lustre/obdclass/jobid.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2011, 2014, Intel Corporation.
  27  *
  28  * Copyright 2017 Cray Inc, all rights reserved.
  29  * Author: Ben Evans.
  30  *
  31  * Store PID->JobID mappings
  32  */
  33
  34 #define DEBUG_SUBSYSTEM S_RPC
  35 #include <linux/user_namespace.h>
  36 #include <linux/uidgid.h>
  37 #include <linux/utsname.h>
  38
  39 #include <libcfs/libcfs.h>
  40 #include <obd_support.h>
  41 #include <obd_class.h>
  42 #include <lustre_net.h>
  43
  44 static struct cfs_hash *jobid_hash;
  45 static struct cfs_hash_ops jobid_hash_ops;
  46 spinlock_t jobid_hash_lock;
  47
  48 #define RESCAN_INTERVAL 30
  49 #define DELETE_INTERVAL 300
  50
  51 char obd_jobid_var[JOBSTATS_JOBID_VAR_MAX_LEN + 1] = JOBSTATS_DISABLE;
  52 char obd_jobid_name[LUSTRE_JOBID_SIZE] = "%e.%u";
  53
  54 /**
  55  * Structure to store a single PID->JobID mapping
  56  */
  57 struct jobid_pid_map {
  58         struct hlist_node       jp_hash;
  59         time64_t                jp_time;
  60         spinlock_t              jp_lock; /* protects jp_jobid */
  61         char                    jp_jobid[LUSTRE_JOBID_SIZE];
  62         unsigned int            jp_joblen;
  63         atomic_t                jp_refcount;
  64         pid_t                   jp_pid;
  65 };
  66
  67 /*
  68  * Jobid can be set for a session (see setsid(2)) by writing to
  69  * a sysfs file from any process in that session.
  70  * The jobids are stored in a hash table indexed by the relevant
  71  * struct pid.  We periodically look for entries where the pid has
  72  * no PIDTYPE_SID tasks any more, and prune them.  This happens within
  73  * 5 seconds of a jobid being added, and every 5 minutes when jobids exist,
  74  * but none are added.
  75  */
  76 #define JOBID_EXPEDITED_CLEAN (5)
  77 #define JOBID_BACKGROUND_CLEAN (5 * 60)
  78
  79 struct session_jobid {
  80         struct pid              *sj_session;
  81         struct rhash_head       sj_linkage;
  82         struct rcu_head         sj_rcu;
  83         char                    sj_jobid[1];
  84 };
  85
  86 static const struct rhashtable_params jobid_params = {
  87         .key_len        = sizeof(struct pid *),
  88         .key_offset     = offsetof(struct session_jobid, sj_session),
  89         .head_offset    = offsetof(struct session_jobid, sj_linkage),
  90 };
  91
  92 static struct rhashtable session_jobids;
  93
  94 /*
  95  * jobid_current must be called with rcu_read_lock held.
  96  * if it returns non-NULL, the string can only be used
  97  * until rcu_read_unlock is called.
