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