fs/ext4/migrate.c

   1 /*
   2  * Copyright IBM Corporation, 2007
   3  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   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_find_extent(inode, lb->first_block, NULL, 0);
  45         if (IS_ERR(path)) {
  46                 retval = PTR_ERR(path);
  47                 path = NULL;
  48                 goto err_out;
  49         }
  50
  51         /*
  52          * Calculate the credit needed to inserting this extent
  53          * Since we are doing this in loop we may accumalate extra
  54          * credit. But below we try to not accumalate too much
  55          * of them by restarting the journal.
  56          */
  57         needed = ext4_ext_calc_credits_for_single_extent(inode,
  58                     lb->last_block - lb->first_block + 1, path);
  59
  60         /*
  61          * Make sure the credit we accumalated is not really high
  62          */
  63         if (needed && ext4_handle_has_enough_credits(handle,
  64                                                 EXT4_RESERVE_TRANS_BLOCKS)) {
  65                 up_write((&EXT4_I(inode)->i_data_sem));
  66                 retval = ext4_journal_restart(handle, needed);
  67                 down_write((&EXT4_I(inode)->i_data_sem));
  68                 if (retval)
  69                         goto err_out;
  70         } else if (needed) {
  71                 retval = ext4_journal_extend(handle, needed);
  72                 if (retval) {
  73                         /*
  74                          * IF not able to extend the journal restart the journal
  75                          */
  76                         up_write((&EXT4_I(inode)->i_data_sem));
  77                         retval = ext4_journal_restart(handle, needed);
  78                         down_write((&EXT4_I(inode)->i_data_sem));
  79                         if (retval)
  80                                 goto err_out;
  81                 }
  82         }
  83         retval = ext4_ext_insert_extent(handle, inode, &path, &newext, 0);
  84 err_out:
  85         up_write((&EXT4_I(inode)->i_data_sem));
  86         ext4_ext_drop_refs(path);
  87         kfree(path);
  88         lb->first_pblock = 0;
  89         return retval;
  90 }
  91
  92 static int update_extent_range(handle_t *handle, struct inode *inode,
  93                                ext4_fsblk_t pblock, struct migrate_struct *lb)
  94 {
  95         int retval;
  96         /*
  97          * See if we can add on to the existing range (if it exists)
  98          */
  99         if (lb->first_pblock &&
 100                 (lb->last_pblock+1 == pblock) &&
 101                 (lb->last_block+1 == lb->curr_block)) {
 102                 lb->last_pblock = pblock;
 103                 lb->last_block = lb->curr_block;
 104                 lb->curr_block++;
 105                 return 0;
 106         }
 107         /*
 108          * Start a new range.
 109          */
 110         retval = finish_range(handle, inode, lb);
 111         lb->first_pblock = lb->last_pblock = pblock;
 112         lb->first_block = lb->last_block = lb->curr_block;
 113         lb->curr_block++;
 114         return retval;
 115 }
 116
 117 static int update_ind_extent_range(handle_t *handle, struct inode *inode,
 118                                    ext4_fsblk_t pblock,
 119                                    struct migrate_struct *lb)
 120 {
 121         struct buffer_head *bh;
 122         __le32 *i_data;
 123         int i, retval = 0;
 124         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 125
 126         bh = sb_bread(inode->i_sb, pblock);
 127         if (!bh)
 128                 return -EIO;
 129
 130         i_data = (__le32 *)bh->b_data;
 131         for (i = 0; i < max_entries; i++) {
 132                 if (i_data[i]) {
 133                         retval = update_extent_range(handle, inode,
 134                                                 le32_to_cpu(i_data[i]), lb);
 135                         if (retval)
 136                                 break;
 137                 } else {
 138                         lb->curr_block++;
 139                 }
 140         }
 141         put_bh(bh);
 142         return retval;
 143
 144 }
 145
 146 static int update_dind_extent_range(handle_t *handle, struct inode *inode,
 147                                     ext4_fsblk_t pblock,
 148                                     struct migrate_struct *lb)
 149 {
 150         struct buffer_head *bh;
 151         __le32 *i_data;
 152         int i, retval = 0;
 153         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 154
