xref: /openbmc/linux/fs/nfs/nfs4session.c (revision 293d5b43) 
1 /*
2  * fs/nfs/nfs4session.c
3  *
4  * Copyright (c) 2012 Trond Myklebust <Trond.Myklebust@netapp.com>
5  *
6  */
7 #include <linux/kernel.h>
8 #include <linux/errno.h>
9 #include <linux/string.h>
10 #include <linux/printk.h>
11 #include <linux/slab.h>
12 #include <linux/sunrpc/sched.h>
13 #include <linux/sunrpc/bc_xprt.h>
14 #include <linux/nfs.h>
15 #include <linux/nfs4.h>
16 #include <linux/nfs_fs.h>
17 #include <linux/module.h>
18 
19 #include "nfs4_fs.h"
20 #include "internal.h"
21 #include "nfs4session.h"
22 #include "callback.h"
23 
24 #define NFSDBG_FACILITY		NFSDBG_STATE
25 
26 static void nfs4_init_slot_table(struct nfs4_slot_table *tbl, const char *queue)
27 {
28 	tbl->highest_used_slotid = NFS4_NO_SLOT;
29 	spin_lock_init(&tbl->slot_tbl_lock);
30 	rpc_init_priority_wait_queue(&tbl->slot_tbl_waitq, queue);
31 	init_completion(&tbl->complete);
32 }
33 
34 /*
35  * nfs4_shrink_slot_table - free retired slots from the slot table
36  */
37 static void nfs4_shrink_slot_table(struct nfs4_slot_table  *tbl, u32 newsize)
38 {
39 	struct nfs4_slot **p;
40 	if (newsize >= tbl->max_slots)
41 		return;
42 
43 	p = &tbl->slots;
44 	while (newsize--)
45 		p = &(*p)->next;
46 	while (*p) {
47 		struct nfs4_slot *slot = *p;
48 
49 		*p = slot->next;
50 		kfree(slot);
51 		tbl->max_slots--;
52 	}
53 }
54 
55 /**
56  * nfs4_slot_tbl_drain_complete - wake waiters when drain is complete
57  * @tbl - controlling slot table
58  *
59  */
60 void nfs4_slot_tbl_drain_complete(struct nfs4_slot_table *tbl)
61 {
62 	if (nfs4_slot_tbl_draining(tbl))
63 		complete(&tbl->complete);
64 }
65 
66 /*
67  * nfs4_free_slot - free a slot and efficiently update slot table.
68  *
69  * freeing a slot is trivially done by clearing its respective bit
70  * in the bitmap.
71  * If the freed slotid equals highest_used_slotid we want to update it
72  * so that the server would be able to size down the slot table if needed,
73  * otherwise we know that the highest_used_slotid is still in use.
74  * When updating highest_used_slotid there may be "holes" in the bitmap
75  * so we need to scan down from highest_used_slotid to 0 looking for the now
76  * highest slotid in use.
77  * If none found, highest_used_slotid is set to NFS4_NO_SLOT.
78  *
79  * Must be called while holding tbl->slot_tbl_lock
80  */
81 void nfs4_free_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot)
82 {
83 	u32 slotid = slot->slot_nr;
84 
85 	/* clear used bit in bitmap */
86 	__clear_bit(slotid, tbl->used_slots);
87 
88 	/* update highest_used_slotid when it is freed */
89 	if (slotid == tbl->highest_used_slotid) {
90 		u32 new_max = find_last_bit(tbl->used_slots, slotid);
91 		if (new_max < slotid)
92 			tbl->highest_used_slotid = new_max;
93 		else {
94 			tbl->highest_used_slotid = NFS4_NO_SLOT;
95 			nfs4_slot_tbl_drain_complete(tbl);
96 		}
97 	}
98 	dprintk("%s: slotid %u highest_used_slotid %u\n", __func__,
99 		slotid, tbl->highest_used_slotid);
100 }
101 
102 static struct nfs4_slot *nfs4_new_slot(struct nfs4_slot_table  *tbl,
103 		u32 slotid, u32 seq_init, gfp_t gfp_mask)
104 {
105 	struct nfs4_slot *slot;
106 
107 	slot = kzalloc(sizeof(*slot), gfp_mask);
108 	if (slot) {
109 		slot->table = tbl;
110 		slot->slot_nr = slotid;
111 		slot->seq_nr = seq_init;
112 	}
113 	return slot;
114 }
115 
116 static struct nfs4_slot *nfs4_find_or_create_slot(struct nfs4_slot_table  *tbl,
117 		u32 slotid, u32 seq_init, gfp_t gfp_mask)
118 {
119 	struct nfs4_slot **p, *slot;
120 
121 	p = &tbl->slots;
122 	for (;;) {
123 		if (*p == NULL) {
124 			*p = nfs4_new_slot(tbl, tbl->max_slots,
125 					seq_init, gfp_mask);
126 			if (*p == NULL)
127 				break;
128 			tbl->max_slots++;
129 		}
130 		slot = *p;
131 		if (slot->slot_nr == slotid)
132 			return slot;
133 		p = &slot->next;
134 	}
135 	return ERR_PTR(-ENOMEM);
136 }
137 
138 static void nfs4_lock_slot(struct nfs4_slot_table *tbl,
139 		struct nfs4_slot *slot)
140 {
141 	u32 slotid = slot->slot_nr;
142 
143 	__set_bit(slotid, tbl->used_slots);
144 	if (slotid > tbl->highest_used_slotid ||
145 	    tbl->highest_used_slotid == NFS4_NO_SLOT)
146 		tbl->highest_used_slotid = slotid;
147 	slot->generation = tbl->generation;
148 }
149 
150 /*
151  * nfs4_try_to_lock_slot - Given a slot try to allocate it
152  *
153  * Note: must be called with the slot_tbl_lock held.
