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/jbd2.h>
  36 #include <linux/highuid.h>
  37 #include <linux/pagemap.h>
  38 #include <linux/quotaops.h>
  39 #include <linux/string.h>
  40 #include <linux/slab.h>
  41 #include <linux/falloc.h>
  42 #include <asm/uaccess.h>
  43 #include <linux/fiemap.h>
  44 #include "ext4_jbd2.h"
  45 #include "ext4_extents.h"
  46
  47
  48 /*
  49  * ext_pblock:
  50  * combine low and high parts of physical block number into ext4_fsblk_t
  51  */
  52 ext4_fsblk_t ext_pblock(struct ext4_extent *ex)
  53 {
  54         ext4_fsblk_t block;
  55
  56         block = le32_to_cpu(ex->ee_start_lo);
  57         block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
  58         return block;
  59 }
  60
  61 /*
  62  * idx_pblock:
  63  * combine low and high parts of a leaf physical block number into ext4_fsblk_t
  64  */
  65 ext4_fsblk_t idx_pblock(struct ext4_extent_idx *ix)
  66 {
  67         ext4_fsblk_t block;
  68
  69         block = le32_to_cpu(ix->ei_leaf_lo);
  70         block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
  71         return block;
  72 }
  73
  74 /*
  75  * ext4_ext_store_pblock:
  76  * stores a large physical block number into an extent struct,
  77  * breaking it into parts
  78  */
  79 void ext4_ext_store_pblock(struct ext4_extent *ex, ext4_fsblk_t pb)
  80 {
  81         ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
  82         ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 0xffff);
  83 }
  84
  85 /*
  86  * ext4_idx_store_pblock:
  87  * stores a large physical block number into an index struct,
  88  * breaking it into parts
  89  */
  90 static void ext4_idx_store_pblock(struct ext4_extent_idx *ix, ext4_fsblk_t pb)
  91 {
  92         ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
  93         ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 0xffff);
  94 }
  95
  96 static int ext4_ext_truncate_extend_restart(handle_t *handle,
  97                                             struct inode *inode,
  98                                             int needed)
  99 {
 100         int err;
 101
 102         if (!ext4_handle_valid(handle))
 103                 return 0;
 104         if (handle->h_buffer_credits > needed)
 105                 return 0;
 106         err = ext4_journal_extend(handle, needed);
 107         if (err <= 0)
 108                 return err;
 109         err = ext4_truncate_restart_trans(handle, inode, needed);
 110         /*
 111          * We have dropped i_data_sem so someone might have cached again
 112          * an extent we are going to truncate.
 113          */
 114         ext4_ext_invalidate_cache(inode);
 115
 116         return err;
 117 }
 118
 119 /*
 120  * could return:
 121  *  - EROFS
 122  *  - ENOMEM
 123  */
 124 static int ext4_ext_get_access(handle_t *handle, struct inode *inode,
 125                                 struct ext4_ext_path *path)
 126 {
 127         if (path->p_bh) {
 128                 /* path points to block */
 129                 return ext4_journal_get_write_access(handle, path->p_bh);
 130         }
 131         /* path points to leaf/index in inode body */
 132         /* we use in-core data, no need to protect them */
 133         return 0;
 134 }
 135
 136 /*
 137  * could return:
 138  *  - EROFS
 139  *  - ENOMEM
 140  *  - EIO
 141  */
 142 static int ext4_ext_dirty(handle_t *handle, struct inode *inode,
 143                                 struct ext4_ext_path *path)
 144 {
 145         int err;
 146         if (path->p_bh) {
 147                 /* path points to block */
 148                 err = ext4_handle_dirty_metadata(handle, inode, path->p_bh);
 149         } else {
 150                 /* path points to leaf/index in inode body */
 151                 err = ext4_mark_inode_dirty(handle, inode);
 152         }
 153         return err;
 154 }
 155
 156 static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
 157                               struct ext4_ext_path *path,
 158                               ext4_lblk_t block)
 159 {
 160         struct ext4_inode_info *ei = EXT4_I(inode);
 161         ext4_fsblk_t bg_start;
 162         ext4_fsblk_t last_block;
 163         ext4_grpblk_t colour;
 164         ext4_group_t block_group;
 165         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 166         int depth;
 167
 168         if (path) {
 169                 struct ext4_extent *ex;
 170                 depth = path->p_depth;
 171
 172                 /* try to predict block placement */
 173                 ex = path[depth].p_ext;
 174                 if (ex)
 175                         return ext_pblock(ex)+(block-le32_to_cpu(ex->ee_block));
 176
 177                 /* it looks like index is empty;
 178                  * try to find starting block from index itself */
 179                 if (path[depth].p_bh)
 180                         return path[depth].p_bh->b_blocknr;
 181         }
 182
 183         /* OK. use inode's group */
 184         block_group = ei->i_block_group;
 185         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 186                 /*
 187                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 188                  * block groups per flexgroup, reserve the first block
 189                  * group for directories and special files.  Regular
 190                  * files will start at the second block group.  This
 191                  * tends to speed up directory access and improves
 192                  * fsck times.
 193                  */
 194                 block_group &= ~(flex_size-1);
 195                 if (S_ISREG(inode->i_mode))
 196                         block_group++;
 197         }
 198         bg_start = (block_group * EXT4_BLOCKS_PER_GROUP(inode->i_sb)) +
 199                 le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_first_data_block);
 200         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 201
 202         /*
 203          * If we are doing delayed allocation, we don't need take
 204          * colour into account.
 205          */
 206         if (test_opt(inode->i_sb, DELALLOC))
 207                 return bg_start;
 208
 209         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 210                 colour = (current->pid % 16) *
 211                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 212         else
 213                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
 214         return bg_start + colour + block;
 215 }
 216
 217 /*
 218  * Allocation for a meta data block
 219  */
 220 static ext4_fsblk_t
 221 ext4_ext_new_meta_block(handle_t *handle, struct inode *inode,
 222                         struct ext4_ext_path *path,
 223                         struct ext4_extent *ex, int *err)
 224 {
 225         ext4_fsblk_t goal, newblock;
 226
 227         goal = ext4_ext_find_goal(inode, path, le32_to_cpu(ex->ee_block));
 228         newblock = ext4_new_meta_blocks(handle, inode, goal, NULL, err);
 229         return newblock;
 230 }
 231
 232 static inline int ext4_ext_space_block(struct inode *inode, int check)
 233 {
 234         int size;
 235
 236         size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
 237                         / sizeof(struct ext4_extent);
 238         if (!check) {
 239 #ifdef AGGRESSIVE_TEST
 240                 if (size > 6)
 241                         size = 6;
 242 #endif
 243         }
 244         return size;
 245 }
 246
 247 static inline int ext4_ext_space_block_idx(struct inode *inode, int check)
 248 {
 249         int size;
 250
 251         size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
 252                         / sizeof(struct ext4_extent_idx);
 253         if (!check) {
 254 #ifdef AGGRESSIVE_TEST
 255                 if (size > 5)
 256                         size = 5;
 257 #endif
 258         }
 259         return size;
 260 }
 261
 262 static inline int ext4_ext_space_root(struct inode *inode, int check)
 263 {
 264         int size;
 265
 266         size = sizeof(EXT4_I(inode)->i_data);
 267         size -= sizeof(struct ext4_extent_header);
 268         size /= sizeof(struct ext4_extent);
 269         if (!check) {
 270 #ifdef AGGRESSIVE_TEST
 271                 if (size > 3)
 272                         size = 3;
 273 #endif
 274         }
 275         return size;
 276 }
 277
 278 static inline int ext4_ext_space_root_idx(struct inode *inode, int check)
 279 {
 280         int size;
 281
 282         size = sizeof(EXT4_I(inode)->i_data);
 283         size -= sizeof(struct ext4_extent_header);
 284         size /= sizeof(struct ext4_extent_idx);
 285         if (!check) {
 286 #ifdef AGGRESSIVE_TEST
 287                 if (size > 4)
 288                         size = 4;
 289 #endif
 290         }
 291         return size;
 292 }
 293
 294 /*
 295  * Calculate the number of metadata blocks needed
 296  * to allocate @blocks
 297  * Worse case is one block per extent
 298  */
 299 int ext4_ext_calc_metadata_amount(struct inode *inode, sector_t lblock)
 300 {
 301         struct ext4_inode_info *ei = EXT4_I(inode);
 302         int idxs, num = 0;
 303
 304         idxs = ((inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
 305                 / sizeof(struct ext4_extent_idx));
 306
 307         /*
 308          * If the new delayed allocation block is contiguous with the
 309          * previous da block, it can share index blocks with the
 310          * previous block, so we only need to allocate a new index
 311          * block every idxs leaf blocks.  At ldxs**2 blocks, we need
 312          * an additional index block, and at ldxs**3 blocks, yet
 313          * another index blocks.
 314          */
 315         if (ei->i_da_metadata_calc_len &&
 316             ei->i_da_metadata_calc_last_lblock+1 == lblock) {
 317                 if ((ei->i_da_metadata_calc_len % idxs) == 0)
 318                         num++;
 319                 if ((ei->i_da_metadata_calc_len % (idxs*idxs)) == 0)
 320                         num++;
 321                 if ((ei->i_da_metadata_calc_len % (idxs*idxs*idxs)) == 0) {
 322                         num++;
 323                         ei->i_da_metadata_calc_len = 0;
 324                 } else
 325                         ei->i_da_metadata_calc_len++;
 326                 ei->i_da_metadata_calc_last_lblock++;
 327                 return num;
 328         }
 329
 330         /*
 331          * In the worst case we need a new set of index blocks at
 332          * every level of the inode's extent tree.
 333          */
 334         ei->i_da_metadata_calc_len = 1;
 335         ei->i_da_metadata_calc_last_lblock = lblock;
 336         return ext_depth(inode) + 1;
 337 }
 338
 339 static int
 340 ext4_ext_max_entries(struct inode *inode, int depth)
 341 {
 342         int max;
 343
 344         if (depth == ext_depth(inode)) {
 345                 if (depth == 0)
 346                         max = ext4_ext_space_root(inode, 1);
 347                 else
 348                         max = ext4_ext_space_root_idx(inode, 1);
 349         } else {
 350                 if (depth == 0)
 351                         max = ext4_ext_space_block(inode, 1);
 352                 else
 353                         max = ext4_ext_space_block_idx(inode, 1);
 354         }
 355
 356         return max;
 357 }
 358
 359 static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext)
 360 {
 361         ext4_fsblk_t block = ext_pblock(ext);
 362         int len = ext4_ext_get_actual_len(ext);
 363
 364         return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, len);
 365 }
 366
 367 static int ext4_valid_extent_idx(struct inode *inode,
 368                                 struct ext4_extent_idx *ext_idx)
 369 {
 370         ext4_fsblk_t block = idx_pblock(ext_idx);
 371
 372         return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, 1);
 373 }
 374
 375 static int ext4_valid_extent_entries(struct inode *inode,
 376                                 struct ext4_extent_header *eh,
 377                                 int depth)
 378 {
 379         struct ext4_extent *ext;
 380         struct ext4_extent_idx *ext_idx;
 381         unsigned short entries;
 382         if (eh->eh_entries == 0)
 383                 return 1;
 384
 385         entries = le16_to_cpu(eh->eh_entries);
 386
 387         if (depth == 0) {
 388                 /* leaf entries */
 389                 ext = EXT_FIRST_EXTENT(eh);
 390                 while (entries) {
 391                         if (!ext4_valid_extent(inode, ext))
 392                                 return 0;
 393                         ext++;
 394                         entries--;
 395                 }
 396         } else {
 397                 ext_idx = EXT_FIRST_INDEX(eh);
 398                 while (entries) {
 399                         if (!ext4_valid_extent_idx(inode, ext_idx))
 400                                 return 0;
 401                         ext_idx++;
 402                         entries--;
 403                 }
 404         }
 405         return 1;
 406 }
 407
 408 static int __ext4_ext_check(const char *function, struct inode *inode,
 409                                         struct ext4_extent_header *eh,
 410                                         int depth)
 411 {
 412         const char *error_msg;
 413         int max = 0;
 414
 415         if (unlikely(eh->eh_magic != EXT4_EXT_MAGIC)) {
 416                 error_msg = "invalid magic";
 417                 goto corrupted;
 418         }
 419         if (unlikely(le16_to_cpu(eh->eh_depth) != depth)) {
 420                 error_msg = "unexpected eh_depth";
 421                 goto corrupted;
 422         }
 423         if (unlikely(eh->eh_max == 0)) {
 424                 error_msg = "invalid eh_max";
 425                 goto corrupted;
 426         }
 427         max = ext4_ext_max_entries(inode, depth);
 428         if (unlikely(le16_to_cpu(eh->eh_max) > max)) {
 429                 error_msg = "too large eh_max";
 430                 goto corrupted;
 431         }
 432         if (unlikely(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max))) {
 433                 error_msg = "invalid eh_entries";
 434                 goto corrupted;
 435         }
 436         if (!ext4_valid_extent_entries(inode, eh, depth)) {
 437                 error_msg = "invalid extent entries";
 438                 goto corrupted;
 439         }
 440         return 0;
 441
 442 corrupted:
 443         __ext4_error(inode->i_sb, function,
 444                         "bad header/extent in inode #%lu: %s - magic %x, "
 445                         "entries %u, max %u(%u), depth %u(%u)",
 446                         inode->i_ino, error_msg, le16_to_cpu(eh->eh_magic),
 447                         le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max),
 448                         max, le16_to_cpu(eh->eh_depth), depth);
 449
 450         return -EIO;
 451 }
 452
 453 #define ext4_ext_check(inode, eh, depth)        \
 454         __ext4_ext_check(__func__, inode, eh, depth)
 455
 456 int ext4_ext_check_inode(struct inode *inode)
 457 {
 458         return ext4_ext_check(inode, ext_inode_hdr(inode), ext_depth(inode));
 459 }
 460
 461 #ifdef EXT_DEBUG
 462 static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path)
 463 {
 464         int k, l = path->p_depth;
 465
 466         ext_debug("path:");
 467         for (k = 0; k <= l; k++, path++) {
 468                 if (path->p_idx) {
 469                   ext_debug("  %d->%llu", le32_to_cpu(path->p_idx->ei_block),
 470                             idx_pblock(path->p_idx));
 471                 } else if (path->p_ext) {
 472                         ext_debug("  %d:[%d]%d:%llu ",
 473                                   le32_to_cpu(path->p_ext->ee_block),
 474                                   ext4_ext_is_uninitialized(path->p_ext),
 475                                   ext4_ext_get_actual_len(path->p_ext),
 476                                   ext_pblock(path->p_ext));
 477                 } else
 478                         ext_debug("  []");
 479         }
 480         ext_debug("\n");
 481 }
 482
 483 static void ext4_ext_show_leaf(struct inode *inode, struct ext4_ext_path *path)
 484 {
 485         int depth = ext_depth(inode);
 486         struct ext4_extent_header *eh;
 487         struct ext4_extent *ex;
 488         int i;
 489
 490         if (!path)
 491                 return;
 492
 493         eh = path[depth].p_hdr;
 494         ex = EXT_FIRST_EXTENT(eh);
 495
 496         ext_debug("Displaying leaf extents for inode %lu\n", inode->i_ino);
 497
 498         for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ex++) {
 499                 ext_debug("%d:[%d]%d:%llu ", le32_to_cpu(ex->ee_block),
 500                           ext4_ext_is_uninitialized(ex),
 501                           ext4_ext_get_actual_len(ex), ext_pblock(ex));
 502         }
 503         ext_debug("\n");
 504 }
 505 #else
 506 #define ext4_ext_show_path(inode, path)
 507 #define ext4_ext_show_leaf(inode, path)
 508 #endif
 509
 510 void ext4_ext_drop_refs(struct ext4_ext_path *path)
 511 {
 512         int depth = path->p_depth;
 513         int i;
 514
 515         for (i = 0; i <= depth; i++, path++)
 516                 if (path->p_bh) {
 517                         brelse(path->p_bh);
 518                         path->p_bh = NULL;
 519                 }
 520 }
 521
 522 /*
 523  * ext4_ext_binsearch_idx:
 524  * binary search for the closest index of the given block
 525  * the header must be checked before calling this
 526  */
 527 static void
 528 ext4_ext_binsearch_idx(struct inode *inode,
 529                         struct ext4_ext_path *path, ext4_lblk_t block)
 530 {
 531         struct ext4_extent_header *eh = path->p_hdr;
 532         struct ext4_extent_idx *r, *l, *m;
 533
 534
 535         ext_debug("binsearch for %u(idx):  ", block);
 536
 537         l = EXT_FIRST_INDEX(eh) + 1;
 538         r = EXT_LAST_INDEX(eh);
 539         while (l <= r) {
 540                 m = l + (r - l) / 2;
 541                 if (block < le32_to_cpu(m->ei_block))
 542                         r = m - 1;
 543                 else
 544                         l = m + 1;
 545                 ext_debug("%p(%u):%p(%u):%p(%u) ", l, le32_to_cpu(l->ei_block),
 546                                 m, le32_to_cpu(m->ei_block),
 547                                 r, le32_to_cpu(r->ei_block));
 548         }
 549
 550         path->p_idx = l - 1;
 551         ext_debug("  -> %d->%lld ", le32_to_cpu(path->p_idx->ei_block),
 552                   idx_pblock(path->p_idx));
 553
 554 #ifdef CHECK_BINSEARCH
 555         {
 556                 struct ext4_extent_idx *chix, *ix;
 557                 int k;
 558
 559                 chix = ix = EXT_FIRST_INDEX(eh);
 560                 for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ix++) {
 561                   if (k != 0 &&
 562                       le32_to_cpu(ix->ei_block) <= le32_to_cpu(ix[-1].ei_block)) {
 563                                 printk(KERN_DEBUG "k=%d, ix=0x%p, "
 564                                        "first=0x%p\n", k,
 565                                        ix, EXT_FIRST_INDEX(eh));
 566                                 printk(KERN_DEBUG "%u <= %u\n",
 567                                        le32_to_cpu(ix->ei_block),
 568                                        le32_to_cpu(ix[-1].ei_block));
 569                         }
 570                         BUG_ON(k && le32_to_cpu(ix->ei_block)
 571                                            <= le32_to_cpu(ix[-1].ei_block));
 572                         if (block < le32_to_cpu(ix->ei_block))
 573                                 break;
 574                         chix = ix;
 575                 }
 576                 BUG_ON(chix != path->p_idx);
 577         }
 578 #endif
 579
 580 }
 581
 582 /*
 583  * ext4_ext_binsearch:
 584  * binary search for closest extent of the given block
 585  * the header must be checked before calling this
 586  */
 587 static void
 588 ext4_ext_binsearch(struct inode *inode,
 589                 struct ext4_ext_path *path, ext4_lblk_t block)
 590 {
 591         struct ext4_extent_header *eh = path->p_hdr;
 592         struct ext4_extent *r, *l, *m;
 593
 594         if (eh->eh_entries == 0) {
 595                 /*
 596                  * this leaf is empty:
 597                  * we get such a leaf in split/add case
 598                  */
 599                 return;
 600         }
 601
 602         ext_debug("binsearch for %u:  ", block);
 603
 604         l = EXT_FIRST_EXTENT(eh) + 1;
 605         r = EXT_LAST_EXTENT(eh);
 606
 607         while (l <= r) {
 608                 m = l + (r - l) / 2;
 609                 if (block < le32_to_cpu(m->ee_block))
 610                         r = m - 1;
 611                 else
 612                         l = m + 1;
 613                 ext_debug("%p(%u):%p(%u):%p(%u) ", l, le32_to_cpu(l->ee_block),
 614                                 m, le32_to_cpu(m->ee_block),
 615                                 r, le32_to_cpu(r->ee_block));
 616         }
 617
 618         path->p_ext = l - 1;
 619         ext_debug("  -> %d:%llu:[%d]%d ",
 620                         le32_to_cpu(path->p_ext->ee_block),
 621                         ext_pblock(path->p_ext),
 622                         ext4_ext_is_uninitialized(path->p_ext),
 623                         ext4_ext_get_actual_len(path->p_ext));
 624
 625 #ifdef CHECK_BINSEARCH
 626         {
 627                 struct ext4_extent *chex, *ex;
 628                 int k;
 629
 630                 chex = ex = EXT_FIRST_EXTENT(eh);
 631                 for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ex++) {
