fs/ocfs2/extent_map.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * extent_map.c
   5  *
   6  * In-memory extent map for OCFS2.  Man, this code was prettier in
   7  * the library.
   8  *
   9  * Copyright (C) 2004 Oracle.  All rights reserved.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public
  13  * License, version 2,  as published by the Free Software Foundation.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public
  21  * License along with this program; if not, write to the
  22  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23  * Boston, MA 021110-1307, USA.
  24  */
  25
  26 #include <linux/fs.h>
  27 #include <linux/init.h>
  28 #include <linux/types.h>
  29 #include <linux/slab.h>
  30 #include <linux/rbtree.h>
  31
  32 #define MLOG_MASK_PREFIX ML_EXTENT_MAP
  33 #include <cluster/masklog.h>
  34
  35 #include "ocfs2.h"
  36
  37 #include "extent_map.h"
  38 #include "inode.h"
  39 #include "super.h"
  40
  41 #include "buffer_head_io.h"
  42
  43
  44 /*
  45  * SUCK SUCK SUCK
  46  * Our headers are so bad that struct ocfs2_extent_map is in ocfs.h
  47  */
  48
  49 struct ocfs2_extent_map_entry {
  50         struct rb_node e_node;
  51         int e_tree_depth;
  52         struct ocfs2_extent_rec e_rec;
  53 };
  54
  55 struct ocfs2_em_insert_context {
  56         int need_left;
  57         int need_right;
  58         struct ocfs2_extent_map_entry *new_ent;
  59         struct ocfs2_extent_map_entry *old_ent;
  60         struct ocfs2_extent_map_entry *left_ent;
  61         struct ocfs2_extent_map_entry *right_ent;
  62 };
  63
  64 static kmem_cache_t *ocfs2_em_ent_cachep = NULL;
  65
  66
  67 static struct ocfs2_extent_map_entry *
  68 ocfs2_extent_map_lookup(struct ocfs2_extent_map *em,
  69                         u32 cpos, u32 clusters,
  70                         struct rb_node ***ret_p,
  71                         struct rb_node **ret_parent);
  72 static int ocfs2_extent_map_insert(struct inode *inode,
  73                                    struct ocfs2_extent_rec *rec,
  74                                    int tree_depth);
  75 static int ocfs2_extent_map_insert_entry(struct ocfs2_extent_map *em,
  76                                          struct ocfs2_extent_map_entry *ent);
  77 static int ocfs2_extent_map_find_leaf(struct inode *inode,
  78                                       u32 cpos, u32 clusters,
  79                                       struct ocfs2_extent_list *el);
  80 static int ocfs2_extent_map_lookup_read(struct inode *inode,
  81                                         u32 cpos, u32 clusters,
  82                                         struct ocfs2_extent_map_entry **ret_ent);
  83 static int ocfs2_extent_map_try_insert(struct inode *inode,
  84                                        struct ocfs2_extent_rec *rec,
  85                                        int tree_depth,
  86                                        struct ocfs2_em_insert_context *ctxt);
  87
  88 /* returns 1 only if the rec contains all the given clusters -- that is that
  89  * rec's cpos is <= the cluster cpos and that the rec endpoint (cpos +
  90  * clusters) is >= the argument's endpoint */
  91 static int ocfs2_extent_rec_contains_clusters(struct ocfs2_extent_rec *rec,
  92                                               u32 cpos, u32 clusters)
  93 {
  94         if (le32_to_cpu(rec->e_cpos) > cpos)
  95                 return 0;
  96         if (cpos + clusters > le32_to_cpu(rec->e_cpos) +
  97                               le32_to_cpu(rec->e_clusters))
  98                 return 0;
  99         return 1;
 100 }
 101
 102
 103 /*
 104  * Find an entry in the tree that intersects the region passed in.
 105  * Note that this will find straddled intervals, it is up to the
 106  * callers to enforce any boundary conditions.
 107  *
 108  * Callers must hold ip_lock.  This lookup is not guaranteed to return
 109  * a tree_depth 0 match, and as such can race inserts if the lock
 110  * were not held.
 111  *
 112  * The rb_node garbage lets insertion share the search.  Trivial
 113  * callers pass NULL.
 114  */
 115 static struct ocfs2_extent_map_entry *
 116 ocfs2_extent_map_lookup(struct ocfs2_extent_map *em,
 117                         u32 cpos, u32 clusters,
 118                         struct rb_node ***ret_p,
 119                         struct rb_node **ret_parent)
 120 {
 121         struct rb_node **p = &em->em_extents.rb_node;
 122         struct rb_node *parent = NULL;
 123         struct ocfs2_extent_map_entry *ent = NULL;
 124
 125         while (*p)
 126         {
 127                 parent = *p;
 128                 ent = rb_entry(parent, struct ocfs2_extent_map_entry,
 129                                e_node);
 130                 if ((cpos + clusters) <= le32_to_cpu(ent->e_rec.e_cpos)) {
 131                         p = &(*p)->rb_left;
 132                         ent = NULL;
 133                 } else if (cpos >= (le32_to_cpu(ent->e_rec.e_cpos) +
 134                                     le32_to_cpu(ent->e_rec.e_clusters))) {
 135                         p = &(*p)->rb_right;
 136                         ent = NULL;
 137                 } else
 138                         break;
 139         }
 140
 141         if (ret_p != NULL)
 142                 *ret_p = p;
 143         if (ret_parent != NULL)
 144                 *ret_parent = parent;
 145         return ent;
 146 }
 147
 148 /*
 149  * Find the leaf containing the interval we want.  While we're on our
 150  * way down the tree, fill in every record we see at any depth, because
 151  * we might want it later.
