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 #ifdef __KERNEL__
  48 #include <libcfs/libcfs.h>
  49 #else
  50 #include <liblustre.h>
  51 #endif
  52
  53 #include <obd.h>
  54 #include "lov_internal.h"
  55
  56 #define pool_tgt(_p, _i) \
  57                 _p->pool_lobd->u.lov.lov_tgts[_p->pool_obds.op_array[_i]]
  58
  59 static void lov_pool_getref(struct pool_desc *pool)
  60 {
  61         CDEBUG(D_INFO, "pool %p\n", pool);
  62         cfs_atomic_inc(&pool->pool_refcount);
  63 }
  64
  65 void lov_pool_putref(struct pool_desc *pool)
  66 {
  67         CDEBUG(D_INFO, "pool %p\n", pool);
  68         if (cfs_atomic_dec_and_test(&pool->pool_refcount)) {
  69                 LASSERT(cfs_hlist_unhashed(&pool->pool_hash));
  70                 LASSERT(cfs_list_empty(&pool->pool_list));
  71                 LASSERT(pool->pool_proc_entry == NULL);
  72                 lov_ost_pool_free(&(pool->pool_obds));
  73                 OBD_FREE_PTR(pool);
  74                 EXIT;
  75         }
  76 }
  77
  78 void lov_pool_putref_locked(struct pool_desc *pool)
  79 {
  80         CDEBUG(D_INFO, "pool %p\n", pool);
  81         LASSERT(cfs_atomic_read(&pool->pool_refcount) > 1);
  82
  83         cfs_atomic_dec(&pool->pool_refcount);
  84 }
  85
  86 /*
  87  * hash function using a Rotating Hash algorithm
  88  * Knuth, D. The Art of Computer Programming,
  89  * Volume 3: Sorting and Searching,
  90  * Chapter 6.4.
  91  * Addison Wesley, 1973
  92  */
  93 static __u32 pool_hashfn(cfs_hash_t *hash_body, const void *key, unsigned mask)
  94 {
  95         int i;
  96         __u32 result;
  97         char *poolname;
  98
  99         result = 0;
 100         poolname = (char *)key;
 101         for (i = 0; i < LOV_MAXPOOLNAME; i++) {
 102                 if (poolname[i] == '\0')
 103                         break;
 104                 result = (result << 4)^(result >> 28) ^  poolname[i];
 105         }
 106         return (result % mask);
 107 }
 108
 109 static void *pool_key(cfs_hlist_node_t *hnode)
 110 {
 111         struct pool_desc *pool;
 112
 113         pool = cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 114         return (pool->pool_name);
 115 }
 116
 117 static int pool_hashkey_keycmp(const void *key, cfs_hlist_node_t *compared_hnode)
 118 {
 119         char *pool_name;
 120         struct pool_desc *pool;
 121
 122         pool_name = (char *)key;
 123         pool = cfs_hlist_entry(compared_hnode, struct pool_desc, pool_hash);
 124         return !strncmp(pool_name, pool->pool_name, LOV_MAXPOOLNAME);
 125 }
 126
 127 static void *pool_hashobject(cfs_hlist_node_t *hnode)
 128 {
 129         return cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 130 }
 131
 132 static void pool_hashrefcount_get(cfs_hash_t *hs, cfs_hlist_node_t *hnode)
 133 {
 134         struct pool_desc *pool;
 135
 136         pool = cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 137         lov_pool_getref(pool);
 138 }
 139
 140 static void pool_hashrefcount_put_locked(cfs_hash_t *hs,
 141                                          cfs_hlist_node_t *hnode)
 142 {
 143         struct pool_desc *pool;
 144
 145         pool = cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 146         lov_pool_putref_locked(pool);
 147 }
 148
 149 cfs_hash_ops_t pool_hash_operations = {
 150         .hs_hash        = pool_hashfn,
 151         .hs_key         = pool_key,
 152         .hs_keycmp      = pool_hashkey_keycmp,
 153         .hs_object      = pool_hashobject,
 154         .hs_get         = pool_hashrefcount_get,