  98  */
  99 char *jobid_current(void)
 100 {
 101         struct pid *sid = task_session(current);
 102         struct session_jobid *sj;
 103
 104         sj = rhashtable_lookup_fast(&session_jobids, &sid, jobid_params);
 105         if (sj)
 106                 return sj->sj_jobid;
 107         return NULL;
 108 }
 109
 110 static void jobid_prune_expedite(void);
 111 /*
 112  * jobid_set_current will try to add a new entry
 113  * to the table.  If one exists with the same key, the
 114  * jobid will be replaced
 115  */
 116 int jobid_set_current(char *jobid)
 117 {
 118         struct pid *sid;
 119         struct session_jobid *sj, *origsj;
 120         int ret;
 121         int len = strlen(jobid);
 122
 123         sj = kmalloc(sizeof(*sj) + len, GFP_KERNEL);
 124         if (!sj)
 125                 return -ENOMEM;
 126         rcu_read_lock();
 127         sid = task_session(current);
 128         sj->sj_session = get_pid(sid);
 129         strncpy(sj->sj_jobid, jobid, len+1);
 130         origsj = rhashtable_lookup_get_insert_fast(&session_jobids,
 131                                                    &sj->sj_linkage,
 132                                                    jobid_params);
 133         if (origsj == NULL) {
 134                 /* successful insert */
 135                 rcu_read_unlock();
 136                 jobid_prune_expedite();
 137                 return 0;
 138         }
 139
 140         if (IS_ERR(origsj)) {
 141                 put_pid(sj->sj_session);
 142                 kfree(sj);
 143                 rcu_read_unlock();
 144                 return PTR_ERR(origsj);
 145         }
 146         ret = rhashtable_replace_fast(&session_jobids,
 147                                       &origsj->sj_linkage,
 148                                       &sj->sj_linkage,
 149                                       jobid_params);
 150         if (ret) {
 151                 put_pid(sj->sj_session);
 152                 kfree(sj);
 153                 rcu_read_unlock();
 154                 return ret;
 155         }
 156         put_pid(origsj->sj_session);
 157         rcu_read_unlock();
 158         kfree_rcu(origsj, sj_rcu);
 159         jobid_prune_expedite();
 160
 161         return 0;
 162 }
 163
 164 static void jobid_free(void *vsj, void *arg)
 165 {
 166         struct session_jobid *sj = vsj;
 167
 168         put_pid(sj->sj_session);
 169         kfree(sj);
 170 }
 171
 172 static void jobid_prune(struct work_struct *work);
 173 static DECLARE_DELAYED_WORK(jobid_prune_work, jobid_prune);
 174 static int jobid_prune_expedited;
 175 static void jobid_prune(struct work_struct *work)
 176 {
 177         int remaining = 0;
 178         struct rhashtable_iter iter;
 179         struct session_jobid *sj;
 180
 181         jobid_prune_expedited = 0;
 182         rhashtable_walk_enter(&session_jobids, &iter);
 183         rhashtable_walk_start(&iter);
 184         while ((sj = rhashtable_walk_next(&iter)) != NULL) {
 185                 if (!hlist_empty(&sj->sj_session->tasks[PIDTYPE_SID])) {
 186                         remaining++;
 187                         continue;
 188                 }
 189                 if (rhashtable_remove_fast(&session_jobids,
 190                                            &sj->sj_linkage,
 191                                            jobid_params) == 0) {
 192                         put_pid(sj->sj_session);
 193                         kfree_rcu(sj, sj_rcu);
 194                 }
 195         }
 196         rhashtable_walk_stop(&iter);
 197         rhashtable_walk_exit(&iter);
 198         if (remaining)
 199                 schedule_delayed_work(&jobid_prune_work,
 200                                       cfs_time_seconds(JOBID_BACKGROUND_CLEAN));
 201 }
 202
 203 static void jobid_prune_expedite(void)
 204 {
 205         if (!jobid_prune_expedited) {
 206                 jobid_prune_expedited = 1;
 207                 mod_delayed_work(system_wq, &jobid_prune_work,
 208                                  cfs_time_seconds(JOBID_EXPEDITED_CLEAN));
 209         }
 210 }
 211
 212 /*
 213  * Get jobid of current process by reading the environment variable
 214  * stored in between the "env_start" & "env_end" of task struct.
 215  *
 216  * If some job scheduler doesn't store jobid in the "env_start/end",
 217  * then an upcall could be issued here to get the jobid by utilizing
 218  * the userspace tools/API. Then, the jobid must be cached.
