kernel/drivers/staging/lustre/lustre/lov/lov_pool.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 [sun.com URL with a
  18  * copy of GPLv2].
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2012, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * lustre/lov/lov_pool.c
  37  *
  38  * OST pool methods
  39  *
  40  * Author: Jacques-Charles LAFOUCRIERE <jc.lafoucriere@cea.fr>
  41  * Author: Alex Lyashkov <Alexey.Lyashkov@Sun.COM>
  42  * Author: Nathaniel Rutman <Nathan.Rutman@Sun.COM>
  43  */
  44
  45 #define DEBUG_SUBSYSTEM S_LOV
  46
  47 #include "../../include/linux/libcfs/libcfs.h"
  48
  49 #include "../include/obd.h"
  50 #include "lov_internal.h"
  51
  52 #define pool_tgt(_p, _i) \
  53                 _p->pool_lobd->u.lov.lov_tgts[_p->pool_obds.op_array[_i]]
  54
  55 static void lov_pool_getref(struct pool_desc *pool)
  56 {
  57         CDEBUG(D_INFO, "pool %p\n", pool);
  58         atomic_inc(&pool->pool_refcount);
  59 }
  60
  61 void lov_pool_putref(struct pool_desc *pool)
  62 {
  63         CDEBUG(D_INFO, "pool %p\n", pool);
  64         if (atomic_dec_and_test(&pool->pool_refcount)) {
  65                 LASSERT(hlist_unhashed(&pool->pool_hash));
  66                 LASSERT(list_empty(&pool->pool_list));
  67                 LASSERT(pool->pool_proc_entry == NULL);
  68                 lov_ost_pool_free(&(pool->pool_rr.lqr_pool));
  69                 lov_ost_pool_free(&(pool->pool_obds));
  70                 OBD_FREE_PTR(pool);
  71         }
  72 }
  73
  74 static void lov_pool_putref_locked(struct pool_desc *pool)
  75 {
  76         CDEBUG(D_INFO, "pool %p\n", pool);
  77         LASSERT(atomic_read(&pool->pool_refcount) > 1);
  78
  79         atomic_dec(&pool->pool_refcount);
  80 }
  81
  82 /*
  83  * hash function using a Rotating Hash algorithm
  84  * Knuth, D. The Art of Computer Programming,
  85  * Volume 3: Sorting and Searching,
  86  * Chapter 6.4.
  87  * Addison Wesley, 1973
  88  */
  89 static __u32 pool_hashfn(struct cfs_hash *hash_body, const void *key, unsigned mask)
  90 {
  91         int i;
  92         __u32 result;
  93         char *poolname;
  94
  95         result = 0;
  96         poolname = (char *)key;
  97         for (i = 0; i < LOV_MAXPOOLNAME; i++) {
  98                 if (poolname[i] == '\0')
  99                         break;
 100                 result = (result << 4)^(result >> 28) ^  poolname[i];
 101         }
 102         return (result % mask);
 103 }
 104
 105 static void *pool_key(struct hlist_node *hnode)
 106 {
 107         struct pool_desc *pool;
 108
 109         pool = hlist_entry(hnode, struct pool_desc, pool_hash);
 110         return pool->pool_name;
 111 }
 112
 113 static int pool_hashkey_keycmp(const void *key, struct hlist_node *compared_hnode)
 114 {
 115         char *pool_name;
 116         struct pool_desc *pool;
 117
 118         pool_name = (char *)key;
 119         pool = hlist_entry(compared_hnode, struct pool_desc, pool_hash);
 120         return !strncmp(pool_name, pool->pool_name, LOV_MAXPOOLNAME);
 121 }
 122
 123 static void *pool_hashobject(struct hlist_node *hnode)
 124 {
 125         return hlist_entry(hnode, struct pool_desc, pool_hash);
 126 }
 127
 128 static void pool_hashrefcount_get(struct cfs_hash *hs, struct hlist_node *hnode)
 129 {
 130         struct pool_desc *pool;
 131
 132         pool = hlist_entry(hnode, struct pool_desc, pool_hash);
 133         lov_pool_getref(pool);
 134 }
 135
 136 static void pool_hashrefcount_put_locked(struct cfs_hash *hs,
 137                                          struct hlist_node *hnode)
 138 {
 139         struct pool_desc *pool;
 140
