fs/ext4/extents.c

   1 /*
   2  * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
   3  * Written by Alex Tomas <alex@clusterfs.com>
   4  *
   5  * Architecture independence:
   6  *   Copyright (c) 2005, Bull S.A.
   7  *   Written by Pierre Peiffer <pierre.peiffer@bull.net>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public Licens
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
  21  */
  22
  23 /*
  24  * Extents support for EXT4
  25  *
  26  * TODO:
  27  *   - ext4*_error() should be used in some situations
  28  *   - analyze all BUG()/BUG_ON(), use -EIO where appropriate
  29  *   - smart tree reduction
  30  */
  31
  32 #include <linux/module.h>
  33 #include <linux/fs.h>
  34 #include <linux/time.h>
  35 #include <linux/ext4_jbd2.h>
  36 #include <linux/jbd.h>
  37 #include <linux/highuid.h>
  38 #include <linux/pagemap.h>
  39 #include <linux/quotaops.h>
  40 #include <linux/string.h>
  41 #include <linux/slab.h>
  42 #include <linux/ext4_fs_extents.h>
  43 #include <asm/uaccess.h>
  44
  45
  46 /*
  47  * ext_pblock:
  48  * combine low and high parts of physical block number into ext4_fsblk_t
  49  */
  50 static ext4_fsblk_t ext_pblock(struct ext4_extent *ex)
  51 {
  52         ext4_fsblk_t block;
  53
  54         block = le32_to_cpu(ex->ee_start);
  55         block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
  56         return block;
  57 }
  58
  59 /*
  60  * idx_pblock:
  61  * combine low and high parts of a leaf physical block number into ext4_fsblk_t
  62  */
  63 static ext4_fsblk_t idx_pblock(struct ext4_extent_idx *ix)
  64 {
  65         ext4_fsblk_t block;
  66
  67         block = le32_to_cpu(ix->ei_leaf);
  68         block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
  69         return block;
  70 }
  71
  72 /*
  73  * ext4_ext_store_pblock:
  74  * stores a large physical block number into an extent struct,
  75  * breaking it into parts
  76  */
  77 static void ext4_ext_store_pblock(struct ext4_extent *ex, ext4_fsblk_t pb)
  78 {
  79         ex->ee_start = cpu_to_le32((unsigned long) (pb & 0xffffffff));
  80         ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 0xffff);
  81 }
  82
  83 /*
  84  * ext4_idx_store_pblock:
  85  * stores a large physical block number into an index struct,
  86  * breaking it into parts
  87  */
  88 static void ext4_idx_store_pblock(struct ext4_extent_idx *ix, ext4_fsblk_t pb)
  89 {
  90         ix->ei_leaf = cpu_to_le32((unsigned long) (pb & 0xffffffff));
  91         ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 0xffff);
  92 }
  93
  94 static int ext4_ext_check_header(const char *function, struct inode *inode,
  95                                 struct ext4_extent_header *eh)
  96 {
  97         const char *error_msg = NULL;
  98
  99         if (unlikely(eh->eh_magic != EXT4_EXT_MAGIC)) {
 100                 error_msg = "invalid magic";
 101                 goto corrupted;
 102         }
 103         if (unlikely(eh->eh_max == 0)) {
 104                 error_msg = "invalid eh_max";
 105                 goto corrupted;
 106         }
 107         if (unlikely(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max))) {
 108                 error_msg = "invalid eh_entries";
 109                 goto corrupted;
 110         }
 111         return 0;
 112
 113 corrupted:
 114         ext4_error(inode->i_sb, function,
 115                         "bad header in inode #%lu: %s - magic %x, "
 116                         "entries %u, max %u, depth %u",
 117                         inode->i_ino, error_msg, le16_to_cpu(eh->eh_magic),
 118                         le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max),
 119                         le16_to_cpu(eh->eh_depth));
 120
 121         return -EIO;
 122 }
 123
 124 static handle_t *ext4_ext_journal_restart(handle_t *handle, int needed)
 125 {
 126         int err;
 127
 128         if (handle->h_buffer_credits > needed)
 129                 return handle;
 130         if (!ext4_journal_extend(handle, needed))
 131                 return handle;
 132         err = ext4_journal_restart(handle, needed);
 133
 134         return handle;
 135 }
 136
 137 /*
 138  * could return:
 139  *  - EROFS
 140  *  - ENOMEM
 141  */
 142 static int ext4_ext_get_access(handle_t *handle, struct inode *inode,
 143                                 struct ext4_ext_path *path)
 144 {
 145         if (path->p_bh) {
 146                 /* path points to block */
 147                 return ext4_journal_get_write_access(handle, path->p_bh);
 148         }
 149         /* path points to leaf/index in inode body */
 150         /* we use in-core data, no need to protect them */
 151         return 0;
 152 }
 153
 154 /*
 155  * could return:
 156  *  - EROFS
 157  *  - ENOMEM
 158  *  - EIO
 159  */
 160 static int ext4_ext_dirty(handle_t *handle, struct inode *inode,
 161                                 struct ext4_ext_path *path)
 162 {
 163         int err;
 164         if (path->p_bh) {
 165                 /* path points to block */
 166                 err = ext4_journal_dirty_metadata(handle, path->p_bh);
 167         } else {
 168                 /* path points to leaf/index in inode body */
 169                 err = ext4_mark_inode_dirty(handle, inode);
 170         }
 171         return err;
 172 }
 173
 174 static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
 175                               struct ext4_ext_path *path,
 176                               ext4_fsblk_t block)
 177 {
 178         struct ext4_inode_info *ei = EXT4_I(inode);
 179         ext4_fsblk_t bg_start;
 180         ext4_grpblk_t colour;
 181         int depth;
 182
 183         if (path) {
 184                 struct ext4_extent *ex;
 185                 depth = path->p_depth;
 186
 187                 /* try to predict block placement */
 188                 ex = path[depth].p_ext;
 189                 if (ex)
 190                         return ext_pblock(ex)+(block-le32_to_cpu(ex->ee_block));
 191
 192                 /* it looks like index is empty;
 193                  * try to find starting block from index itself */
 194                 if (path[depth].p_bh)
 195                         return path[depth].p_bh->b_blocknr;
 196         }
 197
 198         /* OK. use inode's group */
 199         bg_start = (ei->i_block_group * EXT4_BLOCKS_PER_GROUP(inode->i_sb)) +
 200                 le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_first_data_block);
 201         colour = (current->pid % 16) *
 202                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 203         return bg_start + colour + block;
 204 }
 205
 206 static ext4_fsblk_t
 207 ext4_ext_new_block(handle_t *handle, struct inode *inode,
 208                         struct ext4_ext_path *path,
 209                         struct ext4_extent *ex, int *err)
 210 {
 211         ext4_fsblk_t goal, newblock;
 212
 213         goal = ext4_ext_find_goal(inode, path, le32_to_cpu(ex->ee_block));
 214         newblock = ext4_new_block(handle, inode, goal, err);
 215         return newblock;
 216 }
 217
 218 static int ext4_ext_space_block(struct inode *inode)
 219 {
 220         int size;
 221
 222         size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
 223                         / sizeof(struct ext4_extent);
 224 #ifdef AGGRESSIVE_TEST
 225         if (size > 6)
 226                 size = 6;
 227 #endif
 228         return size;
 229 }
 230
 231 static int ext4_ext_space_block_idx(struct inode *inode)
 232 {
 233         int size;
 234
 235         size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
 236                         / sizeof(struct ext4_extent_idx);
 237 #ifdef AGGRESSIVE_TEST
 238         if (size > 5)
 239                 size = 5;
 240 #endif
 241         return size;
 242 }
 243
 244 static int ext4_ext_space_root(struct inode *inode)
 245 {
 246         int size;
 247
 248         size = sizeof(EXT4_I(inode)->i_data);
 249         size -= sizeof(struct ext4_extent_header);
 250         size /= sizeof(struct ext4_extent);
 251 #ifdef AGGRESSIVE_TEST
 252         if (size > 3)
 253                 size = 3;
 254 #endif
 255         return size;
 256 }
 257
 258 static int ext4_ext_space_root_idx(struct inode *inode)
 259 {
 260         int size;
 261
 262         size = sizeof(EXT4_I(inode)->i_data);
 263         size -= sizeof(struct ext4_extent_header);
 264         size /= sizeof(struct ext4_extent_idx);
 265 #ifdef AGGRESSIVE_TEST
 266         if (size > 4)
 267                 size = 4;
 268 #endif
 269         return size;
 270 }
 271
 272 #ifdef EXT_DEBUG
 273 static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path)
 274 {
 275         int k, l = path->p_depth;
 276
 277         ext_debug("path:");
 278         for (k = 0; k <= l; k++, path++) {
 279                 if (path->p_idx) {
 280                   ext_debug("  %d->%llu", le32_to_cpu(path->p_idx->ei_block),
 281                             idx_pblock(path->p_idx));
 282                 } else if (path->p_ext) {
 283                         ext_debug("  %d:%d:%llu ",
 284                                   le32_to_cpu(path->p_ext->ee_block),
 285                                   le16_to_cpu(path->p_ext->ee_len),
 286                                   ext_pblock(path->p_ext));
 287                 } else
 288                         ext_debug("  []");
 289         }
 290         ext_debug("\n");
 291 }
 292
 293 static void ext4_ext_show_leaf(struct inode *inode, struct ext4_ext_path *path)
 294 {
 295         int depth = ext_depth(inode);
 296         struct ext4_extent_header *eh;
 297         struct ext4_extent *ex;
 298         int i;
 299
 300         if (!path)
 301                 return;
 302
 303         eh = path[depth].p_hdr;
 304         ex = EXT_FIRST_EXTENT(eh);
 305
 306         for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ex++) {
 307                 ext_debug("%d:%d:%llu ", le32_to_cpu(ex->ee_block),
 308                           le16_to_cpu(ex->ee_len), ext_pblock(ex));
 309         }
 310         ext_debug("\n");
 311 }
 312 #else
 313 #define ext4_ext_show_path(inode,path)
 314 #define ext4_ext_show_leaf(inode,path)
 315 #endif
 316
 317 static void ext4_ext_drop_refs(struct ext4_ext_path *path)
 318 {
 319         int depth = path->p_depth;
 320         int i;
 321
 322         for (i = 0; i <= depth; i++, path++)
 323                 if (path->p_bh) {
 324                         brelse(path->p_bh);
 325                         path->p_bh = NULL;
 326                 }
 327 }
 328
 329 /*
 330  * ext4_ext_binsearch_idx:
 331  * binary search for the closest index of the given block
 332  */
 333 static void
 334 ext4_ext_binsearch_idx(struct inode *inode, struct ext4_ext_path *path, int block)
 335 {
 336         struct ext4_extent_header *eh = path->p_hdr;
 337         struct ext4_extent_idx *r, *l, *m;
 338
 339         BUG_ON(eh->eh_magic != EXT4_EXT_MAGIC);
 340         BUG_ON(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max));
 341         BUG_ON(le16_to_cpu(eh->eh_entries) <= 0);
