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 static void nfs4_lock_slot(struct nfs4_slot_table *tbl,
 139                 struct nfs4_slot *slot)
 140 {
 141         u32 slotid = slot->slot_nr;
 142
 143         __set_bit(slotid, tbl->used_slots);
 144         if (slotid > tbl->highest_used_slotid ||
 145             tbl->highest_used_slotid == NFS4_NO_SLOT)
 146                 tbl->highest_used_slotid = slotid;
 147         slot->generation = tbl->generation;
 148 }
 149
 150 /*
 151  * nfs4_try_to_lock_slot - Given a slot try to allocate it
 152  *
 153  * Note: must be called with the slot_tbl_lock held.
 154  */
 155 bool nfs4_try_to_lock_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot)
 156 {
 157         if (nfs4_test_locked_slot(tbl, slot->slot_nr))
 158                 return false;
 159         nfs4_lock_slot(tbl, slot);
 160         return true;
 161 }
 162
 163 /*
 164  * nfs4_lookup_slot - Find a slot but don't allocate it
 165  *
 166  * Note: must be called with the slot_tbl_lock held.
 167  */
 168 struct nfs4_slot *nfs4_lookup_slot(struct nfs4_slot_table *tbl, u32 slotid)
 169 {
 170         if (slotid <= tbl->max_slotid)
 171                 return nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
 172         return ERR_PTR(-E2BIG);
 173 }
 174
 175 /*
 176  * nfs4_alloc_slot - efficiently look for a free slot
 177  *
 178  * nfs4_alloc_slot looks for an unset bit in the used_slots bitmap.
 179  * If found, we mark the slot as used, update the highest_used_slotid,
 180  * and respectively set up the sequence operation args.
 181  *
 182  * Note: must be called with under the slot_tbl_lock.
 183  */
 184 struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl)
 185 {
 186         struct nfs4_slot *ret = ERR_PTR(-EBUSY);
 187         u32 slotid;
 188
 189         dprintk("--> %s used_slots=%04lx highest_used=%u max_slots=%u\n",
 190                 __func__, tbl->used_slots[0], tbl->highest_used_slotid,
 191                 tbl->max_slotid + 1);
 192         slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slotid + 1);
 193         if (slotid <= tbl->max_slotid) {
 194                 ret = nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
 195                 if (!IS_ERR(ret))
 196                         nfs4_lock_slot(tbl, ret);
 197         }
 198         dprintk("<-- %s used_slots=%04lx highest_used=%u slotid=%u\n",
 199                 __func__, tbl->used_slots[0], tbl->highest_used_slotid,
 200                 !IS_ERR(ret) ? ret->slot_nr : NFS4_NO_SLOT);
 201         return ret;
 202 }
 203
 204 static int nfs4_grow_slot_table(struct nfs4_slot_table *tbl,
 205                  u32 max_reqs, u32 ivalue)
 206 {
 207         if (max_reqs <= tbl->max_slots)
 208                 return 0;
 209         if (!IS_ERR(nfs4_find_or_create_slot(tbl, max_reqs - 1, ivalue, GFP_NOFS)))
 210                 return 0;
 211         return -ENOMEM;
 212 }
 213
 214 static void nfs4_reset_slot_table(struct nfs4_slot_table *tbl,
 215                 u32 server_highest_slotid,
 216                 u32 ivalue)
 217 {
 218         struct nfs4_slot **p;
 219
 220         nfs4_shrink_slot_table(tbl, server_highest_slotid + 1);
 221         p = &tbl->slots;
 222         while (*p) {
 223                 (*p)->seq_nr = ivalue;
 224                 (*p)->interrupted = 0;
 225                 p = &(*p)->next;
 226         }
 227         tbl->highest_used_slotid = NFS4_NO_SLOT;
 228         tbl->target_highest_slotid = server_highest_slotid;
 229         tbl->server_highest_slotid = server_highest_slotid;
 230         tbl->d_target_highest_slotid = 0;
 231         tbl->d2_target_highest_slotid = 0;
 232         tbl->max_slotid = server_highest_slotid;
 233 }
 234
 235 /*
 236  * (re)Initialise a slot table
 237  */
 238 static int nfs4_realloc_slot_table(struct nfs4_slot_table *tbl,
 239                 u32 max_reqs, u32 ivalue)
 240 {
 241         int ret;
 242
 243         dprintk("--> %s: max_reqs=%u, tbl->max_slots %u\n", __func__,
 244                 max_reqs, tbl->max_slots);
 245
 246         if (max_reqs > NFS4_MAX_SLOT_TABLE)
 247                 max_reqs = NFS4_MAX_SLOT_TABLE;
 248