 155         .hs_put_locked  = pool_hashrefcount_put_locked,
 156
 157 };
 158
 159 #ifdef LPROCFS
 160 /* ifdef needed for liblustre support */
 161 /*
 162  * pool /proc seq_file methods
 163  */
 164 /*
 165  * iterator is used to go through the target pool entries
 166  * index is the current entry index in the lp_array[] array
 167  * index >= pos returned to the seq_file interface
 168  * pos is from 0 to (pool->pool_obds.op_count - 1)
 169  */
 170 #define POOL_IT_MAGIC 0xB001CEA0
 171 struct pool_iterator {
 172         int magic;
 173         struct pool_desc *pool;
 174         int idx;        /* from 0 to pool_tgt_size - 1 */
 175 };
 176
 177 static void *pool_proc_next(struct seq_file *s, void *v, loff_t *pos)
 178 {
 179         struct pool_iterator *iter = (struct pool_iterator *)s->private;
 180         int prev_idx;
 181
 182         LASSERTF(iter->magic == POOL_IT_MAGIC, "%08X", iter->magic);
 183
 184         /* test if end of file */
 185         if (*pos >= pool_tgt_count(iter->pool))
 186                 return NULL;
 187
 188         /* iterate to find a non empty entry */
 189         prev_idx = iter->idx;
 190         down_read(&pool_tgt_rw_sem(iter->pool));
 191         iter->idx++;
 192         if (iter->idx == pool_tgt_count(iter->pool)) {
 193                 iter->idx = prev_idx; /* we stay on the last entry */
 194                 up_read(&pool_tgt_rw_sem(iter->pool));
 195                 return NULL;
 196         }
 197         up_read(&pool_tgt_rw_sem(iter->pool));
 198         (*pos)++;
 199         /* return != NULL to continue */
 200         return iter;
 201 }
 202
 203 static void *pool_proc_start(struct seq_file *s, loff_t *pos)
 204 {
 205         struct pool_desc *pool = (struct pool_desc *)s->private;
 206         struct pool_iterator *iter;
 207
 208         lov_pool_getref(pool);
 209         if ((pool_tgt_count(pool) == 0) ||
 210             (*pos >= pool_tgt_count(pool))) {
 211                 /* iter is not created, so stop() has no way to
 212                  * find pool to dec ref */
 213                 lov_pool_putref(pool);
 214                 return NULL;
 215         }
 216
 217         OBD_ALLOC_PTR(iter);
 218         if (!iter)
 219                 return ERR_PTR(-ENOMEM);
 220         iter->magic = POOL_IT_MAGIC;
 221         iter->pool = pool;
 222         iter->idx = 0;
 223
 224         /* we use seq_file private field to memorized iterator so
 225          * we can free it at stop() */
 226         /* /!\ do not forget to restore it to pool before freeing it */
 227         s->private = iter;
 228         if (*pos > 0) {
 229                 loff_t i;
 230                 void *ptr;
 231
 232                 i = 0;
 233                 do {
 234                      ptr = pool_proc_next(s, &iter, &i);
 235                 } while ((i < *pos) && (ptr != NULL));
 236                 return ptr;
 237         }
 238         return iter;
 239 }
 240
 241 static void pool_proc_stop(struct seq_file *s, void *v)
 242 {
 243         struct pool_iterator *iter = (struct pool_iterator *)s->private;
 244
 245         /* in some cases stop() method is called 2 times, without
 246          * calling start() method (see seq_read() from fs/seq_file.c)
 247          * we have to free only if s->private is an iterator */
 248         if ((iter) && (iter->magic == POOL_IT_MAGIC)) {
 249                 /* we restore s->private so next call to pool_proc_start()
 250                  * will work */
 251                 s->private = iter->pool;
