fs/ext4/migrate.c

   1 /*
   2  * Copyright IBM Corporation, 2007
   3  * Author Aneesh Kumar K.V <[email protected]>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of version 2.1 of the GNU Lesser General Public License
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  12  *
  13  */
  14
  15 #include <linux/slab.h>
  16 #include "ext4_jbd2.h"
  17 #include "ext4_extents.h"
  18
  19 /*
  20  * The contiguous blocks details which can be
  21  * represented by a single extent
  22  */
  23 struct migrate_struct {
  24         ext4_lblk_t first_block, last_block, curr_block;
  25         ext4_fsblk_t first_pblock, last_pblock;
  26 };
  27
  28 static int finish_range(handle_t *handle, struct inode *inode,
  29                                 struct migrate_struct *lb)
  30
  31 {
  32         int retval = 0, needed;
  33         struct ext4_extent newext;
  34         struct ext4_ext_path *path;
  35         if (lb->first_pblock == 0)
  36                 return 0;
  37
  38         /* Add the extent to temp inode*/
  39         newext.ee_block = cpu_to_le32(lb->first_block);
  40         newext.ee_len   = cpu_to_le16(lb->last_block - lb->first_block + 1);
  41         ext4_ext_store_pblock(&newext, lb->first_pblock);
  42         /* Locking only for convinience since we are operating on temp inode */
  43         down_write(&EXT4_I(inode)->i_data_sem);
  44         path = ext4_ext_find_extent(inode, lb->first_block, NULL, 0);
  45
  46         if (IS_ERR(path)) {
  47                 retval = PTR_ERR(path);
  48                 path = NULL;
  49                 goto err_out;
  50         }
  51
  52         /*
  53          * Calculate the credit needed to inserting this extent
  54          * Since we are doing this in loop we may accumalate extra
  55          * credit. But below we try to not accumalate too much
  56          * of them by restarting the journal.
  57          */
  58         needed = ext4_ext_calc_credits_for_single_extent(inode,
  59                     lb->last_block - lb->first_block + 1, path);
  60
  61         /*
  62          * Make sure the credit we accumalated is not really high
  63          */
  64         if (needed && ext4_handle_has_enough_credits(handle,
  65                                                 EXT4_RESERVE_TRANS_BLOCKS)) {
  66                 up_write((&EXT4_I(inode)->i_data_sem));
  67                 retval = ext4_journal_restart(handle, needed);
  68                 down_write((&EXT4_I(inode)->i_data_sem));
  69                 if (retval)
  70                         goto err_out;
  71         } else if (needed) {
  72                 retval = ext4_journal_extend(handle, needed);
  73                 if (retval) {
  74                         /*
  75                          * IF not able to extend the journal restart the journal
  76                          */
  77                         up_write((&EXT4_I(inode)->i_data_sem));
  78                         retval = ext4_journal_restart(handle, needed);
  79                         down_write((&EXT4_I(inode)->i_data_sem));
  80                         if (retval)
  81                                 goto err_out;
  82                 }
  83         }
  84         retval = ext4_ext_insert_extent(handle, inode, path, &newext, 0);
  85 err_out:
  86         up_write((&EXT4_I(inode)->i_data_sem));
  87         if (path) {
  88                 ext4_ext_drop_refs(path);
  89                 kfree(path);
  90         }
  91         lb->first_pblock = 0;
  92         return retval;
  93 }
  94
  95 static int update_extent_range(handle_t *handle, struct inode *inode,
  96                                ext4_fsblk_t pblock, struct migrate_struct *lb)
  97 {
  98         int retval;
  99         /*
 100          * See if we can add on to the existing range (if it exists)
 101          */
 102         if (lb->first_pblock &&
 103                 (lb->last_pblock+1 == pblock) &&
 104                 (lb->last_block+1 == lb->curr_block)) {
 105                 lb->last_pblock = pblock;
 106                 lb->last_block = lb->curr_block;
 107                 lb->curr_block++;
 108                 return 0;
 109         }
 110         /*
 111          * Start a new range.