 219  */
 220 int jobid_get_from_environ(char *jobid_var, char *jobid, int *jobid_len)
 221 {
 222         int rc;
 223
 224         rc = cfs_get_environ(jobid_var, jobid, jobid_len);
 225         if (!rc)
 226                 goto out;
 227
 228         if (rc == -EOVERFLOW) {
 229                 /* For the PBS_JOBID and LOADL_STEP_ID keys (which are
 230                  * variable length strings instead of just numbers), it
 231                  * might make sense to keep the unique parts for JobID,
 232                  * instead of just returning an error.  That means a
 233                  * larger temp buffer for cfs_get_environ(), then
 234                  * truncating the string at some separator to fit into
 235                  * the specified jobid_len.  Fix later if needed. */
 236                 static ktime_t printed;
 237
 238                 if (unlikely(ktime_to_ns(printed) == 0 ||
 239                              ktime_after(ktime_get(),
 240                                          ktime_add_ns(printed,
 241                                                       3600*24*NSEC_PER_SEC)))) {
 242                         LCONSOLE_WARN("jobid: '%s' value too large (%d)\n",
 243                                       obd_jobid_var, *jobid_len);
 244                         printed = ktime_get();
 245                 }
 246
 247                 rc = 0;
 248         } else {
 249                 CDEBUG_LIMIT((rc == -ENOENT || rc == -EINVAL ||
 250                               rc == -EDEADLK) ? D_INFO : D_ERROR,
 251                              "jobid: get '%s' failed: rc = %d\n",
 252                              obd_jobid_var, rc);
 253         }
 254
 255 out:
 256         return rc;
 257 }
 258
 259 /*
 260  * jobid_should_free_item
 261  *
 262  * Each item is checked to see if it should be released
 263  * Removed from hash table by caller
 264  * Actually freed in jobid_put_locked
 265  *
 266  * Returns 1 if item is to be freed, 0 if it is to be kept
 267  */
 268
 269 static int jobid_should_free_item(void *obj, void *data)
 270 {
 271         char *jobid = data;
 272         struct jobid_pid_map *pidmap = obj;
 273         int rc = 0;
 274
 275         if (obj == NULL)
 276                 return 0;
 277
 278         if (jobid == NULL) {
 279                 WARN_ON_ONCE(atomic_read(&pidmap->jp_refcount) != 1);
 280                 return 1;
 281         }
 282
 283         spin_lock(&pidmap->jp_lock);
 284         /* prevent newly inserted items from deleting */
 285         if (jobid[0] == '\0' && atomic_read(&pidmap->jp_refcount) == 1)
 286                 rc = 1;
 287         else if (ktime_get_real_seconds() - pidmap->jp_time > DELETE_INTERVAL)
 288                 rc = 1;
 289         else if (strcmp(pidmap->jp_jobid, jobid) == 0)
 290                 rc = 1;
 291         spin_unlock(&pidmap->jp_lock);
 292
 293         return rc;
 294 }
 295
 296 /*
 297  * jobid_name_is_valid
 298  *
 299  * Checks if the jobid is a Lustre process
 300  *
 301  * Returns true if jobid is valid
 302  * Returns false if jobid looks like it's a Lustre process
 303  */
 304 static bool jobid_name_is_valid(char *jobid)
 305 {
 306         const char *const lustre_reserved[] = { "ll_ping", "ptlrpc",
 307                                                 "ldlm", "ll_sa", NULL };
 308         int i;
 309
 310         if (jobid[0] == '\0')
 311                 return false;
 312
 313         for (i = 0; lustre_reserved[i] != NULL; i++) {
 314                 if (strncmp(jobid, lustre_reserved[i],
 315                             strlen(lustre_reserved[i])) == 0)
 316                         return false;
 317         }
 318         return true;
 319 }
 320
 321 /*
 322  * jobid_get_from_cache()
 323  *
 324  * Returns contents of jobid_var from process environment for current PID,
 325  * or from the per-session jobid table.
 326  * Values fetch from process environment will be cached for some time to avoid
 327  * the overhead of scanning the environment.
