lustre/lov/lov_pool.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  * GPL HEADER START
   5  *
   6  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 only,
  10  * as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License version 2 for more details (a copy is included
  16  * in the LICENSE file that accompanied this code).
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * version 2 along with this program; If not, see [sun.com URL with a
  20  * copy of GPLv2].
  21  *
  22  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  23  * CA 95054 USA or visit www.sun.com if you need additional information or
  24  * have any questions.
  25  *
  26  * GPL HEADER END
  27  */
  28 /*
  29  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  30  * Use is subject to license terms.
  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 static void lov_pool_getref(struct pool_desc *pool)
  57 {
  58         CDEBUG(D_INFO, "pool %p\n", pool);
  59         cfs_atomic_inc(&pool->pool_refcount);
  60 }
  61
  62 void lov_pool_putref(struct pool_desc *pool)
  63 {
  64         CDEBUG(D_INFO, "pool %p\n", pool);
  65         if (cfs_atomic_dec_and_test(&pool->pool_refcount)) {
  66                 LASSERT(cfs_hlist_unhashed(&pool->pool_hash));
  67                 LASSERT(cfs_list_empty(&pool->pool_list));
  68                 LASSERT(pool->pool_proc_entry == NULL);
  69                 lov_ost_pool_free(&(pool->pool_rr.lqr_pool));
  70                 lov_ost_pool_free(&(pool->pool_obds));
  71                 OBD_FREE_PTR(pool);
  72                 EXIT;
  73         }
  74 }
  75
  76 void lov_pool_putref_locked(struct pool_desc *pool)
  77 {
  78         CDEBUG(D_INFO, "pool %p\n", pool);
  79         LASSERT(cfs_atomic_read(&pool->pool_refcount) > 1);
  80
  81         cfs_atomic_dec(&pool->pool_refcount);
  82 }
  83
  84 /*
  85  * hash function using a Rotating Hash algorithm
  86  * Knuth, D. The Art of Computer Programming,
  87  * Volume 3: Sorting and Searching,
  88  * Chapter 6.4.
  89  * Addison Wesley, 1973
  90  */
  91 static __u32 pool_hashfn(cfs_hash_t *hash_body, void *key, unsigned mask)
  92 {
  93         int i;
  94         __u32 result;
  95         char *poolname;
  96
  97         result = 0;
  98         poolname = (char *)key;
  99         for (i = 0; i < LOV_MAXPOOLNAME; i++) {
 100                 if (poolname[i] == '\0')
 101                         break;
 102                 result = (result << 4)^(result >> 28) ^  poolname[i];
 103         }
 104         return (result % mask);
 105 }
 106
 107 static void *pool_key(cfs_hlist_node_t *hnode)
 108 {
 109         struct pool_desc *pool;
 110
 111         pool = cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 112         return (pool->pool_name);
 113 }
 114
 115 static int pool_hashkey_keycmp(void *key, cfs_hlist_node_t *compared_hnode)
 116 {
 117         char *pool_name;
 118         struct pool_desc *pool;
 119
 120         pool_name = (char *)key;
 121         pool = cfs_hlist_entry(compared_hnode, struct pool_desc, pool_hash);
 122         return !strncmp(pool_name, pool->pool_name, LOV_MAXPOOLNAME);
 123 }
 124
 125 static void *pool_hashobject(cfs_hlist_node_t *hnode)
 126 {
 127         return cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 128 }
 129
 130 static void *pool_hashrefcount_get(cfs_hlist_node_t *hnode)
 131 {
 132         struct pool_desc *pool;
 133
 134         pool = cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 135         lov_pool_getref(pool);
 136         return (pool);
 137 }
 138
 139 static void *pool_hashrefcount_put_locked(cfs_hlist_node_t *hnode)
 140 {
 141         struct pool_desc *pool;
 142