 342
 343         ext_debug("binsearch for %d(idx):  ", block);
 344
 345         l = EXT_FIRST_INDEX(eh) + 1;
 346         r = EXT_FIRST_INDEX(eh) + le16_to_cpu(eh->eh_entries) - 1;
 347         while (l <= r) {
 348                 m = l + (r - l) / 2;
 349                 if (block < le32_to_cpu(m->ei_block))
 350                         r = m - 1;
 351                 else
 352                         l = m + 1;
 353                 ext_debug("%p(%u):%p(%u):%p(%u) ", l, l->ei_block,
 354                                 m, m->ei_block, r, r->ei_block);
 355         }
 356
 357         path->p_idx = l - 1;
 358         ext_debug("  -> %d->%lld ", le32_to_cpu(path->p_idx->ei_block),
 359                   idx_block(path->p_idx));
 360
 361 #ifdef CHECK_BINSEARCH
 362         {
 363                 struct ext4_extent_idx *chix, *ix;
 364                 int k;
 365
 366                 chix = ix = EXT_FIRST_INDEX(eh);
 367                 for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ix++) {
 368                   if (k != 0 &&
 369                       le32_to_cpu(ix->ei_block) <= le32_to_cpu(ix[-1].ei_block)) {
 370                                 printk("k=%d, ix=0x%p, first=0x%p\n", k,
 371                                         ix, EXT_FIRST_INDEX(eh));
 372                                 printk("%u <= %u\n",
 373                                        le32_to_cpu(ix->ei_block),
 374                                        le32_to_cpu(ix[-1].ei_block));
 375                         }
 376                         BUG_ON(k && le32_to_cpu(ix->ei_block)
 377                                            <= le32_to_cpu(ix[-1].ei_block));
 378                         if (block < le32_to_cpu(ix->ei_block))
 379                                 break;
 380                         chix = ix;
 381                 }
 382                 BUG_ON(chix != path->p_idx);
 383         }
 384 #endif
 385
 386 }
 387
 388 /*
 389  * ext4_ext_binsearch:
 390  * binary search for closest extent of the given block
 391  */
 392 static void
 393 ext4_ext_binsearch(struct inode *inode, struct ext4_ext_path *path, int block)
 394 {
 395         struct ext4_extent_header *eh = path->p_hdr;
 396         struct ext4_extent *r, *l, *m;
 397
 398         BUG_ON(eh->eh_magic != EXT4_EXT_MAGIC);
 399         BUG_ON(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max));
 400
 401         if (eh->eh_entries == 0) {
 402                 /*
 403                  * this leaf is empty:
 404                  * we get such a leaf in split/add case
 405                  */
 406                 return;
 407         }
 408
 409         ext_debug("binsearch for %d:  ", block);
 410
 411         l = EXT_FIRST_EXTENT(eh) + 1;
 412         r = EXT_FIRST_EXTENT(eh) + le16_to_cpu(eh->eh_entries) - 1;
 413
 414         while (l <= r) {
 415                 m = l + (r - l) / 2;
 416                 if (block < le32_to_cpu(m->ee_block))
 417                         r = m - 1;
 418                 else
 419                         l = m + 1;
 420                 ext_debug("%p(%u):%p(%u):%p(%u) ", l, l->ee_block,
 421                                 m, m->ee_block, r, r->ee_block);
 422         }
 423
 424         path->p_ext = l - 1;
 425         ext_debug("  -> %d:%llu:%d ",
 426                         le32_to_cpu(path->p_ext->ee_block),
 427                         ext_pblock(path->p_ext),
 428                         le16_to_cpu(path->p_ext->ee_len));
 429
 430 #ifdef CHECK_BINSEARCH
 431         {
 432                 struct ext4_extent *chex, *ex;
 433                 int k;
 434
 435                 chex = ex = EXT_FIRST_EXTENT(eh);
 436                 for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ex++) {
 437                         BUG_ON(k && le32_to_cpu(ex->ee_block)
 438                                           <= le32_to_cpu(ex[-1].ee_block));
 439                         if (block < le32_to_cpu(ex->ee_block))
 440                                 break;
 441                         chex = ex;
 442                 }
 443                 BUG_ON(chex != path->p_ext);
 444         }
 445 #endif
 446
 447 }
 448
 449 int ext4_ext_tree_init(handle_t *handle, struct inode *inode)
 450 {
 451         struct ext4_extent_header *eh;
 452
 453         eh = ext_inode_hdr(inode);
 454         eh->eh_depth = 0;
 455         eh->eh_entries = 0;
 456         eh->eh_magic = EXT4_EXT_MAGIC;
 457         eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode));
 458         ext4_mark_inode_dirty(handle, inode);
 459         ext4_ext_invalidate_cache(inode);
 460         return 0;
 461 }
 462
 463 struct ext4_ext_path *
 464 ext4_ext_find_extent(struct inode *inode, int block, struct ext4_ext_path *path)
 465 {
 466         struct ext4_extent_header *eh;
 467         struct buffer_head *bh;
 468         short int depth, i, ppos = 0, alloc = 0;
 469
 470         eh = ext_inode_hdr(inode);
 471         BUG_ON(eh == NULL);
 472         if (ext4_ext_check_header(__FUNCTION__, inode, eh))
 473                 return ERR_PTR(-EIO);
 474
 475         i = depth = ext_depth(inode);
 476
 477         /* account possible depth increase */
 478         if (!path) {
 479                 path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
 480                                 GFP_NOFS);
 481                 if (!path)
 482                         return ERR_PTR(-ENOMEM);
 483                 alloc = 1;
 484         }
 485         path[0].p_hdr = eh;
 486
 487         /* walk through the tree */
 488         while (i) {
 489                 ext_debug("depth %d: num %d, max %d\n",
 490                           ppos, le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
 491                 ext4_ext_binsearch_idx(inode, path + ppos, block);
 492                 path[ppos].p_block = idx_pblock(path[ppos].p_idx);
 493                 path[ppos].p_depth = i;
 494                 path[ppos].p_ext = NULL;
 495
 496                 bh = sb_bread(inode->i_sb, path[ppos].p_block);
 497                 if (!bh)
 498                         goto err;
 499
 500                 eh = ext_block_hdr(bh);
 501                 ppos++;
 502                 BUG_ON(ppos > depth);
 503                 path[ppos].p_bh = bh;
 504                 path[ppos].p_hdr = eh;
 505                 i--;
 506
 507                 if (ext4_ext_check_header(__FUNCTION__, inode, eh))
 508                         goto err;
 509         }
 510
 511         path[ppos].p_depth = i;
 512         path[ppos].p_hdr = eh;
 513         path[ppos].p_ext = NULL;
 514         path[ppos].p_idx = NULL;
 515
 516         if (ext4_ext_check_header(__FUNCTION__, inode, eh))
 517                 goto err;
 518
 519         /* find extent */
 520         ext4_ext_binsearch(inode, path + ppos, block);
 521
 522         ext4_ext_show_path(inode, path);
 523
 524         return path;
 525
 526 err:
 527         ext4_ext_drop_refs(path);
 528         if (alloc)
 529                 kfree(path);
 530         return ERR_PTR(-EIO);
 531 }
 532
 533 /*
 534  * ext4_ext_insert_index:
 535  * insert new index [@logical;@ptr] into the block at @curp;
 536  * check where to insert: before @curp or after @curp
 537  */
 538 static int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
 539                                 struct ext4_ext_path *curp,
 540                                 int logical, ext4_fsblk_t ptr)
 541 {
 542         struct ext4_extent_idx *ix;
 543         int len, err;
 544
 545         err = ext4_ext_get_access(handle, inode, curp);
 546         if (err)
 547                 return err;
 548
 549         BUG_ON(logical == le32_to_cpu(curp->p_idx->ei_block));
 550         len = EXT_MAX_INDEX(curp->p_hdr) - curp->p_idx;
 551         if (logical > le32_to_cpu(curp->p_idx->ei_block)) {
 552                 /* insert after */
 553                 if (curp->p_idx != EXT_LAST_INDEX(curp->p_hdr)) {
 554                         len = (len - 1) * sizeof(struct ext4_extent_idx);
 555                         len = len < 0 ? 0 : len;
 556                         ext_debug("insert new index %d after: %d. "
 557                                         "move %d from 0x%p to 0x%p\n",
 558                                         logical, ptr, len,
 559                                         (curp->p_idx + 1), (curp->p_idx + 2));
 560                         memmove(curp->p_idx + 2, curp->p_idx + 1, len);
 561                 }
 562                 ix = curp->p_idx + 1;
 563         } else {
 564                 /* insert before */
 565                 len = len * sizeof(struct ext4_extent_idx);
 566                 len = len < 0 ? 0 : len;
 567                 ext_debug("insert new index %d before: %d. "
 568                                 "move %d from 0x%p to 0x%p\n",
 569                                 logical, ptr, len,
 570                                 curp->p_idx, (curp->p_idx + 1));
 571                 memmove(curp->p_idx + 1, curp->p_idx, len);
 572                 ix = curp->p_idx;
 573         }
 574
 575         ix->ei_block = cpu_to_le32(logical);
 576         ext4_idx_store_pblock(ix, ptr);
 577         curp->p_hdr->eh_entries = cpu_to_le16(le16_to_cpu(curp->p_hdr->eh_entries)+1);
 578
 579         BUG_ON(le16_to_cpu(curp->p_hdr->eh_entries)
 580                              > le16_to_cpu(curp->p_hdr->eh_max));
 581         BUG_ON(ix > EXT_LAST_INDEX(curp->p_hdr));
 582
 583         err = ext4_ext_dirty(handle, inode, curp);
 584         ext4_std_error(inode->i_sb, err);
 585
 586         return err;
 587 }
 588
 589 /*
 590  * ext4_ext_split:
 591  * inserts new subtree into the path, using free index entry
 592  * at depth @at:
 593  * - allocates all needed blocks (new leaf and all intermediate index blocks)
 594  * - makes decision where to split
 595  * - moves remaining extents and index entries (right to the split point)
 596  *   into the newly allocated blocks
 597  * - initializes subtree
 598  */
 599 static int ext4_ext_split(handle_t *handle, struct inode *inode,
 600                                 struct ext4_ext_path *path,
 601                                 struct ext4_extent *newext, int at)
 602 {
 603         struct buffer_head *bh = NULL;
 604         int depth = ext_depth(inode);
 605         struct ext4_extent_header *neh;
 606         struct ext4_extent_idx *fidx;
 607         struct ext4_extent *ex;
 608         int i = at, k, m, a;
 609         ext4_fsblk_t newblock, oldblock;
 610         __le32 border;
 611         ext4_fsblk_t *ablocks = NULL; /* array of allocated blocks */
 612         int err = 0;
 613
 614         /* make decision: where to split? */
 615         /* FIXME: now decision is simplest: at current extent */
 616
 617         /* if current leaf will be split, then we should use
 618          * border from split point */
 619         BUG_ON(path[depth].p_ext > EXT_MAX_EXTENT(path[depth].p_hdr));
 620         if (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) {
 621                 border = path[depth].p_ext[1].ee_block;
 622                 ext_debug("leaf will be split."