 141         pool = hlist_entry(hnode, struct pool_desc, pool_hash);
 142         lov_pool_putref_locked(pool);
 143 }
 144
 145 cfs_hash_ops_t pool_hash_operations = {
 146         .hs_hash        = pool_hashfn,
 147         .hs_key  = pool_key,
 148         .hs_keycmp      = pool_hashkey_keycmp,
 149         .hs_object      = pool_hashobject,
 150         .hs_get  = pool_hashrefcount_get,
 151         .hs_put_locked  = pool_hashrefcount_put_locked,
 152
 153 };
 154
 155 #if defined (CONFIG_PROC_FS)
 156 /* ifdef needed for liblustre support */
 157 /*
 158  * pool /proc seq_file methods
 159  */
 160 /*
 161  * iterator is used to go through the target pool entries
 162  * index is the current entry index in the lp_array[] array
 163  * index >= pos returned to the seq_file interface
 164  * pos is from 0 to (pool->pool_obds.op_count - 1)
 165  */
 166 #define POOL_IT_MAGIC 0xB001CEA0
 167 struct pool_iterator {
 168         int magic;
 169         struct pool_desc *pool;
 170         int idx;        /* from 0 to pool_tgt_size - 1 */
 171 };
 172
 173 static void *pool_proc_next(struct seq_file *s, void *v, loff_t *pos)
 174 {
 175         struct pool_iterator *iter = (struct pool_iterator *)s->private;
 176         int prev_idx;
 177
 178         LASSERTF(iter->magic == POOL_IT_MAGIC, "%08X", iter->magic);
 179
 180         /* test if end of file */
 181         if (*pos >= pool_tgt_count(iter->pool))
 182                 return NULL;
 183
 184         /* iterate to find a non empty entry */
 185         prev_idx = iter->idx;
 186         down_read(&pool_tgt_rw_sem(iter->pool));
 187         iter->idx++;
 188         if (iter->idx == pool_tgt_count(iter->pool)) {
 189                 iter->idx = prev_idx; /* we stay on the last entry */
 190                 up_read(&pool_tgt_rw_sem(iter->pool));
 191                 return NULL;
 192         }
 193         up_read(&pool_tgt_rw_sem(iter->pool));
 194         (*pos)++;
 195         /* return != NULL to continue */
 196         return iter;
 197 }
 198
 199 static void *pool_proc_start(struct seq_file *s, loff_t *pos)
 200 {
 201         struct pool_desc *pool = (struct pool_desc *)s->private;
 202         struct pool_iterator *iter;
 203
 204         lov_pool_getref(pool);
 205         if ((pool_tgt_count(pool) == 0) ||
 206             (*pos >= pool_tgt_count(pool))) {
 207                 /* iter is not created, so stop() has no way to
 208                  * find pool to dec ref */
 209                 lov_pool_putref(pool);
 210                 return NULL;
 211         }
 212
 213         OBD_ALLOC_PTR(iter);
 214         if (!iter)
 215                 return ERR_PTR(-ENOMEM);
 216         iter->magic = POOL_IT_MAGIC;
 217         iter->pool = pool;
 218         iter->idx = 0;
 219
 220         /* we use seq_file private field to memorized iterator so
 221          * we can free it at stop() */
 222         /* /!\ do not forget to restore it to pool before freeing it */
 223         s->private = iter;
 224         if (*pos > 0) {
 225                 loff_t i;
 226                 void *ptr;
 227
 228                 i = 0;
 229                 do {
 230                      ptr = pool_proc_next(s, &iter, &i);
 231                 } while ((i < *pos) && (ptr != NULL));
 232                 return ptr;
 233         }
 234         return iter;
 235 }
 236
 237 static void pool_proc_stop(struct seq_file *s, void *v)
 238 {
 239         struct pool_iterator *iter = (struct pool_iterator *)s->private;
 240
 241         /* in some cases stop() method is called 2 times, without
 242          * calling start() method (see seq_read() from fs/seq_file.c)