 112          */
 113         retval = finish_range(handle, inode, lb);
 114         lb->first_pblock = lb->last_pblock = pblock;
 115         lb->first_block = lb->last_block = lb->curr_block;
 116         lb->curr_block++;
 117         return retval;
 118 }
 119
 120 static int update_ind_extent_range(handle_t *handle, struct inode *inode,
 121                                    ext4_fsblk_t pblock,
 122                                    struct migrate_struct *lb)
 123 {
 124         struct buffer_head *bh;
 125         __le32 *i_data;
 126         int i, retval = 0;
 127         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 128
 129         bh = sb_bread(inode->i_sb, pblock);
 130         if (!bh)
 131                 return -EIO;
 132
 133         i_data = (__le32 *)bh->b_data;
 134         for (i = 0; i < max_entries; i++) {
 135                 if (i_data[i]) {
 136                         retval = update_extent_range(handle, inode,
 137                                                 le32_to_cpu(i_data[i]), lb);
 138                         if (retval)
 139                                 break;
 140                 } else {
 141                         lb->curr_block++;
 142                 }
 143         }
 144         put_bh(bh);
 145         return retval;
 146
 147 }
 148
 149 static int update_dind_extent_range(handle_t *handle, struct inode *inode,
 150                                     ext4_fsblk_t pblock,
 151                                     struct migrate_struct *lb)
 152 {
 153         struct buffer_head *bh;
 154         __le32 *i_data;
 155         int i, retval = 0;
 156         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 157
 158         bh = sb_bread(inode->i_sb, pblock);
 159         if (!bh)
 160                 return -EIO;
 161
 162         i_data = (__le32 *)bh->b_data;
 163         for (i = 0; i < max_entries; i++) {
 164                 if (i_data[i]) {
 165                         retval = update_ind_extent_range(handle, inode,
 166                                                 le32_to_cpu(i_data[i]), lb);
 167                         if (retval)
 168                                 break;
 169                 } else {
 170                         /* Only update the file block number */
 171                         lb->curr_block += max_entries;
 172                 }
 173         }
 174         put_bh(bh);
 175         return retval;
 176
 177 }
 178
 179 static int update_tind_extent_range(handle_t *handle, struct inode *inode,
 180                                     ext4_fsblk_t pblock,
 181                                     struct migrate_struct *lb)
 182 {
 183         struct buffer_head *bh;
 184         __le32 *i_data;
 185         int i, retval = 0;
 186         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 187
 188         bh = sb_bread(inode->i_sb, pblock);
 189         if (!bh)
 190                 return -EIO;
 191
 192         i_data = (__le32 *)bh->b_data;
 193         for (i = 0; i < max_entries; i++) {
 194                 if (i_data[i]) {
 195                         retval = update_dind_extent_range(handle, inode,
 196                                                 le32_to_cpu(i_data[i]), lb);
 197                         if (retval)
 198                                 break;
 199                 } else {
 200                         /* Only update the file block number */
 201                         lb->curr_block += max_entries * max_entries;
 202                 }
 203         }
 204         put_bh(bh);
 205         return retval;
 206
 207 }
 208
 209 static int extend_credit_for_blkdel(handle_t *handle, struct inode *inode)
 210 {
 211         int retval = 0, needed;
 212
 213         if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
 214                 return 0;
 215         /*
 216          * We are freeing a blocks. During this we touch
 217          * superblock, group descriptor and block bitmap.
 218          * So allocate a credit of 3. We may update
 219          * quota (user and group).