 632                         BUG_ON(k && le32_to_cpu(ex->ee_block)
 633                                           <= le32_to_cpu(ex[-1].ee_block));
 634                         if (block < le32_to_cpu(ex->ee_block))
 635                                 break;
 636                         chex = ex;
 637                 }
 638                 BUG_ON(chex != path->p_ext);
 639         }
 640 #endif
 641
 642 }
 643
 644 int ext4_ext_tree_init(handle_t *handle, struct inode *inode)
 645 {
 646         struct ext4_extent_header *eh;
 647
 648         eh = ext_inode_hdr(inode);
 649         eh->eh_depth = 0;
 650         eh->eh_entries = 0;
 651         eh->eh_magic = EXT4_EXT_MAGIC;
 652         eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode, 0));
 653         ext4_mark_inode_dirty(handle, inode);
 654         ext4_ext_invalidate_cache(inode);
 655         return 0;
 656 }
 657
 658 struct ext4_ext_path *
 659 ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
 660                                         struct ext4_ext_path *path)
 661 {
 662         struct ext4_extent_header *eh;
 663         struct buffer_head *bh;
 664         short int depth, i, ppos = 0, alloc = 0;
 665
 666         eh = ext_inode_hdr(inode);
 667         depth = ext_depth(inode);
 668
 669         /* account possible depth increase */
 670         if (!path) {
 671                 path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
 672                                 GFP_NOFS);
 673                 if (!path)
 674                         return ERR_PTR(-ENOMEM);
 675                 alloc = 1;
 676         }
 677         path[0].p_hdr = eh;
 678         path[0].p_bh = NULL;
 679
 680         i = depth;
 681         /* walk through the tree */
 682         while (i) {
 683                 int need_to_validate = 0;
 684
 685                 ext_debug("depth %d: num %d, max %d\n",
 686                           ppos, le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
 687
 688                 ext4_ext_binsearch_idx(inode, path + ppos, block);
 689                 path[ppos].p_block = idx_pblock(path[ppos].p_idx);
 690                 path[ppos].p_depth = i;
 691                 path[ppos].p_ext = NULL;
 692
 693                 bh = sb_getblk(inode->i_sb, path[ppos].p_block);
 694                 if (unlikely(!bh))
 695                         goto err;
 696                 if (!bh_uptodate_or_lock(bh)) {
 697                         if (bh_submit_read(bh) < 0) {
 698                                 put_bh(bh);
 699                                 goto err;
 700                         }
 701                         /* validate the extent entries */
 702                         need_to_validate = 1;
 703                 }
 704                 eh = ext_block_hdr(bh);
 705                 ppos++;
 706                 if (unlikely(ppos > depth)) {
 707                         put_bh(bh);
 708                         EXT4_ERROR_INODE(inode,
 709                                          "ppos %d > depth %d", ppos, depth);
 710                         goto err;
 711                 }
 712                 path[ppos].p_bh = bh;
 713                 path[ppos].p_hdr = eh;
 714                 i--;
 715
 716                 if (need_to_validate && ext4_ext_check(inode, eh, i))
 717                         goto err;
 718         }
 719
 720         path[ppos].p_depth = i;
 721         path[ppos].p_ext = NULL;
 722         path[ppos].p_idx = NULL;
 723
 724         /* find extent */
 725         ext4_ext_binsearch(inode, path + ppos, block);
 726         /* if not an empty leaf */
 727         if (path[ppos].p_ext)
 728                 path[ppos].p_block = ext_pblock(path[ppos].p_ext);
 729
 730         ext4_ext_show_path(inode, path);
 731
 732         return path;
 733
 734 err:
 735         ext4_ext_drop_refs(path);
 736         if (alloc)
 737                 kfree(path);
 738         return ERR_PTR(-EIO);
 739 }
 740
 741 /*
 742  * ext4_ext_insert_index:
 743  * insert new index [@logical;@ptr] into the block at @curp;
 744  * check where to insert: before @curp or after @curp
 745  */
 746 int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
 747                                 struct ext4_ext_path *curp,
 748                                 int logical, ext4_fsblk_t ptr)
 749 {
 750         struct ext4_extent_idx *ix;
 751         int len, err;
 752
 753         err = ext4_ext_get_access(handle, inode, curp);
 754         if (err)
 755                 return err;
 756
 757         if (unlikely(logical == le32_to_cpu(curp->p_idx->ei_block))) {
 758                 EXT4_ERROR_INODE(inode,
 759                                  "logical %d == ei_block %d!",
 760                                  logical, le32_to_cpu(curp->p_idx->ei_block));
 761                 return -EIO;
 762         }
 763         len = EXT_MAX_INDEX(curp->p_hdr) - curp->p_idx;
 764         if (logical > le32_to_cpu(curp->p_idx->ei_block)) {
 765                 /* insert after */
 766                 if (curp->p_idx != EXT_LAST_INDEX(curp->p_hdr)) {
 767                         len = (len - 1) * sizeof(struct ext4_extent_idx);
 768                         len = len < 0 ? 0 : len;
 769                         ext_debug("insert new index %d after: %llu. "
 770                                         "move %d from 0x%p to 0x%p\n",
 771                                         logical, ptr, len,
 772                                         (curp->p_idx + 1), (curp->p_idx + 2));
 773                         memmove(curp->p_idx + 2, curp->p_idx + 1, len);
 774                 }
 775                 ix = curp->p_idx + 1;
 776         } else {
 777                 /* insert before */
 778                 len = len * sizeof(struct ext4_extent_idx);
 779                 len = len < 0 ? 0 : len;
 780                 ext_debug("insert new index %d before: %llu. "
 781                                 "move %d from 0x%p to 0x%p\n",
 782                                 logical, ptr, len,
 783                                 curp->p_idx, (curp->p_idx + 1));
 784                 memmove(curp->p_idx + 1, curp->p_idx, len);
 785                 ix = curp->p_idx;
 786         }
 787
 788         ix->ei_block = cpu_to_le32(logical);
 789         ext4_idx_store_pblock(ix, ptr);
 790         le16_add_cpu(&curp->p_hdr->eh_entries, 1);
 791
 792         if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)
 793                              > le16_to_cpu(curp->p_hdr->eh_max))) {
 794                 EXT4_ERROR_INODE(inode,
 795                                  "logical %d == ei_block %d!",
 796                                  logical, le32_to_cpu(curp->p_idx->ei_block));
 797                 return -EIO;
 798         }
 799         if (unlikely(ix > EXT_LAST_INDEX(curp->p_hdr))) {
 800                 EXT4_ERROR_INODE(inode, "ix > EXT_LAST_INDEX!");
 801                 return -EIO;
 802         }
 803
 804         err = ext4_ext_dirty(handle, inode, curp);
 805         ext4_std_error(inode->i_sb, err);
 806
 807         return err;
 808 }
 809
 810 /*
 811  * ext4_ext_split:
 812  * inserts new subtree into the path, using free index entry
 813  * at depth @at:
 814  * - allocates all needed blocks (new leaf and all intermediate index blocks)
 815  * - makes decision where to split
 816  * - moves remaining extents and index entries (right to the split point)
 817  *   into the newly allocated blocks
 818  * - initializes subtree
 819  */
 820 static int ext4_ext_split(handle_t *handle, struct inode *inode,
 821                                 struct ext4_ext_path *path,
 822                                 struct ext4_extent *newext, int at)
 823 {
 824         struct buffer_head *bh = NULL;
 825         int depth = ext_depth(inode);
 826         struct ext4_extent_header *neh;
 827         struct ext4_extent_idx *fidx;
 828         struct ext4_extent *ex;
 829         int i = at, k, m, a;
 830         ext4_fsblk_t newblock, oldblock;
 831         __le32 border;
 832         ext4_fsblk_t *ablocks = NULL; /* array of allocated blocks */
 833         int err = 0;
 834
 835         /* make decision: where to split? */
 836         /* FIXME: now decision is simplest: at current extent */
 837
 838         /* if current leaf will be split, then we should use
 839          * border from split point */
 840         if (unlikely(path[depth].p_ext > EXT_MAX_EXTENT(path[depth].p_hdr))) {
 841                 EXT4_ERROR_INODE(inode, "p_ext > EXT_MAX_EXTENT!");
 842                 return -EIO;
 843         }
 844         if (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) {
 845                 border = path[depth].p_ext[1].ee_block;
 846                 ext_debug("leaf will be split."
 847                                 " next leaf starts at %d\n",
 848                                   le32_to_cpu(border));
 849         } else {
 850                 border = newext->ee_block;
 851                 ext_debug("leaf will be added."
 852                                 " next leaf starts at %d\n",
 853                                 le32_to_cpu(border));
 854         }
 855
 856         /*
 857          * If error occurs, then we break processing
 858          * and mark filesystem read-only. index won't
 859          * be inserted and tree will be in consistent
 860          * state. Next mount will repair buffers too.
 861          */
 862
 863         /*
 864          * Get array to track all allocated blocks.
 865          * We need this to handle errors and free blocks
 866          * upon them.
 867          */
 868         ablocks = kzalloc(sizeof(ext4_fsblk_t) * depth, GFP_NOFS);
 869         if (!ablocks)
 870                 return -ENOMEM;
 871
 872         /* allocate all needed blocks */
 873         ext_debug("allocate %d blocks for indexes/leaf\n", depth - at);
 874         for (a = 0; a < depth - at; a++) {
 875                 newblock = ext4_ext_new_meta_block(handle, inode, path,
 876                                                    newext, &err);
 877                 if (newblock == 0)
 878                         goto cleanup;
 879                 ablocks[a] = newblock;
 880         }
 881
 882         /* initialize new leaf */
 883         newblock = ablocks[--a];
 884         if (unlikely(newblock == 0)) {
 885                 EXT4_ERROR_INODE(inode, "newblock == 0!");
 886                 err = -EIO;
 887                 goto cleanup;
 888         }
 889         bh = sb_getblk(inode->i_sb, newblock);
 890         if (!bh) {
 891                 err = -EIO;
 892                 goto cleanup;
 893         }
 894         lock_buffer(bh);
 895
 896         err = ext4_journal_get_create_access(handle, bh);
 897         if (err)
 898                 goto cleanup;
 899
 900         neh = ext_block_hdr(bh);
 901         neh->eh_entries = 0;
 902         neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
 903         neh->eh_magic = EXT4_EXT_MAGIC;
 904         neh->eh_depth = 0;
 905         ex = EXT_FIRST_EXTENT(neh);
 906
 907         /* move remainder of path[depth] to the new leaf */
 908         if (unlikely(path[depth].p_hdr->eh_entries !=
 909                      path[depth].p_hdr->eh_max)) {
 910                 EXT4_ERROR_INODE(inode, "eh_entries %d != eh_max %d!",
 911                                  path[depth].p_hdr->eh_entries,
 912                                  path[depth].p_hdr->eh_max);
 913                 err = -EIO;
 914                 goto cleanup;
 915         }
 916         /* start copy from next extent */
 917         /* TODO: we could do it by single memmove */
 918         m = 0;
 919         path[depth].p_ext++;
 920         while (path[depth].p_ext <=
 921                         EXT_MAX_EXTENT(path[depth].p_hdr)) {
 922                 ext_debug("move %d:%llu:[%d]%d in new leaf %llu\n",
 923                                 le32_to_cpu(path[depth].p_ext->ee_block),
 924                                 ext_pblock(path[depth].p_ext),
 925                                 ext4_ext_is_uninitialized(path[depth].p_ext),
 926                                 ext4_ext_get_actual_len(path[depth].p_ext),
 927                                 newblock);
 928                 /*memmove(ex++, path[depth].p_ext++,
 929                                 sizeof(struct ext4_extent));
 930                 neh->eh_entries++;*/
 931                 path[depth].p_ext++;
 932                 m++;
 933         }
 934         if (m) {
 935                 memmove(ex, path[depth].p_ext-m, sizeof(struct ext4_extent)*m);
 936                 le16_add_cpu(&neh->eh_entries, m);
 937         }
 938
 939         set_buffer_uptodate(bh);
 940         unlock_buffer(bh);
 941
 942         err = ext4_handle_dirty_metadata(handle, inode, bh);
 943         if (err)
 944                 goto cleanup;
 945         brelse(bh);
 946         bh = NULL;
 947
 948         /* correct old leaf */
 949         if (m) {
 950                 err = ext4_ext_get_access(handle, inode, path + depth);
 951                 if (err)
 952                         goto cleanup;
 953                 le16_add_cpu(&path[depth].p_hdr->eh_entries, -m);
 954                 err = ext4_ext_dirty(handle, inode, path + depth);
 955                 if (err)
 956                         goto cleanup;
 957
 958         }
 959
 960         /* create intermediate indexes */
 961         k = depth - at - 1;
 962         if (unlikely(k < 0)) {
 963                 EXT4_ERROR_INODE(inode, "k %d < 0!", k);
 964                 err = -EIO;
 965                 goto cleanup;
 966         }
 967         if (k)
 968                 ext_debug("create %d intermediate indices\n", k);
 969         /* insert new index into current index block */
 970         /* current depth stored in i var */
 971         i = depth - 1;
 972         while (k--) {
 973                 oldblock = newblock;
 974                 newblock = ablocks[--a];
 975                 bh = sb_getblk(inode->i_sb, newblock);
 976                 if (!bh) {
 977                         err = -EIO;
 978                         goto cleanup;
 979                 }
 980                 lock_buffer(bh);
 981
 982                 err = ext4_journal_get_create_access(handle, bh);
 983                 if (err)
 984                         goto cleanup;
 985
 986                 neh = ext_block_hdr(bh);
 987                 neh->eh_entries = cpu_to_le16(1);
 988                 neh->eh_magic = EXT4_EXT_MAGIC;
 989                 neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
 990                 neh->eh_depth = cpu_to_le16(depth - i);
 991                 fidx = EXT_FIRST_INDEX(neh);
 992                 fidx->ei_block = border;
 993                 ext4_idx_store_pblock(fidx, oldblock);
 994
 995                 ext_debug("int.index at %d (block %llu): %u -> %llu\n",
 996                                 i, newblock, le32_to_cpu(border), oldblock);
 997                 /* copy indexes */
 998                 m = 0;
 999                 path[i].p_idx++;
1000
1001                 ext_debug("cur 0x%p, last 0x%p\n", path[i].p_idx,
1002                                 EXT_MAX_INDEX(path[i].p_hdr));
1003                 if (unlikely(EXT_MAX_INDEX(path[i].p_hdr) !=
1004                                         EXT_LAST_INDEX(path[i].p_hdr))) {
1005                         EXT4_ERROR_INODE(inode,
1006                                          "EXT_MAX_INDEX != EXT_LAST_INDEX ee_block %d!",
1007                                          le32_to_cpu(path[i].p_ext->ee_block));
1008                         err = -EIO;
1009                         goto cleanup;
1010                 }
1011                 while (path[i].p_idx <= EXT_MAX_INDEX(path[i].p_hdr)) {
1012                         ext_debug("%d: move %d:%llu in new index %llu\n", i,
1013                                         le32_to_cpu(path[i].p_idx->ei_block),
1014                                         idx_pblock(path[i].p_idx),
1015                                         newblock);
1016                         /*memmove(++fidx, path[i].p_idx++,
1017                                         sizeof(struct ext4_extent_idx));
1018                         neh->eh_entries++;
1019                         BUG_ON(neh->eh_entries > neh->eh_max);*/
1020                         path[i].p_idx++;
1021                         m++;
1022                 }
1023                 if (m) {
1024                         memmove(++fidx, path[i].p_idx - m,
1025                                 sizeof(struct ext4_extent_idx) * m);
1026                         le16_add_cpu(&neh->eh_entries, m);
1027                 }
1028                 set_buffer_uptodate(bh);
1029                 unlock_buffer(bh);
1030
1031                 err = ext4_handle_dirty_metadata(handle, inode, bh);
1032                 if (err)
1033                         goto cleanup;
1034                 brelse(bh);
1035                 bh = NULL;
1036
1037                 /* correct old index */
1038                 if (m) {
1039                         err = ext4_ext_get_access(handle, inode, path + i);
1040                         if (err)
1041                                 goto cleanup;
1042                         le16_add_cpu(&path[i].p_hdr->eh_entries, -m);
1043                         err = ext4_ext_dirty(handle, inode, path + i);
1044                         if (err)
1045                                 goto cleanup;
1046                 }
1047
1048                 i--;
1049         }
1050
1051         /* insert new index */
1052         err = ext4_ext_insert_index(handle, inode, path + at,
1053                                     le32_to_cpu(border), newblock);
1054
1055 cleanup:
1056         if (bh) {
1057                 if (buffer_locked(bh))
1058                         unlock_buffer(bh);
1059                 brelse(bh);
1060         }
1061
1062         if (err) {
1063                 /* free all allocated blocks in error case */
1064                 for (i = 0; i < depth; i++) {
1065                         if (!ablocks[i])
1066                                 continue;
1067                         ext4_free_blocks(handle, inode, 0, ablocks[i], 1,
1068                                          EXT4_FREE_BLOCKS_METADATA);
1069                 }
1070         }
1071         kfree(ablocks);
1072
1073         return err;
1074 }
1075
1076 /*
1077  * ext4_ext_grow_indepth:
1078  * implements tree growing procedure:
1079  * - allocates new block
1080  * - moves top-level data (index block or leaf) into the new block
1081  * - initializes new top-level, creating index that points to the
1082  *   just created block
1083  */
1084 static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
1085                                         struct ext4_ext_path *path,
1086                                         struct ext4_extent *newext)
1087 {
1088         struct ext4_ext_path *curp = path;
1089         struct ext4_extent_header *neh;
1090         struct ext4_extent_idx *fidx;
1091         struct buffer_head *bh;
1092         ext4_fsblk_t newblock;
1093         int err = 0;
1094
1095         newblock = ext4_ext_new_meta_block(handle, inode, path, newext, &err);
1096         if (newblock == 0)
1097                 return err;
1098
1099         bh = sb_getblk(inode->i_sb, newblock);
1100         if (!bh) {
1101                 err = -EIO;
1102                 ext4_std_error(inode->i_sb, err);
1103                 return err;
1104         }
1105         lock_buffer(bh);
1106
1107         err = ext4_journal_get_create_access(handle, bh);
1108         if (err) {
1109                 unlock_buffer(bh);
1110                 goto out;
1111         }
1112
1113         /* move top-level index/leaf into new block */
1114         memmove(bh->b_data, curp->p_hdr, sizeof(EXT4_I(inode)->i_data));
1115
1116         /* set size of new block */
1117         neh = ext_block_hdr(bh);
1118         /* old root could have indexes or leaves
1119          * so calculate e_max right way */
1120         if (ext_depth(inode))
1121                 neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
1122         else
1123                 neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
1124         neh->eh_magic = EXT4_EXT_MAGIC;
1125         set_buffer_uptodate(bh);
1126         unlock_buffer(bh);
1127
1128         err = ext4_handle_dirty_metadata(handle, inode, bh);
1129         if (err)
1130                 goto out;
1131
1132         /* create index in new top-level index: num,max,pointer */
1133         err = ext4_ext_get_access(handle, inode, curp);
1134         if (err)
1135                 goto out;
1136
1137         curp->p_hdr->eh_magic = EXT4_EXT_MAGIC;
1138         curp->p_hdr->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode, 0));
1139         curp->p_hdr->eh_entries = cpu_to_le16(1);
1140         curp->p_idx = EXT_FIRST_INDEX(curp->p_hdr);
1141
1142         if (path[0].p_hdr->eh_depth)
1143                 curp->p_idx->ei_block =
1144                         EXT_FIRST_INDEX(path[0].p_hdr)->ei_block;
1145         else
1146                 curp->p_idx->ei_block =
1147                         EXT_FIRST_EXTENT(path[0].p_hdr)->ee_block;
1148         ext4_idx_store_pblock(curp->p_idx, newblock);
1149
1150         neh = ext_inode_hdr(inode);
1151         fidx = EXT_FIRST_INDEX(neh);
1152         ext_debug("new root: num %d(%d), lblock %d, ptr %llu\n",
1153                   le16_to_cpu(neh->eh_entries), le16_to_cpu(neh->eh_max),
1154                   le32_to_cpu(fidx->ei_block), idx_pblock(fidx));
1155
1156         neh->eh_depth = cpu_to_le16(path->p_depth + 1);
1157         err = ext4_ext_dirty(handle, inode, curp);
1158 out:
1159         brelse(bh);
1160
1161         return err;
1162 }
1163
1164 /*
1165  * ext4_ext_create_new_leaf:
1166  * finds empty index and adds new leaf.
