drivers/staging/lustre/lustre/fld/fld_cache.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  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) 2007, 2010, Oracle and/or its affiliates. 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/fld/fld_cache.c
  37  *
  38  * FLD (Fids Location Database)
  39  *
  40  * Author: Pravin Shelar <pravin.shelar@sun.com>
  41  * Author: Yury Umanets <umka@clusterfs.com>
  42  */
  43
  44 #define DEBUG_SUBSYSTEM S_FLD
  45
  46 #include "../../include/linux/libcfs/libcfs.h"
  47 #include <linux/module.h>
  48 #include <asm/div64.h>
  49
  50 #include "../include/obd.h"
  51 #include "../include/obd_class.h"
  52 #include "../include/lustre_ver.h"
  53 #include "../include/obd_support.h"
  54 #include "../include/lprocfs_status.h"
  55
  56 #include "../include/lustre_req_layout.h"
  57 #include "../include/lustre_fld.h"
  58 #include "fld_internal.h"
  59
  60 /**
  61  * create fld cache.
  62  */
  63 struct fld_cache *fld_cache_init(const char *name,
  64                                  int cache_size, int cache_threshold)
  65 {
  66         struct fld_cache *cache;
  67
  68         LASSERT(name);
  69         LASSERT(cache_threshold < cache_size);
  70
  71         cache = kzalloc(sizeof(*cache), GFP_NOFS);
  72         if (!cache)
  73                 return ERR_PTR(-ENOMEM);
  74
  75         INIT_LIST_HEAD(&cache->fci_entries_head);
  76         INIT_LIST_HEAD(&cache->fci_lru);
  77
  78         cache->fci_cache_count = 0;
  79         rwlock_init(&cache->fci_lock);
  80
  81         strlcpy(cache->fci_name, name,
  82                 sizeof(cache->fci_name));
  83
  84         cache->fci_cache_size = cache_size;
  85         cache->fci_threshold = cache_threshold;
  86
  87         /* Init fld cache info. */
  88         memset(&cache->fci_stat, 0, sizeof(cache->fci_stat));
  89
  90         CDEBUG(D_INFO, "%s: FLD cache - Size: %d, Threshold: %d\n",
  91                cache->fci_name, cache_size, cache_threshold);
  92
  93         return cache;
  94 }
  95
  96 /**
  97  * destroy fld cache.
  98  */
  99 void fld_cache_fini(struct fld_cache *cache)
 100 {
 101         __u64 pct;
 102
 103         LASSERT(cache);
 104         fld_cache_flush(cache);
 105
 106         if (cache->fci_stat.fst_count > 0) {
 107                 pct = cache->fci_stat.fst_cache * 100;
 108                 do_div(pct, cache->fci_stat.fst_count);
 109         } else {
 110                 pct = 0;
 111         }
 112
 113         CDEBUG(D_INFO, "FLD cache statistics (%s):\n", cache->fci_name);
 114         CDEBUG(D_INFO, "  Total reqs: %llu\n", cache->fci_stat.fst_count);
 115         CDEBUG(D_INFO, "  Cache reqs: %llu\n", cache->fci_stat.fst_cache);
 116         CDEBUG(D_INFO, "  Cache hits: %llu%%\n", pct);
 117
 118         kfree(cache);
 119 }
 120
 121 /**
 122  * delete given node from list.
 123  */
 124 static void fld_cache_entry_delete(struct fld_cache *cache,
 125                                    struct fld_cache_entry *node)
 126 {
 127         list_del(&node->fce_list);
 128         list_del(&node->fce_lru);
 129         cache->fci_cache_count--;
 130         kfree(node);
 131 }
 132
 133 /**
 134  * fix list by checking new entry with NEXT entry in order.