 252                 lov_pool_putref(iter->pool);
 253                 OBD_FREE_PTR(iter);
 254         }
 255         return;
 256 }
 257
 258 static int pool_proc_show(struct seq_file *s, void *v)
 259 {
 260         struct pool_iterator *iter = (struct pool_iterator *)v;
 261         struct lov_tgt_desc *tgt;
 262
 263         LASSERTF(iter->magic == POOL_IT_MAGIC, "%08X", iter->magic);
 264         LASSERT(iter->pool != NULL);
 265         LASSERT(iter->idx <= pool_tgt_count(iter->pool));
 266
 267         down_read(&pool_tgt_rw_sem(iter->pool));
 268         tgt = pool_tgt(iter->pool, iter->idx);
 269         up_read(&pool_tgt_rw_sem(iter->pool));
 270         if (tgt)
 271                 seq_printf(s, "%s\n", obd_uuid2str(&(tgt->ltd_uuid)));
 272
 273         return 0;
 274 }
 275
 276 static struct seq_operations pool_proc_ops = {
 277         .start          = pool_proc_start,
 278         .next           = pool_proc_next,
 279         .stop           = pool_proc_stop,
 280         .show           = pool_proc_show,
 281 };
 282
 283 static int pool_proc_open(struct inode *inode, struct file *file)
 284 {
 285         int rc;
 286
 287         rc = seq_open(file, &pool_proc_ops);
 288         if (!rc) {
 289                 struct seq_file *s = file->private_data;
 290                 s->private = PDE_DATA(inode);
 291         }
 292         return rc;
 293 }
 294
 295 static struct file_operations pool_proc_operations = {
 296         .open           = pool_proc_open,
 297         .read           = seq_read,
 298         .llseek         = seq_lseek,
 299         .release        = seq_release,
 300 };
 301 #endif /* LPROCFS */
 302
 303 void lov_dump_pool(int level, struct pool_desc *pool)
 304 {
 305         int i;
 306
 307         lov_pool_getref(pool);
 308
 309         CDEBUG(level, "pool "LOV_POOLNAMEF" has %d members\n",
 310                pool->pool_name, pool->pool_obds.op_count);
 311         down_read(&pool_tgt_rw_sem(pool));
 312
 313         for (i = 0; i < pool_tgt_count(pool) ; i++) {
 314                 if (!pool_tgt(pool, i) || !(pool_tgt(pool, i))->ltd_exp)
 315                         continue;
 316                 CDEBUG(level, "pool "LOV_POOLNAMEF"[%d] = %s\n",
 317                        pool->pool_name, i,
 318                        obd_uuid2str(&((pool_tgt(pool, i))->ltd_uuid)));
 319         }
 320
 321         up_read(&pool_tgt_rw_sem(pool));
 322         lov_pool_putref(pool);
 323 }
 324
 325 #define LOV_POOL_INIT_COUNT 2
 326 int lov_ost_pool_init(struct ost_pool *op, unsigned int count)
 327 {
 328         ENTRY;
 329
 330         if (count == 0)
 331                 count = LOV_POOL_INIT_COUNT;
 332         op->op_array = NULL;
 333         op->op_count = 0;
 334         init_rwsem(&op->op_rw_sem);
 335         op->op_size = count;
 336         OBD_ALLOC(op->op_array, op->op_size * sizeof(op->op_array[0]));
 337         if (op->op_array == NULL) {
 338                 op->op_size = 0;
 339                 RETURN(-ENOMEM);
 340         }
 341         EXIT;
 342         return 0;
 343 }
 344
 345 /* Caller must hold write op_rwlock */
 346 int lov_ost_pool_extend(struct ost_pool *op, unsigned int min_count)
 347 {
 348         __u32 *new;
 349         int new_size;
 350
 351         LASSERT(min_count != 0);
 352
 353         if (op->op_count < op->op_size)
 354                 return 0;
 355
 356         new_size = max(min_count, 2 * op->op_size);
 357         OBD_ALLOC(new, new_size * sizeof(op->op_array[0]));
 358         if (new == NULL)
 359                 return -ENOMEM;
 360