1167  * if no free index is found, then it requests in-depth growing.
1168  */
1169 static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
1170                                         struct ext4_ext_path *path,
1171                                         struct ext4_extent *newext)
1172 {
1173         struct ext4_ext_path *curp;
1174         int depth, i, err = 0;
1175
1176 repeat:
1177         i = depth = ext_depth(inode);
1178
1179         /* walk up to the tree and look for free index entry */
1180         curp = path + depth;
1181         while (i > 0 && !EXT_HAS_FREE_INDEX(curp)) {
1182                 i--;
1183                 curp--;
1184         }
1185
1186         /* we use already allocated block for index block,
1187          * so subsequent data blocks should be contiguous */
1188         if (EXT_HAS_FREE_INDEX(curp)) {
1189                 /* if we found index with free entry, then use that
1190                  * entry: create all needed subtree and add new leaf */
1191                 err = ext4_ext_split(handle, inode, path, newext, i);
1192                 if (err)
1193                         goto out;
1194
1195                 /* refill path */
1196                 ext4_ext_drop_refs(path);
1197                 path = ext4_ext_find_extent(inode,
1198                                     (ext4_lblk_t)le32_to_cpu(newext->ee_block),
1199                                     path);
1200                 if (IS_ERR(path))
1201                         err = PTR_ERR(path);
1202         } else {
1203                 /* tree is full, time to grow in depth */
1204                 err = ext4_ext_grow_indepth(handle, inode, path, newext);
1205                 if (err)
1206                         goto out;
1207
1208                 /* refill path */
1209                 ext4_ext_drop_refs(path);
1210                 path = ext4_ext_find_extent(inode,
1211                                    (ext4_lblk_t)le32_to_cpu(newext->ee_block),
1212                                     path);
1213                 if (IS_ERR(path)) {
1214                         err = PTR_ERR(path);
1215                         goto out;
1216                 }
1217
1218                 /*
1219                  * only first (depth 0 -> 1) produces free space;
1220                  * in all other cases we have to split the grown tree
1221                  */
1222                 depth = ext_depth(inode);
1223                 if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) {
1224                         /* now we need to split */
1225                         goto repeat;
1226                 }
1227         }
1228
1229 out:
1230         return err;
1231 }
1232
1233 /*
1234  * search the closest allocated block to the left for *logical
1235  * and returns it at @logical + it's physical address at @phys
1236  * if *logical is the smallest allocated block, the function
1237  * returns 0 at @phys
1238  * return value contains 0 (success) or error code
1239  */
1240 int
1241 ext4_ext_search_left(struct inode *inode, struct ext4_ext_path *path,
1242                         ext4_lblk_t *logical, ext4_fsblk_t *phys)
1243 {
1244         struct ext4_extent_idx *ix;
1245         struct ext4_extent *ex;
1246         int depth, ee_len;
1247
1248         if (unlikely(path == NULL)) {
1249                 EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
1250                 return -EIO;
1251         }
1252         depth = path->p_depth;
1253         *phys = 0;
1254
1255         if (depth == 0 && path->p_ext == NULL)
1256                 return 0;
1257
1258         /* usually extent in the path covers blocks smaller
1259          * then *logical, but it can be that extent is the
1260          * first one in the file */
1261
1262         ex = path[depth].p_ext;
1263         ee_len = ext4_ext_get_actual_len(ex);
1264         if (*logical < le32_to_cpu(ex->ee_block)) {
1265                 if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
1266                         EXT4_ERROR_INODE(inode,
1267                                          "EXT_FIRST_EXTENT != ex *logical %d ee_block %d!",
1268                                          *logical, le32_to_cpu(ex->ee_block));
1269                         return -EIO;
1270                 }
1271                 while (--depth >= 0) {
1272                         ix = path[depth].p_idx;
1273                         if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
1274                                 EXT4_ERROR_INODE(inode,
1275                                   "ix (%d) != EXT_FIRST_INDEX (%d) (depth %d)!",
1276                                   ix != NULL ? ix->ei_block : 0,
1277                                   EXT_FIRST_INDEX(path[depth].p_hdr) != NULL ?
1278                                     EXT_FIRST_INDEX(path[depth].p_hdr)->ei_block : 0,
1279                                   depth);
1280                                 return -EIO;
1281                         }
1282                 }
1283                 return 0;
1284         }
1285
1286         if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
1287                 EXT4_ERROR_INODE(inode,
1288                                  "logical %d < ee_block %d + ee_len %d!",
1289                                  *logical, le32_to_cpu(ex->ee_block), ee_len);
1290                 return -EIO;
1291         }
1292
1293         *logical = le32_to_cpu(ex->ee_block) + ee_len - 1;
1294         *phys = ext_pblock(ex) + ee_len - 1;
1295         return 0;
1296 }
1297
1298 /*
1299  * search the closest allocated block to the right for *logical
1300  * and returns it at @logical + it's physical address at @phys
1301  * if *logical is the smallest allocated block, the function
1302  * returns 0 at @phys
1303  * return value contains 0 (success) or error code
1304  */
1305 int
1306 ext4_ext_search_right(struct inode *inode, struct ext4_ext_path *path,
1307                         ext4_lblk_t *logical, ext4_fsblk_t *phys)
1308 {
1309         struct buffer_head *bh = NULL;
1310         struct ext4_extent_header *eh;
1311         struct ext4_extent_idx *ix;
1312         struct ext4_extent *ex;
1313         ext4_fsblk_t block;
1314         int depth;      /* Note, NOT eh_depth; depth from top of tree */
1315         int ee_len;
1316
1317         if (unlikely(path == NULL)) {
1318                 EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
1319                 return -EIO;
1320         }
1321         depth = path->p_depth;
1322         *phys = 0;
1323
1324         if (depth == 0 && path->p_ext == NULL)
1325                 return 0;
1326
1327         /* usually extent in the path covers blocks smaller
1328          * then *logical, but it can be that extent is the
1329          * first one in the file */
1330
1331         ex = path[depth].p_ext;
1332         ee_len = ext4_ext_get_actual_len(ex);
1333         if (*logical < le32_to_cpu(ex->ee_block)) {
1334                 if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
1335                         EXT4_ERROR_INODE(inode,
1336                                          "first_extent(path[%d].p_hdr) != ex",
1337                                          depth);
1338                         return -EIO;
1339                 }
1340                 while (--depth >= 0) {
1341                         ix = path[depth].p_idx;
1342                         if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
1343                                 EXT4_ERROR_INODE(inode,
1344                                                  "ix != EXT_FIRST_INDEX *logical %d!",
1345                                                  *logical);
1346                                 return -EIO;
1347                         }
1348                 }
1349                 *logical = le32_to_cpu(ex->ee_block);
1350                 *phys = ext_pblock(ex);
1351                 return 0;
1352         }
1353
1354         if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
1355                 EXT4_ERROR_INODE(inode,
1356                                  "logical %d < ee_block %d + ee_len %d!",
1357                                  *logical, le32_to_cpu(ex->ee_block), ee_len);
1358                 return -EIO;
1359         }
1360
1361         if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {
1362                 /* next allocated block in this leaf */
1363                 ex++;
1364                 *logical = le32_to_cpu(ex->ee_block);
1365                 *phys = ext_pblock(ex);
1366                 return 0;
1367         }
1368
1369         /* go up and search for index to the right */
1370         while (--depth >= 0) {
1371                 ix = path[depth].p_idx;
1372                 if (ix != EXT_LAST_INDEX(path[depth].p_hdr))
1373                         goto got_index;
1374         }
1375
1376         /* we've gone up to the root and found no index to the right */
1377         return 0;
1378
1379 got_index:
1380         /* we've found index to the right, let's
1381          * follow it and find the closest allocated
1382          * block to the right */
1383         ix++;
1384         block = idx_pblock(ix);
1385         while (++depth < path->p_depth) {
1386                 bh = sb_bread(inode->i_sb, block);
1387                 if (bh == NULL)
1388                         return -EIO;
1389                 eh = ext_block_hdr(bh);
1390                 /* subtract from p_depth to get proper eh_depth */
1391                 if (ext4_ext_check(inode, eh, path->p_depth - depth)) {
1392                         put_bh(bh);
1393                         return -EIO;
1394                 }
1395                 ix = EXT_FIRST_INDEX(eh);
1396                 block = idx_pblock(ix);
1397                 put_bh(bh);
1398         }
1399
1400         bh = sb_bread(inode->i_sb, block);
1401         if (bh == NULL)
1402                 return -EIO;
1403         eh = ext_block_hdr(bh);
1404         if (ext4_ext_check(inode, eh, path->p_depth - depth)) {
1405                 put_bh(bh);
1406                 return -EIO;
1407         }
1408         ex = EXT_FIRST_EXTENT(eh);
1409         *logical = le32_to_cpu(ex->ee_block);
1410         *phys = ext_pblock(ex);
1411         put_bh(bh);
1412         return 0;
1413 }
1414
1415 /*
1416  * ext4_ext_next_allocated_block:
1417  * returns allocated block in subsequent extent or EXT_MAX_BLOCK.
1418  * NOTE: it considers block number from index entry as
1419  * allocated block. Thus, index entries have to be consistent
1420  * with leaves.
1421  */
1422 static ext4_lblk_t
1423 ext4_ext_next_allocated_block(struct ext4_ext_path *path)
1424 {
1425         int depth;
1426
1427         BUG_ON(path == NULL);
1428         depth = path->p_depth;
1429
1430         if (depth == 0 && path->p_ext == NULL)
1431                 return EXT_MAX_BLOCK;
1432
1433         while (depth >= 0) {
1434                 if (depth == path->p_depth) {
1435                         /* leaf */
1436                         if (path[depth].p_ext !=
1437                                         EXT_LAST_EXTENT(path[depth].p_hdr))
1438                           return le32_to_cpu(path[depth].p_ext[1].ee_block);
1439                 } else {
1440                         /* index */
1441                         if (path[depth].p_idx !=
1442                                         EXT_LAST_INDEX(path[depth].p_hdr))
1443                           return le32_to_cpu(path[depth].p_idx[1].ei_block);
1444                 }
1445                 depth--;
1446         }
1447
1448         return EXT_MAX_BLOCK;
1449 }
1450
1451 /*
1452  * ext4_ext_next_leaf_block:
1453  * returns first allocated block from next leaf or EXT_MAX_BLOCK
1454  */
1455 static ext4_lblk_t ext4_ext_next_leaf_block(struct inode *inode,
1456                                         struct ext4_ext_path *path)
1457 {
1458         int depth;
1459
1460         BUG_ON(path == NULL);
1461         depth = path->p_depth;
1462
1463         /* zero-tree has no leaf blocks at all */
1464         if (depth == 0)
1465                 return EXT_MAX_BLOCK;
1466
1467         /* go to index block */
1468         depth--;
1469
1470         while (depth >= 0) {
1471                 if (path[depth].p_idx !=
1472                                 EXT_LAST_INDEX(path[depth].p_hdr))
1473                         return (ext4_lblk_t)
1474                                 le32_to_cpu(path[depth].p_idx[1].ei_block);
1475                 depth--;
1476         }
1477
1478         return EXT_MAX_BLOCK;
1479 }
1480
1481 /*
1482  * ext4_ext_correct_indexes:
1483  * if leaf gets modified and modified extent is first in the leaf,
1484  * then we have to correct all indexes above.
1485  * TODO: do we need to correct tree in all cases?
1486  */
1487 static int ext4_ext_correct_indexes(handle_t *handle, struct inode *inode,
1488                                 struct ext4_ext_path *path)
1489 {
1490         struct ext4_extent_header *eh;
1491         int depth = ext_depth(inode);
1492         struct ext4_extent *ex;
1493         __le32 border;
1494         int k, err = 0;
1495
1496         eh = path[depth].p_hdr;
1497         ex = path[depth].p_ext;
1498
1499         if (unlikely(ex == NULL || eh == NULL)) {
1500                 EXT4_ERROR_INODE(inode,
1501                                  "ex %p == NULL or eh %p == NULL", ex, eh);
1502                 return -EIO;
1503         }
1504
1505         if (depth == 0) {
1506                 /* there is no tree at all */
1507                 return 0;
1508         }
1509
1510         if (ex != EXT_FIRST_EXTENT(eh)) {
1511                 /* we correct tree if first leaf got modified only */
1512                 return 0;
1513         }
1514
1515         /*
1516          * TODO: we need correction if border is smaller than current one
1517          */
1518         k = depth - 1;
1519         border = path[depth].p_ext->ee_block;
1520         err = ext4_ext_get_access(handle, inode, path + k);
1521         if (err)
1522                 return err;
1523         path[k].p_idx->ei_block = border;
1524         err = ext4_ext_dirty(handle, inode, path + k);
1525         if (err)
1526                 return err;
1527
1528         while (k--) {
1529                 /* change all left-side indexes */
1530                 if (path[k+1].p_idx != EXT_FIRST_INDEX(path[k+1].p_hdr))
1531                         break;
1532                 err = ext4_ext_get_access(handle, inode, path + k);
1533                 if (err)
1534                         break;
1535                 path[k].p_idx->ei_block = border;
1536                 err = ext4_ext_dirty(handle, inode, path + k);
1537                 if (err)
1538                         break;
1539         }
1540
1541         return err;
1542 }
1543
1544 int
1545 ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
1546                                 struct ext4_extent *ex2)
1547 {
1548         unsigned short ext1_ee_len, ext2_ee_len, max_len;
1549
1550         /*
1551          * Make sure that either both extents are uninitialized, or
1552          * both are _not_.
1553          */
1554         if (ext4_ext_is_uninitialized(ex1) ^ ext4_ext_is_uninitialized(ex2))
1555                 return 0;
1556
1557         if (ext4_ext_is_uninitialized(ex1))
1558                 max_len = EXT_UNINIT_MAX_LEN;
1559         else
1560                 max_len = EXT_INIT_MAX_LEN;
1561
1562         ext1_ee_len = ext4_ext_get_actual_len(ex1);
1563         ext2_ee_len = ext4_ext_get_actual_len(ex2);
1564
1565         if (le32_to_cpu(ex1->ee_block) + ext1_ee_len !=
1566                         le32_to_cpu(ex2->ee_block))
1567                 return 0;
1568
1569         /*
1570          * To allow future support for preallocated extents to be added
1571          * as an RO_COMPAT feature, refuse to merge to extents if
1572          * this can result in the top bit of ee_len being set.