 220          */
 221         needed = 3 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);
 222
 223         if (ext4_journal_extend(handle, needed) != 0)
 224                 retval = ext4_journal_restart(handle, needed);
 225
 226         return retval;
 227 }
 228
 229 static int free_dind_blocks(handle_t *handle,
 230                                 struct inode *inode, __le32 i_data)
 231 {
 232         int i;
 233         __le32 *tmp_idata;
 234         struct buffer_head *bh;
 235         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 236
 237         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 238         if (!bh)
 239                 return -EIO;
 240
 241         tmp_idata = (__le32 *)bh->b_data;
 242         for (i = 0; i < max_entries; i++) {
 243                 if (tmp_idata[i]) {
 244                         extend_credit_for_blkdel(handle, inode);
 245                         ext4_free_blocks(handle, inode, NULL,
 246                                          le32_to_cpu(tmp_idata[i]), 1,
 247                                          EXT4_FREE_BLOCKS_METADATA |
 248                                          EXT4_FREE_BLOCKS_FORGET);
 249                 }
 250         }
 251         put_bh(bh);
 252         extend_credit_for_blkdel(handle, inode);
 253         ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
 254                          EXT4_FREE_BLOCKS_METADATA |
 255                          EXT4_FREE_BLOCKS_FORGET);
 256         return 0;
 257 }
 258
 259 static int free_tind_blocks(handle_t *handle,
 260                                 struct inode *inode, __le32 i_data)
 261 {
 262         int i, retval = 0;
 263         __le32 *tmp_idata;
 264         struct buffer_head *bh;
 265         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 266
 267         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 268         if (!bh)
 269                 return -EIO;
 270
 271         tmp_idata = (__le32 *)bh->b_data;
 272         for (i = 0; i < max_entries; i++) {
 273                 if (tmp_idata[i]) {
 274                         retval = free_dind_blocks(handle,
 275                                         inode, tmp_idata[i]);
 276                         if (retval) {
 277                                 put_bh(bh);
 278                                 return retval;
 279                         }
 280                 }
 281         }
 282         put_bh(bh);
 283         extend_credit_for_blkdel(handle, inode);
 284         ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
 285                          EXT4_FREE_BLOCKS_METADATA |
 286                          EXT4_FREE_BLOCKS_FORGET);
 287         return 0;
 288 }
 289
 290 static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
 291 {
 292         int retval;
 293
 294         /* ei->i_data[EXT4_IND_BLOCK] */
 295         if (i_data[0]) {
 296                 extend_credit_for_blkdel(handle, inode);
 297                 ext4_free_blocks(handle, inode, NULL,
 298                                 le32_to_cpu(i_data[0]), 1,
 299                                  EXT4_FREE_BLOCKS_METADATA |
 300                                  EXT4_FREE_BLOCKS_FORGET);
 301         }
 302
 303         /* ei->i_data[EXT4_DIND_BLOCK] */
 304         if (i_data[1]) {
 305                 retval = free_dind_blocks(handle, inode, i_data[1]);
 306                 if (retval)
 307                         return retval;
 308         }
 309
 310         /* ei->i_data[EXT4_TIND_BLOCK] */
 311         if (i_data[2]) {
 312                 retval = free_tind_blocks(handle, inode, i_data[2]);
 313                 if (retval)
 314                         return retval;
 315         }
 316         return 0;
 317 }
 318
 319 static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
 320                                                 struct inode *tmp_inode)
 321 {
 322         int retval;
 323         __le32  i_data[3];
 324         struct ext4_inode_info *ei = EXT4_I(inode);
 325         struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);
 326
 327         /*
 328          * One credit accounted for writing the
 329          * i_data field of the original inode
 330          */
 331         retval = ext4_journal_extend(handle, 1);
 332         if (retval) {
 333                 retval = ext4_journal_restart(handle, 1);
 334                 if (retval)
 335                         goto err_out;
 336         }
 337
 338         i_data[0] = ei->i_data[EXT4_IND_BLOCK];
 339         i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
 340         i_data[2] = ei->i_data[EXT4_TIND_BLOCK];
 341
 342         down_write(&EXT4_I(inode)->i_data_sem);
 343         /*
 344          * if EXT4_STATE_EXT_MIGRATE is cleared a block allocation
 345          * happened after we started the migrate. We need to
 346          * fail the migrate
 347          */
 348         if (!ext4_test_inode_state(inode, EXT4_STATE_EXT_MIGRATE)) {
 349                 retval = -EAGAIN;
 350                 up_write(&EXT4_I(inode)->i_data_sem);
 351                 goto err_out;
 352         } else
 353                 ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 354         /*
 355          * We have the extent map build with the tmp inode.