 152  *
 153  * Note that this code is run without ip_lock.  That's because it
 154  * sleeps while reading.  If someone is also filling the extent list at
 155  * the same time we are, we might have to restart.
 156  */
 157 static int ocfs2_extent_map_find_leaf(struct inode *inode,
 158                                       u32 cpos, u32 clusters,
 159                                       struct ocfs2_extent_list *el)
 160 {
 161         int i, ret;
 162         struct buffer_head *eb_bh = NULL;
 163         u64 blkno;
 164         u32 rec_end;
 165         struct ocfs2_extent_block *eb;
 166         struct ocfs2_extent_rec *rec;
 167
 168         /*
 169          * The bh data containing the el cannot change here, because
 170          * we hold alloc_sem.  So we can do this without other
 171          * locks.
 172          */
 173         while (el->l_tree_depth)
 174         {
 175                 blkno = 0;
 176                 for (i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
 177                         rec = &el->l_recs[i];
 178                         rec_end = (le32_to_cpu(rec->e_cpos) +
 179                                    le32_to_cpu(rec->e_clusters));
 180
 181                         ret = -EBADR;
 182                         if (rec_end > OCFS2_I(inode)->ip_clusters) {
 183                                 mlog_errno(ret);
 184                                 ocfs2_error(inode->i_sb,
 185                                             "Extent %d at e_blkno %llu of inode %llu goes past ip_clusters of %u\n",
 186                                             i,
 187                                             (unsigned long long)le64_to_cpu(rec->e_blkno),
 188                                             (unsigned long long)OCFS2_I(inode)->ip_blkno,
 189                                             OCFS2_I(inode)->ip_clusters);
 190                                 goto out_free;
 191                         }
 192
 193                         if (rec_end <= cpos) {
 194                                 ret = ocfs2_extent_map_insert(inode, rec,
 195                                                 le16_to_cpu(el->l_tree_depth));
 196                                 if (ret && (ret != -EEXIST)) {
 197                                         mlog_errno(ret);
 198                                         goto out_free;
 199                                 }
 200                                 continue;
 201                         }
 202                         if ((cpos + clusters) <= le32_to_cpu(rec->e_cpos)) {
 203                                 ret = ocfs2_extent_map_insert(inode, rec,
 204                                                 le16_to_cpu(el->l_tree_depth));
 205                                 if (ret && (ret != -EEXIST)) {
 206                                         mlog_errno(ret);
 207                                         goto out_free;
 208                                 }
 209                                 continue;
 210                         }
 211
 212                         /*
 213                          * We've found a record that matches our
 214                          * interval.  We don't insert it because we're
 215                          * about to traverse it.
 216                          */
 217
 218                         /* Check to see if we're stradling */
 219                         ret = -ESRCH;
 220                         if (!ocfs2_extent_rec_contains_clusters(rec,
 221                                                                 cpos,
 222                                                                 clusters)) {
 223                                 mlog_errno(ret);
 224                                 goto out_free;
 225                         }
 226
 227                         /*
 228                          * If we've already found a record, the el has
 229                          * two records covering the same interval.
 230                          * EEEK!