154  */
155 bool nfs4_try_to_lock_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot)
156 {
157 	if (nfs4_test_locked_slot(tbl, slot->slot_nr))
158 		return false;
159 	nfs4_lock_slot(tbl, slot);
160 	return true;
161 }
162 
163 /*
164  * nfs4_lookup_slot - Find a slot but don't allocate it
165  *
166  * Note: must be called with the slot_tbl_lock held.
167  */
168 struct nfs4_slot *nfs4_lookup_slot(struct nfs4_slot_table *tbl, u32 slotid)
169 {
170 	if (slotid <= tbl->max_slotid)
171 		return nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
172 	return ERR_PTR(-E2BIG);
173 }
174 
175 /*
176  * nfs4_alloc_slot - efficiently look for a free slot
177  *
178  * nfs4_alloc_slot looks for an unset bit in the used_slots bitmap.
179  * If found, we mark the slot as used, update the highest_used_slotid,
180  * and respectively set up the sequence operation args.
181  *
182  * Note: must be called with under the slot_tbl_lock.
183  */
184 struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl)
185 {
186 	struct nfs4_slot *ret = ERR_PTR(-EBUSY);
187 	u32 slotid;
188 
189 	dprintk("--> %s used_slots=%04lx highest_used=%u max_slots=%u\n",
190 		__func__, tbl->used_slots[0], tbl->highest_used_slotid,
191 		tbl->max_slotid + 1);
192 	slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slotid + 1);
193 	if (slotid <= tbl->max_slotid) {
194 		ret = nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
195 		if (!IS_ERR(ret))
196 			nfs4_lock_slot(tbl, ret);
197 	}
198 	dprintk("<-- %s used_slots=%04lx highest_used=%u slotid=%u\n",
199 		__func__, tbl->used_slots[0], tbl->highest_used_slotid,
200 		!IS_ERR(ret) ? ret->slot_nr : NFS4_NO_SLOT);
201 	return ret;
202 }
203 
204 static int nfs4_grow_slot_table(struct nfs4_slot_table *tbl,
205 		 u32 max_reqs, u32 ivalue)
206 {
207 	if (max_reqs <= tbl->max_slots)
208 		return 0;
209 	if (!IS_ERR(nfs4_find_or_create_slot(tbl, max_reqs - 1, ivalue, GFP_NOFS)))
210 		return 0;
211 	return -ENOMEM;
212 }
213 
214 static void nfs4_reset_slot_table(struct nfs4_slot_table *tbl,
215 		u32 server_highest_slotid,
216 		u32 ivalue)
217 {
218 	struct nfs4_slot **p;
219 
220 	nfs4_shrink_slot_table(tbl, server_highest_slotid + 1);
221 	p = &tbl->slots;
222 	while (*p) {
223 		(*p)->seq_nr = ivalue;
224 		(*p)->interrupted = 0;
225 		p = &(*p)->next;
226 	}
227 	tbl->highest_used_slotid = NFS4_NO_SLOT;
228 	tbl->target_highest_slotid = server_highest_slotid;
229 	tbl->server_highest_slotid = server_highest_slotid;
230 	tbl->d_target_highest_slotid = 0;
231 	tbl->d2_target_highest_slotid = 0;
232 	tbl->max_slotid = server_highest_slotid;
233 }
234 
235 /*
236  * (re)Initialise a slot table
237  */
238 static int nfs4_realloc_slot_table(struct nfs4_slot_table *tbl,
239 		u32 max_reqs, u32 ivalue)
240 {
241 	int ret;
242 
243 	dprintk("--> %s: max_reqs=%u, tbl->max_slots %u\n", __func__,
244 		max_reqs, tbl->max_slots);
245 
246 	if (max_reqs > NFS4_MAX_SLOT_TABLE)
247 		max_reqs = NFS4_MAX_SLOT_TABLE;
248 
249 	ret = nfs4_grow_slot_table(tbl, max_reqs, ivalue);
250 	if (ret)
251 		goto out;
252 
253 	spin_lock(&tbl->slot_tbl_lock);
254 	nfs4_reset_slot_table(tbl, max_reqs - 1, ivalue);
255 	spin_unlock(&tbl->slot_tbl_lock);
256 
257 	dprintk("%s: tbl=%p slots=%p max_slots=%u\n", __func__,
258 		tbl, tbl->slots, tbl->max_slots);
259 out:
260 	dprintk("<-- %s: return %d\n", __func__, ret);