 623                                 " next leaf starts at %d\n",
 624                                   le32_to_cpu(border));
 625         } else {
 626                 border = newext->ee_block;
 627                 ext_debug("leaf will be added."
 628                                 " next leaf starts at %d\n",
 629                                 le32_to_cpu(border));
 630         }
 631
 632         /*
 633          * If error occurs, then we break processing
 634          * and mark filesystem read-only. index won't
 635          * be inserted and tree will be in consistent
 636          * state. Next mount will repair buffers too.
 637          */
 638
 639         /*
 640          * Get array to track all allocated blocks.
 641          * We need this to handle errors and free blocks
 642          * upon them.
 643          */
 644         ablocks = kzalloc(sizeof(ext4_fsblk_t) * depth, GFP_NOFS);
 645         if (!ablocks)
 646                 return -ENOMEM;
 647
 648         /* allocate all needed blocks */
 649         ext_debug("allocate %d blocks for indexes/leaf\n", depth - at);
 650         for (a = 0; a < depth - at; a++) {
 651                 newblock = ext4_ext_new_block(handle, inode, path, newext, &err);
 652                 if (newblock == 0)
 653                         goto cleanup;
 654                 ablocks[a] = newblock;
 655         }
 656
 657         /* initialize new leaf */
 658         newblock = ablocks[--a];
 659         BUG_ON(newblock == 0);
 660         bh = sb_getblk(inode->i_sb, newblock);
 661         if (!bh) {
 662                 err = -EIO;
 663                 goto cleanup;
 664         }
 665         lock_buffer(bh);
 666
 667         err = ext4_journal_get_create_access(handle, bh);
 668         if (err)
 669                 goto cleanup;
 670
 671         neh = ext_block_hdr(bh);
 672         neh->eh_entries = 0;
 673         neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode));
 674         neh->eh_magic = EXT4_EXT_MAGIC;
 675         neh->eh_depth = 0;
 676         ex = EXT_FIRST_EXTENT(neh);
 677
 678         /* move remainder of path[depth] to the new leaf */
 679         BUG_ON(path[depth].p_hdr->eh_entries != path[depth].p_hdr->eh_max);
 680         /* start copy from next extent */
 681         /* TODO: we could do it by single memmove */
 682         m = 0;
 683         path[depth].p_ext++;
 684         while (path[depth].p_ext <=
 685                         EXT_MAX_EXTENT(path[depth].p_hdr)) {
 686                 ext_debug("move %d:%llu:%d in new leaf %llu\n",
 687                                 le32_to_cpu(path[depth].p_ext->ee_block),
 688                                 ext_pblock(path[depth].p_ext),
 689                                 le16_to_cpu(path[depth].p_ext->ee_len),
 690                                 newblock);
 691                 /*memmove(ex++, path[depth].p_ext++,
 692                                 sizeof(struct ext4_extent));
 693                 neh->eh_entries++;*/
 694                 path[depth].p_ext++;
 695                 m++;
 696         }
 697         if (m) {
 698                 memmove(ex, path[depth].p_ext-m, sizeof(struct ext4_extent)*m);
 699                 neh->eh_entries = cpu_to_le16(le16_to_cpu(neh->eh_entries)+m);
 700         }
 701
 702         set_buffer_uptodate(bh);
 703         unlock_buffer(bh);
 704
 705         err = ext4_journal_dirty_metadata(handle, bh);
 706         if (err)
 707                 goto cleanup;
 708         brelse(bh);
 709         bh = NULL;
 710
 711         /* correct old leaf */
 712         if (m) {
 713                 err = ext4_ext_get_access(handle, inode, path + depth);
 714                 if (err)
 715                         goto cleanup;
 716                 path[depth].p_hdr->eh_entries =
 717                      cpu_to_le16(le16_to_cpu(path[depth].p_hdr->eh_entries)-m);
 718                 err = ext4_ext_dirty(handle, inode, path + depth);
 719                 if (err)
 720                         goto cleanup;
 721
 722         }
 723
 724         /* create intermediate indexes */
 725         k = depth - at - 1;
 726         BUG_ON(k < 0);
 727         if (k)
 728                 ext_debug("create %d intermediate indices\n", k);
 729         /* insert new index into current index block */
 730         /* current depth stored in i var */
 731         i = depth - 1;
 732         while (k--) {
 733                 oldblock = newblock;
 734                 newblock = ablocks[--a];
 735                 bh = sb_getblk(inode->i_sb, (ext4_fsblk_t)newblock);
 736                 if (!bh) {
 737                         err = -EIO;
 738                         goto cleanup;
 739                 }
 740                 lock_buffer(bh);
 741
 742                 err = ext4_journal_get_create_access(handle, bh);
 743                 if (err)
 744                         goto cleanup;
 745
 746                 neh = ext_block_hdr(bh);
 747                 neh->eh_entries = cpu_to_le16(1);
 748                 neh->eh_magic = EXT4_EXT_MAGIC;
 749                 neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode));
 750                 neh->eh_depth = cpu_to_le16(depth - i);
 751                 fidx = EXT_FIRST_INDEX(neh);
 752                 fidx->ei_block = border;
 753                 ext4_idx_store_pblock(fidx, oldblock);
 754
 755                 ext_debug("int.index at %d (block %llu): %lu -> %llu\n", i,
 756                                 newblock, (unsigned long) le32_to_cpu(border),
 757                                 oldblock);
 758                 /* copy indexes */
 759                 m = 0;
 760                 path[i].p_idx++;
 761
 762                 ext_debug("cur 0x%p, last 0x%p\n", path[i].p_idx,
 763                                 EXT_MAX_INDEX(path[i].p_hdr));
 764                 BUG_ON(EXT_MAX_INDEX(path[i].p_hdr) !=
 765                                 EXT_LAST_INDEX(path[i].p_hdr));
 766                 while (path[i].p_idx <= EXT_MAX_INDEX(path[i].p_hdr)) {
 767                         ext_debug("%d: move %d:%d in new index %llu\n", i,
 768                                         le32_to_cpu(path[i].p_idx->ei_block),
 769                                         idx_pblock(path[i].p_idx),
 770                                         newblock);
 771                         /*memmove(++fidx, path[i].p_idx++,
 772                                         sizeof(struct ext4_extent_idx));
 773                         neh->eh_entries++;
 774                         BUG_ON(neh->eh_entries > neh->eh_max);*/
 775                         path[i].p_idx++;
 776                         m++;
 777                 }
 778                 if (m) {
 779                         memmove(++fidx, path[i].p_idx - m,
 780                                 sizeof(struct ext4_extent_idx) * m);
 781                         neh->eh_entries =
 782                                 cpu_to_le16(le16_to_cpu(neh->eh_entries) + m);
 783                 }
 784                 set_buffer_uptodate(bh);
 785                 unlock_buffer(bh);
 786
 787                 err = ext4_journal_dirty_metadata(handle, bh);
 788                 if (err)
 789                         goto cleanup;
 790                 brelse(bh);
 791                 bh = NULL;
 792
 793                 /* correct old index */
 794                 if (m) {
 795                         err = ext4_ext_get_access(handle, inode, path + i);
 796                         if (err)
 797                                 goto cleanup;
 798                         path[i].p_hdr->eh_entries = cpu_to_le16(le16_to_cpu(path[i].p_hdr->eh_entries)-m);
 799                         err = ext4_ext_dirty(handle, inode, path + i);
 800                         if (err)
 801                                 goto cleanup;
 802                 }
 803
 804                 i--;
 805         }
 806
 807         /* insert new index */
 808         err = ext4_ext_insert_index(handle, inode, path + at,
 809                                     le32_to_cpu(border), newblock);
 810
 811 cleanup:
 812         if (bh) {
 813                 if (buffer_locked(bh))
 814                         unlock_buffer(bh);
 815                 brelse(bh);
 816         }
 817
 818         if (err) {
 819                 /* free all allocated blocks in error case */
 820                 for (i = 0; i < depth; i++) {
 821                         if (!ablocks[i])
 822                                 continue;
 823                         ext4_free_blocks(handle, inode, ablocks[i], 1);
 824                 }
 825         }
 826         kfree(ablocks);
 827
 828         return err;
 829 }
 830
 831 /*
 832  * ext4_ext_grow_indepth:
 833  * implements tree growing procedure:
 834  * - allocates new block
 835  * - moves top-level data (index block or leaf) into the new block
 836  * - initializes new top-level, creating index that points to the
 837  *   just created block
 838  */
 839 static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
 840                                         struct ext4_ext_path *path,
 841                                         struct ext4_extent *newext)
 842 {
 843         struct ext4_ext_path *curp = path;
 844         struct ext4_extent_header *neh;
 845         struct ext4_extent_idx *fidx;
 846         struct buffer_head *bh;
 847         ext4_fsblk_t newblock;
 848         int err = 0;
 849
 850         newblock = ext4_ext_new_block(handle, inode, path, newext, &err);
 851         if (newblock == 0)
 852                 return err;
 853
 854         bh = sb_getblk(inode->i_sb, newblock);
 855         if (!bh) {
 856                 err = -EIO;
 857                 ext4_std_error(inode->i_sb, err);
 858                 return err;
 859         }
 860         lock_buffer(bh);
 861
 862         err = ext4_journal_get_create_access(handle, bh);
 863         if (err) {
 864                 unlock_buffer(bh);
 865                 goto out;
 866         }
 867
 868         /* move top-level index/leaf into new block */
 869         memmove(bh->b_data, curp->p_hdr, sizeof(EXT4_I(inode)->i_data));
 870
 871         /* set size of new block */
 872         neh = ext_block_hdr(bh);
 873         /* old root could have indexes or leaves
 874          * so calculate e_max right way */
 875         if (ext_depth(inode))
 876           neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode));
 877         else
 878           neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode));
 879         neh->eh_magic = EXT4_EXT_MAGIC;
 880         set_buffer_uptodate(bh);
 881         unlock_buffer(bh);
 882
 883         err = ext4_journal_dirty_metadata(handle, bh);
 884         if (err)
 885                 goto out;
 886
 887         /* create index in new top-level index: num,max,pointer */
 888         err = ext4_ext_get_access(handle, inode, curp);
 889         if (err)
 890                 goto out;
 891
 892         curp->p_hdr->eh_magic = EXT4_EXT_MAGIC;
 893         curp->p_hdr->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode));
 894         curp->p_hdr->eh_entries = cpu_to_le16(1);
 895         curp->p_idx = EXT_FIRST_INDEX(curp->p_hdr);
 896         /* FIXME: it works, but actually path[0] can be index */
 897         curp->p_idx->ei_block = EXT_FIRST_EXTENT(path[0].p_hdr)->ee_block;
 898         ext4_idx_store_pblock(curp->p_idx, newblock);
 899
 900         neh = ext_inode_hdr(inode);
 901         fidx = EXT_FIRST_INDEX(neh);
 902         ext_debug("new root: num %d(%d), lblock %d, ptr %llu\n",
 903                   le16_to_cpu(neh->eh_entries), le16_to_cpu(neh->eh_max),
 904                   le32_to_cpu(fidx->ei_block), idx_pblock(fidx));
 905
 906         neh->eh_depth = cpu_to_le16(path->p_depth + 1);
 907         err = ext4_ext_dirty(handle, inode, curp);
 908 out:
 909         brelse(bh);
 910
 911         return err;
 912 }
 913
 914 /*
 915  * ext4_ext_create_new_leaf:
 916  * finds empty index and adds new leaf.