 231                          */
 232                         ret = -EBADR;
 233                         if (blkno) {
 234                                 mlog_errno(ret);
 235                                 ocfs2_error(inode->i_sb,
 236                                             "Multiple extents for (cpos = %u, clusters = %u) on inode %llu; e_blkno %llu and rec %d at e_blkno %llu\n",
 237                                             cpos, clusters,
 238                                             (unsigned long long)OCFS2_I(inode)->ip_blkno,
 239                                             (unsigned long long)blkno, i,
 240                                             (unsigned long long)le64_to_cpu(rec->e_blkno));
 241                                 goto out_free;
 242                         }
 243
 244                         blkno = le64_to_cpu(rec->e_blkno);
 245                 }
 246
 247                 /*
 248                  * We don't support holes, and we're still up
 249                  * in the branches, so we'd better have found someone
 250                  */
 251                 ret = -EBADR;
 252                 if (!blkno) {
 253                         ocfs2_error(inode->i_sb,
 254                                     "No record found for (cpos = %u, clusters = %u) on inode %llu\n",
 255                                     cpos, clusters,
 256                                     (unsigned long long)OCFS2_I(inode)->ip_blkno);
 257                         mlog_errno(ret);
 258                         goto out_free;
 259                 }
 260
 261                 if (eb_bh) {
 262                         brelse(eb_bh);
 263                         eb_bh = NULL;
 264                 }
 265                 ret = ocfs2_read_block(OCFS2_SB(inode->i_sb),
 266                                        blkno, &eb_bh, OCFS2_BH_CACHED,
 267                                        inode);
 268                 if (ret) {
 269                         mlog_errno(ret);
 270                         goto out_free;
 271                 }
 272                 eb = (struct ocfs2_extent_block *)eb_bh->b_data;
 273                 if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
 274                         OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, eb);
 275                         ret = -EIO;
 276                         goto out_free;
 277                 }
 278                 el = &eb->h_list;
 279         }
 280
 281         BUG_ON(el->l_tree_depth);
 282
 283         for (i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
 284                 rec = &el->l_recs[i];
 285
 286                 if ((le32_to_cpu(rec->e_cpos) + le32_to_cpu(rec->e_clusters)) >
 287                     OCFS2_I(inode)->ip_clusters) {
 288                         ret = -EBADR;
 289                         mlog_errno(ret);
 290                         ocfs2_error(inode->i_sb,
 291                                     "Extent %d at e_blkno %llu of inode %llu goes past ip_clusters of %u\n",
 292                                     i,
 293                                     (unsigned long long)le64_to_cpu(rec->e_blkno),
 294                                     (unsigned long long)OCFS2_I(inode)->ip_blkno,
 295                                     OCFS2_I(inode)->ip_clusters);
 296                         return ret;
 297                 }
 298
 299                 ret = ocfs2_extent_map_insert(inode, rec,
 300                                               le16_to_cpu(el->l_tree_depth));
 301                 if (ret) {
 302                         mlog_errno(ret);
 303                         goto out_free;
 304                 }
 305         }
 306
 307         ret = 0;
 308
 309 out_free:
 310         if (eb_bh)
 311                 brelse(eb_bh);
 312
 313         return ret;
 314 }
 315
 316 /*
 317  * This lookup actually will read from disk.  It has one invariant:
 318  * It will never re-traverse blocks.  This means that all inserts should
 319  * be new regions or more granular regions (both allowed by insert).
 320  */
 321 static int ocfs2_extent_map_lookup_read(struct inode *inode,
 322                                         u32 cpos,
 323                                         u32 clusters,
 324                                         struct ocfs2_extent_map_entry **ret_ent)
 325 {
 326         int ret;
 327         u64 blkno;
 328         struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
 329         struct ocfs2_extent_map_entry *ent;
 330         struct buffer_head *bh = NULL;
 331         struct ocfs2_extent_block *eb;
 332         struct ocfs2_dinode *di;
 333         struct ocfs2_extent_list *el;
 334
 335         spin_lock(&OCFS2_I(inode)->ip_lock);
 336         ent = ocfs2_extent_map_lookup(em, cpos, clusters, NULL, NULL);
 337         if (ent) {
 338                 if (!ent->e_tree_depth) {
 339                         spin_unlock(&OCFS2_I(inode)->ip_lock);
 340                         *ret_ent = ent;
 341                         return 0;
 342                 }
 343                 blkno = le64_to_cpu(ent->e_rec.e_blkno);
 344                 spin_unlock(&OCFS2_I(inode)->ip_lock);
 345
 346                 ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), blkno, &bh,
 347                                        OCFS2_BH_CACHED, inode);
 348                 if (ret) {
 349                         mlog_errno(ret);
 350                         if (bh)
 351                                 brelse(bh);
 352                         return ret;
 353                 }
 354                 eb = (struct ocfs2_extent_block *)bh->b_data;
 355                 if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
 356                         OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, eb);
 357                         brelse(bh);
 358                         return -EIO;
 359                 }
 360                 el = &eb->h_list;
 361         } else {
 362                 spin_unlock(&OCFS2_I(inode)->ip_lock);
 363
 364                 ret = ocfs2_read_block(OCFS2_SB(inode->i_sb),
 365                                        OCFS2_I(inode)->ip_blkno, &bh,
 366                                        OCFS2_BH_CACHED, inode);
 367                 if (ret) {
 368                         mlog_errno(ret);
 369                         if (bh)
 370                                 brelse(bh);
 371                         return ret;
 372                 }
 373                 di = (struct ocfs2_dinode *)bh->b_data;
 374                 if (!OCFS2_IS_VALID_DINODE(di)) {
 375                         brelse(bh);
 376                         OCFS2_RO_ON_INVALID_DINODE(inode->i_sb, di);
 377                         return -EIO;
 378                 }
 379                 el = &di->id2.i_list;
 380         }
 381
 382         ret = ocfs2_extent_map_find_leaf(inode, cpos, clusters, el);
 383         brelse(bh);
 384         if (ret) {
 385                 mlog_errno(ret);
 386                 return ret;
 387         }
 388
 389         ent = ocfs2_extent_map_lookup(em, cpos, clusters, NULL, NULL);
 390         if (!ent) {
 391                 ret = -ESRCH;
 392                 mlog_errno(ret);
 393                 return ret;
 394         }
 395
 396         /* FIXME: Make sure this isn't a corruption */
 397         BUG_ON(ent->e_tree_depth);
 398
 399         *ret_ent = ent;
 400
 401         return 0;
 402 }
 403
 404 /*
 405  * Callers must hold ip_lock.  This can insert pieces of the tree,
 406  * thus racing lookup if the lock weren't held.
