1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * fs/nfs/nfs4session.c
4 *
5 * Copyright (c) 2012 Trond Myklebust <Trond.Myklebust@netapp.com>
6 *
7 */
8 #include <linux/kernel.h>
9 #include <linux/errno.h>
10 #include <linux/string.h>
11 #include <linux/printk.h>
12 #include <linux/slab.h>
13 #include <linux/sunrpc/sched.h>
14 #include <linux/sunrpc/bc_xprt.h>
15 #include <linux/nfs.h>
16 #include <linux/nfs4.h>
17 #include <linux/nfs_fs.h>
18 #include <linux/module.h>
19
20 #include "nfs4_fs.h"
21 #include "internal.h"
22 #include "nfs4session.h"
23 #include "callback.h"
24
25 #define NFSDBG_FACILITY NFSDBG_STATE
26
27 static void nfs4_init_slot_table(struct nfs4_slot_table *tbl, const char *queue)
28 {
29 tbl->highest_used_slotid = NFS4_NO_SLOT;
30 spin_lock_init(&tbl->slot_tbl_lock);
31 rpc_init_priority_wait_queue(&tbl->slot_tbl_waitq, queue);
32 init_waitqueue_head(&tbl->slot_waitq);
33 init_completion(&tbl->complete);
34 }
35
36 /*
37 * nfs4_shrink_slot_table - free retired slots from the slot table
38 */
39 static void nfs4_shrink_slot_table(struct nfs4_slot_table *tbl, u32 newsize)
40 {
41 struct nfs4_slot **p;
42 if (newsize >= tbl->max_slots)
43 return;
44
45 p = &tbl->slots;
46 while (newsize--)
47 p = &(*p)->next;
48 while (*p) {
49 struct nfs4_slot *slot = *p;
50
51 *p = slot->next;
52 kfree(slot);
53 tbl->max_slots--;
54 }
55 }
56
57 /**
58 * nfs4_slot_tbl_drain_complete - wake waiters when drain is complete
59 * @tbl: controlling slot table
60 *
61 */
62 void nfs4_slot_tbl_drain_complete(struct nfs4_slot_table *tbl)
63 {
64 if (nfs4_slot_tbl_draining(tbl))
65 complete(&tbl->complete);
66 }
67
68 /*
69 * nfs4_free_slot - free a slot and efficiently update slot table.
70 *
71 * freeing a slot is trivially done by clearing its respective bit
72 * in the bitmap.
73 * If the freed slotid equals highest_used_slotid we want to update it
74 * so that the server would be able to size down the slot table if needed,
75 * otherwise we know that the highest_used_slotid is still in use.
76 * When updating highest_used_slotid there may be "holes" in the bitmap
77 * so we need to scan down from highest_used_slotid to 0 looking for the now
78 * highest slotid in use.
79 * If none found, highest_used_slotid is set to NFS4_NO_SLOT.