 249         ret = nfs4_grow_slot_table(tbl, max_reqs, ivalue);
 250         if (ret)
 251                 goto out;
 252
 253         spin_lock(&tbl->slot_tbl_lock);
 254         nfs4_reset_slot_table(tbl, max_reqs - 1, ivalue);
 255         spin_unlock(&tbl->slot_tbl_lock);
 256
 257         dprintk("%s: tbl=%p slots=%p max_slots=%u\n", __func__,
 258                 tbl, tbl->slots, tbl->max_slots);
 259 out:
 260         dprintk("<-- %s: return %d\n", __func__, ret);
 261         return ret;
 262 }
 263
 264 /*
 265  * nfs4_release_slot_table - release all slot table entries
 266  */
 267 static void nfs4_release_slot_table(struct nfs4_slot_table *tbl)
 268 {
 269         nfs4_shrink_slot_table(tbl, 0);
 270 }
 271
 272 /**
 273  * nfs4_shutdown_slot_table - release resources attached to a slot table
 274  * @tbl: slot table to shut down
 275  *
 276  */
 277 void nfs4_shutdown_slot_table(struct nfs4_slot_table *tbl)
 278 {
 279         nfs4_release_slot_table(tbl);
 280         rpc_destroy_wait_queue(&tbl->slot_tbl_waitq);
 281 }
 282
 283 /**
 284  * nfs4_setup_slot_table - prepare a stand-alone slot table for use
 285  * @tbl: slot table to set up
 286  * @max_reqs: maximum number of requests allowed
 287  * @queue: name to give RPC wait queue
 288  *
 289  * Returns zero on success, or a negative errno.
 290  */
 291 int nfs4_setup_slot_table(struct nfs4_slot_table *tbl, unsigned int max_reqs,
 292                 const char *queue)
 293 {
 294         nfs4_init_slot_table(tbl, queue);
 295         return nfs4_realloc_slot_table(tbl, max_reqs, 0);
 296 }
 297
 298 static bool nfs41_assign_slot(struct rpc_task *task, void *pslot)
 299 {
 300         struct nfs4_sequence_args *args = task->tk_msg.rpc_argp;
 301         struct nfs4_sequence_res *res = task->tk_msg.rpc_resp;
 302         struct nfs4_slot *slot = pslot;
 303         struct nfs4_slot_table *tbl = slot->table;
 304
 305         if (nfs4_slot_tbl_draining(tbl) && !args->sa_privileged)
 306                 return false;
 307         slot->generation = tbl->generation;
 308         args->sa_slot = slot;
 309         res->sr_timestamp = jiffies;
 310         res->sr_slot = slot;
 311         res->sr_status_flags = 0;
 312         res->sr_status = 1;
 313         return true;
 314 }
 315
 316 static bool __nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
 317                 struct nfs4_slot *slot)
 318 {
 319         if (rpc_wake_up_first(&tbl->slot_tbl_waitq, nfs41_assign_slot, slot))
 320                 return true;
 321         return false;
 322 }
 323
 324 bool nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
 325                 struct nfs4_slot *slot)
 326 {
 327         if (slot->slot_nr > tbl->max_slotid)
 328                 return false;
 329         return __nfs41_wake_and_assign_slot(tbl, slot);
 330 }
 331
 332 static bool nfs41_try_wake_next_slot_table_entry(struct nfs4_slot_table *tbl)
 333 {
 334         struct nfs4_slot *slot = nfs4_alloc_slot(tbl);
 335         if (!IS_ERR(slot)) {
 336                 bool ret = __nfs41_wake_and_assign_slot(tbl, slot);
 337                 if (ret)
 338                         return ret;
 339                 nfs4_free_slot(tbl, slot);
 340         }
 341         return false;
 342 }
 343
 344 void nfs41_wake_slot_table(struct nfs4_slot_table *tbl)
 345 {
 346         for (;;) {
 347                 if (!nfs41_try_wake_next_slot_table_entry(tbl))
 348                         break;
 349         }
 350 }
 351
 352 #if defined(CONFIG_NFS_V4_1)
 353
 354 static void nfs41_set_max_slotid_locked(struct nfs4_slot_table *tbl,
 355                 u32 target_highest_slotid)
 356 {
 357         u32 max_slotid;
 358
 359         max_slotid = min(NFS4_MAX_SLOT_TABLE - 1, target_highest_slotid);
 360         if (max_slotid > tbl->server_highest_slotid)
 361                 max_slotid = tbl->server_highest_slotid;
 362         if (max_slotid > tbl->target_highest_slotid)
 363                 max_slotid = tbl->target_highest_slotid;
 364         tbl->max_slotid = max_slotid;
 365         nfs41_wake_slot_table(tbl);
 366 }
 367
 368 /* Update the client's idea of target_highest_slotid */