 407  */
 408 static int ocfs2_extent_map_insert_entry(struct ocfs2_extent_map *em,
 409                                          struct ocfs2_extent_map_entry *ent)
 410 {
 411         struct rb_node **p, *parent;
 412         struct ocfs2_extent_map_entry *old_ent;
 413
 414         old_ent = ocfs2_extent_map_lookup(em, le32_to_cpu(ent->e_rec.e_cpos),
 415                                           le32_to_cpu(ent->e_rec.e_clusters),
 416                                           &p, &parent);
 417         if (old_ent)
 418                 return -EEXIST;
 419
 420         rb_link_node(&ent->e_node, parent, p);
 421         rb_insert_color(&ent->e_node, &em->em_extents);
 422
 423         return 0;
 424 }
 425
 426
 427 /*
 428  * Simple rule: on any return code other than -EAGAIN, anything left
 429  * in the insert_context will be freed.
 430  */
 431 static int ocfs2_extent_map_try_insert(struct inode *inode,
 432                                        struct ocfs2_extent_rec *rec,
 433                                        int tree_depth,
 434                                        struct ocfs2_em_insert_context *ctxt)
 435 {
 436         int ret;
 437         struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
 438         struct ocfs2_extent_map_entry *old_ent;
 439
 440         ctxt->need_left = 0;
 441         ctxt->need_right = 0;
 442         ctxt->old_ent = NULL;
 443
 444         spin_lock(&OCFS2_I(inode)->ip_lock);
 445         ret = ocfs2_extent_map_insert_entry(em, ctxt->new_ent);
 446         if (!ret) {
 447                 ctxt->new_ent = NULL;
 448                 goto out_unlock;
 449         }
 450
 451         old_ent = ocfs2_extent_map_lookup(em, le32_to_cpu(rec->e_cpos),
 452                                           le32_to_cpu(rec->e_clusters), NULL,
 453                                           NULL);
 454
 455         BUG_ON(!old_ent);
 456
 457         ret = -EEXIST;
 458         if (old_ent->e_tree_depth < tree_depth)
 459                 goto out_unlock;
 460
 461         if (old_ent->e_tree_depth == tree_depth) {
 462                 if (!memcmp(rec, &old_ent->e_rec,
 463                             sizeof(struct ocfs2_extent_rec)))
 464                         ret = 0;
 465
 466                 /* FIXME: Should this be ESRCH/EBADR??? */
 467                 goto out_unlock;
 468         }
 469
 470         /*
 471          * We do it in this order specifically so that no actual tree
 472          * changes occur until we have all the pieces we need.  We
 473          * don't want malloc failures to leave an inconsistent tree.
 474          * Whenever we drop the lock, another process could be
 475          * inserting.  Also note that, if another process just beat us
 476          * to an insert, we might not need the same pieces we needed
 477          * the first go round.  In the end, the pieces we need will
 478          * be used, and the pieces we don't will be freed.
 479          */
 480         ctxt->need_left = !!(le32_to_cpu(rec->e_cpos) >
 481                              le32_to_cpu(old_ent->e_rec.e_cpos));
 482         ctxt->need_right = !!((le32_to_cpu(old_ent->e_rec.e_cpos) +
 483                                le32_to_cpu(old_ent->e_rec.e_clusters)) >
 484                               (le32_to_cpu(rec->e_cpos) + le32_to_cpu(rec->e_clusters)));
 485         ret = -EAGAIN;
 486         if (ctxt->need_left) {
 487                 if (!ctxt->left_ent)
 488                         goto out_unlock;
 489                 *(ctxt->left_ent) = *old_ent;
 490                 ctxt->left_ent->e_rec.e_clusters =
 491                         cpu_to_le32(le32_to_cpu(rec->e_cpos) -
 492                                     le32_to_cpu(ctxt->left_ent->e_rec.e_cpos));
 493         }
 494         if (ctxt->need_right) {
 495                 if (!ctxt->right_ent)
 496                         goto out_unlock;
 497                 *(ctxt->right_ent) = *old_ent;
 498                 ctxt->right_ent->e_rec.e_cpos =
 499                         cpu_to_le32(le32_to_cpu(rec->e_cpos) +
 500                                     le32_to_cpu(rec->e_clusters));
 501                 ctxt->right_ent->e_rec.e_clusters =
 502                         cpu_to_le32((le32_to_cpu(old_ent->e_rec.e_cpos) +
 503                                      le32_to_cpu(old_ent->e_rec.e_clusters)) -
 504                                     le32_to_cpu(ctxt->right_ent->e_rec.e_cpos));
 505         }
 506
 507         rb_erase(&old_ent->e_node, &em->em_extents);
 508         /* Now that he's erased, set him up for deletion */
 509         ctxt->old_ent = old_ent;
 510
 511         if (ctxt->need_left) {
 512                 ret = ocfs2_extent_map_insert_entry(em,
 513                                                     ctxt->left_ent);