 155         bh = sb_bread(inode->i_sb, pblock);
 156         if (!bh)
 157                 return -EIO;
 158
 159         i_data = (__le32 *)bh->b_data;
 160         for (i = 0; i < max_entries; i++) {
 161                 if (i_data[i]) {
 162                         retval = update_ind_extent_range(handle, inode,
 163                                                 le32_to_cpu(i_data[i]), lb);
 164                         if (retval)
 165                                 break;
 166                 } else {
 167                         /* Only update the file block number */
 168                         lb->curr_block += max_entries;
 169                 }
 170         }
 171         put_bh(bh);
 172         return retval;
 173
 174 }
 175
 176 static int update_tind_extent_range(handle_t *handle, struct inode *inode,
 177                                     ext4_fsblk_t pblock,
 178                                     struct migrate_struct *lb)
 179 {
 180         struct buffer_head *bh;
 181         __le32 *i_data;
 182         int i, retval = 0;
 183         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 184
 185         bh = sb_bread(inode->i_sb, pblock);
 186         if (!bh)
 187                 return -EIO;
 188
 189         i_data = (__le32 *)bh->b_data;
 190         for (i = 0; i < max_entries; i++) {
 191                 if (i_data[i]) {
 192                         retval = update_dind_extent_range(handle, inode,
 193                                                 le32_to_cpu(i_data[i]), lb);
 194                         if (retval)
 195                                 break;
 196                 } else {
 197                         /* Only update the file block number */
 198                         lb->curr_block += max_entries * max_entries;
 199                 }
 200         }
 201         put_bh(bh);
 202         return retval;
 203
 204 }
 205
 206 static int extend_credit_for_blkdel(handle_t *handle, struct inode *inode)
 207 {
 208         int retval = 0, needed;
 209
 210         if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
 211                 return 0;
 212         /*
 213          * We are freeing a blocks. During this we touch
 214          * superblock, group descriptor and block bitmap.
 215          * So allocate a credit of 3. We may update
 216          * quota (user and group).
 217          */
 218         needed = 3 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);
 219
 220         if (ext4_journal_extend(handle, needed) != 0)
 221                 retval = ext4_journal_restart(handle, needed);
 222
 223         return retval;
 224 }
 225
 226 static int free_dind_blocks(handle_t *handle,
 227                                 struct inode *inode, __le32 i_data)
 228 {
 229         int i;
 230         __le32 *tmp_idata;
 231         struct buffer_head *bh;
 232         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 233
 234         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 235         if (!bh)
 236                 return -EIO;
 237
 238         tmp_idata = (__le32 *)bh->b_data;
 239         for (i = 0; i < max_entries; i++) {
 240                 if (tmp_idata[i]) {
 241                         extend_credit_for_blkdel(handle, inode);
 242                         ext4_free_blocks(handle, inode, NULL,
 243                                          le32_to_cpu(tmp_idata[i]), 1,
 244                                          EXT4_FREE_BLOCKS_METADATA |
 245                                          EXT4_FREE_BLOCKS_FORGET);
 246                 }
 247         }
 248         put_bh(bh);
 249         extend_credit_for_blkdel(handle, inode);
 250         ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
 251                          EXT4_FREE_BLOCKS_METADATA |
 252                          EXT4_FREE_BLOCKS_FORGET);
 253         return 0;
 254 }
 255
 256 static int free_tind_blocks(handle_t *handle,
 257                                 struct inode *inode, __le32 i_data)
 258 {
 259         int i, retval = 0;
 260         __le32 *tmp_idata;
 261         struct buffer_head *bh;
 262         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 263
 264         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 265         if (!bh)
 266                 return -EIO;
 267
 268         tmp_idata = (__le32 *)bh->b_data;
 269         for (i = 0; i < max_entries; i++) {
 270                 if (tmp_idata[i]) {
 271                         retval = free_dind_blocks(handle,
 272                                         inode, tmp_idata[i]);
 273                         if (retval) {
 274                                 put_bh(bh);
