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
26static 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 */
37static 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 */
60void 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 */
81void 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
102static 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
116static 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 */
147struct 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
167out:
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
174static 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
184static 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 */
208static 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);
229out:
230	dprintk("<-- %s: return %d\n", __func__, ret);
231	return ret;
232}
233
234/*
235 * nfs4_release_slot_table - release all slot table entries
236 */
237static void nfs4_release_slot_table(struct nfs4_slot_table *tbl)
238{
239	nfs4_shrink_slot_table(tbl, 0);
240}
241
242/**
243 * nfs4_shutdown_slot_table - release resources attached to a slot table
244 * @tbl: slot table to shut down
245 *
246 */
247void nfs4_shutdown_slot_table(struct nfs4_slot_table *tbl)
248{
249	nfs4_release_slot_table(tbl);
250	rpc_destroy_wait_queue(&tbl->slot_tbl_waitq);
251}
252
253/**
254 * nfs4_setup_slot_table - prepare a stand-alone slot table for use
255 * @tbl: slot table to set up
256 * @max_reqs: maximum number of requests allowed
257 * @queue: name to give RPC wait queue
258 *
259 * Returns zero on success, or a negative errno.
260 */
261int nfs4_setup_slot_table(struct nfs4_slot_table *tbl, unsigned int max_reqs,
262		const char *queue)
263{
264	nfs4_init_slot_table(tbl, queue);
265	return nfs4_realloc_slot_table(tbl, max_reqs, 0);
266}
267
268static bool nfs41_assign_slot(struct rpc_task *task, void *pslot)
269{
270	struct nfs4_sequence_args *args = task->tk_msg.rpc_argp;
271	struct nfs4_sequence_res *res = task->tk_msg.rpc_resp;
272	struct nfs4_slot *slot = pslot;
273	struct nfs4_slot_table *tbl = slot->table;
274
275	if (nfs4_slot_tbl_draining(tbl) && !args->sa_privileged)
276		return false;
277	slot->generation = tbl->generation;
278	args->sa_slot = slot;
279	res->sr_timestamp = jiffies;
280	res->sr_slot = slot;
281	res->sr_status_flags = 0;
282	res->sr_status = 1;
283	return true;
284}
285
286static bool __nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
287		struct nfs4_slot *slot)
288{
289	if (rpc_wake_up_first(&tbl->slot_tbl_waitq, nfs41_assign_slot, slot))
290		return true;
291	return false;
292}
293
294bool nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
295		struct nfs4_slot *slot)
296{
297	if (slot->slot_nr > tbl->max_slotid)
298		return false;
299	return __nfs41_wake_and_assign_slot(tbl, slot);
300}
301
302static bool nfs41_try_wake_next_slot_table_entry(struct nfs4_slot_table *tbl)
303{
304	struct nfs4_slot *slot = nfs4_alloc_slot(tbl);
305	if (!IS_ERR(slot)) {
306		bool ret = __nfs41_wake_and_assign_slot(tbl, slot);
307		if (ret)
308			return ret;
309		nfs4_free_slot(tbl, slot);
310	}
311	return false;
312}
313
314void nfs41_wake_slot_table(struct nfs4_slot_table *tbl)
315{
316	for (;;) {
317		if (!nfs41_try_wake_next_slot_table_entry(tbl))
318			break;
319	}
320}
321
322#if defined(CONFIG_NFS_V4_1)
323
324static void nfs41_set_max_slotid_locked(struct nfs4_slot_table *tbl,
325		u32 target_highest_slotid)
326{
327	u32 max_slotid;
328
329	max_slotid = min(NFS4_MAX_SLOT_TABLE - 1, target_highest_slotid);
