if (list_empty(&vnode->granted_locks) &&
131                     !list_empty(&vnode->pending_locks))
132                         afs_lock_may_be_available(vnode);
133                 spin_unlock(&vnode->lock);
134         }
135 }
136
137 /*
138  * allow the fileserver to explicitly break one callback
139  * - happens when
140  *   - the backing file is changed
141  *   - a lock is released
142  */
143 static void afs_break_one_callback(struct afs_server *server,
144                                    struct afs_fid *fid)
145 {
146         struct afs_vnode *vnode;
147         struct rb_node *p;
148
149         _debug("find");
150         spin_lock(&server->fs_lock);
151         p = server->fs_vnodes.rb_node;
152         while (p) {
153                 vnode = rb_entry(p, struct afs_vnode, server_rb);
154                 if (fid->vid < vnode->fid.vid)
155                         p = p->rb_left;
156                 else if (fid->vid > vnode->fid.vid)
157                         p = p->rb_right;
158                 else if (fid->vnode < vnode->fid.vnode)
159                         p = p->rb_left;
160                 else if (fid->vnode > vnode->fid.vnode)
161                         p = p->rb_right;
162                 else if (fid->unique < vnode->fid.unique)
163                         p = p->rb_left;
164                 else if (fid->unique > vnode->fid.unique)
165                         p = p->rb_right;
166                 else
167                         goto found;
168         }
169
170         /* not found so we just ignore it (it may have moved to another
171          * server) */
172 not_available:
173         _debug("not avail");
174         spin_unlock(&server->fs_lock);
175         _leave("");
176         return;
177
178 found:
179         _debug("found");
180         ASSERTCMP(server, ==, vnode->server);
181
182         if (!igrab(AFS_VNODE_TO_I(vnode)))
183                 goto not_available;
184         spin_unlock(&server->fs_lock);
185
186         afs_break_callback(server, vnode);
187         iput(&vnode->vfs_inode);
188         _leave("");
189 }
190
191 /*
192  * allow the fileserver to break callback promises
193  */
194 void afs_break_callbacks(struct afs_server *server, size_t count,
195                          struct afs_callback callbacks[])
196 {
197         _enter("%p,%zu,", server, count);
198
199         ASSERT(server != NULL);
200         ASSERTCMP(count, <=, AFSCBMAX);
201
202         for (; count > 0; callbacks++, count--) {
203                 _debug("- Fid { vl=%08x n=%u u=%u }  CB { v=%u x=%u t=%u }",
204                        callbacks->fid.vid,
205                        callbacks->fid.vnode,
206                        callbacks->fid.unique,
207                        callbacks->version,
208                        callbacks->expiry,
209                        callbacks->type
210                        );
211                 afs_break_one_callback(server, &callbacks->fid);
212         }
213
214         _leave("");
215         return;
216 }
217
218 /*
219  * record the callback for breaking
220  * - the caller must hold server->cb_lock
221  */
222 static void afs_do_give_up_callback(struct afs_server *server,
223                                     struct afs_vnode *vnode)
224 {
225         struct afs_callback *cb;
226
227         _enter("%p,%p", server, vnode);
228
229         cb = &server->cb_break[server->cb_break_head];
230         cb->fid         = vnode->fid;
231         cb->version     = vnode->cb_version;
232         cb->expiry      = vnode->cb_expiry;
233         cb->type        = vnode->cb_type;
234         smp_wmb();
235         server->cb_break_head =
236                 (server->cb_break_head + 1) &
237                 (ARRAY_SIZE(server->cb_break) - 1);
238
239         /* defer the breaking of callbacks to try and collect as many as
240          * possible to ship in one operation */
241         switch (atomic_inc_return(&server->cb_break_n)) {
242         case 1 ... AFSCBMAX - 1:
243                 queue_delayed_work(afs_callback_update_worker,
244                                    &server->cb_break_work, HZ * 2);
245                 break;
246         case AFSCBMAX:
247                 afs_flush_callback_breaks(server);
248                 break;
249         default:
250                 break;
251         }
252
253         ASSERT(server->cb_promises.rb_node != NULL);
254         rb_erase(&vnode->cb_promise, &server->cb_promises);
255         vnode->cb_promised = false;
256         _leave("");
257 }
258
259 /*
260  * discard the callback on a deleted item
261  */
262 void afs_discard_callback_on_delete(struct afs_vnode *vnode)
263 {
264         struct afs_server *server = vnode->server;
265
266         _enter("%d", vnode->cb_promised);
267
268         if (!vnode->cb_promised) {
269                 _leave(" [not promised]");
270                 return;
271         }
272
273         ASSERT(server != NULL);
274
275         spin_lock(&server->cb_lock);
276         if (vnode->cb_promised) {
277                 ASSERT(server->cb_promises.rb_node != NULL);
278                 rb_erase(&vnode->cb_promise, &server->cb_promises);
279                 vnode->cb_promised = false;
280         }
281         spin_unlock(&server->cb_lock);
282         _leave("");
283 }
284
285 /*
286  * give up the callback registered for a vnode on the file server when the
287  * inode is being cleared
288  */
289 void afs_give_up_callback(struct afs_vnode *vnode)
290 {
291         struct afs_server *server = vnode->server;
292
293         DECLARE_WAITQUEUE(myself, current);
294
295         _enter("%d", vnode->cb_promised);
296
297         _debug("GIVE UP INODE %p", &vnode->vfs_inode);
298
299         if (!vnode->cb_promised) {
300                 _leave(" [not promised]");
301                 return;
302         }
303
304         ASSERT(server != NULL);
305
306         spin_lock(&server->cb_lock);
307         if (vnode->cb_promised && afs_breakring_space(server) == 0) {
308                 add_wait_queue(&server->cb_break_waitq, &myself);