 275                                 return retval;
 276                         }
 277                 }
 278         }
 279         put_bh(bh);
 280         extend_credit_for_blkdel(handle, inode);
 281         ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
 282                          EXT4_FREE_BLOCKS_METADATA |
 283                          EXT4_FREE_BLOCKS_FORGET);
 284         return 0;
 285 }
 286
 287 static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
 288 {
 289         int retval;
 290
 291         /* ei->i_data[EXT4_IND_BLOCK] */
 292         if (i_data[0]) {
 293                 extend_credit_for_blkdel(handle, inode);
 294                 ext4_free_blocks(handle, inode, NULL,
 295                                 le32_to_cpu(i_data[0]), 1,
 296                                  EXT4_FREE_BLOCKS_METADATA |
 297                                  EXT4_FREE_BLOCKS_FORGET);
 298         }
 299
 300         /* ei->i_data[EXT4_DIND_BLOCK] */
 301         if (i_data[1]) {
 302                 retval = free_dind_blocks(handle, inode, i_data[1]);
 303                 if (retval)
 304                         return retval;
 305         }
 306
 307         /* ei->i_data[EXT4_TIND_BLOCK] */
 308         if (i_data[2]) {
 309                 retval = free_tind_blocks(handle, inode, i_data[2]);
 310                 if (retval)
 311                         return retval;
 312         }
 313         return 0;
 314 }
 315
 316 static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
 317                                                 struct inode *tmp_inode)
 318 {
 319         int retval;
 320         __le32  i_data[3];
 321         struct ext4_inode_info *ei = EXT4_I(inode);
 322         struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);
 323
 324         /*
 325          * One credit accounted for writing the
 326          * i_data field of the original inode
 327          */
 328         retval = ext4_journal_extend(handle, 1);
 329         if (retval) {
 330                 retval = ext4_journal_restart(handle, 1);
 331                 if (retval)
 332                         goto err_out;
 333         }
 334
 335         i_data[0] = ei->i_data[EXT4_IND_BLOCK];
 336         i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
 337         i_data[2] = ei->i_data[EXT4_TIND_BLOCK];
 338
 339         down_write(&EXT4_I(inode)->i_data_sem);
 340         /*
 341          * if EXT4_STATE_EXT_MIGRATE is cleared a block allocation
 342          * happened after we started the migrate. We need to
 343          * fail the migrate
 344          */
 345         if (!ext4_test_inode_state(inode, EXT4_STATE_EXT_MIGRATE)) {
 346                 retval = -EAGAIN;
 347                 up_write(&EXT4_I(inode)->i_data_sem);
 348                 goto err_out;
 349         } else
 350                 ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 351         /*
 352          * We have the extent map build with the tmp inode.
 353          * Now copy the i_data across
 354          */
 355         ext4_set_inode_flag(inode, EXT4_INODE_EXTENTS);
 356         memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));
 357
 358         /*
 359          * Update i_blocks with the new blocks that got
 360          * allocated while adding extents for extent index
 361          * blocks.
 362          *
 363          * While converting to extents we need not
 364          * update the orignal inode i_blocks for extent blocks
 365          * via quota APIs. The quota update happened via tmp_inode already.
 366          */
 367         spin_lock(&inode->i_lock);
 368         inode->i_blocks += tmp_inode->i_blocks;
 369         spin_unlock(&inode->i_lock);
 370         up_write(&EXT4_I(inode)->i_data_sem);
 371
 372         /*
 373          * We mark the inode dirty after, because we decrement the
 374          * i_blocks when freeing the indirect meta-data blocks
 375          */
 376         retval = free_ind_block(handle, inode, i_data);
 377         ext4_mark_inode_dirty(handle, inode);
 378
 379 err_out:
 380         return retval;
 381 }
 382
 383 static int free_ext_idx(handle_t *handle, struct inode *inode,
 384                                         struct ext4_extent_idx *ix)
 385 {
 386         int i, retval = 0;
 387         ext4_fsblk_t block;
 388         struct buffer_head *bh;
 389         struct ext4_extent_header *eh;
 390
 391         block = ext4_idx_pblock(ix);
 392         bh = sb_bread(inode->i_sb, block);
 393         if (!bh)
 394                 return -EIO;
 395
 396         eh = (struct ext4_extent_header *)bh->b_data;