 143         pool = cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 144         lov_pool_putref_locked(pool);
 145         return (pool);
 146 }
 147
 148 cfs_hash_ops_t pool_hash_operations = {
 149         .hs_hash        = pool_hashfn,
 150         .hs_key         = pool_key,
 151         .hs_keycmp      = pool_hashkey_keycmp,
 152         .hs_object      = pool_hashobject,
 153         .hs_get         = pool_hashrefcount_get,
 154         .hs_put_locked  = pool_hashrefcount_put_locked,
 155
 156 };
 157
 158 #ifdef LPROCFS
 159 /* ifdef needed for liblustre support */
 160 /*
 161  * pool /proc seq_file methods
 162  */
 163 /*
 164  * iterator is used to go through the target pool entries
 165  * index is the current entry index in the lp_array[] array
 166  * index >= pos returned to the seq_file interface
 167  * pos is from 0 to (pool->pool_obds.op_count - 1)
 168  */
 169 #define POOL_IT_MAGIC 0xB001CEA0
 170 struct pool_iterator {
 171         int magic;
 172         struct pool_desc *pool;
 173         int idx;        /* from 0 to pool_tgt_size - 1 */
 174 };
 175
 176 static void *pool_proc_next(struct seq_file *s, void *v, loff_t *pos)
 177 {
 178         struct pool_iterator *iter = (struct pool_iterator *)s->private;
 179         int prev_idx;
 180
 181         LASSERTF(iter->magic == POOL_IT_MAGIC, "%08X", iter->magic);
 182
 183         /* test if end of file */
 184         if (*pos >= pool_tgt_count(iter->pool))
 185                 return NULL;
 186
 187         /* iterate to find a non empty entry */
 188         prev_idx = iter->idx;
 189         cfs_down_read(&pool_tgt_rw_sem(iter->pool));
 190         iter->idx++;
 191         if (iter->idx == pool_tgt_count(iter->pool)) {
 192                 iter->idx = prev_idx; /* we stay on the last entry */
 193                 cfs_up_read(&pool_tgt_rw_sem(iter->pool));
 194                 return NULL;
 195         }
 196         cfs_up_read(&pool_tgt_rw_sem(iter->pool));
 197         (*pos)++;
 198         /* return != NULL to continue */
 199         return iter;
 200 }
 201
 202 static void *pool_proc_start(struct seq_file *s, loff_t *pos)
 203 {
 204         struct pool_desc *pool = (struct pool_desc *)s->private;
 205         struct pool_iterator *iter;
 206
 207         lov_pool_getref(pool);
 208         if ((pool_tgt_count(pool) == 0) ||
 209             (*pos >= pool_tgt_count(pool))) {
 210                 /* iter is not created, so stop() has no way to
 211                  * find pool to dec ref */
 212                 lov_pool_putref(pool);
 213                 return NULL;
 214         }
 215
 216         OBD_ALLOC_PTR(iter);
 217         if (!iter)
 218                 return ERR_PTR(-ENOMEM);
 219         iter->magic = POOL_IT_MAGIC;
 220         iter->pool = pool;
 221         iter->idx = 0;
 222
 223         /* we use seq_file private field to memorized iterator so
 224          * we can free it at stop() */
 225         /* /!\ do not forget to restore it to pool before freeing it */
 226         s->private = iter;
 227         if (*pos > 0) {
 228                 loff_t i;
 229                 void *ptr;
 230
 231                 i = 0;
 232                 do {
 233                      ptr = pool_proc_next(s, &iter, &i);
 234                 } while ((i < *pos) && (ptr != NULL));
 235                 return ptr;
 236         }
 237         return iter;
 238 }
 239
 240 static void pool_proc_stop(struct seq_file *s, void *v)
 241 {
 242         struct pool_iterator *iter = (struct pool_iterator *)s->private;
 243
 244         /* in some cases stop() method is called 2 times, without
 245          * calling start() method (see seq_read() from fs/seq_file.c)
 246          * we have to free only if s->private is an iterator */
