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