1573          */
1574         if (ext1_ee_len + ext2_ee_len > max_len)
1575                 return 0;
1576 #ifdef AGGRESSIVE_TEST
1577         if (ext1_ee_len >= 4)
1578                 return 0;
1579 #endif
1580
1581         if (ext_pblock(ex1) + ext1_ee_len == ext_pblock(ex2))
1582                 return 1;
1583         return 0;
1584 }
1585
1586 /*
1587  * This function tries to merge the "ex" extent to the next extent in the tree.
1588  * It always tries to merge towards right. If you want to merge towards
1589  * left, pass "ex - 1" as argument instead of "ex".
1590  * Returns 0 if the extents (ex and ex+1) were _not_ merged and returns
1591  * 1 if they got merged.
1592  */
1593 int ext4_ext_try_to_merge(struct inode *inode,
1594                           struct ext4_ext_path *path,
1595                           struct ext4_extent *ex)
1596 {
1597         struct ext4_extent_header *eh;
1598         unsigned int depth, len;
1599         int merge_done = 0;
1600         int uninitialized = 0;
1601
1602         depth = ext_depth(inode);
1603         BUG_ON(path[depth].p_hdr == NULL);
1604         eh = path[depth].p_hdr;
1605
1606         while (ex < EXT_LAST_EXTENT(eh)) {
1607                 if (!ext4_can_extents_be_merged(inode, ex, ex + 1))
1608                         break;
1609                 /* merge with next extent! */
1610                 if (ext4_ext_is_uninitialized(ex))
1611                         uninitialized = 1;
1612                 ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
1613                                 + ext4_ext_get_actual_len(ex + 1));
1614                 if (uninitialized)
1615                         ext4_ext_mark_uninitialized(ex);
1616
1617                 if (ex + 1 < EXT_LAST_EXTENT(eh)) {
1618                         len = (EXT_LAST_EXTENT(eh) - ex - 1)
1619                                 * sizeof(struct ext4_extent);
1620                         memmove(ex + 1, ex + 2, len);
1621                 }
1622                 le16_add_cpu(&eh->eh_entries, -1);
1623                 merge_done = 1;
1624                 WARN_ON(eh->eh_entries == 0);
1625                 if (!eh->eh_entries)
1626                         ext4_error(inode->i_sb,
1627                                    "inode#%lu, eh->eh_entries = 0!",
1628                                    inode->i_ino);
1629         }
1630
1631         return merge_done;
1632 }
1633
1634 /*
1635  * check if a portion of the "newext" extent overlaps with an
1636  * existing extent.
1637  *
1638  * If there is an overlap discovered, it updates the length of the newext
1639  * such that there will be no overlap, and then returns 1.
1640  * If there is no overlap found, it returns 0.
1641  */
1642 unsigned int ext4_ext_check_overlap(struct inode *inode,
1643                                     struct ext4_extent *newext,
1644                                     struct ext4_ext_path *path)
1645 {
1646         ext4_lblk_t b1, b2;
1647         unsigned int depth, len1;
1648         unsigned int ret = 0;
1649
1650         b1 = le32_to_cpu(newext->ee_block);
1651         len1 = ext4_ext_get_actual_len(newext);
1652         depth = ext_depth(inode);
1653         if (!path[depth].p_ext)
1654                 goto out;
1655         b2 = le32_to_cpu(path[depth].p_ext->ee_block);
1656
1657         /*
1658          * get the next allocated block if the extent in the path
1659          * is before the requested block(s)
1660          */
1661         if (b2 < b1) {
1662                 b2 = ext4_ext_next_allocated_block(path);
1663                 if (b2 == EXT_MAX_BLOCK)
1664                         goto out;
1665         }
1666
1667         /* check for wrap through zero on extent logical start block*/
1668         if (b1 + len1 < b1) {
1669                 len1 = EXT_MAX_BLOCK - b1;
1670                 newext->ee_len = cpu_to_le16(len1);
1671                 ret = 1;
1672         }
1673
1674         /* check for overlap */
1675         if (b1 + len1 > b2) {
1676                 newext->ee_len = cpu_to_le16(b2 - b1);
1677                 ret = 1;
1678         }
1679 out:
1680         return ret;
1681 }
1682
1683 /*
1684  * ext4_ext_insert_extent:
1685  * tries to merge requsted extent into the existing extent or
1686  * inserts requested extent as new one into the tree,
1687  * creating new leaf in the no-space case.
1688  */
1689 int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
1690                                 struct ext4_ext_path *path,
1691                                 struct ext4_extent *newext, int flag)
1692 {
1693         struct ext4_extent_header *eh;
1694         struct ext4_extent *ex, *fex;
1695         struct ext4_extent *nearex; /* nearest extent */
1696         struct ext4_ext_path *npath = NULL;
1697         int depth, len, err;
1698         ext4_lblk_t next;
1699         unsigned uninitialized = 0;
1700
1701         if (unlikely(ext4_ext_get_actual_len(newext) == 0)) {
1702                 EXT4_ERROR_INODE(inode, "ext4_ext_get_actual_len(newext) == 0");
1703                 return -EIO;
1704         }
1705         depth = ext_depth(inode);
1706         ex = path[depth].p_ext;
1707         if (unlikely(path[depth].p_hdr == NULL)) {
1708                 EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
1709                 return -EIO;
1710         }
1711
1712         /* try to insert block into found extent and return */
1713         if (ex && !(flag & EXT4_GET_BLOCKS_PRE_IO)
1714                 && ext4_can_extents_be_merged(inode, ex, newext)) {
1715                 ext_debug("append [%d]%d block to %d:[%d]%d (from %llu)\n",
1716                                 ext4_ext_is_uninitialized(newext),
1717                                 ext4_ext_get_actual_len(newext),
1718                                 le32_to_cpu(ex->ee_block),
1719                                 ext4_ext_is_uninitialized(ex),
1720                                 ext4_ext_get_actual_len(ex), ext_pblock(ex));
1721                 err = ext4_ext_get_access(handle, inode, path + depth);
1722                 if (err)
1723                         return err;
1724
1725                 /*
1726                  * ext4_can_extents_be_merged should have checked that either
1727                  * both extents are uninitialized, or both aren't. Thus we
1728                  * need to check only one of them here.
1729                  */
1730                 if (ext4_ext_is_uninitialized(ex))
1731                         uninitialized = 1;
1732                 ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
1733                                         + ext4_ext_get_actual_len(newext));
1734                 if (uninitialized)
1735                         ext4_ext_mark_uninitialized(ex);
1736                 eh = path[depth].p_hdr;
1737                 nearex = ex;
1738                 goto merge;
1739         }
1740
1741 repeat:
1742         depth = ext_depth(inode);
1743         eh = path[depth].p_hdr;
1744         if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max))
1745                 goto has_space;
1746
1747         /* probably next leaf has space for us? */
1748         fex = EXT_LAST_EXTENT(eh);
1749         next = ext4_ext_next_leaf_block(inode, path);
1750         if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block)
1751             && next != EXT_MAX_BLOCK) {
1752                 ext_debug("next leaf block - %d\n", next);
1753                 BUG_ON(npath != NULL);
1754                 npath = ext4_ext_find_extent(inode, next, NULL);
1755                 if (IS_ERR(npath))
1756                         return PTR_ERR(npath);
1757                 BUG_ON(npath->p_depth != path->p_depth);
1758                 eh = npath[depth].p_hdr;
1759                 if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max)) {
1760                         ext_debug("next leaf isnt full(%d)\n",
1761                                   le16_to_cpu(eh->eh_entries));
1762                         path = npath;
1763                         goto repeat;
1764                 }
1765                 ext_debug("next leaf has no free space(%d,%d)\n",
1766                           le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
1767         }
1768
1769         /*
1770          * There is no free space in the found leaf.
1771          * We're gonna add a new leaf in the tree.
1772          */
1773         err = ext4_ext_create_new_leaf(handle, inode, path, newext);
1774         if (err)
1775                 goto cleanup;
1776         depth = ext_depth(inode);
1777         eh = path[depth].p_hdr;
1778
1779 has_space:
1780         nearex = path[depth].p_ext;
1781
1782         err = ext4_ext_get_access(handle, inode, path + depth);
1783         if (err)
1784                 goto cleanup;
1785
1786         if (!nearex) {
1787                 /* there is no extent in this leaf, create first one */
1788                 ext_debug("first extent in the leaf: %d:%llu:[%d]%d\n",
1789                                 le32_to_cpu(newext->ee_block),
1790                                 ext_pblock(newext),
1791                                 ext4_ext_is_uninitialized(newext),
1792                                 ext4_ext_get_actual_len(newext));
1793                 path[depth].p_ext = EXT_FIRST_EXTENT(eh);
1794         } else if (le32_to_cpu(newext->ee_block)
1795                            > le32_to_cpu(nearex->ee_block)) {
1796 /*              BUG_ON(newext->ee_block == nearex->ee_block); */
1797                 if (nearex != EXT_LAST_EXTENT(eh)) {
1798                         len = EXT_MAX_EXTENT(eh) - nearex;
1799                         len = (len - 1) * sizeof(struct ext4_extent);
1800                         len = len < 0 ? 0 : len;
1801                         ext_debug("insert %d:%llu:[%d]%d after: nearest 0x%p, "
1802                                         "move %d from 0x%p to 0x%p\n",
1803                                         le32_to_cpu(newext->ee_block),
1804                                         ext_pblock(newext),
1805                                         ext4_ext_is_uninitialized(newext),
1806                                         ext4_ext_get_actual_len(newext),
1807                                         nearex, len, nearex + 1, nearex + 2);
1808                         memmove(nearex + 2, nearex + 1, len);
1809                 }
1810                 path[depth].p_ext = nearex + 1;
1811         } else {
1812                 BUG_ON(newext->ee_block == nearex->ee_block);
1813                 len = (EXT_MAX_EXTENT(eh) - nearex) * sizeof(struct ext4_extent);
1814                 len = len < 0 ? 0 : len;
1815                 ext_debug("insert %d:%llu:[%d]%d before: nearest 0x%p, "
1816                                 "move %d from 0x%p to 0x%p\n",
1817                                 le32_to_cpu(newext->ee_block),
1818                                 ext_pblock(newext),
1819                                 ext4_ext_is_uninitialized(newext),
1820                                 ext4_ext_get_actual_len(newext),
1821                                 nearex, len, nearex + 1, nearex + 2);
1822                 memmove(nearex + 1, nearex, len);
1823                 path[depth].p_ext = nearex;
1824         }
1825
1826         le16_add_cpu(&eh->eh_entries, 1);
1827         nearex = path[depth].p_ext;
1828         nearex->ee_block = newext->ee_block;
1829         ext4_ext_store_pblock(nearex, ext_pblock(newext));
1830         nearex->ee_len = newext->ee_len;
1831
1832 merge:
1833         /* try to merge extents to the right */
1834         if (!(flag & EXT4_GET_BLOCKS_PRE_IO))
1835                 ext4_ext_try_to_merge(inode, path, nearex);
1836
1837         /* try to merge extents to the left */
1838
1839         /* time to correct all indexes above */
1840         err = ext4_ext_correct_indexes(handle, inode, path);
1841         if (err)
1842                 goto cleanup;
1843
1844         err = ext4_ext_dirty(handle, inode, path + depth);
1845
1846 cleanup:
1847         if (npath) {
1848                 ext4_ext_drop_refs(npath);
1849                 kfree(npath);
1850         }
1851         ext4_ext_invalidate_cache(inode);
1852         return err;
1853 }
1854
1855 int ext4_ext_walk_space(struct inode *inode, ext4_lblk_t block,
1856                         ext4_lblk_t num, ext_prepare_callback func,
1857                         void *cbdata)
1858 {
1859         struct ext4_ext_path *path = NULL;
1860         struct ext4_ext_cache cbex;
1861         struct ext4_extent *ex;
1862         ext4_lblk_t next, start = 0, end = 0;
1863         ext4_lblk_t last = block + num;
1864         int depth, exists, err = 0;
1865
1866         BUG_ON(func == NULL);
1867         BUG_ON(inode == NULL);
1868
1869         while (block < last && block != EXT_MAX_BLOCK) {
1870                 num = last - block;
1871                 /* find extent for this block */
1872                 down_read(&EXT4_I(inode)->i_data_sem);
1873                 path = ext4_ext_find_extent(inode, block, path);
1874                 up_read(&EXT4_I(inode)->i_data_sem);
1875                 if (IS_ERR(path)) {
1876                         err = PTR_ERR(path);
1877                         path = NULL;
1878                         break;
1879                 }
1880
1881                 depth = ext_depth(inode);
1882                 if (unlikely(path[depth].p_hdr == NULL)) {
1883                         EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
1884                         err = -EIO;
1885                         break;
1886                 }
1887                 ex = path[depth].p_ext;
1888                 next = ext4_ext_next_allocated_block(path);
1889
1890                 exists = 0;
1891                 if (!ex) {
1892                         /* there is no extent yet, so try to allocate
1893                          * all requested space */
1894                         start = block;
1895                         end = block + num;
1896                 } else if (le32_to_cpu(ex->ee_block) > block) {
1897                         /* need to allocate space before found extent */
1898                         start = block;
1899                         end = le32_to_cpu(ex->ee_block);
1900                         if (block + num < end)
1901                                 end = block + num;
1902                 } else if (block >= le32_to_cpu(ex->ee_block)
1903                                         + ext4_ext_get_actual_len(ex)) {
1904                         /* need to allocate space after found extent */
1905                         start = block;
1906                         end = block + num;
1907                         if (end >= next)
1908                                 end = next;
1909                 } else if (block >= le32_to_cpu(ex->ee_block)) {
1910                         /*
1911                          * some part of requested space is covered
1912                          * by found extent
1913                          */
1914                         start = block;
1915                         end = le32_to_cpu(ex->ee_block)
1916                                 + ext4_ext_get_actual_len(ex);
1917                         if (block + num < end)
1918                                 end = block + num;
1919                         exists = 1;
1920                 } else {
1921                         BUG();
1922                 }
1923                 BUG_ON(end <= start);
1924
1925                 if (!exists) {
1926                         cbex.ec_block = start;
1927                         cbex.ec_len = end - start;
1928                         cbex.ec_start = 0;
1929                         cbex.ec_type = EXT4_EXT_CACHE_GAP;
1930                 } else {
1931                         cbex.ec_block = le32_to_cpu(ex->ee_block);
1932                         cbex.ec_len = ext4_ext_get_actual_len(ex);
1933                         cbex.ec_start = ext_pblock(ex);
1934                         cbex.ec_type = EXT4_EXT_CACHE_EXTENT;
1935                 }
1936
1937                 if (unlikely(cbex.ec_len == 0)) {
1938                         EXT4_ERROR_INODE(inode, "cbex.ec_len == 0");
1939                         err = -EIO;
1940                         break;
1941                 }
1942                 err = func(inode, path, &cbex, ex, cbdata);
1943                 ext4_ext_drop_refs(path);
1944
1945                 if (err < 0)
1946                         break;
1947
1948                 if (err == EXT_REPEAT)
1949                         continue;
1950                 else if (err == EXT_BREAK) {
1951                         err = 0;
1952                         break;
1953                 }
1954
1955                 if (ext_depth(inode) != depth) {
1956                         /* depth was changed. we have to realloc path */
1957                         kfree(path);
1958                         path = NULL;
1959                 }
1960
1961                 block = cbex.ec_block + cbex.ec_len;
1962         }
1963
1964         if (path) {
1965                 ext4_ext_drop_refs(path);
1966                 kfree(path);
1967         }
1968
1969         return err;
1970 }
1971
1972 static void
1973 ext4_ext_put_in_cache(struct inode *inode, ext4_lblk_t block,
1974                         __u32 len, ext4_fsblk_t start, int type)
1975 {
1976         struct ext4_ext_cache *cex;
1977         BUG_ON(len == 0);
1978         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1979         cex = &EXT4_I(inode)->i_cached_extent;
1980         cex->ec_type = type;
1981         cex->ec_block = block;
1982         cex->ec_len = len;
1983         cex->ec_start = start;
1984         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1985 }
1986
1987 /*
1988  * ext4_ext_put_gap_in_cache:
1989  * calculate boundaries of the gap that the requested block fits into
1990  * and cache this gap
1991  */
1992 static void
1993 ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
1994                                 ext4_lblk_t block)
1995 {
1996         int depth = ext_depth(inode);
1997         unsigned long len;
1998         ext4_lblk_t lblock;
1999         struct ext4_extent *ex;
2000
2001         ex = path[depth].p_ext;
2002         if (ex == NULL) {
2003                 /* there is no extent yet, so gap is [0;-] */
2004                 lblock = 0;
2005                 len = EXT_MAX_BLOCK;
2006                 ext_debug("cache gap(whole file):");
2007         } else if (block < le32_to_cpu(ex->ee_block)) {
2008                 lblock = block;
2009                 len = le32_to_cpu(ex->ee_block) - block;
2010                 ext_debug("cache gap(before): %u [%u:%u]",
2011                                 block,
2012                                 le32_to_cpu(ex->ee_block),
2013                                  ext4_ext_get_actual_len(ex));
2014         } else if (block >= le32_to_cpu(ex->ee_block)
2015                         + ext4_ext_get_actual_len(ex)) {
2016                 ext4_lblk_t next;
2017                 lblock = le32_to_cpu(ex->ee_block)
2018                         + ext4_ext_get_actual_len(ex);
2019
2020                 next = ext4_ext_next_allocated_block(path);
2021                 ext_debug("cache gap(after): [%u:%u] %u",
2022                                 le32_to_cpu(ex->ee_block),
2023                                 ext4_ext_get_actual_len(ex),
2024                                 block);
2025                 BUG_ON(next == lblock);
2026                 len = next - lblock;
2027         } else {
2028                 lblock = len = 0;
2029                 BUG();
2030         }
2031
2032         ext_debug(" -> %u:%lu\n", lblock, len);
2033         ext4_ext_put_in_cache(inode, lblock, len, 0, EXT4_EXT_CACHE_GAP);
2034 }
2035
2036 static int
2037 ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
2038                         struct ext4_extent *ex)
2039 {
2040         struct ext4_ext_cache *cex;
2041         int ret = EXT4_EXT_CACHE_NO;
2042
2043         /*
2044          * We borrow i_block_reservation_lock to protect i_cached_extent
2045          */
2046         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
2047         cex = &EXT4_I(inode)->i_cached_extent;
2048
2049         /* has cache valid data? */
2050         if (cex->ec_type == EXT4_EXT_CACHE_NO)
2051                 goto errout;
2052
2053         BUG_ON(cex->ec_type != EXT4_EXT_CACHE_GAP &&
2054                         cex->ec_type != EXT4_EXT_CACHE_EXTENT);
2055         if (block >= cex->ec_block && block < cex->ec_block + cex->ec_len) {
2056                 ex->ee_block = cpu_to_le32(cex->ec_block);
2057                 ext4_ext_store_pblock(ex, cex->ec_start);
2058                 ex->ee_len = cpu_to_le16(cex->ec_len);
2059                 ext_debug("%u cached by %u:%u:%llu\n",
2060                                 block,
2061                                 cex->ec_block, cex->ec_len, cex->ec_start);
2062                 ret = cex->ec_type;
2063         }
2064 errout:
2065         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
2066         return ret;
2067 }
2068
2069 /*
2070  * ext4_ext_rm_idx:
2071  * removes index from the index block.