 361         /* copy old array to new one */
 362         memcpy(new, op->op_array, op->op_size * sizeof(op->op_array[0]));
 363         OBD_FREE(op->op_array, op->op_size * sizeof(op->op_array[0]));
 364         op->op_array = new;
 365         op->op_size = new_size;
 366         return 0;
 367 }
 368
 369 int lov_ost_pool_add(struct ost_pool *op, __u32 idx, unsigned int min_count)
 370 {
 371         int rc = 0, i;
 372         ENTRY;
 373
 374         down_write(&op->op_rw_sem);
 375
 376         rc = lov_ost_pool_extend(op, min_count);
 377         if (rc)
 378                 GOTO(out, rc);
 379
 380         /* search ost in pool array */
 381         for (i = 0; i < op->op_count; i++) {
 382                 if (op->op_array[i] == idx)
 383                         GOTO(out, rc = -EEXIST);
 384         }
 385         /* ost not found we add it */
 386         op->op_array[op->op_count] = idx;
 387         op->op_count++;
 388         EXIT;
 389 out:
 390         up_write(&op->op_rw_sem);
 391         return rc;
 392 }
 393
 394 int lov_ost_pool_remove(struct ost_pool *op, __u32 idx)
 395 {
 396         int i;
 397         ENTRY;
 398
 399         down_write(&op->op_rw_sem);
 400
 401         for (i = 0; i < op->op_count; i++) {
 402                 if (op->op_array[i] == idx) {
 403                         memmove(&op->op_array[i], &op->op_array[i + 1],
 404                                 (op->op_count - i - 1) * sizeof(op->op_array[0]));
 405                         op->op_count--;
 406                         up_write(&op->op_rw_sem);
 407                         EXIT;
 408                         return 0;
 409                 }
 410         }
 411
 412         up_write(&op->op_rw_sem);
 413         RETURN(-EINVAL);
 414 }
 415
 416 int lov_ost_pool_free(struct ost_pool *op)
 417 {
 418         ENTRY;
 419
 420         if (op->op_size == 0)
 421                 RETURN(0);
 422
 423         down_write(&op->op_rw_sem);
 424
 425         OBD_FREE(op->op_array, op->op_size * sizeof(op->op_array[0]));
 426         op->op_array = NULL;
 427         op->op_count = 0;
 428         op->op_size = 0;
 429
 430         up_write(&op->op_rw_sem);
 431         RETURN(0);
 432 }
 433
 434
 435 int lov_pool_new(struct obd_device *obd, char *poolname)
 436 {
 437         struct lov_obd *lov;
 438         struct pool_desc *new_pool;
 439         int rc;
 440         ENTRY;
 441
 442         lov = &(obd->u.lov);
 443
 444         if (strlen(poolname) > LOV_MAXPOOLNAME)
 445                 RETURN(-ENAMETOOLONG);
 446
 447         OBD_ALLOC_PTR(new_pool);
 448         if (new_pool == NULL)
 449                 RETURN(-ENOMEM);
 450
 451         strncpy(new_pool->pool_name, poolname, LOV_MAXPOOLNAME);
 452         new_pool->pool_name[LOV_MAXPOOLNAME] = '\0';
 453         new_pool->pool_lobd = obd;
 454         /* ref count init to 1 because when created a pool is always used
 455          * up to deletion
 456          */
 457         cfs_atomic_set(&new_pool->pool_refcount, 1);
 458         rc = lov_ost_pool_init(&new_pool->pool_obds, 0);
 459         if (rc)
 460                GOTO(out_err, rc);
 461
 462         CFS_INIT_HLIST_NODE(&new_pool->pool_hash);
 463
 464 #ifdef LPROCFS
 465         /* we need this assert seq_file is not implementated for liblustre */
 466         /* get ref for /proc file */
 467         lov_pool_getref(new_pool);
 468         new_pool->pool_proc_entry = lprocfs_add_simple(lov->lov_pool_proc_entry,
 469                                                         poolname,
 470 #ifndef HAVE_ONLY_PROCFS_SEQ