 328  *
 329  * Return: -ENOMEM if allocating a new pidmap fails
 330  *         -ENOENT if no entry could be found
 331  *         +ve string length for success (something was returned in jobid)
 332  */
 333 static int jobid_get_from_cache(char *jobid, size_t joblen)
 334 {
 335         static time64_t last_expire;
 336         bool expire_cache = false;
 337         pid_t pid = current_pid();
 338         struct jobid_pid_map *pidmap = NULL;
 339         time64_t now = ktime_get_real_seconds();
 340         int rc = 0;
 341         ENTRY;
 342
 343         if (strcmp(obd_jobid_var, JOBSTATS_SESSION) == 0) {
 344                 char *jid;
 345
 346                 rcu_read_lock();
 347                 jid = jobid_current();
 348                 if (jid) {
 349                         strlcpy(jobid, jid, joblen);
 350                         joblen = strlen(jobid);
 351                 } else {
 352                         rc = -ENOENT;
 353                 }
 354                 rcu_read_unlock();
 355                 GOTO(out, rc);
 356         }
 357
 358         LASSERT(jobid_hash != NULL);
 359
 360         /* scan hash periodically to remove old PID entries from cache */
 361         spin_lock(&jobid_hash_lock);
 362         if (unlikely(last_expire + DELETE_INTERVAL <= now)) {
 363                 expire_cache = true;
 364                 last_expire = now;
 365         }
 366         spin_unlock(&jobid_hash_lock);
 367
 368         if (expire_cache)
 369                 cfs_hash_cond_del(jobid_hash, jobid_should_free_item,
 370                                   "intentionally_bad_jobid");
 371
 372         /* first try to find PID in the hash and use that value */
 373         pidmap = cfs_hash_lookup(jobid_hash, &pid);
 374         if (pidmap == NULL) {
 375                 struct jobid_pid_map *pidmap2;
 376
 377                 OBD_ALLOC_PTR(pidmap);
 378                 if (pidmap == NULL)
 379                         GOTO(out, rc = -ENOMEM);
 380
 381                 pidmap->jp_pid = pid;
 382                 pidmap->jp_time = 0;
 383                 pidmap->jp_jobid[0] = '\0';
 384                 spin_lock_init(&pidmap->jp_lock);
 385                 INIT_HLIST_NODE(&pidmap->jp_hash);
 386                 /*
 387                  * @pidmap might be reclaimed just after it is added into
 388                  * hash list, init @jp_refcount as 1 to make sure memory
 389                  * could be not freed during access.
 390                  */
 391                 atomic_set(&pidmap->jp_refcount, 1);
 392
 393                 /*
 394                  * Add the newly created map to the hash, on key collision we
 395                  * lost a racing addition and must destroy our newly allocated
 396                  * map.  The object which exists in the hash will be returned.
 397                  */
 398                 pidmap2 = cfs_hash_findadd_unique(jobid_hash, &pid,
 399                                                   &pidmap->jp_hash);
 400                 if (unlikely(pidmap != pidmap2)) {
 401                         CDEBUG(D_INFO, "jobid: duplicate found for PID=%u\n",
 402                                pid);
 403                         OBD_FREE_PTR(pidmap);
 404                         pidmap = pidmap2;
 405                 }
 406         }
 407
 408         /*
 409          * If pidmap is old (this is always true for new entries) refresh it.
 410          * If obd_jobid_var is not found, cache empty entry and try again
 411          * later, to avoid repeat lookups for PID if obd_jobid_var missing.
 412          */
 413         spin_lock(&pidmap->jp_lock);
 414         if (pidmap->jp_time + RESCAN_INTERVAL <= now) {
 415                 char env_jobid[LUSTRE_JOBID_SIZE] = "";
 416                 int env_len = sizeof(env_jobid);
 417
 418                 pidmap->jp_time = now;
 419
 420                 spin_unlock(&pidmap->jp_lock);
 421                 rc = jobid_get_from_environ(obd_jobid_var, env_jobid, &env_len);
 422
 423                 CDEBUG(D_INFO, "jobid: PID mapping established: %d->%s\n",
 424                        pidmap->jp_pid, env_jobid);
 425                 spin_lock(&pidmap->jp_lock);
 426                 if (!rc) {
 427                         pidmap->jp_joblen = env_len;
 428                         strlcpy(pidmap->jp_jobid, env_jobid,
 429                                 sizeof(pidmap->jp_jobid));
 430                         rc = 0;
 431                 } else if (rc == -ENOENT) {
 432                         /* It might have been deleted, clear out old entry */
 433                         pidmap->jp_joblen = 0;
 434                         pidmap->jp_jobid[0] = '\0';
 435                 }
 436         }
 437
 438         /*
 439          * Regardless of how pidmap was found, if it contains a valid entry
 440          * use that for now.  If there was a technical error (e.g. -ENOMEM)
 441          * use the old cached value until it can be looked up again properly.