 135  */
 136 static void fld_fix_new_list(struct fld_cache *cache)
 137 {
 138         struct fld_cache_entry *f_curr;
 139         struct fld_cache_entry *f_next;
 140         struct lu_seq_range *c_range;
 141         struct lu_seq_range *n_range;
 142         struct list_head *head = &cache->fci_entries_head;
 143
 144 restart_fixup:
 145
 146         list_for_each_entry_safe(f_curr, f_next, head, fce_list) {
 147                 c_range = &f_curr->fce_range;
 148                 n_range = &f_next->fce_range;
 149
 150                 LASSERT(range_is_sane(c_range));
 151                 if (&f_next->fce_list == head)
 152                         break;
 153
 154                 if (c_range->lsr_flags != n_range->lsr_flags)
 155                         continue;
 156
 157                 LASSERTF(c_range->lsr_start <= n_range->lsr_start,
 158                          "cur lsr_start "DRANGE" next lsr_start "DRANGE"\n",
 159                          PRANGE(c_range), PRANGE(n_range));
 160
 161                 /* check merge possibility with next range */
 162                 if (c_range->lsr_end == n_range->lsr_start) {
 163                         if (c_range->lsr_index != n_range->lsr_index)
 164                                 continue;
 165                         n_range->lsr_start = c_range->lsr_start;
 166                         fld_cache_entry_delete(cache, f_curr);
 167                         continue;
 168                 }
 169
 170                 /* check if current range overlaps with next range. */
 171                 if (n_range->lsr_start < c_range->lsr_end) {
 172                         if (c_range->lsr_index == n_range->lsr_index) {
 173                                 n_range->lsr_start = c_range->lsr_start;
 174                                 n_range->lsr_end = max(c_range->lsr_end,
 175                                                        n_range->lsr_end);
 176                                 fld_cache_entry_delete(cache, f_curr);
 177                         } else {
 178                                 if (n_range->lsr_end <= c_range->lsr_end) {
 179                                         *n_range = *c_range;
 180                                         fld_cache_entry_delete(cache, f_curr);
 181                                 } else {
 182                                         n_range->lsr_start = c_range->lsr_end;
 183                                 }
 184                         }
 185
 186                         /* we could have overlap over next
 187                          * range too. better restart.
 188                          */
 189                         goto restart_fixup;
 190                 }
 191
 192                 /* kill duplicates */
 193                 if (c_range->lsr_start == n_range->lsr_start &&
 194                     c_range->lsr_end == n_range->lsr_end)
 195                         fld_cache_entry_delete(cache, f_curr);
 196         }
 197 }
 198
 199 /**
 200  * add node to fld cache
 201  */
 202 static inline void fld_cache_entry_add(struct fld_cache *cache,
 203                                        struct fld_cache_entry *f_new,
 204                                        struct list_head *pos)
 205 {
 206         list_add(&f_new->fce_list, pos);
 207         list_add(&f_new->fce_lru, &cache->fci_lru);
 208
 209         cache->fci_cache_count++;
 210         fld_fix_new_list(cache);
 211 }
 212
 213 /**
 214  * Check if cache needs to be shrunk. If so - do it.
 215  * Remove one entry in list and so on until cache is shrunk enough.
 216  */
 217 static int fld_cache_shrink(struct fld_cache *cache)
 218 {
 219         struct fld_cache_entry *flde;
 220         struct list_head *curr;
 221         int num = 0;
 222
 223         if (cache->fci_cache_count < cache->fci_cache_size)
 224                 return 0;
 225
 226         curr = cache->fci_lru.prev;
 227
 228         while (cache->fci_cache_count + cache->fci_threshold >
 229                cache->fci_cache_size && curr != &cache->fci_lru) {
 230                 flde = list_entry(curr, struct fld_cache_entry, fce_lru);
 231                 curr = curr->prev;
 232                 fld_cache_entry_delete(cache, flde);
 233                 num++;
 234         }
 235
 236         CDEBUG(D_INFO, "%s: FLD cache - Shrunk by %d entries\n",
 237                cache->fci_name, num);
 238
 239         return 0;
 240 }
 241
 242 /**
 243  * kill all fld cache entries.
 244  */
 245 void fld_cache_flush(struct fld_cache *cache)
 246 {
 247         write_lock(&cache->fci_lock);
 248         cache->fci_cache_size = 0;
 249         fld_cache_shrink(cache);
 250         write_unlock(&cache->fci_lock);
 251 }
 252
 253 /**
 254  * punch hole in existing range. divide this range and add new
 255  * entry accordingly.
 256  */
 257
 258 static void fld_cache_punch_hole(struct fld_cache *cache,
 259                                  struct fld_cache_entry *f_curr,
 260                                  struct fld_cache_entry *f_new)
 261 {
 262         const struct lu_seq_range *range = &f_new->fce_range;
 263         const u64 new_start  = range->lsr_start;
 264         const u64 new_end  = range->lsr_end;
 265         struct fld_cache_entry *fldt;
 266
 267         fldt = kzalloc(sizeof(*fldt), GFP_ATOMIC);
 268         if (!fldt) {
 269                 kfree(f_new);
 270                 /* overlap is not allowed, so dont mess up list. */
 271                 return;
 272         }
 273         /*  break f_curr RANGE into three RANGES:
 274          *      f_curr, f_new , fldt
 275          */
 276
 277         /* f_new = *range */
 278
 279         /* fldt */
 280         fldt->fce_range.lsr_start = new_end;
 281         fldt->fce_range.lsr_end = f_curr->fce_range.lsr_end;
 282         fldt->fce_range.lsr_index = f_curr->fce_range.lsr_index;
 283
 284         /* f_curr */
 285         f_curr->fce_range.lsr_end = new_start;
 286
 287         /* add these two entries to list */
 288         fld_cache_entry_add(cache, f_new, &f_curr->fce_list);
 289         fld_cache_entry_add(cache, fldt, &f_new->fce_list);
 290
 291         /* no need to fixup */
 292 }
 293
 294 /**
 295  * handle range overlap in fld cache.