261 	return ret;
262 }
263 
264 /*
265  * nfs4_release_slot_table - release all slot table entries
266  */
267 static void nfs4_release_slot_table(struct nfs4_slot_table *tbl)
268 {
269 	nfs4_shrink_slot_table(tbl, 0);
270 }
271 
272 /**
273  * nfs4_shutdown_slot_table - release resources attached to a slot table
274  * @tbl: slot table to shut down
275  *
276  */
277 void nfs4_shutdown_slot_table(struct nfs4_slot_table *tbl)
278 {
279 	nfs4_release_slot_table(tbl);
280 	rpc_destroy_wait_queue(&tbl->slot_tbl_waitq);
281 }
282 
283 /**
284  * nfs4_setup_slot_table - prepare a stand-alone slot table for use
285  * @tbl: slot table to set up
286  * @max_reqs: maximum number of requests allowed
287  * @queue: name to give RPC wait queue
288  *
289  * Returns zero on success, or a negative errno.
290  */
291 int nfs4_setup_slot_table(struct nfs4_slot_table *tbl, unsigned int max_reqs,
292 		const char *queue)
293 {
294 	nfs4_init_slot_table(tbl, queue);
295 	return nfs4_realloc_slot_table(tbl, max_reqs, 0);
296 }
297 
298 static bool nfs41_assign_slot(struct rpc_task *task, void *pslot)
299 {
300 	struct nfs4_sequence_args *args = task->tk_msg.rpc_argp;
301 	struct nfs4_sequence_res *res = task->tk_msg.rpc_resp;
302 	struct nfs4_slot *slot = pslot;
303 	struct nfs4_slot_table *tbl = slot->table;
304 
305 	if (nfs4_slot_tbl_draining(tbl) && !args->sa_privileged)
306 		return false;
307 	slot->generation = tbl->generation;
308 	args->sa_slot = slot;
309 	res->sr_timestamp = jiffies;
310 	res->sr_slot = slot;
311 	res->sr_status_flags = 0;
312 	res->sr_status = 1;
313 	return true;
314 }
315 
316 static bool __nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
317 		struct nfs4_slot *slot)
318 {
319 	if (rpc_wake_up_first(&tbl->slot_tbl_waitq, nfs41_assign_slot, slot))
320 		return true;
321 	return false;
322 }
323 
324 bool nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
325 		struct nfs4_slot *slot)
326 {
327 	if (slot->slot_nr > tbl->max_slotid)
328 		return false;
329 	return __nfs41_wake_and_assign_slot(tbl, slot);
330 }
331 
332 static bool nfs41_try_wake_next_slot_table_entry(struct nfs4_slot_table *tbl)
333 {
334 	struct nfs4_slot *slot = nfs4_alloc_slot(tbl);
335 	if (!IS_ERR(slot)) {
336 		bool ret = __nfs41_wake_and_assign_slot(tbl, slot);
337 		if (ret)
338 			return ret;
339 		nfs4_free_slot(tbl, slot);
340 	}
341 	return false;
342 }
343 
344 void nfs41_wake_slot_table(struct nfs4_slot_table *tbl)
345 {
346 	for (;;) {
347 		if (!nfs41_try_wake_next_slot_table_entry(tbl))
348 			break;
349 	}
350 }
351 
352 #if defined(CONFIG_NFS_V4_1)
353 
354 static void nfs41_set_max_slotid_locked(struct nfs4_slot_table *tbl,
355 		u32 target_highest_slotid)
356 {
357 	u32 max_slotid;
358 
359 	max_slotid = min(NFS4_MAX_SLOT_TABLE - 1, target_highest_slotid);
360 	if (max_slotid > tbl->server_highest_slotid)
361 		max_slotid = tbl->server_highest_slotid;
362 	if (max_slotid > tbl->target_highest_slotid)
363 		max_slotid = tbl->target_highest_slotid;
364 	tbl->max_slotid = max_slotid;
365 	nfs41_wake_slot_table(tbl);
366 }
367 
368 /* Update the client's idea of target_highest_slotid */
369 static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
370 		u32 target_highest_slotid)
371 {
372 	if (tbl->target_highest_slotid == target_highest_slotid)
373 		return;
374 	tbl->target_highest_slotid = target_highest_slotid;