 917  * if no free index is found, then it requests in-depth growing.
 918  */
 919 static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
 920                                         struct ext4_ext_path *path,
 921                                         struct ext4_extent *newext)
 922 {
 923         struct ext4_ext_path *curp;
 924         int depth, i, err = 0;
 925
 926 repeat:
 927         i = depth = ext_depth(inode);
 928
 929         /* walk up to the tree and look for free index entry */
 930         curp = path + depth;
 931         while (i > 0 && !EXT_HAS_FREE_INDEX(curp)) {
 932                 i--;
 933                 curp--;
 934         }
 935
 936         /* we use already allocated block for index block,
 937          * so subsequent data blocks should be contiguous */
 938         if (EXT_HAS_FREE_INDEX(curp)) {
 939                 /* if we found index with free entry, then use that
 940                  * entry: create all needed subtree and add new leaf */
 941                 err = ext4_ext_split(handle, inode, path, newext, i);
 942
 943                 /* refill path */
 944                 ext4_ext_drop_refs(path);
 945                 path = ext4_ext_find_extent(inode,
 946                                             le32_to_cpu(newext->ee_block),
 947                                             path);
 948                 if (IS_ERR(path))
 949                         err = PTR_ERR(path);
 950         } else {
 951                 /* tree is full, time to grow in depth */
 952                 err = ext4_ext_grow_indepth(handle, inode, path, newext);
 953                 if (err)
 954                         goto out;
 955
 956                 /* refill path */
 957                 ext4_ext_drop_refs(path);
 958                 path = ext4_ext_find_extent(inode,
 959                                             le32_to_cpu(newext->ee_block),
 960                                             path);
 961                 if (IS_ERR(path)) {
 962                         err = PTR_ERR(path);
 963                         goto out;
 964                 }
 965
 966                 /*
 967                  * only first (depth 0 -> 1) produces free space;
 968                  * in all other cases we have to split the grown tree
 969                  */
 970                 depth = ext_depth(inode);
 971                 if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) {
 972                         /* now we need to split */
 973                         goto repeat;
 974                 }
 975         }
 976
 977 out:
 978         return err;
 979 }
 980
 981 /*
 982  * ext4_ext_next_allocated_block:
 983  * returns allocated block in subsequent extent or EXT_MAX_BLOCK.
 984  * NOTE: it considers block number from index entry as
 985  * allocated block. Thus, index entries have to be consistent
 986  * with leaves.
 987  */
 988 static unsigned long
 989 ext4_ext_next_allocated_block(struct ext4_ext_path *path)
 990 {
 991         int depth;
 992
 993         BUG_ON(path == NULL);
 994         depth = path->p_depth;
 995
 996         if (depth == 0 && path->p_ext == NULL)
 997                 return EXT_MAX_BLOCK;
 998
 999         while (depth >= 0) {
1000                 if (depth == path->p_depth) {
1001                         /* leaf */
1002                         if (path[depth].p_ext !=
1003                                         EXT_LAST_EXTENT(path[depth].p_hdr))
1004                           return le32_to_cpu(path[depth].p_ext[1].ee_block);
1005                 } else {
1006                         /* index */
1007                         if (path[depth].p_idx !=
1008                                         EXT_LAST_INDEX(path[depth].p_hdr))
1009                           return le32_to_cpu(path[depth].p_idx[1].ei_block);
1010                 }
1011                 depth--;
1012         }
1013
1014         return EXT_MAX_BLOCK;
1015 }
1016
1017 /*
1018  * ext4_ext_next_leaf_block:
1019  * returns first allocated block from next leaf or EXT_MAX_BLOCK
1020  */
1021 static unsigned ext4_ext_next_leaf_block(struct inode *inode,
1022                                         struct ext4_ext_path *path)
1023 {
1024         int depth;
1025
1026         BUG_ON(path == NULL);
1027         depth = path->p_depth;
1028
1029         /* zero-tree has no leaf blocks at all */
1030         if (depth == 0)
1031                 return EXT_MAX_BLOCK;
1032
1033         /* go to index block */
1034         depth--;
1035
1036         while (depth >= 0) {
1037                 if (path[depth].p_idx !=
1038                                 EXT_LAST_INDEX(path[depth].p_hdr))
1039                   return le32_to_cpu(path[depth].p_idx[1].ei_block);
1040                 depth--;
1041         }
1042
1043         return EXT_MAX_BLOCK;
1044 }
1045
1046 /*
1047  * ext4_ext_correct_indexes:
1048  * if leaf gets modified and modified extent is first in the leaf,
1049  * then we have to correct all indexes above.
1050  * TODO: do we need to correct tree in all cases?
1051  */
1052 int ext4_ext_correct_indexes(handle_t *handle, struct inode *inode,
1053                                 struct ext4_ext_path *path)
1054 {
1055         struct ext4_extent_header *eh;
1056         int depth = ext_depth(inode);
1057         struct ext4_extent *ex;
1058         __le32 border;
1059         int k, err = 0;
1060
1061         eh = path[depth].p_hdr;
1062         ex = path[depth].p_ext;
1063         BUG_ON(ex == NULL);
1064         BUG_ON(eh == NULL);
1065
1066         if (depth == 0) {
1067                 /* there is no tree at all */
1068                 return 0;
1069         }
1070
1071         if (ex != EXT_FIRST_EXTENT(eh)) {
1072                 /* we correct tree if first leaf got modified only */
1073                 return 0;
1074         }
1075
1076         /*
1077          * TODO: we need correction if border is smaller than current one
1078          */
1079         k = depth - 1;
1080         border = path[depth].p_ext->ee_block;
1081         err = ext4_ext_get_access(handle, inode, path + k);
1082         if (err)
1083                 return err;
1084         path[k].p_idx->ei_block = border;
1085         err = ext4_ext_dirty(handle, inode, path + k);
1086         if (err)
1087                 return err;
1088
1089         while (k--) {
1090                 /* change all left-side indexes */
1091                 if (path[k+1].p_idx != EXT_FIRST_INDEX(path[k+1].p_hdr))
1092                         break;
1093                 err = ext4_ext_get_access(handle, inode, path + k);
1094                 if (err)
1095                         break;
1096                 path[k].p_idx->ei_block = border;
1097                 err = ext4_ext_dirty(handle, inode, path + k);
1098                 if (err)
1099                         break;
1100         }
1101
1102         return err;
1103 }
1104
1105 static int
1106 ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
1107                                 struct ext4_extent *ex2)
1108 {
1109         if (le32_to_cpu(ex1->ee_block) + le16_to_cpu(ex1->ee_len) !=
1110                         le32_to_cpu(ex2->ee_block))
1111                 return 0;
1112
1113         /*
1114          * To allow future support for preallocated extents to be added
1115          * as an RO_COMPAT feature, refuse to merge to extents if
1116          * this can result in the top bit of ee_len being set.
1117          */
1118         if (le16_to_cpu(ex1->ee_len) + le16_to_cpu(ex2->ee_len) > EXT_MAX_LEN)
1119                 return 0;
1120 #ifdef AGGRESSIVE_TEST
1121         if (le16_to_cpu(ex1->ee_len) >= 4)
1122                 return 0;
1123 #endif
1124
1125         if (ext_pblock(ex1) + le16_to_cpu(ex1->ee_len) == ext_pblock(ex2))
1126                 return 1;
1127         return 0;
1128 }
1129
1130 /*
1131  * ext4_ext_insert_extent:
1132  * tries to merge requsted extent into the existing extent or
1133  * inserts requested extent as new one into the tree,
1134  * creating new leaf in the no-space case.