 247         if ((iter) && (iter->magic == POOL_IT_MAGIC)) {
 248                 /* we restore s->private so next call to pool_proc_start()
 249                  * will work */
 250                 s->private = iter->pool;
 251                 lov_pool_putref(iter->pool);
 252                 OBD_FREE_PTR(iter);
 253         }
 254         return;
 255 }
 256
 257 static int pool_proc_show(struct seq_file *s, void *v)
 258 {
 259         struct pool_iterator *iter = (struct pool_iterator *)v;
 260         struct lov_tgt_desc *tgt;
 261
 262         LASSERTF(iter->magic == POOL_IT_MAGIC, "%08X", iter->magic);
 263         LASSERT(iter->pool != NULL);
 264         LASSERT(iter->idx <= pool_tgt_count(iter->pool));
 265
 266         cfs_down_read(&pool_tgt_rw_sem(iter->pool));
 267         tgt = pool_tgt(iter->pool, iter->idx);
 268         cfs_up_read(&pool_tgt_rw_sem(iter->pool));
 269         if (tgt)
 270                 seq_printf(s, "%s\n", obd_uuid2str(&(tgt->ltd_uuid)));
 271
 272         return 0;
 273 }
 274
 275 static struct seq_operations pool_proc_ops = {
 276         .start          = pool_proc_start,
 277         .next           = pool_proc_next,
 278         .stop           = pool_proc_stop,
 279         .show           = pool_proc_show,
 280 };
 281
 282 static int pool_proc_open(struct inode *inode, struct file *file)
 283 {
 284         int rc;
 285
 286         rc = seq_open(file, &pool_proc_ops);
 287         if (!rc) {
 288                 struct seq_file *s = file->private_data;
 289                 s->private = PROC_I(inode)->pde->data;
 290         }
 291         return rc;
 292 }
 293
 294 static struct file_operations pool_proc_operations = {
 295         .open           = pool_proc_open,
 296         .read           = seq_read,
 297         .llseek         = seq_lseek,
 298         .release        = seq_release,
 299 };
 300 #endif /* LPROCFS */
 301
 302 void lov_dump_pool(int level, struct pool_desc *pool)
 303 {
 304         int i;
 305
 306         lov_pool_getref(pool);
 307
 308         CDEBUG(level, "pool "LOV_POOLNAMEF" has %d members\n",
 309                pool->pool_name, pool->pool_obds.op_count);
 310         cfs_down_read(&pool_tgt_rw_sem(pool));
 311
 312         for (i = 0; i < pool_tgt_count(pool) ; i++) {
 313                 if (!pool_tgt(pool, i) || !(pool_tgt(pool, i))->ltd_exp)
 314                         continue;
 315                 CDEBUG(level, "pool "LOV_POOLNAMEF"[%d] = %s\n",
 316                        pool->pool_name, i,
 317                        obd_uuid2str(&((pool_tgt(pool, i))->ltd_uuid)));
 318         }
 319
 320         cfs_up_read(&pool_tgt_rw_sem(pool));
 321         lov_pool_putref(pool);
 322 }
 323
 324 #define LOV_POOL_INIT_COUNT 2
 325 int lov_ost_pool_init(struct ost_pool *op, unsigned int count)
 326 {
 327         ENTRY;
 328
 329         if (count == 0)
 330                 count = LOV_POOL_INIT_COUNT;
 331         op->op_array = NULL;
 332         op->op_count = 0;
 333         cfs_init_rwsem(&op->op_rw_sem);
 334         op->op_size = count;
 335         OBD_ALLOC(op->op_array, op->op_size * sizeof(op->op_array[0]));
 336         if (op->op_array == NULL) {
 337                 op->op_size = 0;
 338                 RETURN(-ENOMEM);
 339         }
 340         EXIT;
 341         return 0;
 342 }
 343
 344 /* Caller must hold write op_rwlock */
 345 int lov_ost_pool_extend(struct ost_pool *op, unsigned int min_count)
 346 {
 347         __u32 *new;
 348         int new_size;
 349
 350         LASSERT(min_count != 0);
 351
 352         if (op->op_count < op->op_size)
 353                 return 0;
 354
 355         new_size = max(min_count, 2 * op->op_size);