80 *
81 * Must be called while holding tbl->slot_tbl_lock
82 */
83 void nfs4_free_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot)
84 {
85 u32 slotid = slot->slot_nr;
86
87 /* clear used bit in bitmap */
88 __clear_bit(slotid, tbl->used_slots);
89
90 /* update highest_used_slotid when it is freed */
91 if (slotid == tbl->highest_used_slotid) {
92 u32 new_max = find_last_bit(tbl->used_slots, slotid);
93 if (new_max < slotid)
94 tbl->highest_used_slotid = new_max;
95 else {
96 tbl->highest_used_slotid = NFS4_NO_SLOT;
97 nfs4_slot_tbl_drain_complete(tbl);
98 }
99 }
100 dprintk("%s: slotid %u highest_used_slotid %u\n", __func__,
101 slotid, tbl->highest_used_slotid);
102 }
103
104 static struct nfs4_slot *nfs4_new_slot(struct nfs4_slot_table *tbl,
105 u32 slotid, u32 seq_init, gfp_t gfp_mask)
106 {
107 struct nfs4_slot *slot;
108
109 slot = kzalloc(sizeof(*slot), gfp_mask);
110 if (slot) {
111 slot->table = tbl;
112 slot->slot_nr = slotid;
113 slot->seq_nr = seq_init;
114 slot->seq_nr_highest_sent = seq_init;
115 slot->seq_nr_last_acked = seq_init - 1;
116 }
117 return slot;
118 }
119
120 static struct nfs4_slot *nfs4_find_or_create_slot(struct nfs4_slot_table *tbl,
121 u32 slotid, u32 seq_init, gfp_t gfp_mask)
122 {
123 struct nfs4_slot **p, *slot;
124
125 p = &tbl->slots;
126 for (;;) {
127 if (*p == NULL) {
128 *p = nfs4_new_slot(tbl, tbl->max_slots,
129 seq_init, gfp_mask);
130 if (*p == NULL)
131 break;
132 tbl->max_slots++;
133 }
134 slot = *p;
135 if (slot->slot_nr == slotid)
136 return slot;
137 p = &slot->next;
138 }
139 return ERR_PTR(-ENOMEM);
140 }
141
142 static void nfs4_lock_slot(struct nfs4_slot_table *tbl,
143 struct nfs4_slot *slot)
144 {
145 u32 slotid = slot->slot_nr;
146
147 __set_bit(slotid, tbl->used_slots);
148 if (slotid > tbl->highest_used_slotid ||
149 tbl->highest_used_slotid == NFS4_NO_SLOT)
150 tbl->highest_used_slotid = slotid;
151 slot->generation = tbl->generation;
152 }
153
154 /*
155 * nfs4_try_to_lock_slot - Given a slot try to allocate it
156 *
157 * Note: must be called with the slot_tbl_lock held.
158 */
159 bool nfs4_try_to_lock_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot)
160 {
161 if (nfs4_test_locked_slot(tbl, slot->slot_nr))
162 return false;
163 nfs4_lock_slot(tbl, slot);
164 return true;
165 }
166
167 /*
168 * nfs4_lookup_slot - Find a slot but don't allocate it
169 *
170 * Note: must be called with the slot_tbl_lock held.
171 */
172 struct nfs4_slot *nfs4_lookup_slot(struct nfs4_slot_table *tbl, u32 slotid)
173 {
174 if (slotid <= tbl->max_slotid)
175 return nfs4_find_or_create_slot(tbl, slotid, 0, GFP_NOWAIT);
176 return ERR_PTR(-E2BIG);
177 }
178
179 static int nfs4_slot_get_seqid(struct nfs4_slot_table *tbl, u32 slotid,
180 u32 *seq_nr)
181 __must_hold(&tbl->slot_tbl_lock)
182 {
183 struct nfs4_slot *slot;
184 int ret;
185
186 slot = nfs4_lookup_slot(tbl, slotid);
187 ret = PTR_ERR_OR_ZERO(slot);
188 if (!ret)
189 *seq_nr = slot->seq_nr;
190
191 return ret;
192 }
193
194 /*
195 * nfs4_slot_seqid_in_use - test if a slot sequence id is still in use
196 *
197 * Given a slot table, slot id and sequence number, determine if the
198 * RPC call in question is still in flight. This function is mainly
199 * intended for use by the callback channel.
200 */
201 static bool nfs4_slot_seqid_in_use(struct nfs4_slot_table *tbl,
202 u32 slotid, u32 seq_nr)
203 {
204 u32 cur_seq = 0;
205 bool ret = false;
206
207 spin_lock(&tbl->slot_tbl_lock);
208 if (nfs4_slot_get_seqid(tbl, slotid, &cur_seq) == 0 &&
209 cur_seq == seq_nr && test_bit(slotid, tbl->used_slots))
210 ret = true;
211 spin_unlock(&tbl->slot_tbl_lock);
212 return ret;
213 }
214
215 /*
216 * nfs4_slot_wait_on_seqid - wait until a slot sequence id is complete
217 *
218 * Given a slot table, slot id and sequence number, wait until the
219 * corresponding RPC call completes. This function is mainly
220 * intended for use by the callback channel.