1135  */
1136 int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
1137                                 struct ext4_ext_path *path,
1138                                 struct ext4_extent *newext)
1139 {
1140         struct ext4_extent_header * eh;
1141         struct ext4_extent *ex, *fex;
1142         struct ext4_extent *nearex; /* nearest extent */
1143         struct ext4_ext_path *npath = NULL;
1144         int depth, len, err, next;
1145
1146         BUG_ON(newext->ee_len == 0);
1147         depth = ext_depth(inode);
1148         ex = path[depth].p_ext;
1149         BUG_ON(path[depth].p_hdr == NULL);
1150
1151         /* try to insert block into found extent and return */
1152         if (ex && ext4_can_extents_be_merged(inode, ex, newext)) {
1153                 ext_debug("append %d block to %d:%d (from %llu)\n",
1154                                 le16_to_cpu(newext->ee_len),
1155                                 le32_to_cpu(ex->ee_block),
1156                                 le16_to_cpu(ex->ee_len), ext_pblock(ex));
1157                 err = ext4_ext_get_access(handle, inode, path + depth);
1158                 if (err)
1159                         return err;
1160                 ex->ee_len = cpu_to_le16(le16_to_cpu(ex->ee_len)
1161                                          + le16_to_cpu(newext->ee_len));
1162                 eh = path[depth].p_hdr;
1163                 nearex = ex;
1164                 goto merge;
1165         }
1166
1167 repeat:
1168         depth = ext_depth(inode);
1169         eh = path[depth].p_hdr;
1170         if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max))
1171                 goto has_space;
1172
1173         /* probably next leaf has space for us? */
1174         fex = EXT_LAST_EXTENT(eh);
1175         next = ext4_ext_next_leaf_block(inode, path);
1176         if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block)
1177             && next != EXT_MAX_BLOCK) {
1178                 ext_debug("next leaf block - %d\n", next);
1179                 BUG_ON(npath != NULL);
1180                 npath = ext4_ext_find_extent(inode, next, NULL);
1181                 if (IS_ERR(npath))
1182                         return PTR_ERR(npath);
1183                 BUG_ON(npath->p_depth != path->p_depth);
1184                 eh = npath[depth].p_hdr;
1185                 if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max)) {
1186                         ext_debug("next leaf isnt full(%d)\n",
1187                                   le16_to_cpu(eh->eh_entries));
1188                         path = npath;
1189                         goto repeat;
1190                 }
1191                 ext_debug("next leaf has no free space(%d,%d)\n",
1192                           le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
1193         }
1194
1195         /*
1196          * There is no free space in the found leaf.
1197          * We're gonna add a new leaf in the tree.
1198          */
1199         err = ext4_ext_create_new_leaf(handle, inode, path, newext);
1200         if (err)
1201                 goto cleanup;
1202         depth = ext_depth(inode);
1203         eh = path[depth].p_hdr;
1204
1205 has_space:
1206         nearex = path[depth].p_ext;
1207
1208         err = ext4_ext_get_access(handle, inode, path + depth);
1209         if (err)
1210                 goto cleanup;
1211
1212         if (!nearex) {
1213                 /* there is no extent in this leaf, create first one */
1214                 ext_debug("first extent in the leaf: %d:%llu:%d\n",
1215                                 le32_to_cpu(newext->ee_block),
1216                                 ext_pblock(newext),
1217                                 le16_to_cpu(newext->ee_len));
1218                 path[depth].p_ext = EXT_FIRST_EXTENT(eh);
1219         } else if (le32_to_cpu(newext->ee_block)
1220                            > le32_to_cpu(nearex->ee_block)) {
1221 /*              BUG_ON(newext->ee_block == nearex->ee_block); */
1222                 if (nearex != EXT_LAST_EXTENT(eh)) {
1223                         len = EXT_MAX_EXTENT(eh) - nearex;
1224                         len = (len - 1) * sizeof(struct ext4_extent);
1225                         len = len < 0 ? 0 : len;
1226                         ext_debug("insert %d:%llu:%d after: nearest 0x%p, "
1227                                         "move %d from 0x%p to 0x%p\n",
1228                                         le32_to_cpu(newext->ee_block),
1229                                         ext_pblock(newext),
1230                                         le16_to_cpu(newext->ee_len),
1231                                         nearex, len, nearex + 1, nearex + 2);
1232                         memmove(nearex + 2, nearex + 1, len);
1233                 }
1234                 path[depth].p_ext = nearex + 1;
1235         } else {
1236                 BUG_ON(newext->ee_block == nearex->ee_block);
1237                 len = (EXT_MAX_EXTENT(eh) - nearex) * sizeof(struct ext4_extent);
1238                 len = len < 0 ? 0 : len;
1239                 ext_debug("insert %d:%llu:%d before: nearest 0x%p, "
1240                                 "move %d from 0x%p to 0x%p\n",
1241                                 le32_to_cpu(newext->ee_block),
1242                                 ext_pblock(newext),
1243                                 le16_to_cpu(newext->ee_len),
1244                                 nearex, len, nearex + 1, nearex + 2);
1245                 memmove(nearex + 1, nearex, len);
1246                 path[depth].p_ext = nearex;
1247         }
1248
1249         eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries)+1);
1250         nearex = path[depth].p_ext;
1251         nearex->ee_block = newext->ee_block;
1252         nearex->ee_start = newext->ee_start;
1253         nearex->ee_start_hi = newext->ee_start_hi;
1254         nearex->ee_len = newext->ee_len;
1255
1256 merge:
1257         /* try to merge extents to the right */
1258         while (nearex < EXT_LAST_EXTENT(eh)) {
1259                 if (!ext4_can_extents_be_merged(inode, nearex, nearex + 1))
1260                         break;
1261                 /* merge with next extent! */
1262                 nearex->ee_len = cpu_to_le16(le16_to_cpu(nearex->ee_len)
1263                                              + le16_to_cpu(nearex[1].ee_len));
1264                 if (nearex + 1 < EXT_LAST_EXTENT(eh)) {
1265                         len = (EXT_LAST_EXTENT(eh) - nearex - 1)
1266                                         * sizeof(struct ext4_extent);
1267                         memmove(nearex + 1, nearex + 2, len);
1268                 }
1269                 eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries)-1);
1270                 BUG_ON(eh->eh_entries == 0);
1271         }
1272
1273         /* try to merge extents to the left */
1274
1275         /* time to correct all indexes above */
1276         err = ext4_ext_correct_indexes(handle, inode, path);
1277         if (err)
1278                 goto cleanup;
1279
1280         err = ext4_ext_dirty(handle, inode, path + depth);
1281
1282 cleanup:
1283         if (npath) {
1284                 ext4_ext_drop_refs(npath);
1285                 kfree(npath);
1286         }
1287         ext4_ext_tree_changed(inode);
1288         ext4_ext_invalidate_cache(inode);
1289         return err;
1290 }
1291
1292 int ext4_ext_walk_space(struct inode *inode, unsigned long block,
1293                         unsigned long num, ext_prepare_callback func,
1294                         void *cbdata)
1295 {
1296         struct ext4_ext_path *path = NULL;
1297         struct ext4_ext_cache cbex;
1298         struct ext4_extent *ex;
1299         unsigned long next, start = 0, end = 0;
1300         unsigned long last = block + num;
1301         int depth, exists, err = 0;
1302
1303         BUG_ON(func == NULL);
1304         BUG_ON(inode == NULL);
1305
1306         while (block < last && block != EXT_MAX_BLOCK) {
1307                 num = last - block;
1308                 /* find extent for this block */
1309                 path = ext4_ext_find_extent(inode, block, path);
1310                 if (IS_ERR(path)) {
1311                         err = PTR_ERR(path);
1312                         path = NULL;
1313                         break;
1314                 }
1315
1316                 depth = ext_depth(inode);
1317                 BUG_ON(path[depth].p_hdr == NULL);
1318                 ex = path[depth].p_ext;
1319                 next = ext4_ext_next_allocated_block(path);
1320
1321                 exists = 0;
1322                 if (!ex) {
1323                         /* there is no extent yet, so try to allocate
1324                          * all requested space */
1325                         start = block;
1326                         end = block + num;
1327                 } else if (le32_to_cpu(ex->ee_block) > block) {
1328                         /* need to allocate space before found extent */
1329                         start = block;
1330                         end = le32_to_cpu(ex->ee_block);
1331                         if (block + num < end)
1332                                 end = block + num;
1333                 } else if (block >=
1334                              le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len)) {
1335                         /* need to allocate space after found extent */
1336                         start = block;
1337                         end = block + num;
1338                         if (end >= next)
1339                                 end = next;
1340                 } else if (block >= le32_to_cpu(ex->ee_block)) {
1341                         /*
1342                          * some part of requested space is covered
1343                          * by found extent
1344                          */
1345                         start = block;
1346                         end = le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len);
1347                         if (block + num < end)
1348                                 end = block + num;
1349                         exists = 1;
1350                 } else {
1351                         BUG();
1352                 }
1353                 BUG_ON(end <= start);
1354
1355                 if (!exists) {
1356                         cbex.ec_block = start;
1357                         cbex.ec_len = end - start;
1358                         cbex.ec_start = 0;
1359                         cbex.ec_type = EXT4_EXT_CACHE_GAP;
1360                 } else {
1361                         cbex.ec_block = le32_to_cpu(ex->ee_block);
1362                         cbex.ec_len = le16_to_cpu(ex->ee_len);
1363                         cbex.ec_start = ext_pblock(ex);
1364                         cbex.ec_type = EXT4_EXT_CACHE_EXTENT;
1365                 }
1366
1367                 BUG_ON(cbex.ec_len == 0);
1368                 err = func(inode, path, &cbex, cbdata);
1369                 ext4_ext_drop_refs(path);
1370
1371                 if (err < 0)
1372                         break;
1373                 if (err == EXT_REPEAT)
1374                         continue;