 514                 if (ret)
 515                         goto out_unlock;
 516                 ctxt->left_ent = NULL;
 517         }
 518
 519         if (ctxt->need_right) {
 520                 ret = ocfs2_extent_map_insert_entry(em,
 521                                                     ctxt->right_ent);
 522                 if (ret)
 523                         goto out_unlock;
 524                 ctxt->right_ent = NULL;
 525         }
 526
 527         ret = ocfs2_extent_map_insert_entry(em, ctxt->new_ent);
 528
 529         if (!ret)
 530                 ctxt->new_ent = NULL;
 531
 532 out_unlock:
 533         spin_unlock(&OCFS2_I(inode)->ip_lock);
 534
 535         return ret;
 536 }
 537
 538
 539 static int ocfs2_extent_map_insert(struct inode *inode,
 540                                    struct ocfs2_extent_rec *rec,
 541                                    int tree_depth)
 542 {
 543         int ret;
 544         struct ocfs2_em_insert_context ctxt = {0, };
 545
 546         if ((le32_to_cpu(rec->e_cpos) + le32_to_cpu(rec->e_clusters)) >
 547             OCFS2_I(inode)->ip_map.em_clusters) {
 548                 ret = -EBADR;
 549                 mlog_errno(ret);
 550                 return ret;
 551         }
 552
 553         /* Zero e_clusters means a truncated tail record.  It better be EOF */
 554         if (!rec->e_clusters) {
 555                 if ((le32_to_cpu(rec->e_cpos) + le32_to_cpu(rec->e_clusters)) !=
 556                     OCFS2_I(inode)->ip_map.em_clusters) {
 557                         ret = -EBADR;
 558                         mlog_errno(ret);
 559                         ocfs2_error(inode->i_sb,
 560                                     "Zero e_clusters on non-tail extent record at e_blkno %llu on inode %llu\n",
 561                                     (unsigned long long)le64_to_cpu(rec->e_blkno),
 562                                     (unsigned long long)OCFS2_I(inode)->ip_blkno);
 563                         return ret;
 564                 }
 565
 566                 /* Ignore the truncated tail */
 567                 return 0;
 568         }
 569
 570         ret = -ENOMEM;
 571         ctxt.new_ent = kmem_cache_alloc(ocfs2_em_ent_cachep,
 572                                         GFP_NOFS);
 573         if (!ctxt.new_ent) {
 574                 mlog_errno(ret);
 575                 return ret;
 576         }
 577
 578         ctxt.new_ent->e_rec = *rec;
 579         ctxt.new_ent->e_tree_depth = tree_depth;
 580
 581         do {
 582                 ret = -ENOMEM;
 583                 if (ctxt.need_left && !ctxt.left_ent) {
 584                         ctxt.left_ent =
 585                                 kmem_cache_alloc(ocfs2_em_ent_cachep,
 586                                                  GFP_NOFS);
 587                         if (!ctxt.left_ent)
 588                                 break;
 589                 }
 590                 if (ctxt.need_right && !ctxt.right_ent) {
 591                         ctxt.right_ent =
 592                                 kmem_cache_alloc(ocfs2_em_ent_cachep,
 593                                                  GFP_NOFS);
 594                         if (!ctxt.right_ent)
 595                                 break;
 596                 }
 597
 598                 ret = ocfs2_extent_map_try_insert(inode, rec,
 599                                                   tree_depth, &ctxt);
 600         } while (ret == -EAGAIN);
 601
 602         if (ret < 0)
 603                 mlog_errno(ret);
 604
 605         if (ctxt.left_ent)
 606                 kmem_cache_free(ocfs2_em_ent_cachep, ctxt.left_ent);
 607         if (ctxt.right_ent)
 608                 kmem_cache_free(ocfs2_em_ent_cachep, ctxt.right_ent);
 609         if (ctxt.old_ent)
 610                 kmem_cache_free(ocfs2_em_ent_cachep, ctxt.old_ent);
 611         if (ctxt.new_ent)
 612                 kmem_cache_free(ocfs2_em_ent_cachep, ctxt.new_ent);
 613
 614         return ret;
 615 }
 616
 617 /*
 618  * Append this record to the tail of the extent map.  It must be
 619  * tree_depth 0.  The record might be an extension of an existing
 620  * record, and as such that needs to be handled.  eg:
 621  *
 622  * Existing record in the extent map:
 623  *
 624  *      cpos = 10, len = 10
 625  *      |---------|
 626  *
 627  * New Record:
 628  *
 629  *      cpos = 10, len = 20
 630  *      |------------------|
 631  *
 632  * The passed record is the new on-disk record.  The new_clusters value
 633  * is how many clusters were added to the file.  If the append is a
 634  * contiguous append, the new_clusters has been added to
 635  * rec->e_clusters.  If the append is an entirely new extent, then
 636  * rec->e_clusters is == new_clusters.