221 */
222 int nfs4_slot_wait_on_seqid(struct nfs4_slot_table *tbl,
223 u32 slotid, u32 seq_nr,
224 unsigned long timeout)
225 {
226 if (wait_event_timeout(tbl->slot_waitq,
227 !nfs4_slot_seqid_in_use(tbl, slotid, seq_nr),
228 timeout) == 0)
229 return -ETIMEDOUT;
230 return 0;
231 }
232
233 /*
234 * nfs4_alloc_slot - efficiently look for a free slot
235 *
236 * nfs4_alloc_slot looks for an unset bit in the used_slots bitmap.
237 * If found, we mark the slot as used, update the highest_used_slotid,
238 * and respectively set up the sequence operation args.
239 *
240 * Note: must be called with under the slot_tbl_lock.
241 */
242 struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl)
243 {
244 struct nfs4_slot *ret = ERR_PTR(-EBUSY);
245 u32 slotid;
246
247 dprintk("--> %s used_slots=%04lx highest_used=%u max_slots=%u\n",
248 __func__, tbl->used_slots[0], tbl->highest_used_slotid,
249 tbl->max_slotid + 1);
250 slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slotid + 1);
251 if (slotid <= tbl->max_slotid) {
252 ret = nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
253 if (!IS_ERR(ret))
254 nfs4_lock_slot(tbl, ret);
255 }
256 dprintk("<-- %s used_slots=%04lx highest_used=%u slotid=%u\n",
257 __func__, tbl->used_slots[0], tbl->highest_used_slotid,
258 !IS_ERR(ret) ? ret->slot_nr : NFS4_NO_SLOT);
259 return ret;
260 }
261
262 static int nfs4_grow_slot_table(struct nfs4_slot_table *tbl,
263 u32 max_reqs, u32 ivalue)
264 {
265 if (max_reqs <= tbl->max_slots)
266 return 0;
267 if (!IS_ERR(nfs4_find_or_create_slot(tbl, max_reqs - 1, ivalue, GFP_NOFS)))
268 return 0;
269 return -ENOMEM;
270 }
271
272 static void nfs4_reset_slot_table(struct nfs4_slot_table *tbl,
273 u32 server_highest_slotid,
274 u32 ivalue)
275 {
276 struct nfs4_slot **p;
277
278 nfs4_shrink_slot_table(tbl, server_highest_slotid + 1);
279 p = &tbl->slots;
280 while (*p) {
281 (*p)->seq_nr = ivalue;
282 (*p)->seq_nr_highest_sent = ivalue;
283 (*p)->seq_nr_last_acked = ivalue - 1;
284 p = &(*p)->next;
285 }
286 tbl->highest_used_slotid = NFS4_NO_SLOT;
287 tbl->target_highest_slotid = server_highest_slotid;
288 tbl->server_highest_slotid = server_highest_slotid;
289 tbl->d_target_highest_slotid = 0;
290 tbl->d2_target_highest_slotid = 0;
291 tbl->max_slotid = server_highest_slotid;
292 }
293
294 /*
295 * (re)Initialise a slot table
296 */
297 static int nfs4_realloc_slot_table(struct nfs4_slot_table *tbl,
298 u32 max_reqs, u32 ivalue)
299 {
300 int ret;
301
302 dprintk("--> %s: max_reqs=%u, tbl->max_slots %u\n", __func__,
303 max_reqs, tbl->max_slots);
304
305 if (max_reqs > NFS4_MAX_SLOT_TABLE)
306 max_reqs = NFS4_MAX_SLOT_TABLE;
307
308 ret = nfs4_grow_slot_table(tbl, max_reqs, ivalue);
309 if (ret)
310 goto out;
311
312 spin_lock(&tbl->slot_tbl_lock);
313 nfs4_reset_slot_table(tbl, max_reqs - 1, ivalue);
314 spin_unlock(&tbl->slot_tbl_lock);
315
316 dprintk("%s: tbl=%p slots=%p max_slots=%u\n", __func__,
317 tbl, tbl->slots, tbl->max_slots);
318 out:
319 dprintk("<-- %s: return %d\n", __func__, ret);
320 return ret;
321 }
322
323 /*
324 * nfs4_release_slot_table - release all slot table entries
325 */
326 static void nfs4_release_slot_table(struct nfs4_slot_table *tbl)
327 {
328 nfs4_shrink_slot_table(tbl, 0);
329 }
330
331 /**
332 * nfs4_shutdown_slot_table - release resources attached to a slot table
333 * @tbl: slot table to shut down
334 *
335 */
336 void nfs4_shutdown_slot_table(struct nfs4_slot_table *tbl)
337 {
338 nfs4_release_slot_table(tbl);
339 rpc_destroy_wait_queue(&tbl->slot_tbl_waitq);
340 }
341
342 /**
343 * nfs4_setup_slot_table - prepare a stand-alone slot table for use
344 * @tbl: slot table to set up
345 * @max_reqs: maximum number of requests allowed
346 * @queue: name to give RPC wait queue
347 *
348 * Returns zero on success, or a negative errno.
