xref: /openbmc/linux/fs/nfs/nfs4session.c (revision f7777dcc) 
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 /*
139  * nfs4_alloc_slot - efficiently look for a free slot
140  *
141  * nfs4_alloc_slot looks for an unset bit in the used_slots bitmap.
142  * If found, we mark the slot as used, update the highest_used_slotid,
143  * and respectively set up the sequence operation args.
144  *
145  * Note: must be called with under the slot_tbl_lock.
146  */
147 struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl)
148 {
149 	struct nfs4_slot *ret = ERR_PTR(-EBUSY);
150 	u32 slotid;
151 
152 	dprintk("--> %s used_slots=%04lx highest_used=%u max_slots=%u\n",
153 		__func__, tbl->used_slots[0], tbl->highest_used_slotid,
154 		tbl->max_slotid + 1);
155 	slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slotid + 1);
156 	if (slotid > tbl->max_slotid)
157 		goto out;
158 	ret = nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
159 	if (IS_ERR(ret))
160 		goto out;
161 	__set_bit(slotid, tbl->used_slots);
162 	if (slotid > tbl->highest_used_slotid ||
163 			tbl->highest_used_slotid == NFS4_NO_SLOT)
164 		tbl->highest_used_slotid = slotid;
165 	ret->generation = tbl->generation;
166 
167 out:
168 	dprintk("<-- %s used_slots=%04lx highest_used=%u slotid=%u\n",
169 		__func__, tbl->used_slots[0], tbl->highest_used_slotid,
170 		!IS_ERR(ret) ? ret->slot_nr : NFS4_NO_SLOT);
171 	return ret;
172 }
173 
174 static int nfs4_grow_slot_table(struct nfs4_slot_table *tbl,
175 		 u32 max_reqs, u32 ivalue)
176 {
177 	if (max_reqs <= tbl->max_slots)
178 		return 0;
179 	if (!IS_ERR(nfs4_find_or_create_slot(tbl, max_reqs - 1, ivalue, GFP_NOFS)))
180 		return 0;
181 	return -ENOMEM;
182 }
183 
184 static void nfs4_reset_slot_table(struct nfs4_slot_table *tbl,
185 		u32 server_highest_slotid,
186 		u32 ivalue)
187 {
188 	struct nfs4_slot **p;
189 
190 	nfs4_shrink_slot_table(tbl, server_highest_slotid + 1);
191 	p = &tbl->slots;
192 	while (*p) {
193 		(*p)->seq_nr = ivalue;
194 		(*p)->interrupted = 0;
195 		p = &(*p)->next;
196 	}
197 	tbl->highest_used_slotid = NFS4_NO_SLOT;
198 	tbl->target_highest_slotid = server_highest_slotid;
199 	tbl->server_highest_slotid = server_highest_slotid;
200 	tbl->d_target_highest_slotid = 0;
201 	tbl->d2_target_highest_slotid = 0;
202 	tbl->max_slotid = server_highest_slotid;
203 }
204 
205 /*
206  * (re)Initialise a slot table
207  */
208 static int nfs4_realloc_slot_table(struct nfs4_slot_table *tbl,
209 		u32 max_reqs, u32 ivalue)
210 {
211 	int ret;
212 
213 	dprintk("--> %s: max_reqs=%u, tbl->max_slots %u\n", __func__,
214 		max_reqs, tbl->max_slots);
215 
216 	if (max_reqs > NFS4_MAX_SLOT_TABLE)
217 		max_reqs = NFS4_MAX_SLOT_TABLE;
218 
219 	ret = nfs4_grow_slot_table(tbl, max_reqs, ivalue);
220 	if (ret)
221 		goto out;
222 
223 	spin_lock(&tbl->slot_tbl_lock);
224 	nfs4_reset_slot_table(tbl, max_reqs - 1, ivalue);
225 	spin_unlock(&tbl->slot_tbl_lock);
226 
227 	dprintk("%s: tbl=%p slots=%p max_slots=%u\n", __func__,
228 		tbl, tbl->slots, tbl->max_slots);
229 out:
230 	dprintk("<-- %s: return %d\n", __func__, ret);
231 	return ret;
232 }
233 
234 /**
235  * nfs4_release_slot_table - release resources attached to a slot table
236  * @tbl: slot table to shut down
237  *
238  */
239 void nfs4_release_slot_table(struct nfs4_slot_table *tbl)
240 {
241 	nfs4_shrink_slot_table(tbl, 0);
242 }
243 
244 /**
245  * nfs4_setup_slot_table - prepare a stand-alone slot table for use
246  * @tbl: slot table to set up
247  * @max_reqs: maximum number of requests allowed
248  * @queue: name to give RPC wait queue
249  *
250  * Returns zero on success, or a negative errno.