330	if (max_slotid > tbl->server_highest_slotid)
331		max_slotid = tbl->server_highest_slotid;
332	if (max_slotid > tbl->target_highest_slotid)
333		max_slotid = tbl->target_highest_slotid;
334	tbl->max_slotid = max_slotid;
335	nfs41_wake_slot_table(tbl);
336}
337
338/* Update the client's idea of target_highest_slotid */
339static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
340		u32 target_highest_slotid)
341{
342	if (tbl->target_highest_slotid == target_highest_slotid)
343		return;
344	tbl->target_highest_slotid = target_highest_slotid;
345	tbl->generation++;
346}
347
348void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
349		u32 target_highest_slotid)
350{
351	spin_lock(&tbl->slot_tbl_lock);
352	nfs41_set_target_slotid_locked(tbl, target_highest_slotid);
353	tbl->d_target_highest_slotid = 0;
354	tbl->d2_target_highest_slotid = 0;
355	nfs41_set_max_slotid_locked(tbl, target_highest_slotid);
356	spin_unlock(&tbl->slot_tbl_lock);
357}
358
359static void nfs41_set_server_slotid_locked(struct nfs4_slot_table *tbl,
360		u32 highest_slotid)
361{
362	if (tbl->server_highest_slotid == highest_slotid)
363		return;
364	if (tbl->highest_used_slotid > highest_slotid)
365		return;
366	/* Deallocate slots */
367	nfs4_shrink_slot_table(tbl, highest_slotid + 1);
368	tbl->server_highest_slotid = highest_slotid;
369}
370
371static s32 nfs41_derivative_target_slotid(s32 s1, s32 s2)
372{
373	s1 -= s2;
374	if (s1 == 0)
375		return 0;
376	if (s1 < 0)
377		return (s1 - 1) >> 1;
378	return (s1 + 1) >> 1;
379}
380
381static int nfs41_sign_s32(s32 s1)
382{
383	if (s1 > 0)
384		return 1;
385	if (s1 < 0)
386		return -1;
387	return 0;
388}
389
390static bool nfs41_same_sign_or_zero_s32(s32 s1, s32 s2)
391{
392	if (!s1 || !s2)
393		return true;
394	return nfs41_sign_s32(s1) == nfs41_sign_s32(s2);
395}
396
397/* Try to eliminate outliers by checking for sharp changes in the
398 * derivatives and second derivatives
399 */
400static bool nfs41_is_outlier_target_slotid(struct nfs4_slot_table *tbl,
401		u32 new_target)
402{
403	s32 d_target, d2_target;
404	bool ret = true;
405
406	d_target = nfs41_derivative_target_slotid(new_target,
407			tbl->target_highest_slotid);
408	d2_target = nfs41_derivative_target_slotid(d_target,
409			tbl->d_target_highest_slotid);
410	/* Is first derivative same sign? */
411	if (nfs41_same_sign_or_zero_s32(d_target, tbl->d_target_highest_slotid))
412		ret = false;
413	/* Is second derivative same sign? */
414	if (nfs41_same_sign_or_zero_s32(d2_target, tbl->d2_target_highest_slotid))
415		ret = false;
416	tbl->d_target_highest_slotid = d_target;
417	tbl->d2_target_highest_slotid = d2_target;
418	return ret;
419}
420
421void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
422		struct nfs4_slot *slot,
423		struct nfs4_sequence_res *res)
424{
425	spin_lock(&tbl->slot_tbl_lock);
426	if (!nfs41_is_outlier_target_slotid(tbl, res->sr_target_highest_slotid))
427		nfs41_set_target_slotid_locked(tbl, res->sr_target_highest_slotid);
428	if (tbl->generation == slot->generation)
429		nfs41_set_server_slotid_locked(tbl, res->sr_highest_slotid);
430	nfs41_set_max_slotid_locked(tbl, res->sr_target_highest_slotid);
431	spin_unlock(&tbl->slot_tbl_lock);
432}
433
434static void nfs4_release_session_slot_tables(struct nfs4_session *session)
435{
436	nfs4_release_slot_table(&session->fc_slot_table);
437	nfs4_release_slot_table(&session->bc_slot_table);
438}
439
440/*
441 * Initialize or reset the forechannel and backchannel tables
442 */
443int nfs4_setup_session_slot_tables(struct nfs4_session *ses)