 356         OBD_ALLOC(new, new_size * sizeof(op->op_array[0]));
 357         if (new == NULL)
 358                 return -ENOMEM;
 359
 360         /* copy old array to new one */
 361         memcpy(new, op->op_array, op->op_size * sizeof(op->op_array[0]));
 362         OBD_FREE(op->op_array, op->op_size * sizeof(op->op_array[0]));
 363         op->op_array = new;
 364         op->op_size = new_size;
 365         return 0;
 366 }
 367
 368 int lov_ost_pool_add(struct ost_pool *op, __u32 idx, unsigned int min_count)
 369 {
 370         int rc = 0, i;
 371         ENTRY;
 372
 373         cfs_down_write(&op->op_rw_sem);
 374
 375         rc = lov_ost_pool_extend(op, min_count);
 376         if (rc)
 377                 GOTO(out, rc);
 378
 379         /* search ost in pool array */
 380         for (i = 0; i < op->op_count; i++) {
 381                 if (op->op_array[i] == idx)
 382                         GOTO(out, rc = -EEXIST);
 383         }
 384         /* ost not found we add it */
 385         op->op_array[op->op_count] = idx;
 386         op->op_count++;
 387         EXIT;
 388 out:
 389         cfs_up_write(&op->op_rw_sem);
 390         return rc;
 391 }
 392
 393 int lov_ost_pool_remove(struct ost_pool *op, __u32 idx)
 394 {
 395         int i;
 396         ENTRY;
 397
 398         cfs_down_write(&op->op_rw_sem);
 399
 400         for (i = 0; i < op->op_count; i++) {
 401                 if (op->op_array[i] == idx) {
 402                         memmove(&op->op_array[i], &op->op_array[i + 1],
 403                                 (op->op_count - i - 1) * sizeof(op->op_array[0]));
 404                         op->op_count--;
 405                         cfs_up_write(&op->op_rw_sem);
 406                         EXIT;
 407                         return 0;
 408                 }
 409         }
 410
 411         cfs_up_write(&op->op_rw_sem);
 412         RETURN(-EINVAL);
 413 }
 414
 415 int lov_ost_pool_free(struct ost_pool *op)
 416 {
 417         ENTRY;
 418
 419         if (op->op_size == 0)
 420                 RETURN(0);
 421
 422         cfs_down_write(&op->op_rw_sem);
 423
 424         OBD_FREE(op->op_array, op->op_size * sizeof(op->op_array[0]));
 425         op->op_array = NULL;
 426         op->op_count = 0;
 427         op->op_size = 0;
 428
 429         cfs_up_write(&op->op_rw_sem);
 430         RETURN(0);
 431 }
 432
 433
 434 int lov_pool_new(struct obd_device *obd, char *poolname)
 435 {
 436         struct lov_obd *lov;
 437         struct pool_desc *new_pool;
 438         int rc;
 439         ENTRY;
 440
 441         lov = &(obd->u.lov);
 442
 443         if (strlen(poolname) > LOV_MAXPOOLNAME)
 444                 RETURN(-ENAMETOOLONG);
 445
 446         OBD_ALLOC_PTR(new_pool);
 447         if (new_pool == NULL)
 448                 RETURN(-ENOMEM);
 449
 450         strncpy(new_pool->pool_name, poolname, LOV_MAXPOOLNAME);
 451         new_pool->pool_name[LOV_MAXPOOLNAME] = '\0';
 452         new_pool->pool_lov = lov;
 453         /* ref count init to 1 because when created a pool is always used
 454          * up to deletion
 455          */
 456         cfs_atomic_set(&new_pool->pool_refcount, 1);
 457         rc = lov_ost_pool_init(&new_pool->pool_obds, 0);
 458         if (rc)
 459                GOTO(out_err, rc);
 460
 461         memset(&(new_pool->pool_rr), 0, sizeof(struct lov_qos_rr));
 462         rc = lov_ost_pool_init(&new_pool->pool_rr.lqr_pool, 0);
 463         if (rc)
 464                 GOTO(out_free_pool_obds, rc);
 465
 466         CFS_INIT_HLIST_NODE(&new_pool->pool_hash);
 467
 468 #ifdef LPROCFS
 469         /* we need this assert seq_file is not implementated for liblustre */
 470         /* get ref for /proc file */