1375                 else if (err == EXT_BREAK) {
1376                         err = 0;
1377                         break;
1378                 }
1379
1380                 if (ext_depth(inode) != depth) {
1381                         /* depth was changed. we have to realloc path */
1382                         kfree(path);
1383                         path = NULL;
1384                 }
1385
1386                 block = cbex.ec_block + cbex.ec_len;
1387         }
1388
1389         if (path) {
1390                 ext4_ext_drop_refs(path);
1391                 kfree(path);
1392         }
1393
1394         return err;
1395 }
1396
1397 static void
1398 ext4_ext_put_in_cache(struct inode *inode, __u32 block,
1399                         __u32 len, __u32 start, int type)
1400 {
1401         struct ext4_ext_cache *cex;
1402         BUG_ON(len == 0);
1403         cex = &EXT4_I(inode)->i_cached_extent;
1404         cex->ec_type = type;
1405         cex->ec_block = block;
1406         cex->ec_len = len;
1407         cex->ec_start = start;
1408 }
1409
1410 /*
1411  * ext4_ext_put_gap_in_cache:
1412  * calculate boundaries of the gap that the requested block fits into
1413  * and cache this gap
1414  */
1415 static void
1416 ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
1417                                 unsigned long block)
1418 {
1419         int depth = ext_depth(inode);
1420         unsigned long lblock, len;
1421         struct ext4_extent *ex;
1422
1423         ex = path[depth].p_ext;
1424         if (ex == NULL) {
1425                 /* there is no extent yet, so gap is [0;-] */
1426                 lblock = 0;
1427                 len = EXT_MAX_BLOCK;
1428                 ext_debug("cache gap(whole file):");
1429         } else if (block < le32_to_cpu(ex->ee_block)) {
1430                 lblock = block;
1431                 len = le32_to_cpu(ex->ee_block) - block;
1432                 ext_debug("cache gap(before): %lu [%lu:%lu]",
1433                                 (unsigned long) block,
1434                                 (unsigned long) le32_to_cpu(ex->ee_block),
1435                                 (unsigned long) le16_to_cpu(ex->ee_len));
1436         } else if (block >= le32_to_cpu(ex->ee_block)
1437                             + le16_to_cpu(ex->ee_len)) {
1438                 lblock = le32_to_cpu(ex->ee_block)
1439                          + le16_to_cpu(ex->ee_len);
1440                 len = ext4_ext_next_allocated_block(path);
1441                 ext_debug("cache gap(after): [%lu:%lu] %lu",
1442                                 (unsigned long) le32_to_cpu(ex->ee_block),
1443                                 (unsigned long) le16_to_cpu(ex->ee_len),
1444                                 (unsigned long) block);
1445                 BUG_ON(len == lblock);
1446                 len = len - lblock;
1447         } else {
1448                 lblock = len = 0;
1449                 BUG();
1450         }
1451
1452         ext_debug(" -> %lu:%lu\n", (unsigned long) lblock, len);
1453         ext4_ext_put_in_cache(inode, lblock, len, 0, EXT4_EXT_CACHE_GAP);
1454 }
1455
1456 static int
1457 ext4_ext_in_cache(struct inode *inode, unsigned long block,
1458                         struct ext4_extent *ex)
1459 {
1460         struct ext4_ext_cache *cex;
1461
1462         cex = &EXT4_I(inode)->i_cached_extent;
1463
1464         /* has cache valid data? */
1465         if (cex->ec_type == EXT4_EXT_CACHE_NO)
1466                 return EXT4_EXT_CACHE_NO;
1467
1468         BUG_ON(cex->ec_type != EXT4_EXT_CACHE_GAP &&
1469                         cex->ec_type != EXT4_EXT_CACHE_EXTENT);
1470         if (block >= cex->ec_block && block < cex->ec_block + cex->ec_len) {
1471                 ex->ee_block = cpu_to_le32(cex->ec_block);
1472                 ext4_ext_store_pblock(ex, cex->ec_start);
1473                 ex->ee_len = cpu_to_le16(cex->ec_len);
1474                 ext_debug("%lu cached by %lu:%lu:%llu\n",
1475                                 (unsigned long) block,
1476                                 (unsigned long) cex->ec_block,
1477                                 (unsigned long) cex->ec_len,
1478                                 cex->ec_start);
1479                 return cex->ec_type;
1480         }
1481
1482         /* not in cache */
1483         return EXT4_EXT_CACHE_NO;
1484 }
1485
1486 /*
1487  * ext4_ext_rm_idx:
1488  * removes index from the index block.
1489  * It's used in truncate case only, thus all requests are for
1490  * last index in the block only.
1491  */
1492 int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
1493                         struct ext4_ext_path *path)
1494 {
1495         struct buffer_head *bh;
1496         int err;
1497         ext4_fsblk_t leaf;
1498
1499         /* free index block */
1500         path--;
1501         leaf = idx_pblock(path->p_idx);
1502         BUG_ON(path->p_hdr->eh_entries == 0);
1503         err = ext4_ext_get_access(handle, inode, path);
1504         if (err)
1505                 return err;
1506         path->p_hdr->eh_entries = cpu_to_le16(le16_to_cpu(path->p_hdr->eh_entries)-1);
1507         err = ext4_ext_dirty(handle, inode, path);
1508         if (err)
1509                 return err;
1510         ext_debug("index is empty, remove it, free block %llu\n", leaf);
1511         bh = sb_find_get_block(inode->i_sb, leaf);
1512         ext4_forget(handle, 1, inode, bh, leaf);
1513         ext4_free_blocks(handle, inode, leaf, 1);
1514         return err;
1515 }
1516
1517 /*
1518  * ext4_ext_calc_credits_for_insert:
1519  * This routine returns max. credits that the extent tree can consume.
1520  * It should be OK for low-performance paths like ->writepage()
1521  * To allow many writing processes to fit into a single transaction,
1522  * the caller should calculate credits under truncate_mutex and
1523  * pass the actual path.
1524  */
1525 int ext4_ext_calc_credits_for_insert(struct inode *inode,
1526                                                 struct ext4_ext_path *path)
1527 {
1528         int depth, needed;
1529
1530         if (path) {
1531                 /* probably there is space in leaf? */
1532                 depth = ext_depth(inode);
1533                 if (le16_to_cpu(path[depth].p_hdr->eh_entries)
1534                                 < le16_to_cpu(path[depth].p_hdr->eh_max))
1535                         return 1;
1536         }
1537
1538         /*
1539          * given 32-bit logical block (4294967296 blocks), max. tree
1540          * can be 4 levels in depth -- 4 * 340^4 == 53453440000.
1541          * Let's also add one more level for imbalance.
1542          */
1543         depth = 5;
1544
1545         /* allocation of new data block(s) */
1546         needed = 2;
1547
1548         /*
1549          * tree can be full, so it would need to grow in depth:
1550          * we need one credit to modify old root, credits for
1551          * new root will be added in split accounting
1552          */
1553         needed += 1;
1554
1555         /*
1556          * Index split can happen, we would need:
1557          *    allocate intermediate indexes (bitmap + group)
1558          *  + change two blocks at each level, but root (already included)
1559          */
1560         needed += (depth * 2) + (depth * 2);
1561
1562         /* any allocation modifies superblock */
1563         needed += 1;
1564
1565         return needed;
1566 }
1567
1568 static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
1569                                 struct ext4_extent *ex,
1570                                 unsigned long from, unsigned long to)
1571 {
1572         struct buffer_head *bh;
1573         int i;
1574
1575 #ifdef EXTENTS_STATS
1576         {
1577                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1578                 unsigned short ee_len =  le16_to_cpu(ex->ee_len);
1579                 spin_lock(&sbi->s_ext_stats_lock);
1580                 sbi->s_ext_blocks += ee_len;
1581                 sbi->s_ext_extents++;
1582                 if (ee_len < sbi->s_ext_min)
1583                         sbi->s_ext_min = ee_len;
1584                 if (ee_len > sbi->s_ext_max)
1585                         sbi->s_ext_max = ee_len;
1586                 if (ext_depth(inode) > sbi->s_depth_max)
1587                         sbi->s_depth_max = ext_depth(inode);
1588                 spin_unlock(&sbi->s_ext_stats_lock);
1589         }
1590 #endif
1591         if (from >= le32_to_cpu(ex->ee_block)
1592             && to == le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - 1) {
1593                 /* tail removal */
1594                 unsigned long num;
1595                 ext4_fsblk_t start;
1596                 num = le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - from;
1597                 start = ext_pblock(ex) + le16_to_cpu(ex->ee_len) - num;
1598                 ext_debug("free last %lu blocks starting %llu\n", num, start);
1599                 for (i = 0; i < num; i++) {
1600                         bh = sb_find_get_block(inode->i_sb, start + i);
1601                         ext4_forget(handle, 0, inode, bh, start + i);
1602                 }
1603                 ext4_free_blocks(handle, inode, start, num);
1604         } else if (from == le32_to_cpu(ex->ee_block)
1605                    && to <= le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - 1) {
1606                 printk("strange request: removal %lu-%lu from %u:%u\n",
1607                        from, to, le32_to_cpu(ex->ee_block), le16_to_cpu(ex->ee_len));
1608         } else {
1609                 printk("strange request: removal(2) %lu-%lu from %u:%u\n",
1610                        from, to, le32_to_cpu(ex->ee_block), le16_to_cpu(ex->ee_len));
1611         }
1612         return 0;
1613 }
1614
1615 static int
1616 ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
1617                 struct ext4_ext_path *path, unsigned long start)
1618 {
1619         int err = 0, correct_index = 0;
1620         int depth = ext_depth(inode), credits;
1621         struct ext4_extent_header *eh;
1622         unsigned a, b, block, num;
1623         unsigned long ex_ee_block;
1624         unsigned short ex_ee_len;
1625         struct ext4_extent *ex;
1626
1627         ext_debug("truncate since %lu in leaf\n", start);
1628         if (!path[depth].p_hdr)
1629                 path[depth].p_hdr = ext_block_hdr(path[depth].p_bh);
1630         eh = path[depth].p_hdr;
1631         BUG_ON(eh == NULL);
1632         BUG_ON(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max));
1633         BUG_ON(eh->eh_magic != EXT4_EXT_MAGIC);
1634
1635         /* find where to start removing */
1636         ex = EXT_LAST_EXTENT(eh);
1637
1638         ex_ee_block = le32_to_cpu(ex->ee_block);
1639         ex_ee_len = le16_to_cpu(ex->ee_len);
1640
1641         while (ex >= EXT_FIRST_EXTENT(eh) &&
1642                         ex_ee_block + ex_ee_len > start) {
1643                 ext_debug("remove ext %lu:%u\n", ex_ee_block, ex_ee_len);
1644                 path[depth].p_ext = ex;
1645
1646                 a = ex_ee_block > start ? ex_ee_block : start;
1647                 b = ex_ee_block + ex_ee_len - 1 < EXT_MAX_BLOCK ?