 442          * If a cached missing entry was found, return -ENOENT.
 443          */
 444         if (pidmap->jp_joblen) {
 445                 strlcpy(jobid, pidmap->jp_jobid, joblen);
 446                 joblen = pidmap->jp_joblen;
 447                 rc = 0;
 448         } else if (!rc) {
 449                 rc = -ENOENT;
 450         }
 451         spin_unlock(&pidmap->jp_lock);
 452
 453         cfs_hash_put(jobid_hash, &pidmap->jp_hash);
 454
 455         EXIT;
 456 out:
 457         return rc < 0 ? rc : joblen;
 458 }
 459
 460 /*
 461  * jobid_interpret_string()
 462  *
 463  * Interpret the jobfmt string to expand specified fields, like coredumps do:
 464  *   %e = executable
 465  *   %g = gid
 466  *   %h = hostname
 467  *   %j = jobid from environment
 468  *   %p = pid
 469  *   %u = uid
 470  *
 471  * Unknown escape strings are dropped.  Other characters are copied through,
 472  * excluding whitespace (to avoid making jobid parsing difficult).
 473  *
 474  * Return: -EOVERFLOW if the expanded string does not fit within @joblen
 475  *         0 for success
 476  */
 477 static int jobid_interpret_string(const char *jobfmt, char *jobid,
 478                                   ssize_t joblen)
 479 {
 480         char c;
 481
 482         while ((c = *jobfmt++) && joblen > 1) {
 483                 char f;
 484                 int l;
 485
 486                 if (isspace(c)) /* Don't allow embedded spaces */
 487                         continue;
 488
 489                 if (c != '%') {
 490                         *jobid = c;
 491                         joblen--;
 492                         jobid++;
 493                         continue;
 494                 }
 495
 496                 switch ((f = *jobfmt++)) {
 497                 case 'e': /* executable name */
 498                         l = snprintf(jobid, joblen, "%s", current_comm());
 499                         break;
 500                 case 'g': /* group ID */
 501                         l = snprintf(jobid, joblen, "%u",
 502                                      from_kgid(&init_user_ns, current_fsgid()));
 503                         break;
 504                 case 'h': /* hostname */
 505                         l = snprintf(jobid, joblen, "%s",
 506                                      init_utsname()->nodename);
 507                         break;
 508                 case 'j': /* jobid stored in process environment */
 509                         l = jobid_get_from_cache(jobid, joblen);
 510                         if (l < 0)
 511                                 l = 0;
 512                         break;
 513                 case 'p': /* process ID */
 514                         l = snprintf(jobid, joblen, "%u", current_pid());
 515                         break;
 516                 case 'u': /* user ID */
 517                         l = snprintf(jobid, joblen, "%u",
 518                                      from_kuid(&init_user_ns, current_fsuid()));
 519                         break;
 520                 case '\0': /* '%' at end of format string */
 521                         l = 0;
 522                         goto out;
 523                 default: /* drop unknown %x format strings */
 524                         l = 0;
 525                         break;
 526                 }
 527                 jobid += l;
 528                 joblen -= l;
 529         }
 530         /*
 531          * This points at the end of the buffer, so long as jobid is always
 532          * incremented the same amount as joblen is decremented.