 397         if (eh->eh_depth != 0) {
 398                 ix = EXT_FIRST_INDEX(eh);
 399                 for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 400                         retval = free_ext_idx(handle, inode, ix);
 401                         if (retval)
 402                                 break;
 403                 }
 404         }
 405         put_bh(bh);
 406         extend_credit_for_blkdel(handle, inode);
 407         ext4_free_blocks(handle, inode, NULL, block, 1,
 408                          EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
 409         return retval;
 410 }
 411
 412 /*
 413  * Free the extent meta data blocks only
 414  */
 415 static int free_ext_block(handle_t *handle, struct inode *inode)
 416 {
 417         int i, retval = 0;
 418         struct ext4_inode_info *ei = EXT4_I(inode);
 419         struct ext4_extent_header *eh = (struct ext4_extent_header *)ei->i_data;
 420         struct ext4_extent_idx *ix;
 421         if (eh->eh_depth == 0)
 422                 /*
 423                  * No extra blocks allocated for extent meta data
 424                  */
 425                 return 0;
 426         ix = EXT_FIRST_INDEX(eh);
 427         for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 428                 retval = free_ext_idx(handle, inode, ix);
 429                 if (retval)
 430                         return retval;
 431         }
 432         return retval;
 433 }
 434
 435 int ext4_ext_migrate(struct inode *inode)
 436 {
 437         handle_t *handle;
 438         int retval = 0, i;
 439         __le32 *i_data;
 440         struct ext4_inode_info *ei;
 441         struct inode *tmp_inode = NULL;
 442         struct migrate_struct lb;
 443         unsigned long max_entries;
 444         __u32 goal;
 445         uid_t owner[2];
 446
 447         /*
 448          * If the filesystem does not support extents, or the inode
 449          * already is extent-based, error out.
 450          */
 451         if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
 452                                        EXT4_FEATURE_INCOMPAT_EXTENTS) ||
 453             (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 454                 return -EINVAL;
 455
 456         if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)
 457                 /*
 458                  * don't migrate fast symlink
 459                  */
 460                 return retval;
 461
 462         /*
 463          * Worst case we can touch the allocation bitmaps, a bgd
 464          * block, and a block to link in the orphan list.  We do need
 465          * need to worry about credits for modifying the quota inode.
 466          */
 467         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE,
 468                 4 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb));
 469
 470         if (IS_ERR(handle)) {
 471                 retval = PTR_ERR(handle);
 472                 return retval;
 473         }
 474         goal = (((inode->i_ino - 1) / EXT4_INODES_PER_GROUP(inode->i_sb)) *
 475                 EXT4_INODES_PER_GROUP(inode->i_sb)) + 1;
 476         owner[0] = i_uid_read(inode);
 477         owner[1] = i_gid_read(inode);
 478         tmp_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,
 479                                    S_IFREG, NULL, goal, owner);
 480         if (IS_ERR(tmp_inode)) {
 481                 retval = PTR_ERR(tmp_inode);
 482                 ext4_journal_stop(handle);
 483                 return retval;
 484         }
 485         i_size_write(tmp_inode, i_size_read(inode));
 486         /*
 487          * Set the i_nlink to zero so it will be deleted later
 488          * when we drop inode reference.
 489          */
 490         clear_nlink(tmp_inode);
 491
 492         ext4_ext_tree_init(handle, tmp_inode);
 493         ext4_orphan_add(handle, tmp_inode);
 494         ext4_journal_stop(handle);
 495
 496         /*
 497          * start with one credit accounted for
 498          * superblock modification.
 499          *
 500          * For the tmp_inode we already have committed the
 501          * transaction that created the inode. Later as and
 502          * when we add extents we extent the journal
 503          */
 504         /*
 505          * Even though we take i_mutex we can still cause block
 506          * allocation via mmap write to holes. If we have allocated
 507          * new blocks we fail migrate.  New block allocation will
 508          * clear EXT4_STATE_EXT_MIGRATE flag.  The flag is updated
 509          * with i_data_sem held to prevent racing with block
 510          * allocation.