 637  */
 638 int ocfs2_extent_map_append(struct inode *inode,
 639                             struct ocfs2_extent_rec *rec,
 640                             u32 new_clusters)
 641 {
 642         int ret;
 643         struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
 644         struct ocfs2_extent_map_entry *ent;
 645         struct ocfs2_extent_rec *old;
 646
 647         BUG_ON(!new_clusters);
 648         BUG_ON(le32_to_cpu(rec->e_clusters) < new_clusters);
 649
 650         if (em->em_clusters < OCFS2_I(inode)->ip_clusters) {
 651                 /*
 652                  * Size changed underneath us on disk.  Drop any
 653                  * straddling records and update our idea of
 654                  * i_clusters
 655                  */
 656                 ocfs2_extent_map_drop(inode, em->em_clusters - 1);
 657                 em->em_clusters = OCFS2_I(inode)->ip_clusters;
 658         }
 659
 660         mlog_bug_on_msg((le32_to_cpu(rec->e_cpos) +
 661                          le32_to_cpu(rec->e_clusters)) !=
 662                         (em->em_clusters + new_clusters),
 663                         "Inode %llu:\n"
 664                         "rec->e_cpos = %u + rec->e_clusters = %u = %u\n"
 665                         "em->em_clusters = %u + new_clusters = %u = %u\n",
 666                         (unsigned long long)OCFS2_I(inode)->ip_blkno,
 667                         le32_to_cpu(rec->e_cpos), le32_to_cpu(rec->e_clusters),
 668                         le32_to_cpu(rec->e_cpos) + le32_to_cpu(rec->e_clusters),
 669                         em->em_clusters, new_clusters,
 670                         em->em_clusters + new_clusters);
 671
 672         em->em_clusters += new_clusters;
 673
 674         ret = -ENOENT;
 675         if (le32_to_cpu(rec->e_clusters) > new_clusters) {
 676                 /* This is a contiguous append */
 677                 ent = ocfs2_extent_map_lookup(em, le32_to_cpu(rec->e_cpos), 1,
 678                                               NULL, NULL);
 679                 if (ent) {
 680                         old = &ent->e_rec;
 681                         BUG_ON((le32_to_cpu(rec->e_cpos) +
 682                                 le32_to_cpu(rec->e_clusters)) !=
 683                                  (le32_to_cpu(old->e_cpos) +
 684                                   le32_to_cpu(old->e_clusters) +
 685                                   new_clusters));
 686                         if (ent->e_tree_depth == 0) {
 687                                 BUG_ON(le32_to_cpu(old->e_cpos) !=
 688                                        le32_to_cpu(rec->e_cpos));
 689                                 BUG_ON(le64_to_cpu(old->e_blkno) !=
 690                                        le64_to_cpu(rec->e_blkno));
 691                                 ret = 0;
 692                         }
 693                         /*
 694                          * Let non-leafs fall through as -ENOENT to
 695                          * force insertion of the new leaf.
 696                          */
 697                         le32_add_cpu(&old->e_clusters, new_clusters);
 698                 }
 699         }
 700
 701         if (ret == -ENOENT)
 702                 ret = ocfs2_extent_map_insert(inode, rec, 0);
 703         if (ret < 0)
 704                 mlog_errno(ret);
 705         return ret;
 706 }
 707
 708 #if 0
 709 /* Code here is included but defined out as it completes the extent
 710  * map api and may be used in the future. */
 711
 712 /*
 713  * Look up the record containing this cluster offset.  This record is
 714  * part of the extent map.  Do not free it.  Any changes you make to
 715  * it will reflect in the extent map.  So, if your last extent
 716  * is (cpos = 10, clusters = 10) and you truncate the file by 5
 717  * clusters, you can do:
 718  *
 719  * ret = ocfs2_extent_map_get_rec(em, orig_size - 5, &rec);
 720  * rec->e_clusters -= 5;
 721  *
 722  * The lookup does not read from disk.  If the map isn't filled in for
 723  * an entry, you won't find it.
 724  *
 725  * Also note that the returned record is valid until alloc_sem is
 726  * dropped.  After that, truncate and extend can happen.  Caveat Emptor.
