lustre/lod/lod_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  2008 Sun Microsystems, Inc. All rights reserved
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2012, 2013, 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/lod/lod_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 <libcfs/libcfs.h>
  48 #include <obd.h>
  49 #include "lod_internal.h"
  50
  51 #define pool_tgt(_p, _i) \
  52         OST_TGT(lu2lod_dev((_p)->pool_lobd->obd_lu_dev),(_p)->pool_obds.op_array[_i])
  53
  54 static void lod_pool_getref(struct pool_desc *pool)
  55 {
  56         CDEBUG(D_INFO, "pool %p\n", pool);
  57         atomic_inc(&pool->pool_refcount);
  58 }
  59
  60 void lod_pool_putref(struct pool_desc *pool)
  61 {
  62         CDEBUG(D_INFO, "pool %p\n", pool);
  63         if (atomic_dec_and_test(&pool->pool_refcount)) {
  64                 LASSERT(cfs_hlist_unhashed(&pool->pool_hash));
  65                 LASSERT(cfs_list_empty(&pool->pool_list));
  66                 LASSERT(pool->pool_proc_entry == NULL);
  67                 lod_ost_pool_free(&(pool->pool_rr.lqr_pool));
  68                 lod_ost_pool_free(&(pool->pool_obds));
  69                 OBD_FREE_PTR(pool);
  70                 EXIT;
  71         }
  72 }
  73
  74 void lod_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 /*
  84  * hash function using a Rotating Hash algorithm
  85  * Knuth, D. The Art of Computer Programming,
  86  * Volume 3: Sorting and Searching,
  87  * Chapter 6.4.
  88  * Addison Wesley, 1973
  89  */
  90 static __u32 pool_hashfn(cfs_hash_t *hash_body, const void *key, unsigned mask)
  91 {
  92         int i;
  93         __u32 result;
  94         char *poolname;
  95
  96         result = 0;
  97         poolname = (char *)key;
  98         for (i = 0; i < LOV_MAXPOOLNAME; i++) {
  99                 if (poolname[i] == '\0')
 100                         break;
 101                 result = (result << 4)^(result >> 28) ^  poolname[i];
 102         }
 103         return (result % mask);
 104 }
 105
 106 static void *pool_key(cfs_hlist_node_t *hnode)
 107 {
 108         struct pool_desc *pool;
 109
 110         pool = cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 111         return (pool->pool_name);
 112 }
 113
 114 static int pool_hashkey_keycmp(const void *key, cfs_hlist_node_t *compared_hnode)
 115 {
 116         char *pool_name;
 117         struct pool_desc *pool;
 118
 119         pool_name = (char *)key;
 120         pool = cfs_hlist_entry(compared_hnode, struct pool_desc, pool_hash);
 121         return !strncmp(pool_name, pool->pool_name, LOV_MAXPOOLNAME);
 122 }
 123
 124 static void *pool_hashobject(cfs_hlist_node_t *hnode)
 125 {
 126         return cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 127 }
 128
 129 static void pool_hashrefcount_get(cfs_hash_t *hs, cfs_hlist_node_t *hnode)
 130 {
 131         struct pool_desc *pool;
 132
 133         pool = cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 134         lod_pool_getref(pool);
 135 }
 136
 137 static void pool_hashrefcount_put_locked(cfs_hash_t *hs,
 138                 cfs_hlist_node_t *hnode)
 139 {
 140         struct pool_desc *pool;
 141
 142         pool = cfs_hlist_entry(hnode, struct pool_desc, pool_hash);
 143         lod_pool_putref_locked(pool);
 144 }
 145
 146 cfs_hash_ops_t pool_hash_operations = {
 147         .hs_hash        = pool_hashfn,
 148         .hs_key         = pool_key,
 149         .hs_keycmp      = pool_hashkey_keycmp,
 150         .hs_object      = pool_hashobject,
 151         .hs_get         = pool_hashrefcount_get,
 152         .hs_put_locked  = pool_hashrefcount_put_locked,
 153 };
 154
 155 #ifdef LPROCFS