2072  * It's used in truncate case only, thus all requests are for
2073  * last index in the block only.
2074  */
2075 static int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
2076                         struct ext4_ext_path *path)
2077 {
2078         int err;
2079         ext4_fsblk_t leaf;
2080
2081         /* free index block */
2082         path--;
2083         leaf = idx_pblock(path->p_idx);
2084         if (unlikely(path->p_hdr->eh_entries == 0)) {
2085                 EXT4_ERROR_INODE(inode, "path->p_hdr->eh_entries == 0");
2086                 return -EIO;
2087         }
2088         err = ext4_ext_get_access(handle, inode, path);
2089         if (err)
2090                 return err;
2091         le16_add_cpu(&path->p_hdr->eh_entries, -1);
2092         err = ext4_ext_dirty(handle, inode, path);
2093         if (err)
2094                 return err;
2095         ext_debug("index is empty, remove it, free block %llu\n", leaf);
2096         ext4_free_blocks(handle, inode, 0, leaf, 1,
2097                          EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
2098         return err;
2099 }
2100
2101 /*
2102  * ext4_ext_calc_credits_for_single_extent:
2103  * This routine returns max. credits that needed to insert an extent
2104  * to the extent tree.
2105  * When pass the actual path, the caller should calculate credits
2106  * under i_data_sem.
2107  */
2108 int ext4_ext_calc_credits_for_single_extent(struct inode *inode, int nrblocks,
2109                                                 struct ext4_ext_path *path)
2110 {
2111         if (path) {
2112                 int depth = ext_depth(inode);
2113                 int ret = 0;
2114
2115                 /* probably there is space in leaf? */
2116                 if (le16_to_cpu(path[depth].p_hdr->eh_entries)
2117                                 < le16_to_cpu(path[depth].p_hdr->eh_max)) {
2118
2119                         /*
2120                          *  There are some space in the leaf tree, no
2121                          *  need to account for leaf block credit
2122                          *
2123                          *  bitmaps and block group descriptor blocks
2124                          *  and other metadat blocks still need to be
2125                          *  accounted.
2126                          */
2127                         /* 1 bitmap, 1 block group descriptor */
2128                         ret = 2 + EXT4_META_TRANS_BLOCKS(inode->i_sb);
2129                         return ret;
2130                 }
2131         }
2132
2133         return ext4_chunk_trans_blocks(inode, nrblocks);
2134 }
2135
2136 /*
2137  * How many index/leaf blocks need to change/allocate to modify nrblocks?
2138  *
2139  * if nrblocks are fit in a single extent (chunk flag is 1), then
2140  * in the worse case, each tree level index/leaf need to be changed
2141  * if the tree split due to insert a new extent, then the old tree
2142  * index/leaf need to be updated too
2143  *
2144  * If the nrblocks are discontiguous, they could cause
2145  * the whole tree split more than once, but this is really rare.
2146  */
2147 int ext4_ext_index_trans_blocks(struct inode *inode, int nrblocks, int chunk)
2148 {
2149         int index;
2150         int depth = ext_depth(inode);
2151
2152         if (chunk)
2153                 index = depth * 2;
2154         else
2155                 index = depth * 3;
2156
2157         return index;
2158 }
2159
2160 static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
2161                                 struct ext4_extent *ex,
2162                                 ext4_lblk_t from, ext4_lblk_t to)
2163 {
2164         unsigned short ee_len =  ext4_ext_get_actual_len(ex);
2165         int flags = EXT4_FREE_BLOCKS_FORGET;
2166
2167         if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
2168                 flags |= EXT4_FREE_BLOCKS_METADATA;
2169 #ifdef EXTENTS_STATS
2170         {
2171                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2172                 spin_lock(&sbi->s_ext_stats_lock);
2173                 sbi->s_ext_blocks += ee_len;
2174                 sbi->s_ext_extents++;
2175                 if (ee_len < sbi->s_ext_min)
2176                         sbi->s_ext_min = ee_len;
2177                 if (ee_len > sbi->s_ext_max)
2178                         sbi->s_ext_max = ee_len;
2179                 if (ext_depth(inode) > sbi->s_depth_max)
2180                         sbi->s_depth_max = ext_depth(inode);
2181                 spin_unlock(&sbi->s_ext_stats_lock);
2182         }
2183 #endif
2184         if (from >= le32_to_cpu(ex->ee_block)
2185             && to == le32_to_cpu(ex->ee_block) + ee_len - 1) {
2186                 /* tail removal */
2187                 ext4_lblk_t num;
2188                 ext4_fsblk_t start;
2189
2190                 num = le32_to_cpu(ex->ee_block) + ee_len - from;
2191                 start = ext_pblock(ex) + ee_len - num;
2192                 ext_debug("free last %u blocks starting %llu\n", num, start);
2193                 ext4_free_blocks(handle, inode, 0, start, num, flags);
2194         } else if (from == le32_to_cpu(ex->ee_block)
2195                    && to <= le32_to_cpu(ex->ee_block) + ee_len - 1) {
2196                 printk(KERN_INFO "strange request: removal %u-%u from %u:%u\n",
2197                         from, to, le32_to_cpu(ex->ee_block), ee_len);
2198         } else {
2199                 printk(KERN_INFO "strange request: removal(2) "
2200                                 "%u-%u from %u:%u\n",
2201                                 from, to, le32_to_cpu(ex->ee_block), ee_len);
2202         }
2203         return 0;
2204 }
2205
2206 static int
2207 ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
2208                 struct ext4_ext_path *path, ext4_lblk_t start)
2209 {
2210         int err = 0, correct_index = 0;
2211         int depth = ext_depth(inode), credits;
2212         struct ext4_extent_header *eh;
2213         ext4_lblk_t a, b, block;
2214         unsigned num;
2215         ext4_lblk_t ex_ee_block;
2216         unsigned short ex_ee_len;
2217         unsigned uninitialized = 0;
2218         struct ext4_extent *ex;
2219
2220         /* the header must be checked already in ext4_ext_remove_space() */
2221         ext_debug("truncate since %u in leaf\n", start);
2222         if (!path[depth].p_hdr)
2223                 path[depth].p_hdr = ext_block_hdr(path[depth].p_bh);
2224         eh = path[depth].p_hdr;
2225         if (unlikely(path[depth].p_hdr == NULL)) {
2226                 EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
2227                 return -EIO;
2228         }
2229         /* find where to start removing */
2230         ex = EXT_LAST_EXTENT(eh);
2231
2232         ex_ee_block = le32_to_cpu(ex->ee_block);
2233         ex_ee_len = ext4_ext_get_actual_len(ex);
2234
2235         while (ex >= EXT_FIRST_EXTENT(eh) &&
2236                         ex_ee_block + ex_ee_len > start) {
2237
2238                 if (ext4_ext_is_uninitialized(ex))
2239                         uninitialized = 1;
2240                 else
2241                         uninitialized = 0;
2242
2243                 ext_debug("remove ext %u:[%d]%d\n", ex_ee_block,
2244                          uninitialized, ex_ee_len);
2245                 path[depth].p_ext = ex;
2246
2247                 a = ex_ee_block > start ? ex_ee_block : start;
2248                 b = ex_ee_block + ex_ee_len - 1 < EXT_MAX_BLOCK ?
2249                         ex_ee_block + ex_ee_len - 1 : EXT_MAX_BLOCK;
2250
2251                 ext_debug("  border %u:%u\n", a, b);
2252
2253                 if (a != ex_ee_block && b != ex_ee_block + ex_ee_len - 1) {
2254                         block = 0;
2255                         num = 0;
2256                         BUG();
2257                 } else if (a != ex_ee_block) {
2258                         /* remove tail of the extent */
2259                         block = ex_ee_block;
2260                         num = a - block;
2261                 } else if (b != ex_ee_block + ex_ee_len - 1) {
2262                         /* remove head of the extent */
2263                         block = a;
2264                         num = b - a;
2265                         /* there is no "make a hole" API yet */
2266                         BUG();
2267                 } else {
2268                         /* remove whole extent: excellent! */
2269                         block = ex_ee_block;
2270                         num = 0;
2271                         BUG_ON(a != ex_ee_block);
2272                         BUG_ON(b != ex_ee_block + ex_ee_len - 1);
2273                 }
2274
2275                 /*
2276                  * 3 for leaf, sb, and inode plus 2 (bmap and group
2277                  * descriptor) for each block group; assume two block
2278                  * groups plus ex_ee_len/blocks_per_block_group for
2279                  * the worst case
2280                  */
2281                 credits = 7 + 2*(ex_ee_len/EXT4_BLOCKS_PER_GROUP(inode->i_sb));
2282                 if (ex == EXT_FIRST_EXTENT(eh)) {
2283                         correct_index = 1;
2284                         credits += (ext_depth(inode)) + 1;
2285                 }
2286                 credits += EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);
2287
2288                 err = ext4_ext_truncate_extend_restart(handle, inode, credits);
2289                 if (err)
2290                         goto out;
2291
2292                 err = ext4_ext_get_access(handle, inode, path + depth);
2293                 if (err)
2294                         goto out;
2295
2296                 err = ext4_remove_blocks(handle, inode, ex, a, b);
2297                 if (err)
2298                         goto out;
2299
2300                 if (num == 0) {
2301                         /* this extent is removed; mark slot entirely unused */
2302                         ext4_ext_store_pblock(ex, 0);
2303                         le16_add_cpu(&eh->eh_entries, -1);
2304                 }
2305
2306                 ex->ee_block = cpu_to_le32(block);
2307                 ex->ee_len = cpu_to_le16(num);
2308                 /*
2309                  * Do not mark uninitialized if all the blocks in the
2310                  * extent have been removed.
2311                  */
2312                 if (uninitialized && num)
2313                         ext4_ext_mark_uninitialized(ex);
2314
2315                 err = ext4_ext_dirty(handle, inode, path + depth);
2316                 if (err)
2317                         goto out;
2318
2319                 ext_debug("new extent: %u:%u:%llu\n", block, num,
2320                                 ext_pblock(ex));
2321                 ex--;
2322                 ex_ee_block = le32_to_cpu(ex->ee_block);
2323                 ex_ee_len = ext4_ext_get_actual_len(ex);
2324         }
2325
2326         if (correct_index && eh->eh_entries)
2327                 err = ext4_ext_correct_indexes(handle, inode, path);
2328
2329         /* if this leaf is free, then we should
2330          * remove it from index block above */
2331         if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL)
2332                 err = ext4_ext_rm_idx(handle, inode, path + depth);
2333
2334 out:
2335         return err;
2336 }
2337
2338 /*
2339  * ext4_ext_more_to_rm:
2340  * returns 1 if current index has to be freed (even partial)
2341  */
2342 static int
2343 ext4_ext_more_to_rm(struct ext4_ext_path *path)
2344 {
2345         BUG_ON(path->p_idx == NULL);
2346
2347         if (path->p_idx < EXT_FIRST_INDEX(path->p_hdr))
2348                 return 0;
2349
2350         /*
2351          * if truncate on deeper level happened, it wasn't partial,
2352          * so we have to consider current index for truncation
2353          */
2354         if (le16_to_cpu(path->p_hdr->eh_entries) == path->p_block)
2355                 return 0;
2356         return 1;
2357 }
2358
2359 static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start)
2360 {
2361         struct super_block *sb = inode->i_sb;
2362         int depth = ext_depth(inode);
2363         struct ext4_ext_path *path;
2364         handle_t *handle;
2365         int i = 0, err = 0;
2366
2367         ext_debug("truncate since %u\n", start);
2368
2369         /* probably first extent we're gonna free will be last in block */
2370         handle = ext4_journal_start(inode, depth + 1);
2371         if (IS_ERR(handle))
2372                 return PTR_ERR(handle);
2373
2374         ext4_ext_invalidate_cache(inode);
2375
2376         /*
2377          * We start scanning from right side, freeing all the blocks
2378          * after i_size and walking into the tree depth-wise.
2379          */
2380         path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_NOFS);
2381         if (path == NULL) {
2382                 ext4_journal_stop(handle);
2383                 return -ENOMEM;
2384         }
2385         path[0].p_hdr = ext_inode_hdr(inode);
2386         if (ext4_ext_check(inode, path[0].p_hdr, depth)) {
2387                 err = -EIO;
2388                 goto out;
2389         }
2390         path[0].p_depth = depth;
2391
2392         while (i >= 0 && err == 0) {
2393                 if (i == depth) {
2394                         /* this is leaf block */
2395                         err = ext4_ext_rm_leaf(handle, inode, path, start);
2396                         /* root level has p_bh == NULL, brelse() eats this */
2397                         brelse(path[i].p_bh);
2398                         path[i].p_bh = NULL;
2399                         i--;
2400                         continue;
2401                 }
2402
2403                 /* this is index block */
2404                 if (!path[i].p_hdr) {
2405                         ext_debug("initialize header\n");
2406                         path[i].p_hdr = ext_block_hdr(path[i].p_bh);
2407                 }
2408
2409                 if (!path[i].p_idx) {
2410                         /* this level hasn't been touched yet */
2411                         path[i].p_idx = EXT_LAST_INDEX(path[i].p_hdr);
2412                         path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries)+1;
2413                         ext_debug("init index ptr: hdr 0x%p, num %d\n",
2414                                   path[i].p_hdr,
2415                                   le16_to_cpu(path[i].p_hdr->eh_entries));
2416                 } else {
2417                         /* we were already here, see at next index */
2418                         path[i].p_idx--;
2419                 }
2420
2421                 ext_debug("level %d - index, first 0x%p, cur 0x%p\n",
2422                                 i, EXT_FIRST_INDEX(path[i].p_hdr),
2423                                 path[i].p_idx);
2424                 if (ext4_ext_more_to_rm(path + i)) {
2425                         struct buffer_head *bh;
2426                         /* go to the next level */
2427                         ext_debug("move to level %d (block %llu)\n",
2428                                   i + 1, idx_pblock(path[i].p_idx));
2429                         memset(path + i + 1, 0, sizeof(*path));
2430                         bh = sb_bread(sb, idx_pblock(path[i].p_idx));
2431                         if (!bh) {
2432                                 /* should we reset i_size? */
2433                                 err = -EIO;
2434                                 break;
2435                         }
2436                         if (WARN_ON(i + 1 > depth)) {
2437                                 err = -EIO;
2438                                 break;
2439                         }
2440                         if (ext4_ext_check(inode, ext_block_hdr(bh),
2441                                                         depth - i - 1)) {
2442                                 err = -EIO;
2443                                 break;
2444                         }
2445                         path[i + 1].p_bh = bh;
2446
2447                         /* save actual number of indexes since this
2448                          * number is changed at the next iteration */
2449                         path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries);
2450                         i++;
2451                 } else {
2452                         /* we finished processing this index, go up */
2453                         if (path[i].p_hdr->eh_entries == 0 && i > 0) {
2454                                 /* index is empty, remove it;
2455                                  * handle must be already prepared by the
2456                                  * truncatei_leaf() */
2457                                 err = ext4_ext_rm_idx(handle, inode, path + i);
2458                         }
2459                         /* root level has p_bh == NULL, brelse() eats this */
2460                         brelse(path[i].p_bh);
2461                         path[i].p_bh = NULL;
2462                         i--;
2463                         ext_debug("return to level %d\n", i);
2464                 }
2465         }
2466
2467         /* TODO: flexible tree reduction should be here */
2468         if (path->p_hdr->eh_entries == 0) {
2469                 /*
2470                  * truncate to zero freed all the tree,
2471                  * so we need to correct eh_depth
2472                  */
2473                 err = ext4_ext_get_access(handle, inode, path);
2474                 if (err == 0) {
2475                         ext_inode_hdr(inode)->eh_depth = 0;
2476                         ext_inode_hdr(inode)->eh_max =
2477                                 cpu_to_le16(ext4_ext_space_root(inode, 0));
2478                         err = ext4_ext_dirty(handle, inode, path);
2479                 }
2480         }
2481 out:
2482         ext4_ext_drop_refs(path);
2483         kfree(path);
2484         ext4_journal_stop(handle);
2485
2486         return err;
2487 }
2488
2489 /*
2490  * called at mount time
2491  */
2492 void ext4_ext_init(struct super_block *sb)
2493 {
2494         /*
2495          * possible initialization would be here
2496          */
2497
2498         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
2499 #if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)
2500                 printk(KERN_INFO "EXT4-fs: file extents enabled");
2501 #ifdef AGGRESSIVE_TEST
2502                 printk(", aggressive tests");
2503 #endif
2504 #ifdef CHECK_BINSEARCH
2505                 printk(", check binsearch");
2506 #endif
2507 #ifdef EXTENTS_STATS
2508                 printk(", stats");
2509 #endif
2510                 printk("\n");
2511 #endif
2512 #ifdef EXTENTS_STATS
2513                 spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
2514                 EXT4_SB(sb)->s_ext_min = 1 << 30;
2515                 EXT4_SB(sb)->s_ext_max = 0;
2516 #endif
2517         }
2518 }
2519
2520 /*
2521  * called at umount time
2522  */
2523 void ext4_ext_release(struct super_block *sb)
2524 {
2525         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS))
2526                 return;
2527
2528 #ifdef EXTENTS_STATS
2529         if (EXT4_SB(sb)->s_ext_blocks && EXT4_SB(sb)->s_ext_extents) {
2530                 struct ext4_sb_info *sbi = EXT4_SB(sb);
2531                 printk(KERN_ERR "EXT4-fs: %lu blocks in %lu extents (%lu ave)\n",
2532                         sbi->s_ext_blocks, sbi->s_ext_extents,
2533                         sbi->s_ext_blocks / sbi->s_ext_extents);
2534                 printk(KERN_ERR "EXT4-fs: extents: %lu min, %lu max, max depth %lu\n",
2535                         sbi->s_ext_min, sbi->s_ext_max, sbi->s_depth_max);
2536         }
2537 #endif
2538 }
2539
2540 static void bi_complete(struct bio *bio, int error)
2541 {
2542         complete((struct completion *)bio->bi_private);
2543 }
2544
2545 /* FIXME!! we need to try to merge to left or right after zero-out  */
2546 static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
2547 {
2548         int ret = -EIO;
2549         struct bio *bio;
2550         int blkbits, blocksize;
2551         sector_t ee_pblock;
2552         struct completion event;
2553         unsigned int ee_len, len, done, offset;
2554
2555
2556         blkbits   = inode->i_blkbits;
2557         blocksize = inode->i_sb->s_blocksize;
2558         ee_len    = ext4_ext_get_actual_len(ex);
2559         ee_pblock = ext_pblock(ex);
2560
2561         /* convert ee_pblock to 512 byte sectors */
2562         ee_pblock = ee_pblock << (blkbits - 9);
2563
2564         while (ee_len > 0) {
2565
2566                 if (ee_len > BIO_MAX_PAGES)
2567                         len = BIO_MAX_PAGES;
2568                 else
2569                         len = ee_len;
2570
2571                 bio = bio_alloc(GFP_NOIO, len);
2572                 bio->bi_sector = ee_pblock;
2573                 bio->bi_bdev   = inode->i_sb->s_bdev;
2574
2575                 done = 0;
2576                 offset = 0;
2577                 while (done < len) {
2578                         ret = bio_add_page(bio, ZERO_PAGE(0),
2579                                                         blocksize, offset);
2580                         if (ret != blocksize) {
2581                                 /*
2582                                  * We can't add any more pages because of
2583                                  * hardware limitations.  Start a new bio.