 727  */
 728 int ocfs2_extent_map_get_rec(struct inode *inode, u32 cpos,
 729                              struct ocfs2_extent_rec **rec,
 730                              int *tree_depth)
 731 {
 732         int ret = -ENOENT;
 733         struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
 734         struct ocfs2_extent_map_entry *ent;
 735
 736         *rec = NULL;
 737
 738         if (cpos >= OCFS2_I(inode)->ip_clusters)
 739                 return -EINVAL;
 740
 741         if (cpos >= em->em_clusters) {
 742                 /*
 743                  * Size changed underneath us on disk.  Drop any
 744                  * straddling records and update our idea of
 745                  * i_clusters
 746                  */
 747                 ocfs2_extent_map_drop(inode, em->em_clusters - 1);
 748                 em->em_clusters = OCFS2_I(inode)->ip_clusters ;
 749         }
 750
 751         ent = ocfs2_extent_map_lookup(&OCFS2_I(inode)->ip_map, cpos, 1,
 752                                       NULL, NULL);
 753
 754         if (ent) {
 755                 *rec = &ent->e_rec;
 756                 if (tree_depth)
 757                         *tree_depth = ent->e_tree_depth;
 758                 ret = 0;
 759         }
 760
 761         return ret;
 762 }
 763
 764 int ocfs2_extent_map_get_clusters(struct inode *inode,
 765                                   u32 v_cpos, int count,
 766                                   u32 *p_cpos, int *ret_count)
 767 {
 768         int ret;
 769         u32 coff, ccount;
 770         struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
 771         struct ocfs2_extent_map_entry *ent = NULL;
 772
 773         *p_cpos = ccount = 0;
 774
 775         if ((v_cpos + count) > OCFS2_I(inode)->ip_clusters)
 776                 return -EINVAL;
 777
 778         if ((v_cpos + count) > em->em_clusters) {
 779                 /*
 780                  * Size changed underneath us on disk.  Drop any
 781                  * straddling records and update our idea of
 782                  * i_clusters
 783                  */
 784                 ocfs2_extent_map_drop(inode, em->em_clusters - 1);
 785                 em->em_clusters = OCFS2_I(inode)->ip_clusters;
 786         }
 787
 788
 789         ret = ocfs2_extent_map_lookup_read(inode, v_cpos, count, &ent);
 790         if (ret)
 791                 return ret;
 792
 793         if (ent) {
 794                 /* We should never find ourselves straddling an interval */
 795                 if (!ocfs2_extent_rec_contains_clusters(&ent->e_rec,
 796                                                         v_cpos,
 797                                                         count))
 798                         return -ESRCH;
 799
 800                 coff = v_cpos - le32_to_cpu(ent->e_rec.e_cpos);
 801                 *p_cpos = ocfs2_blocks_to_clusters(inode->i_sb,
 802                                 le64_to_cpu(ent->e_rec.e_blkno)) +
 803                           coff;
 804
 805                 if (ret_count)
 806                         *ret_count = le32_to_cpu(ent->e_rec.e_clusters) - coff;
 807
 808                 return 0;
 809         }
 810
 811
 812         return -ENOENT;
 813 }
 814
 815 #endif  /*  0  */
 816
 817 int ocfs2_extent_map_get_blocks(struct inode *inode,
 818                                 u64 v_blkno, int count,
 819                                 u64 *p_blkno, int *ret_count)
 820 {
 821         int ret;
 822         u64 boff;
 823         u32 cpos, clusters;
 824         int bpc = ocfs2_clusters_to_blocks(inode->i_sb, 1);
 825         struct ocfs2_extent_map_entry *ent = NULL;
 826         struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
 827         struct ocfs2_extent_rec *rec;
 828
 829         *p_blkno = 0;
 830
 831         cpos = ocfs2_blocks_to_clusters(inode->i_sb, v_blkno);
 832         clusters = ocfs2_blocks_to_clusters(inode->i_sb,
 833                                             (u64)count + bpc - 1);
 834         if ((cpos + clusters) > OCFS2_I(inode)->ip_clusters) {
 835                 ret = -EINVAL;
 836                 mlog_errno(ret);
 837                 return ret;
 838         }
 839
 840         if ((cpos + clusters) > em->em_clusters) {
 841                 /*
 842                  * Size changed underneath us on disk.  Drop any
 843                  * straddling records and update our idea of
 844                  * i_clusters
 845                  */
 846                 ocfs2_extent_map_drop(inode, em->em_clusters - 1);
 847                 em->em_clusters = OCFS2_I(inode)->ip_clusters;
 848         }
 849
 850         ret = ocfs2_extent_map_lookup_read(inode, cpos, clusters, &ent);
 851         if (ret) {
 852                 mlog_errno(ret);
 853                 return ret;
 854         }
 855
 856         if (ent)
 857         {
 858                 rec = &ent->e_rec;
 859
 860                 /* We should never find ourselves straddling an interval */
 861                 if (!ocfs2_extent_rec_contains_clusters(rec, cpos, clusters)) {
 862                         ret = -ESRCH;
 863                         mlog_errno(ret);
 864                         return ret;
 865                 }
 866
 867                 boff = ocfs2_clusters_to_blocks(inode->i_sb, cpos -
 868                                                 le32_to_cpu(rec->e_cpos));