1648                         ex_ee_block + ex_ee_len - 1 : EXT_MAX_BLOCK;
1649
1650                 ext_debug("  border %u:%u\n", a, b);
1651
1652                 if (a != ex_ee_block && b != ex_ee_block + ex_ee_len - 1) {
1653                         block = 0;
1654                         num = 0;
1655                         BUG();
1656                 } else if (a != ex_ee_block) {
1657                         /* remove tail of the extent */
1658                         block = ex_ee_block;
1659                         num = a - block;
1660                 } else if (b != ex_ee_block + ex_ee_len - 1) {
1661                         /* remove head of the extent */
1662                         block = a;
1663                         num = b - a;
1664                         /* there is no "make a hole" API yet */
1665                         BUG();
1666                 } else {
1667                         /* remove whole extent: excellent! */
1668                         block = ex_ee_block;
1669                         num = 0;
1670                         BUG_ON(a != ex_ee_block);
1671                         BUG_ON(b != ex_ee_block + ex_ee_len - 1);
1672                 }
1673
1674                 /* at present, extent can't cross block group: */
1675                 /* leaf + bitmap + group desc + sb + inode */
1676                 credits = 5;
1677                 if (ex == EXT_FIRST_EXTENT(eh)) {
1678                         correct_index = 1;
1679                         credits += (ext_depth(inode)) + 1;
1680                 }
1681 #ifdef CONFIG_QUOTA
1682                 credits += 2 * EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
1683 #endif
1684
1685                 handle = ext4_ext_journal_restart(handle, credits);
1686                 if (IS_ERR(handle)) {
1687                         err = PTR_ERR(handle);
1688                         goto out;
1689                 }
1690
1691                 err = ext4_ext_get_access(handle, inode, path + depth);
1692                 if (err)
1693                         goto out;
1694
1695                 err = ext4_remove_blocks(handle, inode, ex, a, b);
1696                 if (err)
1697                         goto out;
1698
1699                 if (num == 0) {
1700                         /* this extent is removed; mark slot entirely unused */
1701                         ext4_ext_store_pblock(ex, 0);
1702                         eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries)-1);
1703                 }
1704
1705                 ex->ee_block = cpu_to_le32(block);
1706                 ex->ee_len = cpu_to_le16(num);
1707
1708                 err = ext4_ext_dirty(handle, inode, path + depth);
1709                 if (err)
1710                         goto out;
1711
1712                 ext_debug("new extent: %u:%u:%llu\n", block, num,
1713                                 ext_pblock(ex));
1714                 ex--;
1715                 ex_ee_block = le32_to_cpu(ex->ee_block);
1716                 ex_ee_len = le16_to_cpu(ex->ee_len);
1717         }
1718
1719         if (correct_index && eh->eh_entries)
1720                 err = ext4_ext_correct_indexes(handle, inode, path);
1721
1722         /* if this leaf is free, then we should
1723          * remove it from index block above */
1724         if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL)
1725                 err = ext4_ext_rm_idx(handle, inode, path + depth);
1726
1727 out:
1728         return err;
1729 }
1730
1731 /*
1732  * ext4_ext_more_to_rm:
1733  * returns 1 if current index has to be freed (even partial)
1734  */
1735 static int
1736 ext4_ext_more_to_rm(struct ext4_ext_path *path)
1737 {
1738         BUG_ON(path->p_idx == NULL);
1739
1740         if (path->p_idx < EXT_FIRST_INDEX(path->p_hdr))
1741                 return 0;
1742
1743         /*
1744          * if truncate on deeper level happened, it wasn't partial,
1745          * so we have to consider current index for truncation
1746          */
1747         if (le16_to_cpu(path->p_hdr->eh_entries) == path->p_block)
1748                 return 0;
1749         return 1;
1750 }
1751
1752 int ext4_ext_remove_space(struct inode *inode, unsigned long start)
1753 {
1754         struct super_block *sb = inode->i_sb;
1755         int depth = ext_depth(inode);
1756         struct ext4_ext_path *path;
1757         handle_t *handle;
1758         int i = 0, err = 0;
1759
1760         ext_debug("truncate since %lu\n", start);
1761
1762         /* probably first extent we're gonna free will be last in block */
1763         handle = ext4_journal_start(inode, depth + 1);
1764         if (IS_ERR(handle))
1765                 return PTR_ERR(handle);
1766
1767         ext4_ext_invalidate_cache(inode);
1768
1769         /*
1770          * We start scanning from right side, freeing all the blocks
1771          * after i_size and walking into the tree depth-wise.
1772          */
1773         path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_KERNEL);
1774         if (path == NULL) {
1775                 ext4_journal_stop(handle);
1776                 return -ENOMEM;
1777         }
1778         path[0].p_hdr = ext_inode_hdr(inode);
1779         if (ext4_ext_check_header(__FUNCTION__, inode, path[0].p_hdr)) {
1780                 err = -EIO;
1781                 goto out;
1782         }
1783         path[0].p_depth = depth;
1784
1785         while (i >= 0 && err == 0) {
1786                 if (i == depth) {
1787                         /* this is leaf block */
1788                         err = ext4_ext_rm_leaf(handle, inode, path, start);
1789                         /* root level has p_bh == NULL, brelse() eats this */
1790                         brelse(path[i].p_bh);
1791                         path[i].p_bh = NULL;
1792                         i--;
1793                         continue;
1794                 }
1795
1796                 /* this is index block */
1797                 if (!path[i].p_hdr) {
1798                         ext_debug("initialize header\n");
1799                         path[i].p_hdr = ext_block_hdr(path[i].p_bh);
1800                         if (ext4_ext_check_header(__FUNCTION__, inode,
1801                                                         path[i].p_hdr)) {
1802                                 err = -EIO;
1803                                 goto out;
1804                         }
1805                 }
1806
1807                 BUG_ON(le16_to_cpu(path[i].p_hdr->eh_entries)
1808                            > le16_to_cpu(path[i].p_hdr->eh_max));
1809                 BUG_ON(path[i].p_hdr->eh_magic != EXT4_EXT_MAGIC);
1810
1811                 if (!path[i].p_idx) {
1812                         /* this level hasn't been touched yet */
1813                         path[i].p_idx = EXT_LAST_INDEX(path[i].p_hdr);
1814                         path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries)+1;
1815                         ext_debug("init index ptr: hdr 0x%p, num %d\n",
1816                                   path[i].p_hdr,
1817                                   le16_to_cpu(path[i].p_hdr->eh_entries));
1818                 } else {
1819                         /* we were already here, see at next index */
1820                         path[i].p_idx--;
1821                 }
1822
1823                 ext_debug("level %d - index, first 0x%p, cur 0x%p\n",
1824                                 i, EXT_FIRST_INDEX(path[i].p_hdr),
1825                                 path[i].p_idx);
1826                 if (ext4_ext_more_to_rm(path + i)) {
1827                         /* go to the next level */
1828                         ext_debug("move to level %d (block %llu)\n",
1829                                   i + 1, idx_pblock(path[i].p_idx));
1830                         memset(path + i + 1, 0, sizeof(*path));
1831                         path[i+1].p_bh =
1832                                 sb_bread(sb, idx_pblock(path[i].p_idx));
1833                         if (!path[i+1].p_bh) {
1834                                 /* should we reset i_size? */
1835                                 err = -EIO;
1836                                 break;
1837                         }
1838
1839                         /* save actual number of indexes since this
1840                          * number is changed at the next iteration */
1841                         path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries);
1842                         i++;
1843                 } else {
1844                         /* we finished processing this index, go up */
1845                         if (path[i].p_hdr->eh_entries == 0 && i > 0) {
1846                                 /* index is empty, remove it;
1847                                  * handle must be already prepared by the
1848                                  * truncatei_leaf() */
1849                                 err = ext4_ext_rm_idx(handle, inode, path + i);
1850                         }
1851                         /* root level has p_bh == NULL, brelse() eats this */
1852                         brelse(path[i].p_bh);
1853                         path[i].p_bh = NULL;
1854                         i--;
1855                         ext_debug("return to level %d\n", i);
1856                 }
1857         }
1858
1859         /* TODO: flexible tree reduction should be here */
1860         if (path->p_hdr->eh_entries == 0) {
1861                 /*
1862                  * truncate to zero freed all the tree,
1863                  * so we need to correct eh_depth
1864                  */
1865                 err = ext4_ext_get_access(handle, inode, path);
1866                 if (err == 0) {
1867                         ext_inode_hdr(inode)->eh_depth = 0;
1868                         ext_inode_hdr(inode)->eh_max =
1869                                 cpu_to_le16(ext4_ext_space_root(inode));
1870                         err = ext4_ext_dirty(handle, inode, path);
1871                 }
1872         }
1873 out:
1874         ext4_ext_tree_changed(inode);
1875         ext4_ext_drop_refs(path);
1876         kfree(path);
1877         ext4_journal_stop(handle);
1878
1879         return err;
1880 }
1881
1882 /*
1883  * called at mount time
1884  */
1885 void ext4_ext_init(struct super_block *sb)
1886 {
1887         /*
1888          * possible initialization would be here
1889          */
1890
1891         if (test_opt(sb, EXTENTS)) {
1892                 printk("EXT4-fs: file extents enabled");
1893 #ifdef AGGRESSIVE_TEST
1894                 printk(", aggressive tests");
1895 #endif
1896 #ifdef CHECK_BINSEARCH
1897                 printk(", check binsearch");
1898 #endif
1899 #ifdef EXTENTS_STATS
1900                 printk(", stats");
1901 #endif
1902                 printk("\n");
1903 #ifdef EXTENTS_STATS
1904                 spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