309                 for (;;) {
310                         set_current_state(TASK_UNINTERRUPTIBLE);
311                         if (!vnode->cb_promised ||
312                             afs_breakring_space(server) != 0)
313                                 break;
314                         spin_unlock(&server->cb_lock);
315                         schedule();
316                         spin_lock(&server->cb_lock);
317                 }
318                 remove_wait_queue(&server->cb_break_waitq, &myself);
319                 __set_current_state(TASK_RUNNING);
320         }
321
322         /* of course, it's always possible for the server to break this vnode's
323          * callback first... */
324         if (vnode->cb_promised)
325                 afs_do_give_up_callback(server, vnode);
326
327         spin_unlock(&server->cb_lock);
328         _leave("");
329 }
330
331 /*
332  * dispatch a deferred give up callbacks operation
333  */
334 void afs_dispatch_give_up_callbacks(struct work_struct *work)
335 {
336         struct afs_server *server =
337                 container_of(work, struct afs_server, cb_break_work.work);
338
339         _enter("");
340
341         /* tell the fileserver to discard the callback promises it has
342          * - in the event of ENOMEM or some other error, we just forget that we
343          *   had callbacks entirely, and the server will call us later to break
344          *   them
345          */
346         afs_fs_give_up_callbacks(server, &afs_async_call);
347 }
348
349 /*
350  * flush the outstanding callback breaks on a server
351  */
352 void afs_flush_callback_breaks(struct afs_server *server)
353 {
354         cancel_delayed_work(&server->cb_break_work);
355         queue_delayed_work(afs_callback_update_worker,
356                            &server->cb_break_work, 0);
357 }
358
359 #if 0
360 /*
361  * update a bunch of callbacks
362  */
363 static void afs_callback_updater(struct work_struct *work)
364 {
365         struct afs_server *server;
366         struct afs_vnode *vnode, *xvnode;
367         time_t now;
368         long timeout;
369         int ret;
370
371         server = container_of(work, struct afs_server, updater);
372
373         _enter("");
374
375         now = get_seconds();
376
377         /* find the first vnode to update */
378         spin_lock(&server->cb_lock);
379         for (;;) {
380                 if (RB_EMPTY_ROOT(&server->cb_promises)) {
381                         spin_unlock(&server->cb_lock);
382                         _leave(" [nothing]");
383                         return;
384                 }
385
386                 vnode = rb_entry(rb_first(&server->cb_promises),
387                                  struct afs_vnode, cb_promise);
388                 if (atomic_read(&vnode->usage) > 0)
389                         break;
390                 rb_erase(&vnode->cb_promise, &server->cb_promises);
391                 vnode->cb_promised = false;
392         }
393
394         timeout = vnode->update_at - now;
395         if (timeout > 0) {
396                 queue_delayed_work(afs_vnode_update_worker,
397                                    &afs_vnode_update, timeout * HZ);
398                 spin_unlock(&server->cb_lock);
399                 _leave(" [nothing]");
400                 return;
401         }
402
403         list_del_init(&vnode->update);
404         atomic_inc(&vnode->usage);
405         spin_unlock(&server->cb_lock);
406
407         /* we can now perform the update */
408         _debug("update %s", vnode->vldb.name);
409         vnode->state = AFS_VL_UPDATING;
410         vnode->upd_rej_cnt = 0;
411         vnode->upd_busy_cnt = 0;
412
413         ret = afs_vnode_update_record(vl, &vldb);
414         switch (ret) {
415         case 0:
416                 afs_vnode_apply_update(vl, &vldb);
417                 vnode->state = AFS_VL_UPDATING;
418                 break;
419         case -ENOMEDIUM:
420                 vnode->state = AFS_VL_VOLUME_DELETED;
421                 break;
422         default:
423                 vnode->state = AFS_VL_UNCERTAIN;
424                 break;
425         }
426
427         /* and then reschedule */
428         _debug("reschedule");
429         vnode->update_at = get_seconds() + afs_vnode_update_timeout;
430
431         spin_lock(&server->cb_lock);
432
433         if (!list_empty(&server->cb_promises)) {
434                 /* next update in 10 minutes, but wait at least 1 second more
435                  * than the newest record already queued so that we don't spam
436                  * the VL server suddenly with lots of requests
437                  */
438                 xvnode = list_entry(server->cb_promises.prev,
439                                     struct afs_vnode, update);
440                 if (vnode->update_at <= xvnode->update_at)
441                         vnode->update_at = xvnode->update_at + 1;
442                 xvnode = list_entry(server->cb_promises.next,
443                                     struct afs_vnode, update);
444                 timeout = xvnode->update_at - now;
445                 if (timeout < 0)
446                         timeout = 0;
447         } else {
448                 timeout = afs_vnode_update_timeout;
449         }
450
451         list_add_tail(&vnode->update, &server->cb_promises);
452
453         _debug("timeout %ld", timeout);
454         queue_delayed_work(afs_vnode_update_worker,
455                            &afs_vnode_update, timeout * HZ);
456         spin_unlock(&server->cb_lock);
457         afs_put_vnode(vl);
458 }
459 #endif
460
461 /*
462  * initialise the callback update process
463  */
464 int __init afs_callback_update_init(void)
465 {
466         afs_callback_update_worker =
467                 create_singlethread_workqueue("kafs_callbackd");
468         return afs_callback_update_worker ? 0 : -ENOMEM;
469 }
470
471 /*
472  * shut down the callback update process
473  */
474 void afs_callback_update_kill(void)
475 {
476         destroy_workqueue(afs_callback_update_worker);
477 }