 356          * Now copy the i_data across
 357          */
 358         ext4_set_inode_flag(inode, EXT4_INODE_EXTENTS);
 359         memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));
 360
 361         /*
 362          * Update i_blocks with the new blocks that got
 363          * allocated while adding extents for extent index
 364          * blocks.
 365          *
 366          * While converting to extents we need not
 367          * update the orignal inode i_blocks for extent blocks
 368          * via quota APIs. The quota update happened via tmp_inode already.
 369          */
 370         spin_lock(&inode->i_lock);
 371         inode->i_blocks += tmp_inode->i_blocks;
 372         spin_unlock(&inode->i_lock);
 373         up_write(&EXT4_I(inode)->i_data_sem);
 374
 375         /*
 376          * We mark the inode dirty after, because we decrement the
 377          * i_blocks when freeing the indirect meta-data blocks
 378          */
 379         retval = free_ind_block(handle, inode, i_data);
 380         ext4_mark_inode_dirty(handle, inode);
 381
 382 err_out:
 383         return retval;
 384 }
 385
 386 static int free_ext_idx(handle_t *handle, struct inode *inode,
 387                                         struct ext4_extent_idx *ix)
 388 {
 389         int i, retval = 0;
 390         ext4_fsblk_t block;
 391         struct buffer_head *bh;
 392         struct ext4_extent_header *eh;
 393
 394         block = ext4_idx_pblock(ix);
 395         bh = sb_bread(inode->i_sb, block);
 396         if (!bh)
 397                 return -EIO;
 398
 399         eh = (struct ext4_extent_header *)bh->b_data;
 400         if (eh->eh_depth != 0) {
 401                 ix = EXT_FIRST_INDEX(eh);
 402                 for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 403                         retval = free_ext_idx(handle, inode, ix);
 404                         if (retval)
 405                                 break;
 406                 }
 407         }
 408         put_bh(bh);
 409         extend_credit_for_blkdel(handle, inode);
 410         ext4_free_blocks(handle, inode, NULL, block, 1,
 411                          EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
 412         return retval;
 413 }
 414
 415 /*
 416  * Free the extent meta data blocks only
 417  */
 418 static int free_ext_block(handle_t *handle, struct inode *inode)
 419 {
 420         int i, retval = 0;
 421         struct ext4_inode_info *ei = EXT4_I(inode);
 422         struct ext4_extent_header *eh = (struct ext4_extent_header *)ei->i_data;
 423         struct ext4_extent_idx *ix;
 424         if (eh->eh_depth == 0)
 425                 /*
 426                  * No extra blocks allocated for extent meta data
 427                  */
 428                 return 0;
 429         ix = EXT_FIRST_INDEX(eh);
 430         for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 431                 retval = free_ext_idx(handle, inode, ix);
 432                 if (retval)
 433                         return retval;
 434         }
 435         return retval;
 436 }
 437
 438 int ext4_ext_migrate(struct inode *inode)
 439 {
 440         handle_t *handle;
 441         int retval = 0, i;
 442         __le32 *i_data;
 443         struct ext4_inode_info *ei;
 444         struct inode *tmp_inode = NULL;
 445         struct migrate_struct lb;
 446         unsigned long max_entries;
 447         __u32 goal;
 448         uid_t owner[2];
 449
 450         /*
 451          * If the filesystem does not support extents, or the inode
 452          * already is extent-based, error out.
 453          */
 454         if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
 455                                        EXT4_FEATURE_INCOMPAT_EXTENTS) ||
 456             (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 457                 return -EINVAL;
 458
 459         if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)
 460                 /*
 461                  * don't migrate fast symlink
 462                  */
 463                 return retval;
 464
 465         /*
 466          * Worst case we can touch the allocation bitmaps, a bgd
 467          * block, and a block to link in the orphan list.  We do need
 468          * need to worry about credits for modifying the quota inode.