 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 lod_pool_iterator {
 168         int               lpi_magic;
 169         int               lpi_idx;      /* from 0 to pool_tgt_size - 1 */
 170         struct pool_desc *lpi_pool;
 171 };
 172
 173 static void *pool_proc_next(struct seq_file *s, void *v, loff_t *pos)
 174 {
 175         struct lod_pool_iterator *iter = s->private;
 176         int prev_idx;
 177
 178         LASSERTF(iter->lpi_magic == POOL_IT_MAGIC, "%08X\n", iter->lpi_magic);
 179
 180         /* test if end of file */
 181         if (*pos >= pool_tgt_count(iter->lpi_pool))
 182                 return NULL;
 183
 184         /* iterate to find a non empty entry */
 185         prev_idx = iter->lpi_idx;
 186         down_read(&pool_tgt_rw_sem(iter->lpi_pool));
 187         iter->lpi_idx++;
 188         if (iter->lpi_idx == pool_tgt_count(iter->lpi_pool)) {
 189                 iter->lpi_idx = prev_idx; /* we stay on the last entry */
 190                 up_read(&pool_tgt_rw_sem(iter->lpi_pool));
 191                 return NULL;
 192         }
 193         up_read(&pool_tgt_rw_sem(iter->lpi_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 = s->private;
 202         struct lod_pool_iterator *iter;
 203
 204         lod_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                 lod_pool_putref(pool);
 210                 return NULL;
 211         }
 212
 213         OBD_ALLOC_PTR(iter);
 214         if (!iter)
 215                 return ERR_PTR(-ENOMEM);
 216         iter->lpi_magic = POOL_IT_MAGIC;
 217         iter->lpi_pool = pool;
 218         iter->lpi_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 lod_pool_iterator *iter = 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 != NULL && (iter->lpi_magic == POOL_IT_MAGIC)) {
 245                 /* we restore s->private so next call to pool_proc_start()
 246                  * will work */
 247                 s->private = iter->lpi_pool;
 248                 lod_pool_putref(iter->lpi_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 lod_pool_iterator *iter = v;
 257         struct lod_tgt_desc  *osc_desc;
 258
 259         LASSERTF(iter->lpi_magic == POOL_IT_MAGIC, "%08X\n", iter->lpi_magic);
 260         LASSERT(iter->lpi_pool != NULL);
 261         LASSERT(iter->lpi_idx <= pool_tgt_count(iter->lpi_pool));
 262
 263         down_read(&pool_tgt_rw_sem(iter->lpi_pool));
 264         osc_desc = pool_tgt(iter->lpi_pool, iter->lpi_idx);
 265         up_read(&pool_tgt_rw_sem(iter->lpi_pool));
 266         if (osc_desc)
 267                 seq_printf(s, "%s\n", obd_uuid2str(&(osc_desc->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 /* LPROCFS */
 298
 299 void lod_dump_pool(int level, struct pool_desc *pool)
 300 {
 301         int i;
 302
 303         lod_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         lod_pool_putref(pool);
 319 }
 320
 321 #define LOD_POOL_INIT_COUNT 2
 322 int lod_ost_pool_init(struct ost_pool *op, unsigned int count)
 323 {
 324         ENTRY;
 325
 326         if (count == 0)
 327                 count = LOD_POOL_INIT_COUNT;
 328         op->op_array = NULL;
 329         op->op_count = 0;
 330         init_rwsem(&op->op_rw_sem);
 331         op->op_size = count;
 332         OBD_ALLOC(op->op_array, op->op_size * sizeof(op->op_array[0]));
 333         if (op->op_array == NULL) {
 334                 op->op_size = 0;
 335                 RETURN(-ENOMEM);
 336         }
 337         EXIT;
 338         return 0;
 339 }
 340
 341 /* Caller must hold write op_rwlock */
 342 int lod_ost_pool_extend(struct ost_pool *op, unsigned int min_count)
 343 {
 344         __u32 *new;
 345         int new_size;
 346