 471                                                         NULL, NULL,
 472 #endif
 473                                                         new_pool,
 474                                                         &pool_proc_operations);
 475         if (IS_ERR(new_pool->pool_proc_entry)) {
 476                 CWARN("Cannot add proc pool entry "LOV_POOLNAMEF"\n", poolname);
 477                 new_pool->pool_proc_entry = NULL;
 478                 lov_pool_putref(new_pool);
 479         }
 480         CDEBUG(D_INFO, "pool %p - proc %p\n", new_pool, new_pool->pool_proc_entry);
 481 #endif
 482
 483         spin_lock(&obd->obd_dev_lock);
 484         cfs_list_add_tail(&new_pool->pool_list, &lov->lov_pool_list);
 485         lov->lov_pool_count++;
 486         spin_unlock(&obd->obd_dev_lock);
 487
 488         /* add to find only when it fully ready  */
 489         rc = cfs_hash_add_unique(lov->lov_pools_hash_body, poolname,
 490                                  &new_pool->pool_hash);
 491         if (rc)
 492                 GOTO(out_err, rc = -EEXIST);
 493
 494         CDEBUG(D_CONFIG, LOV_POOLNAMEF" is pool #%d\n",
 495                poolname, lov->lov_pool_count);
 496
 497         RETURN(0);
 498
 499 out_err:
 500         spin_lock(&obd->obd_dev_lock);
 501         cfs_list_del_init(&new_pool->pool_list);
 502         lov->lov_pool_count--;
 503         spin_unlock(&obd->obd_dev_lock);
 504         lprocfs_remove(&new_pool->pool_proc_entry);
 505         lov_ost_pool_free(&new_pool->pool_obds);
 506         OBD_FREE_PTR(new_pool);
 507
 508         return rc;
 509 }
 510
 511 int lov_pool_del(struct obd_device *obd, char *poolname)
 512 {
 513         struct lov_obd *lov;
 514         struct pool_desc *pool;
 515         ENTRY;
 516
 517         lov = &(obd->u.lov);
 518
 519         /* lookup and kill hash reference */
 520         pool = cfs_hash_del_key(lov->lov_pools_hash_body, poolname);
 521         if (pool == NULL)
 522                 RETURN(-ENOENT);
 523
 524         if (pool->pool_proc_entry != NULL) {
 525                 CDEBUG(D_INFO, "proc entry %p\n", pool->pool_proc_entry);
 526                 lprocfs_remove(&pool->pool_proc_entry);
 527                 lov_pool_putref(pool);
 528         }
 529
 530         spin_lock(&obd->obd_dev_lock);
 531         cfs_list_del_init(&pool->pool_list);
 532         lov->lov_pool_count--;
 533         spin_unlock(&obd->obd_dev_lock);
 534
 535         /* release last reference */
 536         lov_pool_putref(pool);
 537
 538         RETURN(0);
 539 }
 540
 541
 542 int lov_pool_add(struct obd_device *obd, char *poolname, char *ostname)
 543 {
 544         struct obd_uuid ost_uuid;
 545         struct lov_obd *lov;
 546         struct pool_desc *pool;
 547         unsigned int lov_idx;
 548         int rc;
 549         ENTRY;
 550
 551         lov = &(obd->u.lov);
 552
 553         pool = cfs_hash_lookup(lov->lov_pools_hash_body, poolname);
 554         if (pool == NULL)
 555                 RETURN(-ENOENT);
 556
 557         obd_str2uuid(&ost_uuid, ostname);
 558
 559
 560         /* search ost in lov array */
 561         obd_getref(obd);
 562         for (lov_idx = 0; lov_idx < lov->desc.ld_tgt_count; lov_idx++) {
 563                 if (!lov->lov_tgts[lov_idx])
 564                         continue;
 565                 if (obd_uuid_equals(&ost_uuid,
 566                                     &(lov->lov_tgts[lov_idx]->ltd_uuid)))
 567                         break;
 568         }
 569         /* test if ost found in lov */
