fs/nfs/nfs4session.c

   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) */