 296  */
 297 static void fld_cache_overlap_handle(struct fld_cache *cache,
 298                                      struct fld_cache_entry *f_curr,
 299                                      struct fld_cache_entry *f_new)
 300 {
 301         const struct lu_seq_range *range = &f_new->fce_range;
 302         const u64 new_start  = range->lsr_start;
 303         const u64 new_end  = range->lsr_end;
 304         const u32 mdt = range->lsr_index;
 305
 306         /* this is overlap case, these case are checking overlapping with
 307          * prev range only. fixup will handle overlapping with next range.
 308          */
 309
 310         if (f_curr->fce_range.lsr_index == mdt) {
 311                 f_curr->fce_range.lsr_start = min(f_curr->fce_range.lsr_start,
 312                                                   new_start);
 313
 314                 f_curr->fce_range.lsr_end = max(f_curr->fce_range.lsr_end,
 315                                                 new_end);
 316
 317                 kfree(f_new);
 318                 fld_fix_new_list(cache);
 319
 320         } else if (new_start <= f_curr->fce_range.lsr_start &&
 321                         f_curr->fce_range.lsr_end <= new_end) {
 322                 /* case 1: new range completely overshadowed existing range.
 323                  *       e.g. whole range migrated. update fld cache entry
 324                  */
 325
 326                 f_curr->fce_range = *range;
 327                 kfree(f_new);
 328                 fld_fix_new_list(cache);
 329
 330         } else if (f_curr->fce_range.lsr_start < new_start &&
 331                         new_end < f_curr->fce_range.lsr_end) {
 332                 /* case 2: new range fit within existing range. */
 333
 334                 fld_cache_punch_hole(cache, f_curr, f_new);
 335
 336         } else  if (new_end <= f_curr->fce_range.lsr_end) {
 337                 /* case 3: overlap:
 338                  *       [new_start [c_start  new_end)  c_end)
 339                  */
 340
 341                 LASSERT(new_start <= f_curr->fce_range.lsr_start);
 342
 343                 f_curr->fce_range.lsr_start = new_end;
 344                 fld_cache_entry_add(cache, f_new, f_curr->fce_list.prev);
 345
 346         } else if (f_curr->fce_range.lsr_start <= new_start) {
 347                 /* case 4: overlap:
 348                  *       [c_start [new_start c_end) new_end)
 349                  */
 350
 351                 LASSERT(f_curr->fce_range.lsr_end <= new_end);
 352
 353                 f_curr->fce_range.lsr_end = new_start;
 354                 fld_cache_entry_add(cache, f_new, &f_curr->fce_list);
 355         } else
 356                 CERROR("NEW range ="DRANGE" curr = "DRANGE"\n",
 357                        PRANGE(range), PRANGE(&f_curr->fce_range));
 358 }
 359
 360 struct fld_cache_entry
 361 *fld_cache_entry_create(const struct lu_seq_range *range)
 362 {
 363         struct fld_cache_entry *f_new;
 364
 365         LASSERT(range_is_sane(range));
 366
 367         f_new = kzalloc(sizeof(*f_new), GFP_NOFS);
 368         if (!f_new)
 369                 return ERR_PTR(-ENOMEM);
 370
 371         f_new->fce_range = *range;
 372         return f_new;
 373 }
 374
 375 /**
 376  * Insert FLD entry in FLD cache.
 377  *
 378  * This function handles all cases of merging and breaking up of
 379  * ranges.
 380  */
 381 static int fld_cache_insert_nolock(struct fld_cache *cache,
 382                                    struct fld_cache_entry *f_new)
 383 {
 384         struct fld_cache_entry *f_curr;
 385         struct fld_cache_entry *n;
 386         struct list_head *head;
 387         struct list_head *prev = NULL;
 388         const u64 new_start  = f_new->fce_range.lsr_start;
 389         const u64 new_end  = f_new->fce_range.lsr_end;
 390         __u32 new_flags  = f_new->fce_range.lsr_flags;
 391
 392         /*
 393          * Duplicate entries are eliminated in insert op.