349 */
350 int nfs4_setup_slot_table(struct nfs4_slot_table *tbl, unsigned int max_reqs,
351 const char *queue)
352 {
353 nfs4_init_slot_table(tbl, queue);
354 return nfs4_realloc_slot_table(tbl, max_reqs, 0);
355 }
356
357 static bool nfs41_assign_slot(struct rpc_task *task, void *pslot)
358 {
359 struct nfs4_sequence_args *args = task->tk_msg.rpc_argp;
360 struct nfs4_sequence_res *res = task->tk_msg.rpc_resp;
361 struct nfs4_slot *slot = pslot;
362 struct nfs4_slot_table *tbl = slot->table;
363
364 if (nfs4_slot_tbl_draining(tbl) && !args->sa_privileged)
365 return false;
366 slot->generation = tbl->generation;
367 args->sa_slot = slot;
368 res->sr_timestamp = jiffies;
369 res->sr_slot = slot;
370 res->sr_status_flags = 0;
371 res->sr_status = 1;
372 return true;
373 }
374
375 static bool __nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
376 struct nfs4_slot *slot)
377 {
378 if (rpc_wake_up_first(&tbl->slot_tbl_waitq, nfs41_assign_slot, slot))
379 return true;
380 return false;
381 }
382
383 bool nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
384 struct nfs4_slot *slot)
385 {
386 if (slot->slot_nr > tbl->max_slotid)
387 return false;
388 return __nfs41_wake_and_assign_slot(tbl, slot);
389 }
390
391 static bool nfs41_try_wake_next_slot_table_entry(struct nfs4_slot_table *tbl)
392 {
393 struct nfs4_slot *slot = nfs4_alloc_slot(tbl);
394 if (!IS_ERR(slot)) {
395 bool ret = __nfs41_wake_and_assign_slot(tbl, slot);
396 if (ret)
397 return ret;
398 nfs4_free_slot(tbl, slot);
399 }
400 return false;
401 }
402
403 void nfs41_wake_slot_table(struct nfs4_slot_table *tbl)
404 {
405 for (;;) {
406 if (!nfs41_try_wake_next_slot_table_entry(tbl))
407 break;
408 }
409 }
410
411 #if defined(CONFIG_NFS_V4_1)
412
413 static void nfs41_set_max_slotid_locked(struct nfs4_slot_table *tbl,
414 u32 target_highest_slotid)
415 {
416 u32 max_slotid;
417
418 max_slotid = min(NFS4_MAX_SLOT_TABLE - 1, target_highest_slotid);
419 if (max_slotid > tbl->server_highest_slotid)
420 max_slotid = tbl->server_highest_slotid;
421 if (max_slotid > tbl->target_highest_slotid)
422 max_slotid = tbl->target_highest_slotid;
423 tbl->max_slotid = max_slotid;
424 nfs41_wake_slot_table(tbl);
425 }
426
427 /* Update the client's idea of target_highest_slotid */
428 static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
429 u32 target_highest_slotid)
430 {
431 if (tbl->target_highest_slotid == target_highest_slotid)
432 return;
433 tbl->target_highest_slotid = target_highest_slotid;
434 tbl->generation++;
435 }
436
437 void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
438 u32 target_highest_slotid)
439 {
440 spin_lock(&tbl->slot_tbl_lock);
441 nfs41_set_target_slotid_locked(tbl, target_highest_slotid);
442 tbl->d_target_highest_slotid = 0;
443 tbl->d2_target_highest_slotid = 0;
444 nfs41_set_max_slotid_locked(tbl, target_highest_slotid);
445 spin_unlock(&tbl->slot_tbl_lock);
446 }
447
448 static void nfs41_set_server_slotid_locked(struct nfs4_slot_table *tbl,
449 u32 highest_slotid)
450 {
451 if (tbl->server_highest_slotid == highest_slotid)