1905                 EXT4_SB(sb)->s_ext_min = 1 << 30;
1906                 EXT4_SB(sb)->s_ext_max = 0;
1907 #endif
1908         }
1909 }
1910
1911 /*
1912  * called at umount time
1913  */
1914 void ext4_ext_release(struct super_block *sb)
1915 {
1916         if (!test_opt(sb, EXTENTS))
1917                 return;
1918
1919 #ifdef EXTENTS_STATS
1920         if (EXT4_SB(sb)->s_ext_blocks && EXT4_SB(sb)->s_ext_extents) {
1921                 struct ext4_sb_info *sbi = EXT4_SB(sb);
1922                 printk(KERN_ERR "EXT4-fs: %lu blocks in %lu extents (%lu ave)\n",
1923                         sbi->s_ext_blocks, sbi->s_ext_extents,
1924                         sbi->s_ext_blocks / sbi->s_ext_extents);
1925                 printk(KERN_ERR "EXT4-fs: extents: %lu min, %lu max, max depth %lu\n",
1926                         sbi->s_ext_min, sbi->s_ext_max, sbi->s_depth_max);
1927         }
1928 #endif
1929 }
1930
1931 int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
1932                         ext4_fsblk_t iblock,
1933                         unsigned long max_blocks, struct buffer_head *bh_result,
1934                         int create, int extend_disksize)
1935 {
1936         struct ext4_ext_path *path = NULL;
1937         struct ext4_extent newex, *ex;
1938         ext4_fsblk_t goal, newblock;
1939         int err = 0, depth;
1940         unsigned long allocated = 0;
1941
1942         __clear_bit(BH_New, &bh_result->b_state);
1943         ext_debug("blocks %d/%lu requested for inode %u\n", (int) iblock,
1944                         max_blocks, (unsigned) inode->i_ino);
1945         mutex_lock(&EXT4_I(inode)->truncate_mutex);
1946
1947         /* check in cache */
1948         goal = ext4_ext_in_cache(inode, iblock, &newex);
1949         if (goal) {
1950                 if (goal == EXT4_EXT_CACHE_GAP) {
1951                         if (!create) {
1952                                 /* block isn't allocated yet and
1953                                  * user doesn't want to allocate it */
1954                                 goto out2;
1955                         }
1956                         /* we should allocate requested block */
1957                 } else if (goal == EXT4_EXT_CACHE_EXTENT) {
1958                         /* block is already allocated */
1959                         newblock = iblock
1960                                    - le32_to_cpu(newex.ee_block)
1961                                    + ext_pblock(&newex);
1962                         /* number of remaining blocks in the extent */
1963                         allocated = le16_to_cpu(newex.ee_len) -
1964                                         (iblock - le32_to_cpu(newex.ee_block));
1965                         goto out;
1966                 } else {
1967                         BUG();
1968                 }
1969         }
1970
1971         /* find extent for this block */
1972         path = ext4_ext_find_extent(inode, iblock, NULL);
1973         if (IS_ERR(path)) {
1974                 err = PTR_ERR(path);
1975                 path = NULL;
1976                 goto out2;
1977         }
1978
1979         depth = ext_depth(inode);
1980
1981         /*
1982          * consistent leaf must not be empty;
1983          * this situation is possible, though, _during_ tree modification;
1984          * this is why assert can't be put in ext4_ext_find_extent()
1985          */
1986         BUG_ON(path[depth].p_ext == NULL && depth != 0);
1987
1988         ex = path[depth].p_ext;
1989         if (ex) {
1990                 unsigned long ee_block = le32_to_cpu(ex->ee_block);
1991                 ext4_fsblk_t ee_start = ext_pblock(ex);
1992                 unsigned short ee_len  = le16_to_cpu(ex->ee_len);
1993
1994                 /*
1995                  * Allow future support for preallocated extents to be added
1996                  * as an RO_COMPAT feature:
1997                  * Uninitialized extents are treated as holes, except that
1998                  * we avoid (fail) allocating new blocks during a write.
1999                  */
2000                 if (ee_len > EXT_MAX_LEN)
2001                         goto out2;
2002                 /* if found extent covers block, simply return it */
2003                 if (iblock >= ee_block && iblock < ee_block + ee_len) {
2004                         newblock = iblock - ee_block + ee_start;
2005                         /* number of remaining blocks in the extent */
2006                         allocated = ee_len - (iblock - ee_block);
2007                         ext_debug("%d fit into %lu:%d -> %llu\n", (int) iblock,
2008                                         ee_block, ee_len, newblock);
2009                         ext4_ext_put_in_cache(inode, ee_block, ee_len,
2010                                                 ee_start, EXT4_EXT_CACHE_EXTENT);
2011                         goto out;
2012                 }
2013         }
2014
2015         /*
2016          * requested block isn't allocated yet;
2017          * we couldn't try to create block if create flag is zero
2018          */
2019         if (!create) {
2020                 /* put just found gap into cache to speed up
2021                  * subsequent requests */
2022                 ext4_ext_put_gap_in_cache(inode, path, iblock);
2023                 goto out2;
2024         }
2025         /*
2026          * Okay, we need to do block allocation.  Lazily initialize the block
2027          * allocation info here if necessary.
2028          */
2029         if (S_ISREG(inode->i_mode) && (!EXT4_I(inode)->i_block_alloc_info))
2030                 ext4_init_block_alloc_info(inode);
2031
2032         /* allocate new block */
2033         goal = ext4_ext_find_goal(inode, path, iblock);
2034         allocated = max_blocks;
2035         newblock = ext4_new_blocks(handle, inode, goal, &allocated, &err);
2036         if (!newblock)
2037                 goto out2;
2038         ext_debug("allocate new block: goal %llu, found %llu/%lu\n",
2039                         goal, newblock, allocated);
2040
2041         /* try to insert new extent into found leaf and return */
2042         newex.ee_block = cpu_to_le32(iblock);
2043         ext4_ext_store_pblock(&newex, newblock);
2044         newex.ee_len = cpu_to_le16(allocated);
2045         err = ext4_ext_insert_extent(handle, inode, path, &newex);
2046         if (err)
2047                 goto out2;
2048
2049         if (extend_disksize && inode->i_size > EXT4_I(inode)->i_disksize)
2050                 EXT4_I(inode)->i_disksize = inode->i_size;
2051
2052         /* previous routine could use block we allocated */
2053         newblock = ext_pblock(&newex);
2054         __set_bit(BH_New, &bh_result->b_state);
2055
2056         ext4_ext_put_in_cache(inode, iblock, allocated, newblock,
2057                                 EXT4_EXT_CACHE_EXTENT);
2058 out:
2059         if (allocated > max_blocks)
2060                 allocated = max_blocks;
2061         ext4_ext_show_leaf(inode, path);
2062         __set_bit(BH_Mapped, &bh_result->b_state);
2063         bh_result->b_bdev = inode->i_sb->s_bdev;
2064         bh_result->b_blocknr = newblock;
2065 out2:
2066         if (path) {
2067                 ext4_ext_drop_refs(path);
2068                 kfree(path);
2069         }
2070         mutex_unlock(&EXT4_I(inode)->truncate_mutex);
2071
2072         return err ? err : allocated;
2073 }
2074
2075 void ext4_ext_truncate(struct inode * inode, struct page *page)
2076 {
2077         struct address_space *mapping = inode->i_mapping;
2078         struct super_block *sb = inode->i_sb;
2079         unsigned long last_block;
2080         handle_t *handle;
2081         int err = 0;
2082
2083         /*
2084          * probably first extent we're gonna free will be last in block
2085          */
2086         err = ext4_writepage_trans_blocks(inode) + 3;
2087         handle = ext4_journal_start(inode, err);
2088         if (IS_ERR(handle)) {
2089                 if (page) {
2090                         clear_highpage(page);
2091                         flush_dcache_page(page);
2092                         unlock_page(page);
2093                         page_cache_release(page);
2094                 }
2095                 return;
2096         }
2097
2098         if (page)
2099                 ext4_block_truncate_page(handle, page, mapping, inode->i_size);
2100
2101         mutex_lock(&EXT4_I(inode)->truncate_mutex);
2102         ext4_ext_invalidate_cache(inode);
2103
2104         /*
2105          * TODO: optimization is possible here.
2106          * Probably we need not scan at all,
2107          * because page truncation is enough.
2108          */
2109         if (ext4_orphan_add(handle, inode))
2110                 goto out_stop;
2111
2112         /* we have to know where to truncate from in crash case */
2113         EXT4_I(inode)->i_disksize = inode->i_size;
2114         ext4_mark_inode_dirty(handle, inode);
2115
2116         last_block = (inode->i_size + sb->s_blocksize - 1)
2117                         >> EXT4_BLOCK_SIZE_BITS(sb);
2118         err = ext4_ext_remove_space(inode, last_block);
2119
2120         /* In a multi-transaction truncate, we only make the final
2121          * transaction synchronous. */
2122         if (IS_SYNC(inode))
2123                 handle->h_sync = 1;
2124
2125 out_stop:
2126         /*
2127          * If this was a simple ftruncate() and the file will remain alive,
2128          * then we need to clear up the orphan record which we created above.
2129          * However, if this was a real unlink then we were called by
2130          * ext4_delete_inode(), and we allow that function to clean up the
2131          * orphan info for us.
2132          */
2133         if (inode->i_nlink)
2134                 ext4_orphan_del(handle, inode);
2135
2136         mutex_unlock(&EXT4_I(inode)->truncate_mutex);
2137         ext4_journal_stop(handle);
2138 }
2139
2140 /*
2141  * ext4_ext_writepage_trans_blocks:
2142  * calculate max number of blocks we could modify
2143  * in order to allocate new block for an inode
2144  */
2145 int ext4_ext_writepage_trans_blocks(struct inode *inode, int num)
2146 {
2147         int needed;
2148
2149         needed = ext4_ext_calc_credits_for_insert(inode, NULL);
2150
2151         /* caller wants to allocate num blocks, but note it includes sb */
2152         needed = needed * num - (num - 1);
2153
2154 #ifdef CONFIG_QUOTA
2155         needed += 2 * EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
2156 #endif
2157
2158         return needed;
2159 }
2160
2161 EXPORT_SYMBOL(ext4_mark_inode_dirty);
2162 EXPORT_SYMBOL(ext4_ext_invalidate_cache);
2163 EXPORT_SYMBOL(ext4_ext_insert_extent);
2164 EXPORT_SYMBOL(ext4_ext_walk_space);
2165 EXPORT_SYMBOL(ext4_ext_find_goal);
2166 EXPORT_SYMBOL(ext4_ext_calc_credits_for_insert);
2167