 469          */
 470         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE,
 471                 4 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb));
 472
 473         if (IS_ERR(handle)) {
 474                 retval = PTR_ERR(handle);
 475                 return retval;
 476         }
 477         goal = (((inode->i_ino - 1) / EXT4_INODES_PER_GROUP(inode->i_sb)) *
 478                 EXT4_INODES_PER_GROUP(inode->i_sb)) + 1;
 479         owner[0] = i_uid_read(inode);
 480         owner[1] = i_gid_read(inode);
 481         tmp_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,
 482                                    S_IFREG, NULL, goal, owner);
 483         if (IS_ERR(tmp_inode)) {
 484                 retval = PTR_ERR(tmp_inode);
 485                 ext4_journal_stop(handle);
 486                 return retval;
 487         }
 488         i_size_write(tmp_inode, i_size_read(inode));
 489         /*
 490          * Set the i_nlink to zero so it will be deleted later
 491          * when we drop inode reference.
 492          */
 493         clear_nlink(tmp_inode);
 494
 495         ext4_ext_tree_init(handle, tmp_inode);
 496         ext4_orphan_add(handle, tmp_inode);
 497         ext4_journal_stop(handle);
 498
 499         /*
 500          * start with one credit accounted for
 501          * superblock modification.
 502          *
 503          * For the tmp_inode we already have committed the
 504          * transaction that created the inode. Later as and
 505          * when we add extents we extent the journal
 506          */
 507         /*
 508          * Even though we take i_mutex we can still cause block
 509          * allocation via mmap write to holes. If we have allocated
 510          * new blocks we fail migrate.  New block allocation will
 511          * clear EXT4_STATE_EXT_MIGRATE flag.  The flag is updated
 512          * with i_data_sem held to prevent racing with block
 513          * allocation.
 514          */
 515         down_read(&EXT4_I(inode)->i_data_sem);
 516         ext4_set_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 517         up_read((&EXT4_I(inode)->i_data_sem));
 518
 519         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
 520         if (IS_ERR(handle)) {
 521                 /*
 522                  * It is impossible to update on-disk structures without
 523                  * a handle, so just rollback in-core changes and live other
 524                  * work to orphan_list_cleanup()
 525                  */
 526                 ext4_orphan_del(NULL, tmp_inode);
 527                 retval = PTR_ERR(handle);
 528                 goto out;
 529         }
 530
 531         ei = EXT4_I(inode);
 532         i_data = ei->i_data;
 533         memset(&lb, 0, sizeof(lb));
 534
 535         /* 32 bit block address 4 bytes */
 536         max_entries = inode->i_sb->s_blocksize >> 2;
 537         for (i = 0; i < EXT4_NDIR_BLOCKS; i++) {
 538                 if (i_data[i]) {
 539                         retval = update_extent_range(handle, tmp_inode,
 540                                                 le32_to_cpu(i_data[i]), &lb);
 541                         if (retval)
 542                                 goto err_out;
 543                 } else
 544                         lb.curr_block++;
 545         }
 546         if (i_data[EXT4_IND_BLOCK]) {
 547                 retval = update_ind_extent_range(handle, tmp_inode,
 548                                 le32_to_cpu(i_data[EXT4_IND_BLOCK]), &lb);
 549                         if (retval)
 550                                 goto err_out;
 551         } else
 552                 lb.curr_block += max_entries;
 553         if (i_data[EXT4_DIND_BLOCK]) {
 554                 retval = update_dind_extent_range(handle, tmp_inode,
 555                                 le32_to_cpu(i_data[EXT4_DIND_BLOCK]), &lb);
 556                         if (retval)
 557                                 goto err_out;
 558         } else
 559                 lb.curr_block += max_entries * max_entries;
 560         if (i_data[EXT4_TIND_BLOCK]) {
 561                 retval = update_tind_extent_range(handle, tmp_inode,
 562                                 le32_to_cpu(i_data[EXT4_TIND_BLOCK]), &lb);