 347         LASSERT(min_count != 0);
 348
 349         if (op->op_count < op->op_size)
 350                 return 0;
 351
 352         new_size = max(min_count, 2 * op->op_size);
 353         OBD_ALLOC(new, new_size * sizeof(op->op_array[0]));
 354         if (new == NULL)
 355                 return -ENOMEM;
 356
 357         /* copy old array to new one */
 358         memcpy(new, op->op_array, op->op_size * sizeof(op->op_array[0]));
 359         OBD_FREE(op->op_array, op->op_size * sizeof(op->op_array[0]));
 360         op->op_array = new;
 361         op->op_size = new_size;
 362         return 0;
 363 }
 364
 365 int lod_ost_pool_add(struct ost_pool *op, __u32 idx, unsigned int min_count)
 366 {
 367         int rc = 0, i;
 368         ENTRY;
 369
 370         down_write(&op->op_rw_sem);
 371
 372         rc = lod_ost_pool_extend(op, min_count);
 373         if (rc)
 374                 GOTO(out, rc);
 375
 376         /* search ost in pool array */
 377         for (i = 0; i < op->op_count; i++) {
 378                 if (op->op_array[i] == idx)
 379                         GOTO(out, rc = -EEXIST);
 380         }
 381         /* ost not found we add it */
 382         op->op_array[op->op_count] = idx;
 383         op->op_count++;
 384         EXIT;
 385 out:
 386         up_write(&op->op_rw_sem);
 387         return rc;
 388 }
 389
 390 int lod_ost_pool_remove(struct ost_pool *op, __u32 idx)
 391 {
 392         int i;
 393         ENTRY;
 394
 395         down_write(&op->op_rw_sem);
 396
 397         for (i = 0; i < op->op_count; i++) {
 398                 if (op->op_array[i] == idx) {
 399                         memmove(&op->op_array[i], &op->op_array[i + 1],
 400                                 (op->op_count - i - 1) * sizeof(op->op_array[0]));
 401                         op->op_count--;
 402                         up_write(&op->op_rw_sem);
 403                         EXIT;
 404                         return 0;
 405                 }
 406         }
 407
 408         up_write(&op->op_rw_sem);
 409         RETURN(-EINVAL);
 410 }
 411
 412 int lod_ost_pool_free(struct ost_pool *op)
 413 {
 414         ENTRY;
 415
 416         if (op->op_size == 0)
 417                 RETURN(0);
 418
 419         down_write(&op->op_rw_sem);
 420
 421         OBD_FREE(op->op_array, op->op_size * sizeof(op->op_array[0]));
 422         op->op_array = NULL;
 423         op->op_count = 0;
 424         op->op_size = 0;
 425
 426         up_write(&op->op_rw_sem);
 427         RETURN(0);
 428 }
 429
 430 int lod_pool_new(struct obd_device *obd, char *poolname)
 431 {
 432         struct lod_device *lod = lu2lod_dev(obd->obd_lu_dev);
 433         struct pool_desc  *new_pool;
 434         int rc;
 435         ENTRY;
 436
 437         if (strlen(poolname) > LOV_MAXPOOLNAME)
 438                 RETURN(-ENAMETOOLONG);
 439
 440         OBD_ALLOC_PTR(new_pool);
 441         if (new_pool == NULL)
 442                 RETURN(-ENOMEM);
 443
 444         strlcpy(new_pool->pool_name, poolname, sizeof(new_pool->pool_name));
 445         new_pool->pool_lobd = obd;
 446         /* ref count init to 1 because when created a pool is always used
 447          * up to deletion
 448          */
 449         atomic_set(&new_pool->pool_refcount, 1);
 450         rc = lod_ost_pool_init(&new_pool->pool_obds, 0);
 451         if (rc)
 452                 GOTO(out_err, rc);
 453
 454         memset(&new_pool->pool_rr, 0, sizeof(new_pool->pool_rr));
 455         rc = lod_ost_pool_init(&new_pool->pool_rr.lqr_pool, 0);
 456         if (rc)
 457                 GOTO(out_free_pool_obds, rc);
 458
 459         INIT_HLIST_NODE(&new_pool->pool_hash);
 460
 461 #ifdef LPROCFS
 462         lod_pool_getref(new_pool);