2584                                  */
2585                                 break;
2586                         }
2587                         done++;
2588                         offset += blocksize;
2589                         if (offset >= PAGE_CACHE_SIZE)
2590                                 offset = 0;
2591                 }
2592
2593                 init_completion(&event);
2594                 bio->bi_private = &event;
2595                 bio->bi_end_io = bi_complete;
2596                 submit_bio(WRITE, bio);
2597                 wait_for_completion(&event);
2598
2599                 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
2600                         ret = 0;
2601                 else {
2602                         ret = -EIO;
2603                         break;
2604                 }
2605                 bio_put(bio);
2606                 ee_len    -= done;
2607                 ee_pblock += done  << (blkbits - 9);
2608         }
2609         return ret;
2610 }
2611
2612 #define EXT4_EXT_ZERO_LEN 7
2613 /*
2614  * This function is called by ext4_ext_get_blocks() if someone tries to write
2615  * to an uninitialized extent. It may result in splitting the uninitialized
2616  * extent into multiple extents (upto three - one initialized and two
2617  * uninitialized).
2618  * There are three possibilities:
2619  *   a> There is no split required: Entire extent should be initialized
2620  *   b> Splits in two extents: Write is happening at either end of the extent
2621  *   c> Splits in three extents: Somone is writing in middle of the extent
2622  */
2623 static int ext4_ext_convert_to_initialized(handle_t *handle,
2624                                                 struct inode *inode,
2625                                                 struct ext4_ext_path *path,
2626                                                 ext4_lblk_t iblock,
2627                                                 unsigned int max_blocks)
2628 {
2629         struct ext4_extent *ex, newex, orig_ex;
2630         struct ext4_extent *ex1 = NULL;
2631         struct ext4_extent *ex2 = NULL;
2632         struct ext4_extent *ex3 = NULL;
2633         struct ext4_extent_header *eh;
2634         ext4_lblk_t ee_block;
2635         unsigned int allocated, ee_len, depth;
2636         ext4_fsblk_t newblock;
2637         int err = 0;
2638         int ret = 0;
2639
2640         depth = ext_depth(inode);
2641         eh = path[depth].p_hdr;
2642         ex = path[depth].p_ext;
2643         ee_block = le32_to_cpu(ex->ee_block);
2644         ee_len = ext4_ext_get_actual_len(ex);
2645         allocated = ee_len - (iblock - ee_block);
2646         newblock = iblock - ee_block + ext_pblock(ex);
2647         ex2 = ex;
2648         orig_ex.ee_block = ex->ee_block;
2649         orig_ex.ee_len   = cpu_to_le16(ee_len);
2650         ext4_ext_store_pblock(&orig_ex, ext_pblock(ex));
2651
2652         err = ext4_ext_get_access(handle, inode, path + depth);
2653         if (err)
2654                 goto out;
2655         /* If extent has less than 2*EXT4_EXT_ZERO_LEN zerout directly */
2656         if (ee_len <= 2*EXT4_EXT_ZERO_LEN) {
2657                 err =  ext4_ext_zeroout(inode, &orig_ex);
2658                 if (err)
2659                         goto fix_extent_len;
2660                 /* update the extent length and mark as initialized */
2661                 ex->ee_block = orig_ex.ee_block;
2662                 ex->ee_len   = orig_ex.ee_len;
2663                 ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
2664                 ext4_ext_dirty(handle, inode, path + depth);
2665                 /* zeroed the full extent */
2666                 return allocated;
2667         }
2668
2669         /* ex1: ee_block to iblock - 1 : uninitialized */
2670         if (iblock > ee_block) {
2671                 ex1 = ex;
2672                 ex1->ee_len = cpu_to_le16(iblock - ee_block);
2673                 ext4_ext_mark_uninitialized(ex1);
2674                 ex2 = &newex;
2675         }
2676         /*
2677          * for sanity, update the length of the ex2 extent before
2678          * we insert ex3, if ex1 is NULL. This is to avoid temporary
2679          * overlap of blocks.
2680          */
2681         if (!ex1 && allocated > max_blocks)
2682                 ex2->ee_len = cpu_to_le16(max_blocks);
2683         /* ex3: to ee_block + ee_len : uninitialised */
2684         if (allocated > max_blocks) {
2685                 unsigned int newdepth;
2686                 /* If extent has less than EXT4_EXT_ZERO_LEN zerout directly */
2687                 if (allocated <= EXT4_EXT_ZERO_LEN) {
2688                         /*
2689                          * iblock == ee_block is handled by the zerouout
2690                          * at the beginning.
2691                          * Mark first half uninitialized.
2692                          * Mark second half initialized and zero out the
2693                          * initialized extent
2694                          */
2695                         ex->ee_block = orig_ex.ee_block;
2696                         ex->ee_len   = cpu_to_le16(ee_len - allocated);
2697                         ext4_ext_mark_uninitialized(ex);
2698                         ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
2699                         ext4_ext_dirty(handle, inode, path + depth);
2700
2701                         ex3 = &newex;
2702                         ex3->ee_block = cpu_to_le32(iblock);
2703                         ext4_ext_store_pblock(ex3, newblock);
2704                         ex3->ee_len = cpu_to_le16(allocated);
2705                         err = ext4_ext_insert_extent(handle, inode, path,
2706                                                         ex3, 0);
2707                         if (err == -ENOSPC) {
2708                                 err =  ext4_ext_zeroout(inode, &orig_ex);
2709                                 if (err)
2710                                         goto fix_extent_len;
2711                                 ex->ee_block = orig_ex.ee_block;
2712                                 ex->ee_len   = orig_ex.ee_len;
2713                                 ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
2714                                 ext4_ext_dirty(handle, inode, path + depth);
2715                                 /* blocks available from iblock */
2716                                 return allocated;
2717
2718                         } else if (err)
2719                                 goto fix_extent_len;
2720
2721                         /*
2722                          * We need to zero out the second half because
2723                          * an fallocate request can update file size and
2724                          * converting the second half to initialized extent
2725                          * implies that we can leak some junk data to user
2726                          * space.
2727                          */
2728                         err =  ext4_ext_zeroout(inode, ex3);
2729                         if (err) {
2730                                 /*
2731                                  * We should actually mark the
2732                                  * second half as uninit and return error
2733                                  * Insert would have changed the extent
2734                                  */
2735                                 depth = ext_depth(inode);
2736                                 ext4_ext_drop_refs(path);
2737                                 path = ext4_ext_find_extent(inode,
2738                                                                 iblock, path);
2739                                 if (IS_ERR(path)) {
2740                                         err = PTR_ERR(path);
2741                                         return err;
2742                                 }
2743                                 /* get the second half extent details */
2744                                 ex = path[depth].p_ext;
2745                                 err = ext4_ext_get_access(handle, inode,
2746                                                                 path + depth);
2747                                 if (err)
2748                                         return err;
2749                                 ext4_ext_mark_uninitialized(ex);
2750                                 ext4_ext_dirty(handle, inode, path + depth);
2751                                 return err;
2752                         }
2753
2754                         /* zeroed the second half */
2755                         return allocated;
2756                 }
2757                 ex3 = &newex;
2758                 ex3->ee_block = cpu_to_le32(iblock + max_blocks);
2759                 ext4_ext_store_pblock(ex3, newblock + max_blocks);
2760                 ex3->ee_len = cpu_to_le16(allocated - max_blocks);
2761                 ext4_ext_mark_uninitialized(ex3);
2762                 err = ext4_ext_insert_extent(handle, inode, path, ex3, 0);
2763                 if (err == -ENOSPC) {
2764                         err =  ext4_ext_zeroout(inode, &orig_ex);
2765                         if (err)
2766                                 goto fix_extent_len;
2767                         /* update the extent length and mark as initialized */
2768                         ex->ee_block = orig_ex.ee_block;
2769                         ex->ee_len   = orig_ex.ee_len;
2770                         ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
2771                         ext4_ext_dirty(handle, inode, path + depth);
2772                         /* zeroed the full extent */
2773                         /* blocks available from iblock */
2774                         return allocated;
2775
2776                 } else if (err)
2777                         goto fix_extent_len;
2778                 /*
2779                  * The depth, and hence eh & ex might change
2780                  * as part of the insert above.
2781                  */
2782                 newdepth = ext_depth(inode);
2783                 /*
2784                  * update the extent length after successful insert of the
2785                  * split extent
2786                  */
2787                 orig_ex.ee_len = cpu_to_le16(ee_len -
2788                                                 ext4_ext_get_actual_len(ex3));
2789                 depth = newdepth;
2790                 ext4_ext_drop_refs(path);
2791                 path = ext4_ext_find_extent(inode, iblock, path);
2792                 if (IS_ERR(path)) {
2793                         err = PTR_ERR(path);
2794                         goto out;
2795                 }
2796                 eh = path[depth].p_hdr;
2797                 ex = path[depth].p_ext;
2798                 if (ex2 != &newex)
2799                         ex2 = ex;
2800
2801                 err = ext4_ext_get_access(handle, inode, path + depth);
2802                 if (err)
2803                         goto out;
2804
2805                 allocated = max_blocks;
2806
2807                 /* If extent has less than EXT4_EXT_ZERO_LEN and we are trying
2808                  * to insert a extent in the middle zerout directly
2809                  * otherwise give the extent a chance to merge to left
2810                  */
2811                 if (le16_to_cpu(orig_ex.ee_len) <= EXT4_EXT_ZERO_LEN &&
2812                                                         iblock != ee_block) {
2813                         err =  ext4_ext_zeroout(inode, &orig_ex);
2814                         if (err)
2815                                 goto fix_extent_len;
2816                         /* update the extent length and mark as initialized */
2817                         ex->ee_block = orig_ex.ee_block;
2818                         ex->ee_len   = orig_ex.ee_len;
2819                         ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
2820                         ext4_ext_dirty(handle, inode, path + depth);
2821                         /* zero out the first half */
2822                         /* blocks available from iblock */
2823                         return allocated;
2824                 }
2825         }
2826         /*
2827          * If there was a change of depth as part of the
2828          * insertion of ex3 above, we need to update the length
2829          * of the ex1 extent again here
2830          */
2831         if (ex1 && ex1 != ex) {
2832                 ex1 = ex;
2833                 ex1->ee_len = cpu_to_le16(iblock - ee_block);
2834                 ext4_ext_mark_uninitialized(ex1);
2835                 ex2 = &newex;
2836         }
2837         /* ex2: iblock to iblock + maxblocks-1 : initialised */
2838         ex2->ee_block = cpu_to_le32(iblock);
2839         ext4_ext_store_pblock(ex2, newblock);
2840         ex2->ee_len = cpu_to_le16(allocated);
2841         if (ex2 != ex)
2842                 goto insert;
2843         /*
2844          * New (initialized) extent starts from the first block
2845          * in the current extent. i.e., ex2 == ex
2846          * We have to see if it can be merged with the extent
2847          * on the left.
2848          */
2849         if (ex2 > EXT_FIRST_EXTENT(eh)) {
2850                 /*
2851                  * To merge left, pass "ex2 - 1" to try_to_merge(),
2852                  * since it merges towards right _only_.
2853                  */
2854                 ret = ext4_ext_try_to_merge(inode, path, ex2 - 1);
2855                 if (ret) {
2856                         err = ext4_ext_correct_indexes(handle, inode, path);
2857                         if (err)
2858                                 goto out;
2859                         depth = ext_depth(inode);
2860                         ex2--;
2861                 }
2862         }
2863         /*
2864          * Try to Merge towards right. This might be required
2865          * only when the whole extent is being written to.
2866          * i.e. ex2 == ex and ex3 == NULL.
2867          */
2868         if (!ex3) {
2869                 ret = ext4_ext_try_to_merge(inode, path, ex2);
2870                 if (ret) {
2871                         err = ext4_ext_correct_indexes(handle, inode, path);
2872                         if (err)
2873                                 goto out;
2874                 }
2875         }
2876         /* Mark modified extent as dirty */
2877         err = ext4_ext_dirty(handle, inode, path + depth);
2878         goto out;
2879 insert:
2880         err = ext4_ext_insert_extent(handle, inode, path, &newex, 0);
2881         if (err == -ENOSPC) {
2882                 err =  ext4_ext_zeroout(inode, &orig_ex);
2883                 if (err)
2884                         goto fix_extent_len;
2885                 /* update the extent length and mark as initialized */
2886                 ex->ee_block = orig_ex.ee_block;
2887                 ex->ee_len   = orig_ex.ee_len;
2888                 ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
2889                 ext4_ext_dirty(handle, inode, path + depth);
2890                 /* zero out the first half */
2891                 return allocated;
2892         } else if (err)
2893                 goto fix_extent_len;
2894 out:
2895         ext4_ext_show_leaf(inode, path);
2896         return err ? err : allocated;
2897
2898 fix_extent_len:
2899         ex->ee_block = orig_ex.ee_block;
2900         ex->ee_len   = orig_ex.ee_len;
2901         ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
2902         ext4_ext_mark_uninitialized(ex);
2903         ext4_ext_dirty(handle, inode, path + depth);
2904         return err;
2905 }
2906
2907 /*
2908  * This function is called by ext4_ext_get_blocks() from
2909  * ext4_get_blocks_dio_write() when DIO to write
2910  * to an uninitialized extent.
2911  *
2912  * Writing to an uninitized extent may result in splitting the uninitialized
2913  * extent into multiple /intialized unintialized extents (up to three)
2914  * There are three possibilities:
2915  *   a> There is no split required: Entire extent should be uninitialized
2916  *   b> Splits in two extents: Write is happening at either end of the extent
2917  *   c> Splits in three extents: Somone is writing in middle of the extent
2918  *
2919  * One of more index blocks maybe needed if the extent tree grow after
2920  * the unintialized extent split. To prevent ENOSPC occur at the IO
2921  * complete, we need to split the uninitialized extent before DIO submit
2922  * the IO. The uninitilized extent called at this time will be split
2923  * into three uninitialized extent(at most). After IO complete, the part
2924  * being filled will be convert to initialized by the end_io callback function
2925  * via ext4_convert_unwritten_extents().
2926  *
2927  * Returns the size of uninitialized extent to be written on success.
2928  */
2929 static int ext4_split_unwritten_extents(handle_t *handle,
2930                                         struct inode *inode,
2931                                         struct ext4_ext_path *path,
2932                                         ext4_lblk_t iblock,
2933                                         unsigned int max_blocks,
2934                                         int flags)
2935 {
2936         struct ext4_extent *ex, newex, orig_ex;
2937         struct ext4_extent *ex1 = NULL;
2938         struct ext4_extent *ex2 = NULL;
2939         struct ext4_extent *ex3 = NULL;
2940         struct ext4_extent_header *eh;
2941         ext4_lblk_t ee_block;
2942         unsigned int allocated, ee_len, depth;
2943         ext4_fsblk_t newblock;
2944         int err = 0;
2945
2946         ext_debug("ext4_split_unwritten_extents: inode %lu,"
2947                   "iblock %llu, max_blocks %u\n", inode->i_ino,
2948                   (unsigned long long)iblock, max_blocks);
2949         depth = ext_depth(inode);
2950         eh = path[depth].p_hdr;
2951         ex = path[depth].p_ext;
2952         ee_block = le32_to_cpu(ex->ee_block);
2953         ee_len = ext4_ext_get_actual_len(ex);
2954         allocated = ee_len - (iblock - ee_block);
2955         newblock = iblock - ee_block + ext_pblock(ex);
2956         ex2 = ex;
2957         orig_ex.ee_block = ex->ee_block;
2958         orig_ex.ee_len   = cpu_to_le16(ee_len);
2959         ext4_ext_store_pblock(&orig_ex, ext_pblock(ex));
2960
2961         /*
2962          * If the uninitialized extent begins at the same logical
2963          * block where the write begins, and the write completely
2964          * covers the extent, then we don't need to split it.
2965          */
2966         if ((iblock == ee_block) && (allocated <= max_blocks))
2967                 return allocated;
2968
2969         err = ext4_ext_get_access(handle, inode, path + depth);
2970         if (err)
2971                 goto out;
2972         /* ex1: ee_block to iblock - 1 : uninitialized */
2973         if (iblock > ee_block) {
2974                 ex1 = ex;
2975                 ex1->ee_len = cpu_to_le16(iblock - ee_block);
2976                 ext4_ext_mark_uninitialized(ex1);
2977                 ex2 = &newex;
2978         }
2979         /*
2980          * for sanity, update the length of the ex2 extent before
2981          * we insert ex3, if ex1 is NULL. This is to avoid temporary
2982          * overlap of blocks.