251  */
252 int nfs4_setup_slot_table(struct nfs4_slot_table *tbl, unsigned int max_reqs,
253 		const char *queue)
254 {
255 	nfs4_init_slot_table(tbl, queue);
256 	return nfs4_realloc_slot_table(tbl, max_reqs, 0);
257 }
258 
259 static bool nfs41_assign_slot(struct rpc_task *task, void *pslot)
260 {
261 	struct nfs4_sequence_args *args = task->tk_msg.rpc_argp;
262 	struct nfs4_sequence_res *res = task->tk_msg.rpc_resp;
263 	struct nfs4_slot *slot = pslot;
264 	struct nfs4_slot_table *tbl = slot->table;
265 
266 	if (nfs4_slot_tbl_draining(tbl) && !args->sa_privileged)
267 		return false;
268 	slot->generation = tbl->generation;
269 	args->sa_slot = slot;
270 	res->sr_timestamp = jiffies;
271 	res->sr_slot = slot;
272 	res->sr_status_flags = 0;
273 	res->sr_status = 1;
274 	return true;
275 }
276 
277 static bool __nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
278 		struct nfs4_slot *slot)
279 {
280 	if (rpc_wake_up_first(&tbl->slot_tbl_waitq, nfs41_assign_slot, slot))
281 		return true;
282 	return false;
283 }
284 
285 bool nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
286 		struct nfs4_slot *slot)
287 {
288 	if (slot->slot_nr > tbl->max_slotid)
289 		return false;
290 	return __nfs41_wake_and_assign_slot(tbl, slot);
291 }
292 
293 static bool nfs41_try_wake_next_slot_table_entry(struct nfs4_slot_table *tbl)
294 {
295 	struct nfs4_slot *slot = nfs4_alloc_slot(tbl);
296 	if (!IS_ERR(slot)) {
297 		bool ret = __nfs41_wake_and_assign_slot(tbl, slot);
298 		if (ret)
299 			return ret;
300 		nfs4_free_slot(tbl, slot);
301 	}
302 	return false;
303 }
304 
305 void nfs41_wake_slot_table(struct nfs4_slot_table *tbl)
306 {
307 	for (;;) {
308 		if (!nfs41_try_wake_next_slot_table_entry(tbl))
309 			break;
310 	}
311 }
312 
313 #if defined(CONFIG_NFS_V4_1)
314 
315 static void nfs41_set_max_slotid_locked(struct nfs4_slot_table *tbl,
316 		u32 target_highest_slotid)
317 {
318 	u32 max_slotid;
319 
320 	max_slotid = min(NFS4_MAX_SLOT_TABLE - 1, target_highest_slotid);
321 	if (max_slotid > tbl->server_highest_slotid)
322 		max_slotid = tbl->server_highest_slotid;
323 	if (max_slotid > tbl->target_highest_slotid)
324 		max_slotid = tbl->target_highest_slotid;
325 	tbl->max_slotid = max_slotid;
326 	nfs41_wake_slot_table(tbl);
327 }
328 
329 /* Update the client's idea of target_highest_slotid */
330 static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
331 		u32 target_highest_slotid)
332 {
333 	if (tbl->target_highest_slotid == target_highest_slotid)
334 		return;
335 	tbl->target_highest_slotid = target_highest_slotid;
336 	tbl->generation++;
337 }
338 
339 void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
340 		u32 target_highest_slotid)
341 {
342 	spin_lock(&tbl->slot_tbl_lock);
343 	nfs41_set_target_slotid_locked(tbl, target_highest_slotid);
344 	tbl->d_target_highest_slotid = 0;
345 	tbl->d2_target_highest_slotid = 0;
346 	nfs41_set_max_slotid_locked(tbl, target_highest_slotid);
347 	spin_unlock(&tbl->slot_tbl_lock);
348 }
349 