 533          */
 534 out:
 535         jobid[joblen - 1] = '\0';
 536
 537         return joblen < 0 ? -EOVERFLOW : 0;
 538 }
 539
 540 /*
 541  * Hash initialization, copied from server-side job stats bucket sizes
 542  */
 543 #define HASH_JOBID_BKT_BITS 5
 544 #define HASH_JOBID_CUR_BITS 7
 545 #define HASH_JOBID_MAX_BITS 12
 546
 547 int jobid_cache_init(void)
 548 {
 549         int rc = 0;
 550         ENTRY;
 551
 552         if (jobid_hash)
 553                 return 0;
 554
 555         spin_lock_init(&jobid_hash_lock);
 556         jobid_hash = cfs_hash_create("JOBID_HASH", HASH_JOBID_CUR_BITS,
 557                                      HASH_JOBID_MAX_BITS, HASH_JOBID_BKT_BITS,
 558                                      0, CFS_HASH_MIN_THETA, CFS_HASH_MAX_THETA,
 559                                      &jobid_hash_ops, CFS_HASH_DEFAULT);
 560         if (!jobid_hash) {
 561                 rc = -ENOMEM;
 562         } else {
 563                 rc = rhashtable_init(&session_jobids, &jobid_params);
 564                 if (rc) {
 565                         cfs_hash_putref(jobid_hash);
 566                         jobid_hash = NULL;
 567                 }
 568         }
 569
 570         RETURN(rc);
 571 }
 572 EXPORT_SYMBOL(jobid_cache_init);
 573
 574 void jobid_cache_fini(void)
 575 {
 576         struct cfs_hash *tmp_hash;
 577         ENTRY;
 578
 579         spin_lock(&jobid_hash_lock);
 580         tmp_hash = jobid_hash;
 581         jobid_hash = NULL;
 582         spin_unlock(&jobid_hash_lock);
 583
 584         cancel_delayed_work_sync(&jobid_prune_work);
 585
 586         if (tmp_hash != NULL) {
 587                 cfs_hash_cond_del(tmp_hash, jobid_should_free_item, NULL);
 588                 cfs_hash_putref(tmp_hash);
 589
 590                 rhashtable_free_and_destroy(&session_jobids, jobid_free, NULL);
 591         }
 592
 593
 594         EXIT;
 595 }
 596 EXPORT_SYMBOL(jobid_cache_fini);
 597
 598 /*
 599  * Hash operations for pid<->jobid
 600  */
 601 static unsigned jobid_hashfn(struct cfs_hash *hs, const void *key,
 602                              unsigned mask)
 603 {
 604         return cfs_hash_djb2_hash(key, sizeof(pid_t), mask);
 605 }
 606
 607 static void *jobid_key(struct hlist_node *hnode)
 608 {
 609         struct jobid_pid_map *pidmap;
 610
 611         pidmap = hlist_entry(hnode, struct jobid_pid_map, jp_hash);
 612         return &pidmap->jp_pid;
 613 }
 614
 615 static int jobid_keycmp(const void *key, struct hlist_node *hnode)
 616 {
 617         const pid_t *pid_key1;
 618         const pid_t *pid_key2;
 619
 620         LASSERT(key != NULL);
 621         pid_key1 = (pid_t *)key;
 622         pid_key2 = (pid_t *)jobid_key(hnode);
 623
 624         return *pid_key1 == *pid_key2;
 625 }
 626
 627 static void *jobid_object(struct hlist_node *hnode)
 628 {
 629         return hlist_entry(hnode, struct jobid_pid_map, jp_hash);
 630 }
 631
 632 static void jobid_get(struct cfs_hash *hs, struct hlist_node *hnode)
 633 {
 634         struct jobid_pid_map *pidmap;
 635
 636         pidmap = hlist_entry(hnode, struct jobid_pid_map, jp_hash);
 637
 638         atomic_inc(&pidmap->jp_refcount);
 639 }
 640
 641 static void jobid_put_locked(struct cfs_hash *hs, struct hlist_node *hnode)
 642 {
 643         struct jobid_pid_map *pidmap;
 644
 645         if (hnode == NULL)
 646                 return;
 647
 648         pidmap = hlist_entry(hnode, struct jobid_pid_map, jp_hash);
 649         LASSERT(atomic_read(&pidmap->jp_refcount) > 0);
 650         if (atomic_dec_and_test(&pidmap->jp_refcount)) {
 651                 CDEBUG(D_INFO, "Freeing: %d->%s\n",
 652                        pidmap->jp_pid, pidmap->jp_jobid);
 653
 654                 OBD_FREE_PTR(pidmap);
 655         }
 656 }
 657
 658 static struct cfs_hash_ops jobid_hash_ops = {
 659         .hs_hash        = jobid_hashfn,
 660         .hs_keycmp      = jobid_keycmp,
 661         .hs_key         = jobid_key,
 662         .hs_object      = jobid_object,
 663         .hs_get         = jobid_get,
 664         .hs_put         = jobid_put_locked,
 665         .hs_put_locked  = jobid_put_locked,
 666 };
 667
 668 /**
 669  * Generate the job identifier string for this process for tracking purposes.