2983          */
2984         if (!ex1 && allocated > max_blocks)
2985                 ex2->ee_len = cpu_to_le16(max_blocks);
2986         /* ex3: to ee_block + ee_len : uninitialised */
2987         if (allocated > max_blocks) {
2988                 unsigned int newdepth;
2989                 ex3 = &newex;
2990                 ex3->ee_block = cpu_to_le32(iblock + max_blocks);
2991                 ext4_ext_store_pblock(ex3, newblock + max_blocks);
2992                 ex3->ee_len = cpu_to_le16(allocated - max_blocks);
2993                 ext4_ext_mark_uninitialized(ex3);
2994                 err = ext4_ext_insert_extent(handle, inode, path, ex3, flags);
2995                 if (err == -ENOSPC) {
2996                         err =  ext4_ext_zeroout(inode, &orig_ex);
2997                         if (err)
2998                                 goto fix_extent_len;
2999                         /* update the extent length and mark as initialized */
3000                         ex->ee_block = orig_ex.ee_block;
3001                         ex->ee_len   = orig_ex.ee_len;
3002                         ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
3003                         ext4_ext_dirty(handle, inode, path + depth);
3004                         /* zeroed the full extent */
3005                         /* blocks available from iblock */
3006                         return allocated;
3007
3008                 } else if (err)
3009                         goto fix_extent_len;
3010                 /*
3011                  * The depth, and hence eh & ex might change
3012                  * as part of the insert above.
3013                  */
3014                 newdepth = ext_depth(inode);
3015                 /*
3016                  * update the extent length after successful insert of the
3017                  * split extent
3018                  */
3019                 orig_ex.ee_len = cpu_to_le16(ee_len -
3020                                                 ext4_ext_get_actual_len(ex3));
3021                 depth = newdepth;
3022                 ext4_ext_drop_refs(path);
3023                 path = ext4_ext_find_extent(inode, iblock, path);
3024                 if (IS_ERR(path)) {
3025                         err = PTR_ERR(path);
3026                         goto out;
3027                 }
3028                 eh = path[depth].p_hdr;
3029                 ex = path[depth].p_ext;
3030                 if (ex2 != &newex)
3031                         ex2 = ex;
3032
3033                 err = ext4_ext_get_access(handle, inode, path + depth);
3034                 if (err)
3035                         goto out;
3036
3037                 allocated = max_blocks;
3038         }
3039         /*
3040          * If there was a change of depth as part of the
3041          * insertion of ex3 above, we need to update the length
3042          * of the ex1 extent again here
3043          */
3044         if (ex1 && ex1 != ex) {
3045                 ex1 = ex;
3046                 ex1->ee_len = cpu_to_le16(iblock - ee_block);
3047                 ext4_ext_mark_uninitialized(ex1);
3048                 ex2 = &newex;
3049         }
3050         /*
3051          * ex2: iblock to iblock + maxblocks-1 : to be direct IO written,
3052          * uninitialised still.
3053          */
3054         ex2->ee_block = cpu_to_le32(iblock);
3055         ext4_ext_store_pblock(ex2, newblock);
3056         ex2->ee_len = cpu_to_le16(allocated);
3057         ext4_ext_mark_uninitialized(ex2);
3058         if (ex2 != ex)
3059                 goto insert;
3060         /* Mark modified extent as dirty */
3061         err = ext4_ext_dirty(handle, inode, path + depth);
3062         ext_debug("out here\n");
3063         goto out;
3064 insert:
3065         err = ext4_ext_insert_extent(handle, inode, path, &newex, flags);
3066         if (err == -ENOSPC) {
3067                 err =  ext4_ext_zeroout(inode, &orig_ex);
3068                 if (err)
3069                         goto fix_extent_len;
3070                 /* update the extent length and mark as initialized */
3071                 ex->ee_block = orig_ex.ee_block;
3072                 ex->ee_len   = orig_ex.ee_len;
3073                 ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
3074                 ext4_ext_dirty(handle, inode, path + depth);
3075                 /* zero out the first half */
3076                 return allocated;
3077         } else if (err)
3078                 goto fix_extent_len;
3079 out:
3080         ext4_ext_show_leaf(inode, path);
3081         return err ? err : allocated;
3082
3083 fix_extent_len:
3084         ex->ee_block = orig_ex.ee_block;
3085         ex->ee_len   = orig_ex.ee_len;
3086         ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
3087         ext4_ext_mark_uninitialized(ex);
3088         ext4_ext_dirty(handle, inode, path + depth);
3089         return err;
3090 }
3091 static int ext4_convert_unwritten_extents_endio(handle_t *handle,
3092                                               struct inode *inode,
3093                                               struct ext4_ext_path *path)
3094 {
3095         struct ext4_extent *ex;
3096         struct ext4_extent_header *eh;
3097         int depth;
3098         int err = 0;
3099         int ret = 0;
3100
3101         depth = ext_depth(inode);
3102         eh = path[depth].p_hdr;
3103         ex = path[depth].p_ext;
3104
3105         err = ext4_ext_get_access(handle, inode, path + depth);
3106         if (err)
3107                 goto out;
3108         /* first mark the extent as initialized */
3109         ext4_ext_mark_initialized(ex);
3110
3111         /*
3112          * We have to see if it can be merged with the extent
3113          * on the left.
3114          */
3115         if (ex > EXT_FIRST_EXTENT(eh)) {
3116                 /*
3117                  * To merge left, pass "ex - 1" to try_to_merge(),
3118                  * since it merges towards right _only_.
3119                  */
3120                 ret = ext4_ext_try_to_merge(inode, path, ex - 1);
3121                 if (ret) {
3122                         err = ext4_ext_correct_indexes(handle, inode, path);
3123                         if (err)
3124                                 goto out;
3125                         depth = ext_depth(inode);
3126                         ex--;
3127                 }
3128         }
3129         /*
3130          * Try to Merge towards right.
3131          */
3132         ret = ext4_ext_try_to_merge(inode, path, ex);
3133         if (ret) {
3134                 err = ext4_ext_correct_indexes(handle, inode, path);
3135                 if (err)
3136                         goto out;
3137                 depth = ext_depth(inode);
3138         }
3139         /* Mark modified extent as dirty */
3140         err = ext4_ext_dirty(handle, inode, path + depth);
3141 out:
3142         ext4_ext_show_leaf(inode, path);
3143         return err;
3144 }
3145
3146 static void unmap_underlying_metadata_blocks(struct block_device *bdev,
3147                         sector_t block, int count)
3148 {
3149         int i;
3150         for (i = 0; i < count; i++)
3151                 unmap_underlying_metadata(bdev, block + i);
3152 }
3153
3154 static int
3155 ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
3156                         ext4_lblk_t iblock, unsigned int max_blocks,
3157                         struct ext4_ext_path *path, int flags,
3158                         unsigned int allocated, struct buffer_head *bh_result,
3159                         ext4_fsblk_t newblock)
3160 {
3161         int ret = 0;
3162         int err = 0;
3163         ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
3164
3165         ext_debug("ext4_ext_handle_uninitialized_extents: inode %lu, logical"
3166                   "block %llu, max_blocks %u, flags %d, allocated %u",
3167                   inode->i_ino, (unsigned long long)iblock, max_blocks,
3168                   flags, allocated);
3169         ext4_ext_show_leaf(inode, path);
3170
3171         /* get_block() before submit the IO, split the extent */
3172         if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
3173                 ret = ext4_split_unwritten_extents(handle,
3174                                                 inode, path, iblock,
3175                                                 max_blocks, flags);
3176                 /*
3177                  * Flag the inode(non aio case) or end_io struct (aio case)
3178                  * that this IO needs to convertion to written when IO is
3179                  * completed
3180                  */
3181                 if (io)
3182                         io->flag = EXT4_IO_UNWRITTEN;
3183                 else
3184                         ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
3185                 if (ext4_should_dioread_nolock(inode))
3186                         set_buffer_uninit(bh_result);
3187                 goto out;
3188         }
3189         /* IO end_io complete, convert the filled extent to written */
3190         if ((flags & EXT4_GET_BLOCKS_CONVERT)) {
3191                 ret = ext4_convert_unwritten_extents_endio(handle, inode,
3192                                                         path);
3193                 if (ret >= 0)
3194                         ext4_update_inode_fsync_trans(handle, inode, 1);
3195                 goto out2;
3196         }
3197         /* buffered IO case */
3198         /*
3199          * repeat fallocate creation request
3200          * we already have an unwritten extent
3201          */
3202         if (flags & EXT4_GET_BLOCKS_UNINIT_EXT)
3203                 goto map_out;
3204
3205         /* buffered READ or buffered write_begin() lookup */
3206         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
3207                 /*
3208                  * We have blocks reserved already.  We
3209                  * return allocated blocks so that delalloc
3210                  * won't do block reservation for us.  But
3211                  * the buffer head will be unmapped so that
3212                  * a read from the block returns 0s.
3213                  */
3214                 set_buffer_unwritten(bh_result);
3215                 goto out1;
3216         }
3217
3218         /* buffered write, writepage time, convert*/
3219         ret = ext4_ext_convert_to_initialized(handle, inode,
3220                                                 path, iblock,
3221                                                 max_blocks);
3222         if (ret >= 0)
3223                 ext4_update_inode_fsync_trans(handle, inode, 1);
3224 out:
3225         if (ret <= 0) {
3226                 err = ret;
3227                 goto out2;
3228         } else
3229                 allocated = ret;
3230         set_buffer_new(bh_result);
3231         /*
3232          * if we allocated more blocks than requested
3233          * we need to make sure we unmap the extra block
3234          * allocated. The actual needed block will get
3235          * unmapped later when we find the buffer_head marked
3236          * new.
3237          */
3238         if (allocated > max_blocks) {
3239                 unmap_underlying_metadata_blocks(inode->i_sb->s_bdev,
3240                                         newblock + max_blocks,
3241                                         allocated - max_blocks);
3242                 allocated = max_blocks;
3243         }
3244
3245         /*
3246          * If we have done fallocate with the offset that is already
3247          * delayed allocated, we would have block reservation
3248          * and quota reservation done in the delayed write path.
3249          * But fallocate would have already updated quota and block
3250          * count for this offset. So cancel these reservation
3251          */
3252         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
3253                 ext4_da_update_reserve_space(inode, allocated, 0);
3254
3255 map_out:
3256         set_buffer_mapped(bh_result);
3257 out1:
3258         if (allocated > max_blocks)
3259                 allocated = max_blocks;
3260         ext4_ext_show_leaf(inode, path);
3261         bh_result->b_bdev = inode->i_sb->s_bdev;
3262         bh_result->b_blocknr = newblock;
3263 out2:
3264         if (path) {
3265                 ext4_ext_drop_refs(path);
3266                 kfree(path);
3267         }
3268         return err ? err : allocated;
3269 }
3270 /*
3271  * Block allocation/map/preallocation routine for extents based files
3272  *
3273  *
3274  * Need to be called with
3275  * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system block
3276  * (ie, create is zero). Otherwise down_write(&EXT4_I(inode)->i_data_sem)
3277  *
3278  * return > 0, number of of blocks already mapped/allocated
3279  *          if create == 0 and these are pre-allocated blocks
3280  *              buffer head is unmapped
3281  *          otherwise blocks are mapped
3282  *
3283  * return = 0, if plain look up failed (blocks have not been allocated)
3284  *          buffer head is unmapped
3285  *
3286  * return < 0, error case.
3287  */
3288 int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
3289                         ext4_lblk_t iblock,
3290                         unsigned int max_blocks, struct buffer_head *bh_result,
3291                         int flags)
3292 {
3293         struct ext4_ext_path *path = NULL;
3294         struct ext4_extent_header *eh;
3295         struct ext4_extent newex, *ex, *last_ex;
3296         ext4_fsblk_t newblock;
3297         int err = 0, depth, ret, cache_type;
3298         unsigned int allocated = 0;
3299         struct ext4_allocation_request ar;
3300         ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
3301
3302         __clear_bit(BH_New, &bh_result->b_state);
3303         ext_debug("blocks %u/%u requested for inode %lu\n",
3304                         iblock, max_blocks, inode->i_ino);
3305
3306         /* check in cache */
3307         cache_type = ext4_ext_in_cache(inode, iblock, &newex);
3308         if (cache_type) {
3309                 if (cache_type == EXT4_EXT_CACHE_GAP) {
3310                         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
3311                                 /*
3312                                  * block isn't allocated yet and
3313                                  * user doesn't want to allocate it
3314                                  */
3315                                 goto out2;
3316                         }
3317                         /* we should allocate requested block */
3318                 } else if (cache_type == EXT4_EXT_CACHE_EXTENT) {
3319                         /* block is already allocated */
3320                         newblock = iblock
3321                                    - le32_to_cpu(newex.ee_block)
3322                                    + ext_pblock(&newex);
3323                         /* number of remaining blocks in the extent */
3324                         allocated = ext4_ext_get_actual_len(&newex) -
3325                                         (iblock - le32_to_cpu(newex.ee_block));
3326                         goto out;
3327                 } else {
3328                         BUG();
3329                 }
3330         }
3331
3332         /* find extent for this block */
3333         path = ext4_ext_find_extent(inode, iblock, NULL);
3334         if (IS_ERR(path)) {
3335                 err = PTR_ERR(path);
3336                 path = NULL;
3337                 goto out2;
3338         }
3339
3340         depth = ext_depth(inode);
3341
3342         /*
3343          * consistent leaf must not be empty;
3344          * this situation is possible, though, _during_ tree modification;
3345          * this is why assert can't be put in ext4_ext_find_extent()
3346          */
3347         if (unlikely(path[depth].p_ext == NULL && depth != 0)) {
3348                 EXT4_ERROR_INODE(inode, "bad extent address "
3349                                  "iblock: %d, depth: %d pblock %lld",
3350                                  iblock, depth, path[depth].p_block);
3351                 err = -EIO;
3352                 goto out2;
3353         }
3354         eh = path[depth].p_hdr;
3355
3356         ex = path[depth].p_ext;
3357         if (ex) {
3358                 ext4_lblk_t ee_block = le32_to_cpu(ex->ee_block);
3359                 ext4_fsblk_t ee_start = ext_pblock(ex);
3360                 unsigned short ee_len;
3361
3362                 /*
3363                  * Uninitialized extents are treated as holes, except that
3364                  * we split out initialized portions during a write.
3365                  */
3366                 ee_len = ext4_ext_get_actual_len(ex);
3367                 /* if found extent covers block, simply return it */
3368                 if (iblock >= ee_block && iblock < ee_block + ee_len) {
3369                         newblock = iblock - ee_block + ee_start;
3370                         /* number of remaining blocks in the extent */
3371                         allocated = ee_len - (iblock - ee_block);
3372                         ext_debug("%u fit into %u:%d -> %llu\n", iblock,
3373                                         ee_block, ee_len, newblock);
3374
3375                         /* Do not put uninitialized extent in the cache */
3376                         if (!ext4_ext_is_uninitialized(ex)) {
3377                                 ext4_ext_put_in_cache(inode, ee_block,
3378                                                         ee_len, ee_start,
3379                                                         EXT4_EXT_CACHE_EXTENT);
3380                                 goto out;
3381                         }
3382                         ret = ext4_ext_handle_uninitialized_extents(handle,
3383                                         inode, iblock, max_blocks, path,
3384                                         flags, allocated, bh_result, newblock);
3385                         return ret;
3386                 }
3387         }
3388
3389         /*
3390          * requested block isn't allocated yet;
3391          * we couldn't try to create block if create flag is zero
3392          */
3393         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
3394                 /*
3395                  * put just found gap into cache to speed up
3396                  * subsequent requests
3397                  */
3398                 ext4_ext_put_gap_in_cache(inode, path, iblock);
3399                 goto out2;
3400         }
3401         /*
3402          * Okay, we need to do block allocation.
3403          */
3404
3405         /* find neighbour allocated blocks */
3406         ar.lleft = iblock;
3407         err = ext4_ext_search_left(inode, path, &ar.lleft, &ar.pleft);
3408         if (err)
3409                 goto out2;
3410         ar.lright = iblock;
3411         err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright);
3412         if (err)
3413                 goto out2;
3414
3415         /*
3416          * See if request is beyond maximum number of blocks we can have in
3417          * a single extent. For an initialized extent this limit is
3418          * EXT_INIT_MAX_LEN and for an uninitialized extent this limit is
3419          * EXT_UNINIT_MAX_LEN.
3420          */
3421         if (max_blocks > EXT_INIT_MAX_LEN &&
3422             !(flags & EXT4_GET_BLOCKS_UNINIT_EXT))
3423                 max_blocks = EXT_INIT_MAX_LEN;
3424         else if (max_blocks > EXT_UNINIT_MAX_LEN &&
3425                  (flags & EXT4_GET_BLOCKS_UNINIT_EXT))
3426                 max_blocks = EXT_UNINIT_MAX_LEN;
3427
3428         /* Check if we can really insert (iblock)::(iblock+max_blocks) extent */
3429         newex.ee_block = cpu_to_le32(iblock);
3430         newex.ee_len = cpu_to_le16(max_blocks);
3431         err = ext4_ext_check_overlap(inode, &newex, path);
3432         if (err)
3433                 allocated = ext4_ext_get_actual_len(&newex);
3434         else
3435                 allocated = max_blocks;
3436
3437         /* allocate new block */
3438         ar.inode = inode;
3439         ar.goal = ext4_ext_find_goal(inode, path, iblock);
3440         ar.logical = iblock;
3441         ar.len = allocated;
3442         if (S_ISREG(inode->i_mode))
3443                 ar.flags = EXT4_MB_HINT_DATA;
3444         else
3445                 /* disable in-core preallocation for non-regular files */
3446                 ar.flags = 0;
3447         newblock = ext4_mb_new_blocks(handle, &ar, &err);
3448         if (!newblock)
3449                 goto out2;
3450         ext_debug("allocate new block: goal %llu, found %llu/%u\n",
3451                   ar.goal, newblock, allocated);
3452
3453         /* try to insert new extent into found leaf and return */
3454         ext4_ext_store_pblock(&newex, newblock);
3455         newex.ee_len = cpu_to_le16(ar.len);
3456         /* Mark uninitialized */
3457         if (flags & EXT4_GET_BLOCKS_UNINIT_EXT){
3458                 ext4_ext_mark_uninitialized(&newex);
3459                 /*
3460                  * io_end structure was created for every IO write to an
3461                  * uninitialized extent. To avoid unecessary conversion,
3462                  * here we flag the IO that really needs the conversion.