350 static void nfs41_set_server_slotid_locked(struct nfs4_slot_table *tbl,
351 		u32 highest_slotid)
352 {
353 	if (tbl->server_highest_slotid == highest_slotid)
354 		return;
355 	if (tbl->highest_used_slotid > highest_slotid)
356 		return;
357 	/* Deallocate slots */
358 	nfs4_shrink_slot_table(tbl, highest_slotid + 1);
359 	tbl->server_highest_slotid = highest_slotid;
360 }
361 
362 static s32 nfs41_derivative_target_slotid(s32 s1, s32 s2)
363 {
364 	s1 -= s2;
365 	if (s1 == 0)
366 		return 0;
367 	if (s1 < 0)
368 		return (s1 - 1) >> 1;
369 	return (s1 + 1) >> 1;
370 }
371 
372 static int nfs41_sign_s32(s32 s1)
373 {
374 	if (s1 > 0)
375 		return 1;
376 	if (s1 < 0)
377 		return -1;
378 	return 0;
379 }
380 
381 static bool nfs41_same_sign_or_zero_s32(s32 s1, s32 s2)
382 {
383 	if (!s1 || !s2)
384 		return true;
385 	return nfs41_sign_s32(s1) == nfs41_sign_s32(s2);
386 }
387 
388 /* Try to eliminate outliers by checking for sharp changes in the
389  * derivatives and second derivatives
390  */
391 static bool nfs41_is_outlier_target_slotid(struct nfs4_slot_table *tbl,
392 		u32 new_target)
393 {
394 	s32 d_target, d2_target;
395 	bool ret = true;
396 
397 	d_target = nfs41_derivative_target_slotid(new_target,
398 			tbl->target_highest_slotid);
399 	d2_target = nfs41_derivative_target_slotid(d_target,
400 			tbl->d_target_highest_slotid);
401 	/* Is first derivative same sign? */
402 	if (nfs41_same_sign_or_zero_s32(d_target, tbl->d_target_highest_slotid))
403 		ret = false;
404 	/* Is second derivative same sign? */
405 	if (nfs41_same_sign_or_zero_s32(d2_target, tbl->d2_target_highest_slotid))
406 		ret = false;
407 	tbl->d_target_highest_slotid = d_target;
408 	tbl->d2_target_highest_slotid = d2_target;
409 	return ret;
410 }
411 
412 void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
413 		struct nfs4_slot *slot,
414 		struct nfs4_sequence_res *res)
415 {
416 	spin_lock(&tbl->slot_tbl_lock);
417 	if (!nfs41_is_outlier_target_slotid(tbl, res->sr_target_highest_slotid))
418 		nfs41_set_target_slotid_locked(tbl, res->sr_target_highest_slotid);
419 	if (tbl->generation == slot->generation)
420 		nfs41_set_server_slotid_locked(tbl, res->sr_highest_slotid);
421 	nfs41_set_max_slotid_locked(tbl, res->sr_target_highest_slotid);
422 	spin_unlock(&tbl->slot_tbl_lock);
423 }
424 
425 static void nfs4_destroy_session_slot_tables(struct nfs4_session *session)
426 {
427 	nfs4_release_slot_table(&session->fc_slot_table);
428 	nfs4_release_slot_table(&session->bc_slot_table);
429 }
430 
431 /*
432  * Initialize or reset the forechannel and backchannel tables
433  */
434 int nfs4_setup_session_slot_tables(struct nfs4_session *ses)
435 {
436 	struct nfs4_slot_table *tbl;
437 	int status;
438 
439 	dprintk("--> %s\n", __func__);
440 	/* Fore channel */
441 	tbl = &ses->fc_slot_table;
442 	tbl->session = ses;
443 	status = nfs4_realloc_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
444 	if (status) /* -ENOMEM */
445 		return status;
446 	/* Back channel */
447 	tbl = &ses->bc_slot_table;
