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Linux/fs/nfs/nfs4session.c

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  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 all slot table entries
236  */
237 static 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  */
247 void 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  */
261 int 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 
268 static 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 
286 static 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 
294 bool 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 
302 static 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 
314 void 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 
324 static 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 */
339 static 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 
348 void 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 
359 static 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 
371 static 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 
381 static 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 
390 static 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  */
400 static 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 
421 void 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 
434 static 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  */
443 int 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) /* -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 
466 struct 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 
482 static 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 
488 void 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  */
515 static 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 
530 int 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 
539 int 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 }
563 EXPORT_SYMBOL_GPL(nfs4_init_ds_session);
564 
565 #endif  /* defined(CONFIG_NFS_V4_1) */
566 

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