 243          * we have to free only if s->private is an iterator */
 244         if ((iter) && (iter->magic == POOL_IT_MAGIC)) {
 245                 /* we restore s->private so next call to pool_proc_start()
 246                  * will work */
 247                 s->private = iter->pool;
 248                 lov_pool_putref(iter->pool);
 249                 OBD_FREE_PTR(iter);
 250         }
 251         return;
 252 }
 253
 254 static int pool_proc_show(struct seq_file *s, void *v)
 255 {
 256         struct pool_iterator *iter = (struct pool_iterator *)v;
 257         struct lov_tgt_desc *tgt;
 258
 259         LASSERTF(iter->magic == POOL_IT_MAGIC, "%08X", iter->magic);
 260         LASSERT(iter->pool != NULL);
 261         LASSERT(iter->idx <= pool_tgt_count(iter->pool));
 262
 263         down_read(&pool_tgt_rw_sem(iter->pool));
 264         tgt = pool_tgt(iter->pool, iter->idx);
 265         up_read(&pool_tgt_rw_sem(iter->pool));
 266         if (tgt)
 267                 seq_printf(s, "%s\n", obd_uuid2str(&(tgt->ltd_uuid)));
 268
 269         return 0;
 270 }
 271
 272 static struct seq_operations pool_proc_ops = {
 273         .start    = pool_proc_start,
 274         .next      = pool_proc_next,
 275         .stop      = pool_proc_stop,
 276         .show      = pool_proc_show,
 277 };
 278
 279 static int pool_proc_open(struct inode *inode, struct file *file)
 280 {
 281         int rc;
 282
 283         rc = seq_open(file, &pool_proc_ops);
 284         if (!rc) {
 285                 struct seq_file *s = file->private_data;
 286                 s->private = PDE_DATA(inode);
 287         }
 288         return rc;
 289 }
 290
 291 static struct file_operations pool_proc_operations = {
 292         .open      = pool_proc_open,
 293         .read      = seq_read,
 294         .llseek  = seq_lseek,
 295         .release        = seq_release,
 296 };
 297 #endif /* CONFIG_PROC_FS */
 298
 299 void lov_dump_pool(int level, struct pool_desc *pool)
 300 {
 301         int i;
 302
 303         lov_pool_getref(pool);
 304
 305         CDEBUG(level, "pool "LOV_POOLNAMEF" has %d members\n",
 306                pool->pool_name, pool->pool_obds.op_count);
 307         down_read(&pool_tgt_rw_sem(pool));
 308
 309         for (i = 0; i < pool_tgt_count(pool) ; i++) {
 310                 if (!pool_tgt(pool, i) || !(pool_tgt(pool, i))->ltd_exp)
 311                         continue;
 312                 CDEBUG(level, "pool "LOV_POOLNAMEF"[%d] = %s\n",
 313                        pool->pool_name, i,
 314                        obd_uuid2str(&((pool_tgt(pool, i))->ltd_uuid)));
 315         }
 316
 317         up_read(&pool_tgt_rw_sem(pool));
 318         lov_pool_putref(pool);
 319 }
 320
 321 #define LOV_POOL_INIT_COUNT 2
 322 int lov_ost_pool_init(struct ost_pool *op, unsigned int count)
 323 {
 324         if (count == 0)
 325                 count = LOV_POOL_INIT_COUNT;
 326         op->op_array = NULL;
 327         op->op_count = 0;
 328         init_rwsem(&op->op_rw_sem);
 329         op->op_size = count;
 330         OBD_ALLOC(op->op_array, op->op_size * sizeof(op->op_array[0]));
 331         if (op->op_array == NULL) {
 332                 op->op_size = 0;
 333                 return -ENOMEM;
 334         }
 335         return 0;
 336 }
 337
 338 /* Caller must hold write op_rwlock */
 339 int lov_ost_pool_extend(struct ost_pool *op, unsigned int min_count)
 340 {
 341         __u32 *new;
 342         int new_size;
 343
 344         LASSERT(min_count != 0);
 345
 346         if (op->op_count < op->op_size)
 347                 return 0;
 348
 349         new_size = max(min_count, 2 * op->op_size);