 471         lov_pool_getref(new_pool);
 472         new_pool->pool_proc_entry = lprocfs_add_simple(lov->lov_pool_proc_entry,
 473                                                        poolname, NULL, NULL,
 474                                                        new_pool,
 475                                                        &pool_proc_operations);
 476         if (IS_ERR(new_pool->pool_proc_entry)) {
 477                 CWARN("Cannot add proc pool entry "LOV_POOLNAMEF"\n", poolname);
 478                 new_pool->pool_proc_entry = NULL;
 479                 lov_pool_putref(new_pool);
 480         }
 481         CDEBUG(D_INFO, "pool %p - proc %p\n", new_pool, new_pool->pool_proc_entry);
 482 #endif
 483
 484         cfs_spin_lock(&obd->obd_dev_lock);
 485         cfs_list_add_tail(&new_pool->pool_list, &lov->lov_pool_list);
 486         lov->lov_pool_count++;
 487         cfs_spin_unlock(&obd->obd_dev_lock);
 488
 489         /* add to find only when it fully ready  */
 490         rc = cfs_hash_add_unique(lov->lov_pools_hash_body, poolname,
 491                                  &new_pool->pool_hash);
 492         if (rc)
 493                 GOTO(out_err, rc = -EEXIST);
 494
 495         CDEBUG(D_CONFIG, LOV_POOLNAMEF" is pool #%d\n",
 496                poolname, lov->lov_pool_count);
 497
 498         RETURN(0);
 499
 500 out_err:
 501         cfs_spin_lock(&obd->obd_dev_lock);
 502         cfs_list_del_init(&new_pool->pool_list);
 503         lov->lov_pool_count--;
 504         cfs_spin_unlock(&obd->obd_dev_lock);
 505
 506         lprocfs_remove(&new_pool->pool_proc_entry);
 507
 508         lov_ost_pool_free(&new_pool->pool_rr.lqr_pool);
 509 out_free_pool_obds:
 510         lov_ost_pool_free(&new_pool->pool_obds);
 511         OBD_FREE_PTR(new_pool);
 512         return rc;
 513 }
 514
 515 int lov_pool_del(struct obd_device *obd, char *poolname)
 516 {
 517         struct lov_obd *lov;
 518         struct pool_desc *pool;
 519         ENTRY;
 520
 521         lov = &(obd->u.lov);
 522
 523         /* lookup and kill hash reference */
 524         pool = cfs_hash_del_key(lov->lov_pools_hash_body, poolname);
 525         if (pool == NULL)
 526                 RETURN(-ENOENT);
 527
 528         if (pool->pool_proc_entry != NULL) {
 529                 CDEBUG(D_INFO, "proc entry %p\n", pool->pool_proc_entry);
 530                 lprocfs_remove(&pool->pool_proc_entry);
 531                 lov_pool_putref(pool);
 532         }
 533
 534         cfs_spin_lock(&obd->obd_dev_lock);
 535         cfs_list_del_init(&pool->pool_list);
 536         lov->lov_pool_count--;
 537         cfs_spin_unlock(&obd->obd_dev_lock);
 538
 539         /* release last reference */
 540         lov_pool_putref(pool);
 541
 542         RETURN(0);
 543 }
 544
 545
 546 int lov_pool_add(struct obd_device *obd, char *poolname, char *ostname)
 547 {
 548         struct obd_uuid ost_uuid;
 549         struct lov_obd *lov;
 550         struct pool_desc *pool;
 551         unsigned int lov_idx;
 552         int rc;
 553         ENTRY;
 554
 555         lov = &(obd->u.lov);
 556
 557         pool = cfs_hash_lookup(lov->lov_pools_hash_body, poolname);
 558         if (pool == NULL)
 559                 RETURN(-ENOENT);
 560
 561         obd_str2uuid(&ost_uuid, ostname);
 562
 563
 564         /* search ost in lov array */
 565         obd_getref(obd);
 566         for (lov_idx = 0; lov_idx < lov->desc.ld_tgt_count; lov_idx++) {
 567                 if (!lov->lov_tgts[lov_idx])
 568                         continue;
 569                 if (obd_uuid_equals(&ost_uuid,
 570                                     &(lov->lov_tgts[lov_idx]->ltd_uuid)))
 571                         break;
 572         }