 369 static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
 370                 u32 target_highest_slotid)
 371 {
 372         if (tbl->target_highest_slotid == target_highest_slotid)
 373                 return;
 374         tbl->target_highest_slotid = target_highest_slotid;
 375         tbl->generation++;
 376 }
 377
 378 void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
 379                 u32 target_highest_slotid)
 380 {
 381         spin_lock(&tbl->slot_tbl_lock);
 382         nfs41_set_target_slotid_locked(tbl, target_highest_slotid);
 383         tbl->d_target_highest_slotid = 0;
 384         tbl->d2_target_highest_slotid = 0;
 385         nfs41_set_max_slotid_locked(tbl, target_highest_slotid);
 386         spin_unlock(&tbl->slot_tbl_lock);
 387 }
 388
 389 static void nfs41_set_server_slotid_locked(struct nfs4_slot_table *tbl,
 390                 u32 highest_slotid)
 391 {
 392         if (tbl->server_highest_slotid == highest_slotid)
 393                 return;
 394         if (tbl->highest_used_slotid > highest_slotid)
 395                 return;
 396         /* Deallocate slots */
 397         nfs4_shrink_slot_table(tbl, highest_slotid + 1);
 398         tbl->server_highest_slotid = highest_slotid;
 399 }
 400
 401 static s32 nfs41_derivative_target_slotid(s32 s1, s32 s2)
 402 {
 403         s1 -= s2;
 404         if (s1 == 0)
 405                 return 0;
 406         if (s1 < 0)
 407                 return (s1 - 1) >> 1;
 408         return (s1 + 1) >> 1;
 409 }
 410
 411 static int nfs41_sign_s32(s32 s1)
 412 {
 413         if (s1 > 0)
 414                 return 1;
 415         if (s1 < 0)
 416                 return -1;
 417         return 0;
 418 }
 419
 420 static bool nfs41_same_sign_or_zero_s32(s32 s1, s32 s2)
 421 {
 422         if (!s1 || !s2)
 423                 return true;
 424         return nfs41_sign_s32(s1) == nfs41_sign_s32(s2);
 425 }
 426
 427 /* Try to eliminate outliers by checking for sharp changes in the
 428  * derivatives and second derivatives
 429  */
 430 static bool nfs41_is_outlier_target_slotid(struct nfs4_slot_table *tbl,
 431                 u32 new_target)
 432 {
 433         s32 d_target, d2_target;
 434         bool ret = true;
 435
 436         d_target = nfs41_derivative_target_slotid(new_target,
 437                         tbl->target_highest_slotid);
 438         d2_target = nfs41_derivative_target_slotid(d_target,
 439                         tbl->d_target_highest_slotid);
 440         /* Is first derivative same sign? */
 441         if (nfs41_same_sign_or_zero_s32(d_target, tbl->d_target_highest_slotid))
 442                 ret = false;
 443         /* Is second derivative same sign? */
 444         if (nfs41_same_sign_or_zero_s32(d2_target, tbl->d2_target_highest_slotid))
 445                 ret = false;
 446         tbl->d_target_highest_slotid = d_target;
 447         tbl->d2_target_highest_slotid = d2_target;
 448         return ret;
 449 }
 450
 451 void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
 452                 struct nfs4_slot *slot,
 453                 struct nfs4_sequence_res *res)
 454 {
 455         spin_lock(&tbl->slot_tbl_lock);
 456         if (!nfs41_is_outlier_target_slotid(tbl, res->sr_target_highest_slotid))
 457                 nfs41_set_target_slotid_locked(tbl, res->sr_target_highest_slotid);
 458         if (tbl->generation == slot->generation)
 459                 nfs41_set_server_slotid_locked(tbl, res->sr_highest_slotid);
 460         nfs41_set_max_slotid_locked(tbl, res->sr_target_highest_slotid);
 461         spin_unlock(&tbl->slot_tbl_lock);
 462 }
 463
 464 static void nfs4_release_session_slot_tables(struct nfs4_session *session)
 465 {
 466         nfs4_release_slot_table(&session->fc_slot_table);
 467         nfs4_release_slot_table(&session->bc_slot_table);
 468 }
 469
 470 /*
 471  * Initialize or reset the forechannel and backchannel tables
 472  */
 473 int nfs4_setup_session_slot_tables(struct nfs4_session *ses)
 474 {
 475         struct nfs4_slot_table *tbl;
 476         int status;
 477
 478         dprintk("--> %s\n", __func__);
 479         /* Fore channel */
 480         tbl = &ses->fc_slot_table;
 481         tbl->session = ses;