 350         OBD_ALLOC(new, new_size * sizeof(op->op_array[0]));
 351         if (new == NULL)
 352                 return -ENOMEM;
 353
 354         /* copy old array to new one */
 355         memcpy(new, op->op_array, op->op_size * sizeof(op->op_array[0]));
 356         OBD_FREE(op->op_array, op->op_size * sizeof(op->op_array[0]));
 357         op->op_array = new;
 358         op->op_size = new_size;
 359         return 0;
 360 }
 361
 362 int lov_ost_pool_add(struct ost_pool *op, __u32 idx, unsigned int min_count)
 363 {
 364         int rc = 0, i;
 365
 366         down_write(&op->op_rw_sem);
 367
 368         rc = lov_ost_pool_extend(op, min_count);
 369         if (rc)
 370                 goto out;
 371
 372         /* search ost in pool array */
 373         for (i = 0; i < op->op_count; i++) {
 374                 if (op->op_array[i] == idx) {
 375                         rc = -EEXIST;
 376                         goto out;
 377                 }
 378         }
 379         /* ost not found we add it */
 380         op->op_array[op->op_count] = idx;
 381         op->op_count++;
 382 out:
 383         up_write(&op->op_rw_sem);
 384         return rc;
 385 }
 386
 387 int lov_ost_pool_remove(struct ost_pool *op, __u32 idx)
 388 {
 389         int i;
 390
 391         down_write(&op->op_rw_sem);
 392
 393         for (i = 0; i < op->op_count; i++) {
 394                 if (op->op_array[i] == idx) {
 395                         memmove(&op->op_array[i], &op->op_array[i + 1],
 396                                 (op->op_count - i - 1) * sizeof(op->op_array[0]));
 397                         op->op_count--;
 398                         up_write(&op->op_rw_sem);
 399                         return 0;
 400                 }
 401         }
 402
 403         up_write(&op->op_rw_sem);
 404         return -EINVAL;
 405 }
 406
 407 int lov_ost_pool_free(struct ost_pool *op)
 408 {
 409         if (op->op_size == 0)
 410                 return 0;
 411
 412         down_write(&op->op_rw_sem);
 413
 414         OBD_FREE(op->op_array, op->op_size * sizeof(op->op_array[0]));
 415         op->op_array = NULL;
 416         op->op_count = 0;
 417         op->op_size = 0;
 418
 419         up_write(&op->op_rw_sem);
 420         return 0;
 421 }
 422
 423
 424 int lov_pool_new(struct obd_device *obd, char *poolname)
 425 {
 426         struct lov_obd *lov;
 427         struct pool_desc *new_pool;
 428         int rc;
 429
 430         lov = &(obd->u.lov);
 431
 432         if (strlen(poolname) > LOV_MAXPOOLNAME)
 433                 return -ENAMETOOLONG;
 434
 435         OBD_ALLOC_PTR(new_pool);
 436         if (new_pool == NULL)
 437                 return -ENOMEM;
 438
 439         strncpy(new_pool->pool_name, poolname, LOV_MAXPOOLNAME);
 440         new_pool->pool_name[LOV_MAXPOOLNAME] = '\0';
 441         new_pool->pool_lobd = obd;
 442         /* ref count init to 1 because when created a pool is always used
 443          * up to deletion
 444          */
 445         atomic_set(&new_pool->pool_refcount, 1);
 446         rc = lov_ost_pool_init(&new_pool->pool_obds, 0);
 447         if (rc)
 448                 goto out_err;
 449
 450         memset(&(new_pool->pool_rr), 0, sizeof(struct lov_qos_rr));
 451         rc = lov_ost_pool_init(&new_pool->pool_rr.lqr_pool, 0);
 452         if (rc)
 453                 goto out_free_pool_obds;
 454
 455         INIT_HLIST_NODE(&new_pool->pool_hash);
 456
 457 #if defined (CONFIG_PROC_FS)
 458         /* we need this assert seq_file is not implemented for liblustre */
 459         /* get ref for /proc file */
 460         lov_pool_getref(new_pool);