 670  *
 671  * Fill in @jobid string based on the value of obd_jobid_var:
 672  * JOBSTATS_DISABLE:      none
 673  * JOBSTATS_NODELOCAL:    content of obd_jobid_name (jobid_interpret_string())
 674  * JOBSTATS_PROCNAME_UID: process name/UID
 675  * JOBSTATS_SESSION       per-session value set by
 676  *                            /sys/fs/lustre/jobid_this_session
 677  * anything else:         look up obd_jobid_var in the processes environment
 678  *
 679  * Return -ve error number, 0 on success.
 680  */
 681 int lustre_get_jobid(char *jobid, size_t joblen)
 682 {
 683         int rc = 0;
 684         ENTRY;
 685
 686         if (unlikely(joblen < 2)) {
 687                 if (joblen == 1)
 688                         jobid[0] = '\0';
 689                 RETURN(-EINVAL);
 690         }
 691
 692         if (strcmp(obd_jobid_var, JOBSTATS_DISABLE) == 0) {
 693                 /* Jobstats isn't enabled */
 694                 memset(jobid, 0, joblen);
 695         } else if (strcmp(obd_jobid_var, JOBSTATS_NODELOCAL) == 0) {
 696                 /* Whole node dedicated to single job */
 697                 rc = jobid_interpret_string(obd_jobid_name, jobid, joblen);
 698         } else if (strcmp(obd_jobid_var, JOBSTATS_PROCNAME_UID) == 0) {
 699                 rc = jobid_interpret_string("%e.%u", jobid, joblen);
 700         } else if (strcmp(obd_jobid_var, JOBSTATS_SESSION) == 0) {
 701                 char *jid;
 702
 703                 rcu_read_lock();
 704                 jid = jobid_current();
 705                 if (jid)
 706                         strlcpy(jobid, jid, sizeof(jobid));
 707                 rcu_read_unlock();
 708         } else if (jobid_name_is_valid(current_comm())) {
 709                 /*
 710                  * obd_jobid_var holds the jobid environment variable name.
 711                  * Skip initial check if obd_jobid_name already uses "%j",
 712                  * otherwise try just "%j" first, then fall back to whatever
 713                  * is in obd_jobid_name if obd_jobid_var is not found.
 714                  */
 715                 rc = -EAGAIN;
 716                 if (!strnstr(obd_jobid_name, "%j", joblen))
 717                         rc = jobid_get_from_cache(jobid, joblen);
 718
 719                 /* fall back to jobid_node if jobid_var not in environment */
 720                 if (rc < 0) {
 721                         int rc2 = jobid_interpret_string(obd_jobid_name,
 722                                                          jobid, joblen);
 723                         if (!rc2)
 724                                 rc = 0;
 725                 }
 726         }
 727
 728         RETURN(rc);
 729 }
 730 EXPORT_SYMBOL(lustre_get_jobid);
 731
 732 /*
 733  * lustre_jobid_clear
 734  *
 735  * Search cache for JobID given by @find_jobid.
 736  * If any entries in the hash table match the value, they are removed
 737  */
 738 void lustre_jobid_clear(const char *find_jobid)
 739 {
 740         char jobid[LUSTRE_JOBID_SIZE];
 741         char *end;
 742
 743         if (jobid_hash == NULL)
 744                 return;
 745
 746         strlcpy(jobid, find_jobid, sizeof(jobid));
 747         /* trim \n off the end of the incoming jobid */
 748         end = strchr(jobid, '\n');
 749         if (end && *end == '\n')
 750                 *end = '\0';
 751
 752         CDEBUG(D_INFO, "Clearing Jobid: %s\n", jobid);
 753         cfs_hash_cond_del(jobid_hash, jobid_should_free_item, jobid);
 754
 755         CDEBUG(D_INFO, "%d items remain in jobID table\n",
 756                atomic_read(&jobid_hash->hs_count));
 757 }