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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@cambridge.redhat.com> | |
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 | } |