 463         new_pool->pool_proc_entry = lprocfs_add_simple(lod->lod_pool_proc_entry,
 464                                                        poolname,
 465 #ifndef HAVE_ONLY_PROCFS_SEQ
 466                                                        NULL, NULL,
 467 #endif
 468                                                        new_pool,
 469                                                        &pool_proc_operations);
 470         if (IS_ERR(new_pool->pool_proc_entry)) {
 471                 CDEBUG(D_CONFIG, "%s: cannot add proc entry "LOV_POOLNAMEF"\n",
 472                        obd->obd_name, poolname);
 473                 new_pool->pool_proc_entry = NULL;
 474                 lod_pool_putref(new_pool);
 475         }
 476         CDEBUG(D_INFO, "pool %p - proc %p\n", new_pool,
 477                new_pool->pool_proc_entry);
 478 #endif
 479
 480         spin_lock(&obd->obd_dev_lock);
 481         cfs_list_add_tail(&new_pool->pool_list, &lod->lod_pool_list);
 482         lod->lod_pool_count++;
 483         spin_unlock(&obd->obd_dev_lock);
 484
 485         /* add to find only when it fully ready  */
 486         rc = cfs_hash_add_unique(lod->lod_pools_hash_body, poolname,
 487                                  &new_pool->pool_hash);
 488         if (rc)
 489                 GOTO(out_err, rc = -EEXIST);
 490
 491         CDEBUG(D_CONFIG, LOV_POOLNAMEF" is pool #%d\n",
 492                         poolname, lod->lod_pool_count);
 493
 494         RETURN(0);
 495
 496 out_err:
 497         spin_lock(&obd->obd_dev_lock);
 498         cfs_list_del_init(&new_pool->pool_list);
 499         lod->lod_pool_count--;
 500         spin_unlock(&obd->obd_dev_lock);
 501
 502         lprocfs_remove(&new_pool->pool_proc_entry);
 503
 504         lod_ost_pool_free(&new_pool->pool_rr.lqr_pool);
 505 out_free_pool_obds:
 506         lod_ost_pool_free(&new_pool->pool_obds);
 507         OBD_FREE_PTR(new_pool);
 508         return rc;
 509 }
 510
 511 int lod_pool_del(struct obd_device *obd, char *poolname)
 512 {
 513         struct lod_device *lod = lu2lod_dev(obd->obd_lu_dev);
 514         struct pool_desc  *pool;
 515         ENTRY;
 516
 517         /* lookup and kill hash reference */
 518         pool = cfs_hash_del_key(lod->lod_pools_hash_body, poolname);
 519         if (pool == NULL)
 520                 RETURN(-ENOENT);
 521
 522         if (pool->pool_proc_entry != NULL) {
 523                 CDEBUG(D_INFO, "proc entry %p\n", pool->pool_proc_entry);
 524                 lprocfs_remove(&pool->pool_proc_entry);
 525                 lod_pool_putref(pool);
 526         }
 527
 528         spin_lock(&obd->obd_dev_lock);
 529         cfs_list_del_init(&pool->pool_list);
 530         lod->lod_pool_count--;
 531         spin_unlock(&obd->obd_dev_lock);
 532
 533         /* release last reference */
 534         lod_pool_putref(pool);
 535
 536         RETURN(0);
 537 }
 538
 539
 540 int lod_pool_add(struct obd_device *obd, char *poolname, char *ostname)
 541 {
 542         struct lod_device *lod = lu2lod_dev(obd->obd_lu_dev);
 543         struct obd_uuid    ost_uuid;
 544         struct pool_desc  *pool;
 545         unsigned int       idx;
 546         int                rc = -EINVAL;
 547         ENTRY;
 548
 549         pool = cfs_hash_lookup(lod->lod_pools_hash_body, poolname);
 550         if (pool == NULL)
 551                 RETURN(-ENOENT);
 552
 553         obd_str2uuid(&ost_uuid, ostname);
 554
 555         /* search ost in lod array */
 556         lod_getref(&lod->lod_ost_descs);
 557         lod_foreach_ost(lod, idx) {
 558                 if (obd_uuid_equals(&ost_uuid, &OST_TGT(lod, idx)->ltd_uuid)) {
 559                         rc = 0;