375 	tbl->generation++;
376 }
377 
378 void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
379 		u32 target_highest_slotid)
380 {
381 	spin_lock(&tbl->slot_tbl_lock);
382 	nfs41_set_target_slotid_locked(tbl, target_highest_slotid);
383 	tbl->d_target_highest_slotid = 0;
384 	tbl->d2_target_highest_slotid = 0;
385 	nfs41_set_max_slotid_locked(tbl, target_highest_slotid);
386 	spin_unlock(&tbl->slot_tbl_lock);
387 }
388 
389 static void nfs41_set_server_slotid_locked(struct nfs4_slot_table *tbl,
390 		u32 highest_slotid)
391 {
392 	if (tbl->server_highest_slotid == highest_slotid)
393 		return;
394 	if (tbl->highest_used_slotid > highest_slotid)
395 		return;
396 	/* Deallocate slots */
397 	nfs4_shrink_slot_table(tbl, highest_slotid + 1);
398 	tbl->server_highest_slotid = highest_slotid;
399 }
400 
401 static s32 nfs41_derivative_target_slotid(s32 s1, s32 s2)
402 {
403 	s1 -= s2;
404 	if (s1 == 0)
405 		return 0;
406 	if (s1 < 0)
407 		return (s1 - 1) >> 1;
408 	return (s1 + 1) >> 1;
409 }
410 
411 static int nfs41_sign_s32(s32 s1)
412 {
413 	if (s1 > 0)
414 		return 1;
415 	if (s1 < 0)
416 		return -1;
417 	return 0;
418 }
419 
420 static bool nfs41_same_sign_or_zero_s32(s32 s1, s32 s2)
421 {
422 	if (!s1 || !s2)
423 		return true;
424 	return nfs41_sign_s32(s1) == nfs41_sign_s32(s2);
425 }
426 
427 /* Try to eliminate outliers by checking for sharp changes in the
428  * derivatives and second derivatives
429  */
430 static bool nfs41_is_outlier_target_slotid(struct nfs4_slot_table *tbl,
431 		u32 new_target)
432 {
433 	s32 d_target, d2_target;
434 	bool ret = true;
435 
436 	d_target = nfs41_derivative_target_slotid(new_target,
437 			tbl->target_highest_slotid);
438 	d2_target = nfs41_derivative_target_slotid(d_target,
439 			tbl->d_target_highest_slotid);
440 	/* Is first derivative same sign? */
441 	if (nfs41_same_sign_or_zero_s32(d_target, tbl->d_target_highest_slotid))
442 		ret = false;
443 	/* Is second derivative same sign? */
444 	if (nfs41_same_sign_or_zero_s32(d2_target, tbl->d2_target_highest_slotid))
445 		ret = false;
446 	tbl->d_target_highest_slotid = d_target;
447 	tbl->d2_target_highest_slotid = d2_target;
448 	return ret;
449 }
450 
451 void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
452 		struct nfs4_slot *slot,
453 		struct nfs4_sequence_res *res)
454 {
455 	spin_lock(&tbl->slot_tbl_lock);
456 	if (!nfs41_is_outlier_target_slotid(tbl, res->sr_target_highest_slotid))
457 		nfs41_set_target_slotid_locked(tbl, res->sr_target_highest_slotid);
458 	if (tbl->generation == slot->generation)
459 		nfs41_set_server_slotid_locked(tbl, res->sr_highest_slotid);
460 	nfs41_set_max_slotid_locked(tbl, res->sr_target_highest_slotid);
461 	spin_unlock(&tbl->slot_tbl_lock);
462 }
463 
464 static void nfs4_release_session_slot_tables(struct nfs4_session *session)
465 {
466 	nfs4_release_slot_table(&session->fc_slot_table);
467 	nfs4_release_slot_table(&session->bc_slot_table);
468 }
469 
470 /*
471  * Initialize or reset the forechannel and backchannel tables
472  */
473 int nfs4_setup_session_slot_tables(struct nfs4_session *ses)
474 {
475 	struct nfs4_slot_table *tbl;
476 	int status;
477 
478 	dprintk("--> %s\n", __func__);
479 	/* Fore channel */
480 	tbl = &ses->fc_slot_table;
481 	tbl->session = ses;
482 	status = nfs4_realloc_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