444{
445	struct nfs4_slot_table *tbl;
446	int status;
447
448	dprintk("--> %s\n", __func__);
449	/* Fore channel */
450	tbl = &ses->fc_slot_table;
451	tbl->session = ses;
452	status = nfs4_realloc_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
453	if (status || !(ses->flags & SESSION4_BACK_CHAN)) /* -ENOMEM */
454		return status;
455	/* Back channel */
456	tbl = &ses->bc_slot_table;
457	tbl->session = ses;
458	status = nfs4_realloc_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
459	if (status && tbl->slots == NULL)
460		/* Fore and back channel share a connection so get
461		 * both slot tables or neither */
462		nfs4_release_session_slot_tables(ses);
463	return status;
464}
465
466struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp)
467{
468	struct nfs4_session *session;
469
470	session = kzalloc(sizeof(struct nfs4_session), GFP_NOFS);
471	if (!session)
472		return NULL;
473
474	nfs4_init_slot_table(&session->fc_slot_table, "ForeChannel Slot table");
475	nfs4_init_slot_table(&session->bc_slot_table, "BackChannel Slot table");
476	session->session_state = 1<<NFS4_SESSION_INITING;
477
478	session->clp = clp;
479	return session;
480}
481
482static void nfs4_destroy_session_slot_tables(struct nfs4_session *session)
483{
484	nfs4_shutdown_slot_table(&session->fc_slot_table);
485	nfs4_shutdown_slot_table(&session->bc_slot_table);
486}
487
488void nfs4_destroy_session(struct nfs4_session *session)
489{
490	struct rpc_xprt *xprt;
491	struct rpc_cred *cred;
492
493	cred = nfs4_get_clid_cred(session->clp);
494	nfs4_proc_destroy_session(session, cred);
495	if (cred)
496		put_rpccred(cred);
497
498	rcu_read_lock();
499	xprt = rcu_dereference(session->clp->cl_rpcclient->cl_xprt);
500	rcu_read_unlock();
501	dprintk("%s Destroy backchannel for xprt %p\n",
502		__func__, xprt);
503	xprt_destroy_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
504	nfs4_destroy_session_slot_tables(session);
505	kfree(session);
506}
507
508/*
509 * With sessions, the client is not marked ready until after a
510 * successful EXCHANGE_ID and CREATE_SESSION.
511 *
512 * Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
513 * other versions of NFS can be tried.
514 */
515static int nfs41_check_session_ready(struct nfs_client *clp)
516{
517	int ret;
518
519	if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
520		ret = nfs4_client_recover_expired_lease(clp);
521		if (ret)
522			return ret;
523	}
524	if (clp->cl_cons_state < NFS_CS_READY)
525		return -EPROTONOSUPPORT;
526	smp_rmb();
527	return 0;
528}
529
530int nfs4_init_session(struct nfs_client *clp)
531{
532	if (!nfs4_has_session(clp))
533		return 0;
534
535	clear_bit(NFS4_SESSION_INITING, &clp->cl_session->session_state);
536	return nfs41_check_session_ready(clp);
537}
538
539int nfs4_init_ds_session(struct nfs_client *clp, unsigned long lease_time)
540{
541	struct nfs4_session *session = clp->cl_session;
542	int ret;
543
544	spin_lock(&clp->cl_lock);
545	if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
546		/*
547		 * Do not set NFS_CS_CHECK_LEASE_TIME instead set the
548		 * DS lease to be equal to the MDS lease.
549		 */
550		clp->cl_lease_time = lease_time;
551		clp->cl_last_renewal = jiffies;
552	}
553	spin_unlock(&clp->cl_lock);
554
555	ret = nfs41_check_session_ready(clp);
556	if (ret)
557		return ret;
558	/* Test for the DS role */
559	if (!is_ds_client(clp))
560		return -ENODEV;
561	return 0;
562}
563EXPORT_SYMBOL_GPL(nfs4_init_ds_session);
564
565#endif	/* defined(CONFIG_NFS_V4_1) */
566