3463                  * For non asycn direct IO case, flag the inode state
3464                  * that we need to perform convertion when IO is done.
3465                  */
3466                 if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
3467                         if (io)
3468                                 io->flag = EXT4_IO_UNWRITTEN;
3469                         else
3470                                 ext4_set_inode_state(inode,
3471                                                      EXT4_STATE_DIO_UNWRITTEN);
3472                 }
3473                 if (ext4_should_dioread_nolock(inode))
3474                         set_buffer_uninit(bh_result);
3475         }
3476
3477         if (unlikely(EXT4_I(inode)->i_flags & EXT4_EOFBLOCKS_FL)) {
3478                 if (unlikely(!eh->eh_entries)) {
3479                         EXT4_ERROR_INODE(inode,
3480                                          "eh->eh_entries == 0 ee_block %d",
3481                                          ex->ee_block);
3482                         err = -EIO;
3483                         goto out2;
3484                 }
3485                 last_ex = EXT_LAST_EXTENT(eh);
3486                 if (iblock + ar.len > le32_to_cpu(last_ex->ee_block)
3487                     + ext4_ext_get_actual_len(last_ex))
3488                         EXT4_I(inode)->i_flags &= ~EXT4_EOFBLOCKS_FL;
3489         }
3490         err = ext4_ext_insert_extent(handle, inode, path, &newex, flags);
3491         if (err) {
3492                 /* free data blocks we just allocated */
3493                 /* not a good idea to call discard here directly,
3494                  * but otherwise we'd need to call it every free() */
3495                 ext4_discard_preallocations(inode);
3496                 ext4_free_blocks(handle, inode, 0, ext_pblock(&newex),
3497                                  ext4_ext_get_actual_len(&newex), 0);
3498                 goto out2;
3499         }
3500
3501         /* previous routine could use block we allocated */
3502         newblock = ext_pblock(&newex);
3503         allocated = ext4_ext_get_actual_len(&newex);
3504         if (allocated > max_blocks)
3505                 allocated = max_blocks;
3506         set_buffer_new(bh_result);
3507
3508         /*
3509          * Update reserved blocks/metadata blocks after successful
3510          * block allocation which had been deferred till now.
3511          */
3512         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
3513                 ext4_da_update_reserve_space(inode, allocated, 1);
3514
3515         /*
3516          * Cache the extent and update transaction to commit on fdatasync only
3517          * when it is _not_ an uninitialized extent.
3518          */
3519         if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0) {
3520                 ext4_ext_put_in_cache(inode, iblock, allocated, newblock,
3521                                                 EXT4_EXT_CACHE_EXTENT);
3522                 ext4_update_inode_fsync_trans(handle, inode, 1);
3523         } else
3524                 ext4_update_inode_fsync_trans(handle, inode, 0);
3525 out:
3526         if (allocated > max_blocks)
3527                 allocated = max_blocks;
3528         ext4_ext_show_leaf(inode, path);
3529         set_buffer_mapped(bh_result);
3530         bh_result->b_bdev = inode->i_sb->s_bdev;
3531         bh_result->b_blocknr = newblock;
3532 out2:
3533         if (path) {
3534                 ext4_ext_drop_refs(path);
3535                 kfree(path);
3536         }
3537         return err ? err : allocated;
3538 }
3539
3540 void ext4_ext_truncate(struct inode *inode)
3541 {
3542         struct address_space *mapping = inode->i_mapping;
3543         struct super_block *sb = inode->i_sb;
3544         ext4_lblk_t last_block;
3545         handle_t *handle;
3546         int err = 0;
3547
3548         /*
3549          * probably first extent we're gonna free will be last in block
3550          */
3551         err = ext4_writepage_trans_blocks(inode);
3552         handle = ext4_journal_start(inode, err);
3553         if (IS_ERR(handle))
3554                 return;
3555
3556         if (inode->i_size & (sb->s_blocksize - 1))
3557                 ext4_block_truncate_page(handle, mapping, inode->i_size);
3558
3559         if (ext4_orphan_add(handle, inode))
3560                 goto out_stop;
3561
3562         down_write(&EXT4_I(inode)->i_data_sem);
3563         ext4_ext_invalidate_cache(inode);
3564
3565         ext4_discard_preallocations(inode);
3566
3567         /*
3568          * TODO: optimization is possible here.
3569          * Probably we need not scan at all,
3570          * because page truncation is enough.
3571          */
3572
3573         /* we have to know where to truncate from in crash case */
3574         EXT4_I(inode)->i_disksize = inode->i_size;
3575         ext4_mark_inode_dirty(handle, inode);
3576
3577         last_block = (inode->i_size + sb->s_blocksize - 1)
3578                         >> EXT4_BLOCK_SIZE_BITS(sb);
3579         err = ext4_ext_remove_space(inode, last_block);
3580
3581         /* In a multi-transaction truncate, we only make the final
3582          * transaction synchronous.
3583          */
3584         if (IS_SYNC(inode))
3585                 ext4_handle_sync(handle);
3586
3587 out_stop:
3588         up_write(&EXT4_I(inode)->i_data_sem);
3589         /*
3590          * If this was a simple ftruncate() and the file will remain alive,
3591          * then we need to clear up the orphan record which we created above.
3592          * However, if this was a real unlink then we were called by
3593          * ext4_delete_inode(), and we allow that function to clean up the
3594          * orphan info for us.
3595          */
3596         if (inode->i_nlink)
3597                 ext4_orphan_del(handle, inode);
3598
3599         inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
3600         ext4_mark_inode_dirty(handle, inode);
3601         ext4_journal_stop(handle);
3602 }
3603
3604 static void ext4_falloc_update_inode(struct inode *inode,
3605                                 int mode, loff_t new_size, int update_ctime)
3606 {
3607         struct timespec now;
3608
3609         if (update_ctime) {
3610                 now = current_fs_time(inode->i_sb);
3611                 if (!timespec_equal(&inode->i_ctime, &now))
3612                         inode->i_ctime = now;
3613         }
3614         /*
3615          * Update only when preallocation was requested beyond
3616          * the file size.
3617          */
3618         if (!(mode & FALLOC_FL_KEEP_SIZE)) {
3619                 if (new_size > i_size_read(inode))
3620                         i_size_write(inode, new_size);
3621                 if (new_size > EXT4_I(inode)->i_disksize)
3622                         ext4_update_i_disksize(inode, new_size);
3623         } else {
3624                 /*
3625                  * Mark that we allocate beyond EOF so the subsequent truncate
3626                  * can proceed even if the new size is the same as i_size.
3627                  */
3628                 if (new_size > i_size_read(inode))
3629                         EXT4_I(inode)->i_flags |= EXT4_EOFBLOCKS_FL;
3630         }
3631
3632 }
3633
3634 /*
3635  * preallocate space for a file. This implements ext4's fallocate inode
3636  * operation, which gets called from sys_fallocate system call.
3637  * For block-mapped files, posix_fallocate should fall back to the method
3638  * of writing zeroes to the required new blocks (the same behavior which is
3639  * expected for file systems which do not support fallocate() system call).
3640  */
3641 long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
3642 {
3643         handle_t *handle;
3644         ext4_lblk_t block;
3645         loff_t new_size;
3646         unsigned int max_blocks;
3647         int ret = 0;
3648         int ret2 = 0;
3649         int retries = 0;
3650         struct buffer_head map_bh;
3651         unsigned int credits, blkbits = inode->i_blkbits;
3652
3653         /*
3654          * currently supporting (pre)allocate mode for extent-based
3655          * files _only_
3656          */
3657         if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
3658                 return -EOPNOTSUPP;
3659
3660         /* preallocation to directories is currently not supported */
3661         if (S_ISDIR(inode->i_mode))
3662                 return -ENODEV;
3663
3664         block = offset >> blkbits;
3665         /*
3666          * We can't just convert len to max_blocks because
3667          * If blocksize = 4096 offset = 3072 and len = 2048
3668          */
3669         max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
3670                                                         - block;
3671         /*
3672          * credits to insert 1 extent into extent tree
3673          */
3674         credits = ext4_chunk_trans_blocks(inode, max_blocks);
3675         mutex_lock(&inode->i_mutex);
3676 retry:
3677         while (ret >= 0 && ret < max_blocks) {
3678                 block = block + ret;
3679                 max_blocks = max_blocks - ret;
3680                 handle = ext4_journal_start(inode, credits);
3681                 if (IS_ERR(handle)) {
3682                         ret = PTR_ERR(handle);
3683                         break;
3684                 }
3685                 map_bh.b_state = 0;
3686                 ret = ext4_get_blocks(handle, inode, block,
3687                                       max_blocks, &map_bh,
3688                                       EXT4_GET_BLOCKS_CREATE_UNINIT_EXT);
3689                 if (ret <= 0) {
3690 #ifdef EXT4FS_DEBUG
3691                         WARN_ON(ret <= 0);
3692                         printk(KERN_ERR "%s: ext4_ext_get_blocks "
3693                                     "returned error inode#%lu, block=%u, "
3694                                     "max_blocks=%u", __func__,
3695                                     inode->i_ino, block, max_blocks);
3696 #endif
3697                         ext4_mark_inode_dirty(handle, inode);
3698                         ret2 = ext4_journal_stop(handle);
3699                         break;
3700                 }
3701                 if ((block + ret) >= (EXT4_BLOCK_ALIGN(offset + len,
3702                                                 blkbits) >> blkbits))
3703                         new_size = offset + len;
3704                 else
3705                         new_size = (block + ret) << blkbits;
3706
3707                 ext4_falloc_update_inode(inode, mode, new_size,
3708                                                 buffer_new(&map_bh));
3709                 ext4_mark_inode_dirty(handle, inode);
3710                 ret2 = ext4_journal_stop(handle);
3711                 if (ret2)
3712                         break;
3713         }
3714         if (ret == -ENOSPC &&
3715                         ext4_should_retry_alloc(inode->i_sb, &retries)) {
3716                 ret = 0;
3717                 goto retry;
3718         }
3719         mutex_unlock(&inode->i_mutex);
3720         return ret > 0 ? ret2 : ret;
3721 }
3722
3723 /*
3724  * This function convert a range of blocks to written extents
3725  * The caller of this function will pass the start offset and the size.
3726  * all unwritten extents within this range will be converted to
3727  * written extents.
3728  *
3729  * This function is called from the direct IO end io call back
3730  * function, to convert the fallocated extents after IO is completed.
3731  * Returns 0 on success.
3732  */
3733 int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
3734                                     ssize_t len)
3735 {
3736         handle_t *handle;
3737         ext4_lblk_t block;
3738         unsigned int max_blocks;
3739         int ret = 0;
3740         int ret2 = 0;
3741         struct buffer_head map_bh;
3742         unsigned int credits, blkbits = inode->i_blkbits;
3743
3744         block = offset >> blkbits;
3745         /*
3746          * We can't just convert len to max_blocks because
3747          * If blocksize = 4096 offset = 3072 and len = 2048
3748          */
3749         max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
3750                                                         - block;
3751         /*
3752          * credits to insert 1 extent into extent tree
3753          */
3754         credits = ext4_chunk_trans_blocks(inode, max_blocks);
3755         while (ret >= 0 && ret < max_blocks) {
3756                 block = block + ret;
3757                 max_blocks = max_blocks - ret;
3758                 handle = ext4_journal_start(inode, credits);
3759                 if (IS_ERR(handle)) {
3760                         ret = PTR_ERR(handle);
3761                         break;
3762                 }
3763                 map_bh.b_state = 0;
3764                 ret = ext4_get_blocks(handle, inode, block,
3765                                       max_blocks, &map_bh,
3766                                       EXT4_GET_BLOCKS_IO_CONVERT_EXT);
3767                 if (ret <= 0) {
3768                         WARN_ON(ret <= 0);
3769                         printk(KERN_ERR "%s: ext4_ext_get_blocks "
3770                                     "returned error inode#%lu, block=%u, "
3771                                     "max_blocks=%u", __func__,
3772                                     inode->i_ino, block, max_blocks);
3773                 }
3774                 ext4_mark_inode_dirty(handle, inode);
3775                 ret2 = ext4_journal_stop(handle);
3776                 if (ret <= 0 || ret2 )
3777                         break;
3778         }
3779         return ret > 0 ? ret2 : ret;
3780 }
3781 /*
3782  * Callback function called for each extent to gather FIEMAP information.
3783  */
3784 static int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path,
3785                        struct ext4_ext_cache *newex, struct ext4_extent *ex,
3786                        void *data)
3787 {
3788         struct fiemap_extent_info *fieinfo = data;
3789         unsigned char blksize_bits = inode->i_sb->s_blocksize_bits;
3790         __u64   logical;
3791         __u64   physical;
3792         __u64   length;
3793         __u32   flags = 0;
3794         int     error;
3795
3796         logical =  (__u64)newex->ec_block << blksize_bits;
3797
3798         if (newex->ec_type == EXT4_EXT_CACHE_GAP) {
3799                 pgoff_t offset;
3800                 struct page *page;
3801                 struct buffer_head *bh = NULL;
3802
3803                 offset = logical >> PAGE_SHIFT;
3804                 page = find_get_page(inode->i_mapping, offset);
3805                 if (!page || !page_has_buffers(page))
3806                         return EXT_CONTINUE;
3807
3808                 bh = page_buffers(page);
3809
3810                 if (!bh)
3811                         return EXT_CONTINUE;
3812
3813                 if (buffer_delay(bh)) {
3814                         flags |= FIEMAP_EXTENT_DELALLOC;
3815                         page_cache_release(page);
3816                 } else {
3817                         page_cache_release(page);
3818                         return EXT_CONTINUE;
3819                 }
3820         }
3821
3822         physical = (__u64)newex->ec_start << blksize_bits;
3823         length =   (__u64)newex->ec_len << blksize_bits;
3824
3825         if (ex && ext4_ext_is_uninitialized(ex))
3826                 flags |= FIEMAP_EXTENT_UNWRITTEN;
3827
3828         /*
3829          * If this extent reaches EXT_MAX_BLOCK, it must be last.
3830          *
3831          * Or if ext4_ext_next_allocated_block is EXT_MAX_BLOCK,
3832          * this also indicates no more allocated blocks.
3833          *
3834          * XXX this might miss a single-block extent at EXT_MAX_BLOCK
3835          */
3836         if (ext4_ext_next_allocated_block(path) == EXT_MAX_BLOCK ||
3837             newex->ec_block + newex->ec_len - 1 == EXT_MAX_BLOCK) {
3838                 loff_t size = i_size_read(inode);
3839                 loff_t bs = EXT4_BLOCK_SIZE(inode->i_sb);
3840
3841                 flags |= FIEMAP_EXTENT_LAST;
3842                 if ((flags & FIEMAP_EXTENT_DELALLOC) &&
3843                     logical+length > size)
3844                         length = (size - logical + bs - 1) & ~(bs-1);
3845         }
3846
3847         error = fiemap_fill_next_extent(fieinfo, logical, physical,
3848                                         length, flags);
3849         if (error < 0)
3850                 return error;
3851         if (error == 1)
3852                 return EXT_BREAK;
3853
3854         return EXT_CONTINUE;
3855 }
3856
3857 /* fiemap flags we can handle specified here */
3858 #define EXT4_FIEMAP_FLAGS       (FIEMAP_FLAG_SYNC|FIEMAP_FLAG_XATTR)
3859
3860 static int ext4_xattr_fiemap(struct inode *inode,
3861                                 struct fiemap_extent_info *fieinfo)
3862 {
3863         __u64 physical = 0;
3864         __u64 length;
3865         __u32 flags = FIEMAP_EXTENT_LAST;
3866         int blockbits = inode->i_sb->s_blocksize_bits;
3867         int error = 0;
3868
3869         /* in-inode? */
3870         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
3871                 struct ext4_iloc iloc;
3872                 int offset;     /* offset of xattr in inode */
3873
3874                 error = ext4_get_inode_loc(inode, &iloc);
3875                 if (error)
3876                         return error;
3877                 physical = iloc.bh->b_blocknr << blockbits;
3878                 offset = EXT4_GOOD_OLD_INODE_SIZE +
3879                                 EXT4_I(inode)->i_extra_isize;
3880                 physical += offset;
3881                 length = EXT4_SB(inode->i_sb)->s_inode_size - offset;
3882                 flags |= FIEMAP_EXTENT_DATA_INLINE;
3883         } else { /* external block */
3884                 physical = EXT4_I(inode)->i_file_acl << blockbits;
3885                 length = inode->i_sb->s_blocksize;
3886         }
3887
3888         if (physical)
3889                 error = fiemap_fill_next_extent(fieinfo, 0, physical,
3890                                                 length, flags);
3891         return (error < 0 ? error : 0);
3892 }
3893
3894 int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
3895                 __u64 start, __u64 len)
3896 {
3897         ext4_lblk_t start_blk;
3898         int error = 0;
3899
3900         /* fallback to generic here if not in extents fmt */
3901         if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
3902                 return generic_block_fiemap(inode, fieinfo, start, len,
3903                         ext4_get_block);
3904
3905         if (fiemap_check_flags(fieinfo, EXT4_FIEMAP_FLAGS))
3906                 return -EBADR;
3907
3908         if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) {
3909                 error = ext4_xattr_fiemap(inode, fieinfo);
3910         } else {
3911                 ext4_lblk_t len_blks;
3912                 __u64 last_blk;
3913
3914                 start_blk = start >> inode->i_sb->s_blocksize_bits;
3915                 last_blk = (start + len - 1) >> inode->i_sb->s_blocksize_bits;
3916                 if (last_blk >= EXT_MAX_BLOCK)
3917                         last_blk = EXT_MAX_BLOCK-1;
3918                 len_blks = ((ext4_lblk_t) last_blk) - start_blk + 1;
3919
3920                 /*
3921                  * Walk the extent tree gathering extent information.
3922                  * ext4_ext_fiemap_cb will push extents back to user.
3923                  */
3924                 error = ext4_ext_walk_space(inode, start_blk, len_blks,
3925                                           ext4_ext_fiemap_cb, fieinfo);
3926         }
3927
3928         return error;
3929 }
3930