 560                         break;
 561                 }
 562         }
 563
 564         if (rc)
 565                 GOTO(out, rc);
 566
 567         rc = lod_ost_pool_add(&pool->pool_obds, idx, lod->lod_osts_size);
 568         if (rc)
 569                 GOTO(out, rc);
 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         EXIT;
 577 out:
 578         lod_putref(lod, &lod->lod_ost_descs);
 579         lod_pool_putref(pool);
 580         return rc;
 581 }
 582
 583 int lod_pool_remove(struct obd_device *obd, char *poolname, char *ostname)
 584 {
 585         struct lod_device *lod = lu2lod_dev(obd->obd_lu_dev);
 586         struct obd_uuid    ost_uuid;
 587         struct pool_desc  *pool;
 588         unsigned int       idx;
 589         int                rc = -EINVAL;
 590         ENTRY;
 591
 592         pool = cfs_hash_lookup(lod->lod_pools_hash_body, poolname);
 593         if (pool == NULL)
 594                 RETURN(-ENOENT);
 595
 596         obd_str2uuid(&ost_uuid, ostname);
 597
 598         lod_getref(&lod->lod_ost_descs);
 599         /* search ost in lod array, to get index */
 600         cfs_foreach_bit(lod->lod_ost_bitmap, idx) {
 601                 if (obd_uuid_equals(&ost_uuid, &OST_TGT(lod, idx)->ltd_uuid)) {
 602                         rc = 0;
 603                         break;
 604                 }
 605         }
 606
 607         /* test if ost found in lod array */
 608         if (rc)
 609                 GOTO(out, rc);
 610
 611         lod_ost_pool_remove(&pool->pool_obds, idx);
 612
 613         pool->pool_rr.lqr_dirty = 1;
 614
 615         CDEBUG(D_CONFIG, "%s removed from "LOV_POOLNAMEF"\n", ostname,
 616                poolname);
 617
 618         EXIT;
 619 out:
 620         lod_putref(lod, &lod->lod_ost_descs);
 621         lod_pool_putref(pool);
 622         return rc;
 623 }
 624
 625 int lod_check_index_in_pool(__u32 idx, struct pool_desc *pool)
 626 {
 627         int i, rc;
 628         ENTRY;
 629
 630         /* caller may no have a ref on pool if it got the pool
 631          * without calling lod_find_pool() (e.g. go through the lod pool
 632          * list)
 633          */
 634         lod_pool_getref(pool);
 635
 636         down_read(&pool_tgt_rw_sem(pool));
 637
 638         for (i = 0; i < pool_tgt_count(pool); i++) {
 639                 if (pool_tgt_array(pool)[i] == idx)
 640                         GOTO(out, rc = 0);
 641         }
 642         rc = -ENOENT;
 643         EXIT;
 644 out:
 645         up_read(&pool_tgt_rw_sem(pool));
 646
 647         lod_pool_putref(pool);
 648         return rc;
 649 }
 650
 651 struct pool_desc *lod_find_pool(struct lod_device *lod, char *poolname)
 652 {
 653         struct pool_desc *pool;
 654
 655         pool = NULL;
 656         if (poolname[0] != '\0') {
 657                 pool = cfs_hash_lookup(lod->lod_pools_hash_body, poolname);
 658                 if (pool == NULL)
 659                         CDEBUG(D_CONFIG, "%s: request for an unknown pool ("
 660                                LOV_POOLNAMEF")\n",
 661                                lod->lod_child_exp->exp_obd->obd_name, poolname);
 662                 if (pool != NULL && pool_tgt_count(pool) == 0) {
 663                         CDEBUG(D_CONFIG, "%s: request for an empty pool ("
 664                                LOV_POOLNAMEF")\n",
 665                                lod->lod_child_exp->exp_obd->obd_name, poolname);
 666                         /* pool is ignored, so we remove ref on it */
 667                         lod_pool_putref(pool);
 668                         pool = NULL;
 669                 }
 670         }
 671         return pool;
 672 }
 673