xref: /openbmc/linux/fs/afs/callback.c (revision aac5987a) 
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, true);
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 	mod_delayed_work(afs_callback_update_worker, &server->cb_break_work, 0);
355 }
356 
357 #if 0
358 /*
359  * update a bunch of callbacks
360  */
361 static void afs_callback_updater(struct work_struct *work)
362 {
363 	struct afs_server *server;
364 	struct afs_vnode *vnode, *xvnode;
365 	time_t now;
366 	long timeout;
367 	int ret;
368 
369 	server = container_of(work, struct afs_server, updater);
370 
371 	_enter("");
372 
373 	now = get_seconds();
374 
375 	/* find the first vnode to update */
376 	spin_lock(&server->cb_lock);
377 	for (;;) {
378 		if (RB_EMPTY_ROOT(&server->cb_promises)) {
379 			spin_unlock(&server->cb_lock);
380 			_leave(" [nothing]");
381 			return;
382 		}
383 
384 		vnode = rb_entry(rb_first(&server->cb_promises),
385 				 struct afs_vnode, cb_promise);
386 		if (atomic_read(&vnode->usage) > 0)
387 			break;
388 		rb_erase(&vnode->cb_promise, &server->cb_promises);
389 		vnode->cb_promised = false;
390 	}
391 
392 	timeout = vnode->update_at - now;
393 	if (timeout > 0) {
394 		queue_delayed_work(afs_vnode_update_worker,
395 				   &afs_vnode_update, timeout * HZ);
396 		spin_unlock(&server->cb_lock);
397 		_leave(" [nothing]");
398 		return;
399 	}
400 
401 	list_del_init(&vnode->update);
402 	atomic_inc(&vnode->usage);
403 	spin_unlock(&server->cb_lock);
404 
405 	/* we can now perform the update */
406 	_debug("update %s", vnode->vldb.name);
407 	vnode->state = AFS_VL_UPDATING;
408 	vnode->upd_rej_cnt = 0;
409 	vnode->upd_busy_cnt = 0;
410 
411 	ret = afs_vnode_update_record(vl, &vldb);
412 	switch (ret) {
413 	case 0:
414 		afs_vnode_apply_update(vl, &vldb);
415 		vnode->state = AFS_VL_UPDATING;
416 		break;
417 	case -ENOMEDIUM:
418 		vnode->state = AFS_VL_VOLUME_DELETED;
419 		break;
420 	default:
421 		vnode->state = AFS_VL_UNCERTAIN;
422 		break;
423 	}
424 
425 	/* and then reschedule */
426 	_debug("reschedule");
427 	vnode->update_at = get_seconds() + afs_vnode_update_timeout;
428 
429 	spin_lock(&server->cb_lock);
430 
431 	if (!list_empty(&server->cb_promises)) {
432 		/* next update in 10 minutes, but wait at least 1 second more
433 		 * than the newest record already queued so that we don't spam
434 		 * the VL server suddenly with lots of requests
435 		 */
436 		xvnode = list_entry(server->cb_promises.prev,
437 				    struct afs_vnode, update);
438 		if (vnode->update_at <= xvnode->update_at)
439 			vnode->update_at = xvnode->update_at + 1;
440 		xvnode = list_entry(server->cb_promises.next,
441 				    struct afs_vnode, update);
442 		timeout = xvnode->update_at - now;
443 		if (timeout < 0)
444 			timeout = 0;
445 	} else {
446 		timeout = afs_vnode_update_timeout;
447 	}
448 
449 	list_add_tail(&vnode->update, &server->cb_promises);
450 
451 	_debug("timeout %ld", timeout);
452 	queue_delayed_work(afs_vnode_update_worker,
453 			   &afs_vnode_update, timeout * HZ);
454 	spin_unlock(&server->cb_lock);
455 	afs_put_vnode(vl);
456 }
457 #endif
458 
459 /*
460  * initialise the callback update process
461  */
462 int __init afs_callback_update_init(void)
463 {
464 	afs_callback_update_worker = alloc_ordered_workqueue("kafs_callbackd",
465 							     WQ_MEM_RECLAIM);
466 	return afs_callback_update_worker ? 0 : -ENOMEM;
467 }
468 
469 /*
470  * shut down the callback update process
471  */
472 void afs_callback_update_kill(void)
473 {
474 	destroy_workqueue(afs_callback_update_worker);
475 }
476