 573         /* test if ost found in lov */
 574         if (lov_idx == lov->desc.ld_tgt_count)
 575                 GOTO(out, rc = -EINVAL);
 576
 577         rc = lov_ost_pool_add(&pool->pool_obds, lov_idx, lov->lov_tgt_size);
 578         if (rc)
 579                 GOTO(out, rc);
 580
 581         pool->pool_rr.lqr_dirty = 1;
 582
 583         CDEBUG(D_CONFIG, "Added %s to "LOV_POOLNAMEF" as member %d\n",
 584                ostname, poolname,  pool_tgt_count(pool));
 585
 586         EXIT;
 587 out:
 588         obd_putref(obd);
 589         lov_pool_putref(pool);
 590         return rc;
 591 }
 592
 593 int lov_pool_remove(struct obd_device *obd, char *poolname, char *ostname)
 594 {
 595         struct obd_uuid ost_uuid;
 596         struct lov_obd *lov;
 597         struct pool_desc *pool;
 598         unsigned int lov_idx;
 599         int rc = 0;
 600         ENTRY;
 601
 602         lov = &(obd->u.lov);
 603
 604         pool = cfs_hash_lookup(lov->lov_pools_hash_body, poolname);
 605         if (pool == NULL)
 606                 RETURN(-ENOENT);
 607
 608         obd_str2uuid(&ost_uuid, ostname);
 609
 610         obd_getref(obd);
 611         /* search ost in lov array, to get index */
 612         for (lov_idx = 0; lov_idx < lov->desc.ld_tgt_count; lov_idx++) {
 613                 if (!lov->lov_tgts[lov_idx])
 614                         continue;
 615
 616                 if (obd_uuid_equals(&ost_uuid,
 617                                     &(lov->lov_tgts[lov_idx]->ltd_uuid)))
 618                         break;
 619         }
 620
 621         /* test if ost found in lov */
 622         if (lov_idx == lov->desc.ld_tgt_count)
 623                 GOTO(out, rc = -EINVAL);
 624
 625         lov_ost_pool_remove(&pool->pool_obds, lov_idx);
 626
 627         pool->pool_rr.lqr_dirty = 1;
 628
 629         CDEBUG(D_CONFIG, "%s removed from "LOV_POOLNAMEF"\n", ostname,
 630                poolname);
 631
 632         EXIT;
 633 out:
 634         obd_putref(obd);
 635         lov_pool_putref(pool);
 636         return rc;
 637 }
 638
 639 int lov_check_index_in_pool(__u32 idx, struct pool_desc *pool)
 640 {
 641         int i, rc;
 642         ENTRY;
 643
 644         /* caller may no have a ref on pool if it got the pool
 645          * without calling lov_find_pool() (e.g. go through the lov pool
 646          * list)
 647          */
 648         lov_pool_getref(pool);
 649
 650         cfs_down_read(&pool_tgt_rw_sem(pool));
 651
 652         for (i = 0; i < pool_tgt_count(pool); i++) {
 653                 if (pool_tgt_array(pool)[i] == idx)
 654                         GOTO(out, rc = 0);
 655         }
 656         rc = -ENOENT;
 657         EXIT;
 658 out:
 659         cfs_up_read(&pool_tgt_rw_sem(pool));
 660
 661         lov_pool_putref(pool);
 662         return rc;
 663 }
 664
 665 struct pool_desc *lov_find_pool(struct lov_obd *lov, char *poolname)
 666 {
 667         struct pool_desc *pool;
 668
 669         pool = NULL;
 670         if (poolname[0] != '\0') {
 671                 pool = cfs_hash_lookup(lov->lov_pools_hash_body, poolname);
 672                 if (pool == NULL)
 673                         CWARN("Request for an unknown pool ("LOV_POOLNAMEF")\n",
 674                               poolname);
 675                 if ((pool != NULL) && (pool_tgt_count(pool) == 0)) {
 676                         CWARN("Request for an empty pool ("LOV_POOLNAMEF")\n",
 677                                poolname);
 678                         /* pool is ignored, so we remove ref on it */
 679                         lov_pool_putref(pool);
 680                         pool = NULL;
 681                 }
 682         }
 683         return pool;
 684 }
 685