452 return;
453 if (tbl->highest_used_slotid > highest_slotid)
454 return;
455 /* Deallocate slots */
456 nfs4_shrink_slot_table(tbl, highest_slotid + 1);
457 tbl->server_highest_slotid = highest_slotid;
458 }
459
460 static s32 nfs41_derivative_target_slotid(s32 s1, s32 s2)
461 {
462 s1 -= s2;
463 if (s1 == 0)
464 return 0;
465 if (s1 < 0)
466 return (s1 - 1) >> 1;
467 return (s1 + 1) >> 1;
468 }
469
470 static int nfs41_sign_s32(s32 s1)
471 {
472 if (s1 > 0)
473 return 1;
474 if (s1 < 0)
475 return -1;
476 return 0;
477 }
478
479 static bool nfs41_same_sign_or_zero_s32(s32 s1, s32 s2)
480 {
481 if (!s1 || !s2)
482 return true;
483 return nfs41_sign_s32(s1) == nfs41_sign_s32(s2);
484 }
485
486 /* Try to eliminate outliers by checking for sharp changes in the
487 * derivatives and second derivatives
488 */
489 static bool nfs41_is_outlier_target_slotid(struct nfs4_slot_table *tbl,
490 u32 new_target)
491 {
492 s32 d_target, d2_target;
493 bool ret = true;
494
495 d_target = nfs41_derivative_target_slotid(new_target,
496 tbl->target_highest_slotid);
497 d2_target = nfs41_derivative_target_slotid(d_target,
498 tbl->d_target_highest_slotid);
499 /* Is first derivative same sign? */
500 if (nfs41_same_sign_or_zero_s32(d_target, tbl->d_target_highest_slotid))
501 ret = false;
502 /* Is second derivative same sign? */
503 if (nfs41_same_sign_or_zero_s32(d2_target, tbl->d2_target_highest_slotid))
504 ret = false;
505 tbl->d_target_highest_slotid = d_target;
506 tbl->d2_target_highest_slotid = d2_target;
507 return ret;
508 }
509
510 void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
511 struct nfs4_slot *slot,
512 struct nfs4_sequence_res *res)
513 {
514 u32 target_highest_slotid = min(res->sr_target_highest_slotid,
515 NFS4_MAX_SLOTID);
516 u32 highest_slotid = min(res->sr_highest_slotid, NFS4_MAX_SLOTID);
517
518 spin_lock(&tbl->slot_tbl_lock);
519 if (!nfs41_is_outlier_target_slotid(tbl, target_highest_slotid))
520 nfs41_set_target_slotid_locked(tbl, target_highest_slotid);
521 if (tbl->generation == slot->generation)
522 nfs41_set_server_slotid_locked(tbl, highest_slotid);
523 nfs41_set_max_slotid_locked(tbl, target_highest_slotid);
524 spin_unlock(&tbl->slot_tbl_lock);
525 }
526
527 static void nfs4_release_session_slot_tables(struct nfs4_session *session)
528 {
529 nfs4_release_slot_table(&session->fc_slot_table);
530 nfs4_release_slot_table(&session->bc_slot_table);
531 }
532
533 /*
534 * Initialize or reset the forechannel and backchannel tables
535 */
536 int nfs4_setup_session_slot_tables(struct nfs4_session *ses)
537 {
538 struct nfs4_slot_table *tbl;
539 int status;
540
541 dprintk("--> %s\n", __func__);
542 /* Fore channel */
543 tbl = &ses->fc_slot_table;
544 tbl->session = ses;
545 status = nfs4_realloc_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
546 if (status || !(ses->flags & SESSION4_BACK_CHAN)) /* -ENOMEM */
547 return status;
548 /* Back channel */
549 tbl = &ses->bc_slot_table;
550 tbl->session = ses;
551 status = nfs4_realloc_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