 394          * So we don't need to search new entry before starting
 395          * insertion loop.
 396          */
 397
 398         if (!cache->fci_no_shrink)
 399                 fld_cache_shrink(cache);
 400
 401         head = &cache->fci_entries_head;
 402
 403         list_for_each_entry_safe(f_curr, n, head, fce_list) {
 404                 /* add list if next is end of list */
 405                 if (new_end < f_curr->fce_range.lsr_start ||
 406                     (new_end == f_curr->fce_range.lsr_start &&
 407                      new_flags != f_curr->fce_range.lsr_flags))
 408                         break;
 409
 410                 prev = &f_curr->fce_list;
 411                 /* check if this range is to left of new range. */
 412                 if (new_start < f_curr->fce_range.lsr_end &&
 413                     new_flags == f_curr->fce_range.lsr_flags) {
 414                         fld_cache_overlap_handle(cache, f_curr, f_new);
 415                         goto out;
 416                 }
 417         }
 418
 419         if (!prev)
 420                 prev = head;
 421
 422         CDEBUG(D_INFO, "insert range "DRANGE"\n", PRANGE(&f_new->fce_range));
 423         /* Add new entry to cache and lru list. */
 424         fld_cache_entry_add(cache, f_new, prev);
 425 out:
 426         return 0;
 427 }
 428
 429 int fld_cache_insert(struct fld_cache *cache,
 430                      const struct lu_seq_range *range)
 431 {
 432         struct fld_cache_entry  *flde;
 433         int rc;
 434
 435         flde = fld_cache_entry_create(range);
 436         if (IS_ERR(flde))
 437                 return PTR_ERR(flde);
 438
 439         write_lock(&cache->fci_lock);
 440         rc = fld_cache_insert_nolock(cache, flde);
 441         write_unlock(&cache->fci_lock);
 442         if (rc)
 443                 kfree(flde);
 444
 445         return rc;
 446 }
 447
 448 /**
 449  * Delete FLD entry in FLD cache.
 450  *
 451  */
 452
 453 struct fld_cache_entry
 454 *fld_cache_entry_lookup_nolock(struct fld_cache *cache,
 455                               struct lu_seq_range *range)
 456 {
 457         struct fld_cache_entry *flde;
 458         struct fld_cache_entry *got = NULL;
 459         struct list_head *head;
 460
 461         head = &cache->fci_entries_head;
 462         list_for_each_entry(flde, head, fce_list) {
 463                 if (range->lsr_start == flde->fce_range.lsr_start ||
 464                     (range->lsr_end == flde->fce_range.lsr_end &&
 465                      range->lsr_flags == flde->fce_range.lsr_flags)) {
 466                         got = flde;
 467                         break;
 468                 }
 469         }
 470
 471         return got;
 472 }
 473
 474 /**
 475  * lookup \a seq sequence for range in fld cache.
 476  */
 477 struct fld_cache_entry
 478 *fld_cache_entry_lookup(struct fld_cache *cache, struct lu_seq_range *range)
 479 {
 480         struct fld_cache_entry *got = NULL;
 481
 482         read_lock(&cache->fci_lock);
 483         got = fld_cache_entry_lookup_nolock(cache, range);
 484         read_unlock(&cache->fci_lock);
 485         return got;
 486 }
 487
 488 /**
 489  * lookup \a seq sequence for range in fld cache.
 490  */
 491 int fld_cache_lookup(struct fld_cache *cache,
 492                      const u64 seq, struct lu_seq_range *range)
 493 {
 494         struct fld_cache_entry *flde;
 495         struct fld_cache_entry *prev = NULL;
 496         struct list_head *head;
 497
 498         read_lock(&cache->fci_lock);
 499         head = &cache->fci_entries_head;
 500
 501         cache->fci_stat.fst_count++;
 502         list_for_each_entry(flde, head, fce_list) {
 503                 if (flde->fce_range.lsr_start > seq) {
 504                         if (prev)
 505                                 *range = prev->fce_range;
 506                         break;
 507                 }
 508
 509                 prev = flde;
 510                 if (range_within(&flde->fce_range, seq)) {
 511                         *range = flde->fce_range;
 512
 513                         cache->fci_stat.fst_cache++;
 514                         read_unlock(&cache->fci_lock);
 515                         return 0;
 516                 }
 517         }
 518         read_unlock(&cache->fci_lock);
 519         return -ENOENT;
 520 }