 869                 boff += (v_blkno & (u64)(bpc - 1));
 870                 *p_blkno = le64_to_cpu(rec->e_blkno) + boff;
 871
 872                 if (ret_count) {
 873                         *ret_count = ocfs2_clusters_to_blocks(inode->i_sb,
 874                                         le32_to_cpu(rec->e_clusters)) - boff;
 875                 }
 876
 877                 return 0;
 878         }
 879
 880         return -ENOENT;
 881 }
 882
 883 int ocfs2_extent_map_init(struct inode *inode)
 884 {
 885         struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
 886
 887         em->em_extents = RB_ROOT;
 888         em->em_clusters = 0;
 889
 890         return 0;
 891 }
 892
 893 /* Needs the lock */
 894 static void __ocfs2_extent_map_drop(struct inode *inode,
 895                                     u32 new_clusters,
 896                                     struct rb_node **free_head,
 897                                     struct ocfs2_extent_map_entry **tail_ent)
 898 {
 899         struct rb_node *node, *next;
 900         struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
 901         struct ocfs2_extent_map_entry *ent;
 902
 903         *free_head = NULL;
 904
 905         ent = NULL;
 906         node = rb_last(&em->em_extents);
 907         while (node)
 908         {
 909                 next = rb_prev(node);
 910
 911                 ent = rb_entry(node, struct ocfs2_extent_map_entry,
 912                                e_node);
 913                 if (le32_to_cpu(ent->e_rec.e_cpos) < new_clusters)
 914                         break;
 915
 916                 rb_erase(&ent->e_node, &em->em_extents);
 917
 918                 node->rb_right = *free_head;
 919                 *free_head = node;
 920
 921                 ent = NULL;
 922                 node = next;
 923         }
 924
 925         /* Do we have an entry straddling new_clusters? */
 926         if (tail_ent) {
 927                 if (ent &&
 928                     ((le32_to_cpu(ent->e_rec.e_cpos) +
 929                       le32_to_cpu(ent->e_rec.e_clusters)) > new_clusters))
 930                         *tail_ent = ent;
 931                 else
 932                         *tail_ent = NULL;
 933         }
 934 }
 935
 936 static void __ocfs2_extent_map_drop_cleanup(struct rb_node *free_head)
 937 {
 938         struct rb_node *node;
 939         struct ocfs2_extent_map_entry *ent;
 940
 941         while (free_head) {
 942                 node = free_head;
 943                 free_head = node->rb_right;
 944
 945                 ent = rb_entry(node, struct ocfs2_extent_map_entry,
 946                                e_node);
 947                 kmem_cache_free(ocfs2_em_ent_cachep, ent);
 948         }
 949 }
 950
 951 /*
 952  * Remove all entries past new_clusters, inclusive of an entry that
 953  * contains new_clusters.  This is effectively a cache forget.
 954  *
 955  * If you want to also clip the last extent by some number of clusters,
 956  * you need to call ocfs2_extent_map_trunc().
 957  * This code does not check or modify ip_clusters.
 958  */
 959 int ocfs2_extent_map_drop(struct inode *inode, u32 new_clusters)
 960 {
 961         struct rb_node *free_head = NULL;
 962         struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
 963         struct ocfs2_extent_map_entry *ent;
 964
 965         spin_lock(&OCFS2_I(inode)->ip_lock);
 966
 967         __ocfs2_extent_map_drop(inode, new_clusters, &free_head, &ent);
 968
 969         if (ent) {
 970                 rb_erase(&ent->e_node, &em->em_extents);
 971                 ent->e_node.rb_right = free_head;
 972                 free_head = &ent->e_node;
 973         }
 974
 975         spin_unlock(&OCFS2_I(inode)->ip_lock);
 976
 977         if (free_head)
 978                 __ocfs2_extent_map_drop_cleanup(free_head);
 979
 980         return 0;
 981 }
 982
 983 /*
 984  * Remove all entries past new_clusters and also clip any extent
 985  * straddling new_clusters, if there is one.  This does not check
 986  * or modify ip_clusters
 987  */
 988 int ocfs2_extent_map_trunc(struct inode *inode, u32 new_clusters)
 989 {
 990         struct rb_node *free_head = NULL;
 991         struct ocfs2_extent_map_entry *ent = NULL;
 992
 993         spin_lock(&OCFS2_I(inode)->ip_lock);
 994
 995         __ocfs2_extent_map_drop(inode, new_clusters, &free_head, &ent);
 996
 997         if (ent)
 998                 ent->e_rec.e_clusters = cpu_to_le32(new_clusters -
 999                                                le32_to_cpu(ent->e_rec.e_cpos));
1000
1001         OCFS2_I(inode)->ip_map.em_clusters = new_clusters;
1002
1003         spin_unlock(&OCFS2_I(inode)->ip_lock);
1004
1005         if (free_head)
1006                 __ocfs2_extent_map_drop_cleanup(free_head);
1007
1008         return 0;
1009 }
1010
1011 int __init init_ocfs2_extent_maps(void)
1012 {
1013         ocfs2_em_ent_cachep =
1014                 kmem_cache_create("ocfs2_em_ent",
1015                                   sizeof(struct ocfs2_extent_map_entry),
1016                                   0, SLAB_HWCACHE_ALIGN, NULL, NULL);
1017         if (!ocfs2_em_ent_cachep)
1018                 return -ENOMEM;
1019
1020         return 0;
1021 }
1022
1023 void exit_ocfs2_extent_maps(void)
1024 {
1025         kmem_cache_destroy(ocfs2_em_ent_cachep);
1026 }