552 if (status && tbl->slots == NULL)
553 /* Fore and back channel share a connection so get
554 * both slot tables or neither */
555 nfs4_release_session_slot_tables(ses);
556 return status;
557 }
558
559 struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp)
560 {
561 struct nfs4_session *session;
562
563 session = kzalloc(sizeof(struct nfs4_session), GFP_NOFS);
564 if (!session)
565 return NULL;
566
567 nfs4_init_slot_table(&session->fc_slot_table, "ForeChannel Slot table");
568 nfs4_init_slot_table(&session->bc_slot_table, "BackChannel Slot table");
569 session->session_state = 1<<NFS4_SESSION_INITING;
570
571 session->clp = clp;
572 return session;
573 }
574
575 static void nfs4_destroy_session_slot_tables(struct nfs4_session *session)
576 {
577 nfs4_shutdown_slot_table(&session->fc_slot_table);
578 nfs4_shutdown_slot_table(&session->bc_slot_table);
579 }
580
581 void nfs4_destroy_session(struct nfs4_session *session)
582 {
583 struct rpc_xprt *xprt;
584 const struct cred *cred;
585
586 cred = nfs4_get_clid_cred(session->clp);
587 nfs4_proc_destroy_session(session, cred);
588 put_cred(cred);
589
590 rcu_read_lock();
591 xprt = rcu_dereference(session->clp->cl_rpcclient->cl_xprt);
592 rcu_read_unlock();
593 dprintk("%s Destroy backchannel for xprt %p\n",
594 __func__, xprt);
595 xprt_destroy_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
596 nfs4_destroy_session_slot_tables(session);
597 kfree(session);
598 }
599
600 /*
601 * With sessions, the client is not marked ready until after a
602 * successful EXCHANGE_ID and CREATE_SESSION.
603 *
604 * Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
605 * other versions of NFS can be tried.
606 */
607 static int nfs41_check_session_ready(struct nfs_client *clp)
608 {
609 int ret;
610
611 if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
612 ret = nfs4_client_recover_expired_lease(clp);
613 if (ret)
614 return ret;
615 }
616 if (clp->cl_cons_state < NFS_CS_READY)
617 return -EPROTONOSUPPORT;
618 smp_rmb();
619 return 0;
620 }
621
622 int nfs4_init_session(struct nfs_client *clp)
623 {
624 if (!nfs4_has_session(clp))
625 return 0;
626
627 clear_bit(NFS4_SESSION_INITING, &clp->cl_session->session_state);
628 return nfs41_check_session_ready(clp);
629 }
630
631 int nfs4_init_ds_session(struct nfs_client *clp, unsigned long lease_time)
632 {
633 struct nfs4_session *session = clp->cl_session;
634 int ret;
635
636 spin_lock(&clp->cl_lock);
637 if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
638 /*
639 * Do not set NFS_CS_CHECK_LEASE_TIME instead set the
640 * DS lease to be equal to the MDS lease.
641 */
642 clp->cl_lease_time = lease_time;
643 clp->cl_last_renewal = jiffies;
644 }
645 spin_unlock(&clp->cl_lock);
646
647 ret = nfs41_check_session_ready(clp);
648 if (ret)
649 return ret;
650 /* Test for the DS role */
651 if (!is_ds_client(clp))
652 return -ENODEV;
653 return 0;
654 }
655 EXPORT_SYMBOL_GPL(nfs4_init_ds_session);
656
657 #endif /* defined(CONFIG_NFS_V4_1) */
658
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