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
27static 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 */
39static 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 */
62void 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 */
83void 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
104static 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
120static 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
142static 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 */
159bool 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 */
172struct 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
179static 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 */
201static 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 */
222int 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 */
242struct 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
262static 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
272static 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 */
297static 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);
318out:
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 */
326static 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 */
336void 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 */
350int 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
357static 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
375static 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
383bool 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
391static 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
403void 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
413static 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 */
428static 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
437void 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
448static 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
460static 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
470static 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
479static 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 */
489static 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
510void 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
527static 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 */
536int 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
559struct 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
575static 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
581void 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 */
607static 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
622int 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
631int 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}
655EXPORT_SYMBOL_GPL(nfs4_init_ds_session);
656
657#endif	/* defined(CONFIG_NFS_V4_1) */
658