 461         new_pool->pool_proc_entry = lprocfs_add_simple(lov->lov_pool_proc_entry,
 462                                                        poolname, new_pool,
 463                                                        &pool_proc_operations);
 464         if (IS_ERR(new_pool->pool_proc_entry)) {
 465                 CWARN("Cannot add proc pool entry "LOV_POOLNAMEF"\n", poolname);
 466                 new_pool->pool_proc_entry = NULL;
 467                 lov_pool_putref(new_pool);
 468         }
 469         CDEBUG(D_INFO, "pool %p - proc %p\n", new_pool, new_pool->pool_proc_entry);
 470 #endif
 471
 472         spin_lock(&obd->obd_dev_lock);
 473         list_add_tail(&new_pool->pool_list, &lov->lov_pool_list);
 474         lov->lov_pool_count++;
 475         spin_unlock(&obd->obd_dev_lock);
 476
 477         /* add to find only when it fully ready  */
 478         rc = cfs_hash_add_unique(lov->lov_pools_hash_body, poolname,
 479                                  &new_pool->pool_hash);
 480         if (rc) {
 481                 rc = -EEXIST;
 482                 goto out_err;
 483         }
 484
 485         CDEBUG(D_CONFIG, LOV_POOLNAMEF" is pool #%d\n",
 486                poolname, lov->lov_pool_count);
 487
 488         return 0;
 489
 490 out_err:
 491         spin_lock(&obd->obd_dev_lock);
 492         list_del_init(&new_pool->pool_list);
 493         lov->lov_pool_count--;
 494         spin_unlock(&obd->obd_dev_lock);
 495
 496         lprocfs_remove(&new_pool->pool_proc_entry);
 497
 498         lov_ost_pool_free(&new_pool->pool_rr.lqr_pool);
 499 out_free_pool_obds:
 500         lov_ost_pool_free(&new_pool->pool_obds);
 501         OBD_FREE_PTR(new_pool);
 502         return rc;
 503 }
 504
 505 int lov_pool_del(struct obd_device *obd, char *poolname)
 506 {
 507         struct lov_obd *lov;
 508         struct pool_desc *pool;
 509
 510         lov = &(obd->u.lov);
 511
 512         /* lookup and kill hash reference */
 513         pool = cfs_hash_del_key(lov->lov_pools_hash_body, poolname);
 514         if (pool == NULL)
 515                 return -ENOENT;
 516
 517         if (pool->pool_proc_entry != NULL) {
 518                 CDEBUG(D_INFO, "proc entry %p\n", pool->pool_proc_entry);
 519                 lprocfs_remove(&pool->pool_proc_entry);
 520                 lov_pool_putref(pool);
 521         }
 522
 523         spin_lock(&obd->obd_dev_lock);
 524         list_del_init(&pool->pool_list);
 525         lov->lov_pool_count--;
 526         spin_unlock(&obd->obd_dev_lock);
 527
 528         /* release last reference */
 529         lov_pool_putref(pool);
 530
 531         return 0;
 532 }
 533
 534
 535 int lov_pool_add(struct obd_device *obd, char *poolname, char *ostname)
 536 {
 537         struct obd_uuid ost_uuid;
 538         struct lov_obd *lov;
 539         struct pool_desc *pool;
 540         unsigned int lov_idx;
 541         int rc;
 542
 543         lov = &(obd->u.lov);
 544
 545         pool = cfs_hash_lookup(lov->lov_pools_hash_body, poolname);
 546         if (pool == NULL)
 547                 return -ENOENT;
 548
 549         obd_str2uuid(&ost_uuid, ostname);
 550
 551
 552         /* search ost in lov array */
 553         obd_getref(obd);
 554         for (lov_idx = 0; lov_idx < lov->desc.ld_tgt_count; lov_idx++) {
 555                 if (!lov->lov_tgts[lov_idx])
 556                         continue;
 557                 if (obd_uuid_equals(&ost_uuid,
 558                                     &(lov->lov_tgts[lov_idx]->ltd_uuid)))
 559                         break;
 560         }
 561         /* test if ost found in lov */
 562         if (lov_idx == lov->desc.ld_tgt_count) {