448 	tbl->session = ses;
449 	status = nfs4_realloc_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
450 	if (status && tbl->slots == NULL)
451 		/* Fore and back channel share a connection so get
452 		 * both slot tables or neither */
453 		nfs4_destroy_session_slot_tables(ses);
454 	return status;
455 }
456 
457 struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp)
458 {
459 	struct nfs4_session *session;
460 
461 	session = kzalloc(sizeof(struct nfs4_session), GFP_NOFS);
462 	if (!session)
463 		return NULL;
464 
465 	nfs4_init_slot_table(&session->fc_slot_table, "ForeChannel Slot table");
466 	nfs4_init_slot_table(&session->bc_slot_table, "BackChannel Slot table");
467 	session->session_state = 1<<NFS4_SESSION_INITING;
468 
469 	session->clp = clp;
470 	return session;
471 }
472 
473 void nfs4_destroy_session(struct nfs4_session *session)
474 {
475 	struct rpc_xprt *xprt;
476 	struct rpc_cred *cred;
477 
478 	cred = nfs4_get_clid_cred(session->clp);
479 	nfs4_proc_destroy_session(session, cred);
480 	if (cred)
481 		put_rpccred(cred);
482 
483 	rcu_read_lock();
484 	xprt = rcu_dereference(session->clp->cl_rpcclient->cl_xprt);
485 	rcu_read_unlock();
486 	dprintk("%s Destroy backchannel for xprt %p\n",
487 		__func__, xprt);
488 	xprt_destroy_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
489 	nfs4_destroy_session_slot_tables(session);
490 	kfree(session);
491 }
492 
493 /*
494  * With sessions, the client is not marked ready until after a
495  * successful EXCHANGE_ID and CREATE_SESSION.
496  *
497  * Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
498  * other versions of NFS can be tried.
499  */
500 static int nfs41_check_session_ready(struct nfs_client *clp)
501 {
502 	int ret;
503 
504 	if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
505 		ret = nfs4_client_recover_expired_lease(clp);
506 		if (ret)
507 			return ret;
508 	}
509 	if (clp->cl_cons_state < NFS_CS_READY)
510 		return -EPROTONOSUPPORT;
511 	smp_rmb();
512 	return 0;
513 }
514 
515 int nfs4_init_session(struct nfs_client *clp)
516 {
517 	if (!nfs4_has_session(clp))
518 		return 0;
519 
520 	clear_bit(NFS4_SESSION_INITING, &clp->cl_session->session_state);
521 	return nfs41_check_session_ready(clp);
522 }
523 
524 int nfs4_init_ds_session(struct nfs_client *clp, unsigned long lease_time)
525 {
526 	struct nfs4_session *session = clp->cl_session;
527 	int ret;
528 
529 	spin_lock(&clp->cl_lock);
530 	if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
531 		/*
532 		 * Do not set NFS_CS_CHECK_LEASE_TIME instead set the
533 		 * DS lease to be equal to the MDS lease.
534 		 */
535 		clp->cl_lease_time = lease_time;
536 		clp->cl_last_renewal = jiffies;
537 	}
538 	spin_unlock(&clp->cl_lock);
539 
540 	ret = nfs41_check_session_ready(clp);
541 	if (ret)
542 		return ret;
543 	/* Test for the DS role */
544 	if (!is_ds_client(clp))
545 		return -ENODEV;
546 	return 0;
547 }
548 EXPORT_SYMBOL_GPL(nfs4_init_ds_session);
549 
550 #endif	/* defined(CONFIG_NFS_V4_1) */
551