 563                         if (retval)
 564                                 goto err_out;
 565         }
 566         /*
 567          * Build the last extent
 568          */
 569         retval = finish_range(handle, tmp_inode, &lb);
 570 err_out:
 571         if (retval)
 572                 /*
 573                  * Failure case delete the extent information with the
 574                  * tmp_inode
 575                  */
 576                 free_ext_block(handle, tmp_inode);
 577         else {
 578                 retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
 579                 if (retval)
 580                         /*
 581                          * if we fail to swap inode data free the extent
 582                          * details of the tmp inode
 583                          */
 584                         free_ext_block(handle, tmp_inode);
 585         }
 586
 587         /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
 588         if (ext4_journal_extend(handle, 1) != 0)
 589                 ext4_journal_restart(handle, 1);
 590
 591         /*
 592          * Mark the tmp_inode as of size zero
 593          */
 594         i_size_write(tmp_inode, 0);
 595
 596         /*
 597          * set the  i_blocks count to zero
 598          * so that the ext4_delete_inode does the
 599          * right job
 600          *
 601          * We don't need to take the i_lock because
 602          * the inode is not visible to user space.
 603          */
 604         tmp_inode->i_blocks = 0;
 605
 606         /* Reset the extent details */
 607         ext4_ext_tree_init(handle, tmp_inode);
 608         ext4_journal_stop(handle);
 609 out:
 610         unlock_new_inode(tmp_inode);
 611         iput(tmp_inode);
 612
 613         return retval;
 614 }
 615
 616 /*
 617  * Migrate a simple extent-based inode to use the i_blocks[] array
 618  */
 619 int ext4_ind_migrate(struct inode *inode)
 620 {
 621         struct ext4_extent_header       *eh;
 622         struct ext4_super_block         *es = EXT4_SB(inode->i_sb)->s_es;
 623         struct ext4_inode_info          *ei = EXT4_I(inode);
 624         struct ext4_extent              *ex;
 625         unsigned int                    i, len;
 626         ext4_fsblk_t                    blk;
 627         handle_t                        *handle;
 628         int                             ret;
 629
 630         if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
 631                                        EXT4_FEATURE_INCOMPAT_EXTENTS) ||
 632             (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 633                 return -EINVAL;
 634
 635         if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
 636                                        EXT4_FEATURE_RO_COMPAT_BIGALLOC))
 637                 return -EOPNOTSUPP;
 638
 639         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
 640         if (IS_ERR(handle))
 641                 return PTR_ERR(handle);
 642
 643         down_write(&EXT4_I(inode)->i_data_sem);
 644         ret = ext4_ext_check_inode(inode);
 645         if (ret)
 646                 goto errout;
 647
 648         eh = ext_inode_hdr(inode);
 649         ex  = EXT_FIRST_EXTENT(eh);
 650         if (ext4_blocks_count(es) > EXT4_MAX_BLOCK_FILE_PHYS ||
 651             eh->eh_depth != 0 || le16_to_cpu(eh->eh_entries) > 1) {
 652                 ret = -EOPNOTSUPP;
 653                 goto errout;
 654         }
 655         if (eh->eh_entries == 0)
 656                 blk = len = 0;
 657         else {
 658                 len = le16_to_cpu(ex->ee_len);
 659                 blk = ext4_ext_pblock(ex);
 660                 if (len > EXT4_NDIR_BLOCKS) {
 661                         ret = -EOPNOTSUPP;
 662                         goto errout;
 663                 }
 664         }
 665
 666         ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
 667         memset(ei->i_data, 0, sizeof(ei->i_data));
 668         for (i=0; i < len; i++)
 669                 ei->i_data[i] = cpu_to_le32(blk++);
 670         ext4_mark_inode_dirty(handle, inode);
 671 errout:
 672         ext4_journal_stop(handle);
 673         up_write(&EXT4_I(inode)->i_data_sem);
 674         return ret;
 675 }