 570         if (lov_idx == lov->desc.ld_tgt_count)
 571                 GOTO(out, rc = -EINVAL);
 572
 573         rc = lov_ost_pool_add(&pool->pool_obds, lov_idx, lov->lov_tgt_size);
 574         if (rc)
 575                 GOTO(out, rc);
 576
 577         CDEBUG(D_CONFIG, "Added %s to "LOV_POOLNAMEF" as member %d\n",
 578                ostname, poolname,  pool_tgt_count(pool));
 579
 580         EXIT;
 581 out:
 582         obd_putref(obd);
 583         lov_pool_putref(pool);
 584         return rc;
 585 }
 586
 587 int lov_pool_remove(struct obd_device *obd, char *poolname, char *ostname)
 588 {
 589         struct obd_uuid ost_uuid;
 590         struct lov_obd *lov;
 591         struct pool_desc *pool;
 592         unsigned int lov_idx;
 593         int rc = 0;
 594         ENTRY;
 595
 596         lov = &(obd->u.lov);
 597
 598         pool = cfs_hash_lookup(lov->lov_pools_hash_body, poolname);
 599         if (pool == NULL)
 600                 RETURN(-ENOENT);
 601
 602         obd_str2uuid(&ost_uuid, ostname);
 603
 604         obd_getref(obd);
 605         /* search ost in lov array, to get index */
 606         for (lov_idx = 0; lov_idx < lov->desc.ld_tgt_count; lov_idx++) {
 607                 if (!lov->lov_tgts[lov_idx])
 608                         continue;
 609
 610                 if (obd_uuid_equals(&ost_uuid,
 611                                     &(lov->lov_tgts[lov_idx]->ltd_uuid)))
 612                         break;
 613         }
 614
 615         /* test if ost found in lov */
 616         if (lov_idx == lov->desc.ld_tgt_count)
 617                 GOTO(out, rc = -EINVAL);
 618
 619         lov_ost_pool_remove(&pool->pool_obds, lov_idx);
 620
 621         CDEBUG(D_CONFIG, "%s removed from "LOV_POOLNAMEF"\n", ostname,
 622                poolname);
 623
 624         EXIT;
 625 out:
 626         obd_putref(obd);
 627         lov_pool_putref(pool);
 628         return rc;
 629 }
 630
 631 int lov_check_index_in_pool(__u32 idx, struct pool_desc *pool)
 632 {
 633         int i, rc;
 634         ENTRY;
 635
 636         /* caller may no have a ref on pool if it got the pool
 637          * without calling lov_find_pool() (e.g. go through the lov pool
 638          * list)
 639          */
 640         lov_pool_getref(pool);
 641
 642         down_read(&pool_tgt_rw_sem(pool));
 643
 644         for (i = 0; i < pool_tgt_count(pool); i++) {
 645                 if (pool_tgt_array(pool)[i] == idx)
 646                         GOTO(out, rc = 0);
 647         }
 648         rc = -ENOENT;
 649         EXIT;
 650 out:
 651         up_read(&pool_tgt_rw_sem(pool));
 652
 653         lov_pool_putref(pool);
 654         return rc;
 655 }
 656
 657 struct pool_desc *lov_find_pool(struct lov_obd *lov, char *poolname)
 658 {
 659         struct pool_desc *pool;
 660
 661         pool = NULL;
 662         if (poolname[0] != '\0') {
 663                 pool = cfs_hash_lookup(lov->lov_pools_hash_body, poolname);
 664                 if (pool == NULL)
 665                         CWARN("Request for an unknown pool ("LOV_POOLNAMEF")\n",
 666                               poolname);
 667                 if ((pool != NULL) && (pool_tgt_count(pool) == 0)) {
 668                         CWARN("Request for an empty pool ("LOV_POOLNAMEF")\n",
 669                                poolname);
 670                         /* pool is ignored, so we remove ref on it */
 671                         lov_pool_putref(pool);
 672                         pool = NULL;
 673                 }
 674         }
 675         return pool;
 676 }
 677