 563                 rc = -EINVAL;
 564                 goto out;
 565         }
 566
 567         rc = lov_ost_pool_add(&pool->pool_obds, lov_idx, lov->lov_tgt_size);
 568         if (rc)
 569                 goto out;
 570
 571         pool->pool_rr.lqr_dirty = 1;
 572
 573         CDEBUG(D_CONFIG, "Added %s to "LOV_POOLNAMEF" as member %d\n",
 574                ostname, poolname,  pool_tgt_count(pool));
 575
 576 out:
 577         obd_putref(obd);
 578         lov_pool_putref(pool);
 579         return rc;
 580 }
 581
 582 int lov_pool_remove(struct obd_device *obd, char *poolname, char *ostname)
 583 {
 584         struct obd_uuid ost_uuid;
 585         struct lov_obd *lov;
 586         struct pool_desc *pool;
 587         unsigned int lov_idx;
 588         int rc = 0;
 589
 590         lov = &(obd->u.lov);
 591
 592         pool = cfs_hash_lookup(lov->lov_pools_hash_body, poolname);
 593         if (pool == NULL)
 594                 return -ENOENT;
 595
 596         obd_str2uuid(&ost_uuid, ostname);
 597
 598         obd_getref(obd);
 599         /* search ost in lov array, to get index */
 600         for (lov_idx = 0; lov_idx < lov->desc.ld_tgt_count; lov_idx++) {
 601                 if (!lov->lov_tgts[lov_idx])
 602                         continue;
 603
 604                 if (obd_uuid_equals(&ost_uuid,
 605                                     &(lov->lov_tgts[lov_idx]->ltd_uuid)))
 606                         break;
 607         }
 608
 609         /* test if ost found in lov */
 610         if (lov_idx == lov->desc.ld_tgt_count) {
 611                 rc = -EINVAL;
 612                 goto out;
 613         }
 614
 615         lov_ost_pool_remove(&pool->pool_obds, lov_idx);
 616
 617         pool->pool_rr.lqr_dirty = 1;
 618
 619         CDEBUG(D_CONFIG, "%s removed from "LOV_POOLNAMEF"\n", ostname,
 620                poolname);
 621
 622 out:
 623         obd_putref(obd);
 624         lov_pool_putref(pool);
 625         return rc;
 626 }
 627
 628 int lov_check_index_in_pool(__u32 idx, struct pool_desc *pool)
 629 {
 630         int i, rc;
 631
 632         /* caller may no have a ref on pool if it got the pool
 633          * without calling lov_find_pool() (e.g. go through the lov pool
 634          * list)
 635          */
 636         lov_pool_getref(pool);
 637
 638         down_read(&pool_tgt_rw_sem(pool));
 639
 640         for (i = 0; i < pool_tgt_count(pool); i++) {
 641                 if (pool_tgt_array(pool)[i] == idx) {
 642                         rc = 0;
 643                         goto out;
 644                 }
 645         }
 646         rc = -ENOENT;
 647 out:
 648         up_read(&pool_tgt_rw_sem(pool));
 649
 650         lov_pool_putref(pool);
 651         return rc;
 652 }
 653
 654 struct pool_desc *lov_find_pool(struct lov_obd *lov, char *poolname)
 655 {
 656         struct pool_desc *pool;
 657
 658         pool = NULL;
 659         if (poolname[0] != '\0') {
 660                 pool = cfs_hash_lookup(lov->lov_pools_hash_body, poolname);
 661                 if (pool == NULL)
 662                         CWARN("Request for an unknown pool ("LOV_POOLNAMEF")\n",
 663                               poolname);
 664                 if ((pool != NULL) && (pool_tgt_count(pool) == 0)) {
 665                         CWARN("Request for an empty pool ("LOV_POOLNAMEF")\n",
 666                                poolname);
 667                         /* pool is ignored, so we remove ref on it */
 668                         lov_pool_putref(pool);
 669                         pool = NULL;
 670                 }
 671         }
 672         return pool;
 673 }