 482         status = nfs4_realloc_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
 483         if (status || !(ses->flags & SESSION4_BACK_CHAN)) /* -ENOMEM */
 484                 return status;
 485         /* Back channel */
 486         tbl = &ses->bc_slot_table;
 487         tbl->session = ses;
 488         status = nfs4_realloc_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
 489         if (status && tbl->slots == NULL)
 490                 /* Fore and back channel share a connection so get
 491                  * both slot tables or neither */
 492                 nfs4_release_session_slot_tables(ses);
 493         return status;
 494 }
 495
 496 struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp)
 497 {
 498         struct nfs4_session *session;
 499
 500         session = kzalloc(sizeof(struct nfs4_session), GFP_NOFS);
 501         if (!session)
 502                 return NULL;
 503
 504         nfs4_init_slot_table(&session->fc_slot_table, "ForeChannel Slot table");
 505         nfs4_init_slot_table(&session->bc_slot_table, "BackChannel Slot table");
 506         session->session_state = 1<<NFS4_SESSION_INITING;
 507
 508         session->clp = clp;
 509         return session;
 510 }
 511
 512 static void nfs4_destroy_session_slot_tables(struct nfs4_session *session)
 513 {
 514         nfs4_shutdown_slot_table(&session->fc_slot_table);
 515         nfs4_shutdown_slot_table(&session->bc_slot_table);
 516 }
 517
 518 void nfs4_destroy_session(struct nfs4_session *session)
 519 {
 520         struct rpc_xprt *xprt;
 521         struct rpc_cred *cred;
 522
 523         cred = nfs4_get_clid_cred(session->clp);
 524         nfs4_proc_destroy_session(session, cred);
 525         if (cred)
 526                 put_rpccred(cred);
 527
 528         rcu_read_lock();
 529         xprt = rcu_dereference(session->clp->cl_rpcclient->cl_xprt);
 530         rcu_read_unlock();
 531         dprintk("%s Destroy backchannel for xprt %p\n",
 532                 __func__, xprt);
 533         xprt_destroy_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
 534         nfs4_destroy_session_slot_tables(session);
 535         kfree(session);
 536 }
 537
 538 /*
 539  * With sessions, the client is not marked ready until after a
 540  * successful EXCHANGE_ID and CREATE_SESSION.
 541  *
 542  * Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
 543  * other versions of NFS can be tried.
 544  */
 545 static int nfs41_check_session_ready(struct nfs_client *clp)
 546 {
 547         int ret;
 548
 549         if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
 550                 ret = nfs4_client_recover_expired_lease(clp);
 551                 if (ret)
 552                         return ret;
 553         }
 554         if (clp->cl_cons_state < NFS_CS_READY)
 555                 return -EPROTONOSUPPORT;
 556         smp_rmb();
 557         return 0;
 558 }
 559
 560 int nfs4_init_session(struct nfs_client *clp)
 561 {
 562         if (!nfs4_has_session(clp))
 563                 return 0;
 564
 565         clear_bit(NFS4_SESSION_INITING, &clp->cl_session->session_state);
 566         return nfs41_check_session_ready(clp);
 567 }
 568
 569 int nfs4_init_ds_session(struct nfs_client *clp, unsigned long lease_time)
 570 {
 571         struct nfs4_session *session = clp->cl_session;
 572         int ret;
 573
 574         spin_lock(&clp->cl_lock);
 575         if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
 576                 /*
 577                  * Do not set NFS_CS_CHECK_LEASE_TIME instead set the
 578                  * DS lease to be equal to the MDS lease.
 579                  */
 580                 clp->cl_lease_time = lease_time;
 581                 clp->cl_last_renewal = jiffies;
 582         }
 583         spin_unlock(&clp->cl_lock);
 584
 585         ret = nfs41_check_session_ready(clp);
 586         if (ret)
 587                 return ret;
 588         /* Test for the DS role */
 589         if (!is_ds_client(clp))
 590                 return -ENODEV;
 591         return 0;
 592 }
 593 EXPORT_SYMBOL_GPL(nfs4_init_ds_session);
 594
 595 #endif  /* defined(CONFIG_NFS_V4_1) */