483 	if (status || !(ses->flags & SESSION4_BACK_CHAN)) /* -ENOMEM */
484 		return status;
485 	/* Back channel */
486 	tbl = &ses->bc_slot_table;
487 	tbl->session = ses;
488 	status = nfs4_realloc_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
489 	if (status && tbl->slots == NULL)
490 		/* Fore and back channel share a connection so get
491 		 * both slot tables or neither */
492 		nfs4_release_session_slot_tables(ses);
493 	return status;
494 }
495 
496 struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp)
497 {
498 	struct nfs4_session *session;
499 
500 	session = kzalloc(sizeof(struct nfs4_session), GFP_NOFS);
501 	if (!session)
502 		return NULL;
503 
504 	nfs4_init_slot_table(&session->fc_slot_table, "ForeChannel Slot table");
505 	nfs4_init_slot_table(&session->bc_slot_table, "BackChannel Slot table");
506 	session->session_state = 1<<NFS4_SESSION_INITING;
507 
508 	session->clp = clp;
509 	return session;
510 }
511 
512 static void nfs4_destroy_session_slot_tables(struct nfs4_session *session)
513 {
514 	nfs4_shutdown_slot_table(&session->fc_slot_table);
515 	nfs4_shutdown_slot_table(&session->bc_slot_table);
516 }
517 
518 void nfs4_destroy_session(struct nfs4_session *session)
519 {
520 	struct rpc_xprt *xprt;
521 	struct rpc_cred *cred;
522 
523 	cred = nfs4_get_clid_cred(session->clp);
524 	nfs4_proc_destroy_session(session, cred);
525 	if (cred)
526 		put_rpccred(cred);
527 
528 	rcu_read_lock();
529 	xprt = rcu_dereference(session->clp->cl_rpcclient->cl_xprt);
530 	rcu_read_unlock();
531 	dprintk("%s Destroy backchannel for xprt %p\n",
532 		__func__, xprt);
533 	xprt_destroy_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
534 	nfs4_destroy_session_slot_tables(session);
535 	kfree(session);
536 }
537 
538 /*
539  * With sessions, the client is not marked ready until after a
540  * successful EXCHANGE_ID and CREATE_SESSION.
541  *
542  * Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
543  * other versions of NFS can be tried.
544  */
545 static int nfs41_check_session_ready(struct nfs_client *clp)
546 {
547 	int ret;
548 
549 	if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
550 		ret = nfs4_client_recover_expired_lease(clp);
551 		if (ret)
552 			return ret;
553 	}
554 	if (clp->cl_cons_state < NFS_CS_READY)
555 		return -EPROTONOSUPPORT;
556 	smp_rmb();
557 	return 0;
558 }
559 
560 int nfs4_init_session(struct nfs_client *clp)
561 {
562 	if (!nfs4_has_session(clp))
563 		return 0;
564 
565 	clear_bit(NFS4_SESSION_INITING, &clp->cl_session->session_state);
566 	return nfs41_check_session_ready(clp);
567 }
568 
569 int nfs4_init_ds_session(struct nfs_client *clp, unsigned long lease_time)
570 {
571 	struct nfs4_session *session = clp->cl_session;
572 	int ret;
573 
574 	spin_lock(&clp->cl_lock);
575 	if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
576 		/*
577 		 * Do not set NFS_CS_CHECK_LEASE_TIME instead set the
578 		 * DS lease to be equal to the MDS lease.
579 		 */
580 		clp->cl_lease_time = lease_time;
581 		clp->cl_last_renewal = jiffies;
582 	}
583 	spin_unlock(&clp->cl_lock);
584 
585 	ret = nfs41_check_session_ready(clp);
586 	if (ret)
587 		return ret;
588 	/* Test for the DS role */
589 	if (!is_ds_client(clp))
590 		return -ENODEV;
591 	return 0;
592 }
593 EXPORT_SYMBOL_GPL(nfs4_init_ds_session);
594 
595 #endif	/* defined(CONFIG_NFS_V4_1) */
596