 511          */
 512         down_read(&EXT4_I(inode)->i_data_sem);
 513         ext4_set_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 514         up_read((&EXT4_I(inode)->i_data_sem));
 515
 516         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
 517         if (IS_ERR(handle)) {
 518                 /*
 519                  * It is impossible to update on-disk structures without
 520                  * a handle, so just rollback in-core changes and live other
 521                  * work to orphan_list_cleanup()
 522                  */
 523                 ext4_orphan_del(NULL, tmp_inode);
 524                 retval = PTR_ERR(handle);
 525                 goto out;
 526         }
 527
 528         ei = EXT4_I(inode);
 529         i_data = ei->i_data;
 530         memset(&lb, 0, sizeof(lb));
 531
 532         /* 32 bit block address 4 bytes */
 533         max_entries = inode->i_sb->s_blocksize >> 2;
 534         for (i = 0; i < EXT4_NDIR_BLOCKS; i++) {
 535                 if (i_data[i]) {
 536                         retval = update_extent_range(handle, tmp_inode,
 537                                                 le32_to_cpu(i_data[i]), &lb);
 538                         if (retval)
 539                                 goto err_out;
 540                 } else
 541                         lb.curr_block++;
 542         }
 543         if (i_data[EXT4_IND_BLOCK]) {
 544                 retval = update_ind_extent_range(handle, tmp_inode,
 545                                 le32_to_cpu(i_data[EXT4_IND_BLOCK]), &lb);
 546                         if (retval)
 547                                 goto err_out;
 548         } else
 549                 lb.curr_block += max_entries;
 550         if (i_data[EXT4_DIND_BLOCK]) {
 551                 retval = update_dind_extent_range(handle, tmp_inode,
 552                                 le32_to_cpu(i_data[EXT4_DIND_BLOCK]), &lb);
 553                         if (retval)
 554                                 goto err_out;
 555         } else
 556                 lb.curr_block += max_entries * max_entries;
 557         if (i_data[EXT4_TIND_BLOCK]) {
 558                 retval = update_tind_extent_range(handle, tmp_inode,
 559                                 le32_to_cpu(i_data[EXT4_TIND_BLOCK]), &lb);
 560                         if (retval)
 561                                 goto err_out;
 562         }
 563         /*
 564          * Build the last extent
 565          */
 566         retval = finish_range(handle, tmp_inode, &lb);
 567 err_out:
 568         if (retval)
 569                 /*
 570                  * Failure case delete the extent information with the
 571                  * tmp_inode
 572                  */
 573                 free_ext_block(handle, tmp_inode);
 574         else {
 575                 retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
 576                 if (retval)
 577                         /*
 578                          * if we fail to swap inode data free the extent
 579                          * details of the tmp inode
 580                          */
 581                         free_ext_block(handle, tmp_inode);
 582         }
 583
 584         /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
 585         if (ext4_journal_extend(handle, 1) != 0)
 586                 ext4_journal_restart(handle, 1);
 587
 588         /*
 589          * Mark the tmp_inode as of size zero
 590          */
 591         i_size_write(tmp_inode, 0);
 592
 593         /*
 594          * set the  i_blocks count to zero
 595          * so that the ext4_evict_inode() does the
 596          * right job
 597          *
 598          * We don't need to take the i_lock because
 599          * the inode is not visible to user space.
 600          */
 601         tmp_inode->i_blocks = 0;
 602
 603         /* Reset the extent details */
 604         ext4_ext_tree_init(handle, tmp_inode);
 605         ext4_journal_stop(handle);
 606 out:
 607         unlock_new_inode(tmp_inode);
 608         iput(tmp_inode);
 609
 610         return retval;
 611 }
 612
 613 /*
 614  * Migrate a simple extent-based inode to use the i_blocks[] array
 615  */
 616 int ext4_ind_migrate(struct inode *inode)
 617 {
 618         struct ext4_extent_header       *eh;
 619         struct ext4_super_block         *es = EXT4_SB(inode->i_sb)->s_es;
 620         struct ext4_inode_info          *ei = EXT4_I(inode);
 621         struct ext4_extent              *ex;
 622         unsigned int                    i, len;
 623         ext4_fsblk_t                    blk;
 624         handle_t                        *handle;
 625         int                             ret;
 626
 627         if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
 628                                        EXT4_FEATURE_INCOMPAT_EXTENTS) ||
 629             (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 630                 return -EINVAL;
 631
 632         if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
 633                                        EXT4_FEATURE_RO_COMPAT_BIGALLOC))
 634                 return -EOPNOTSUPP;
 635
 636         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
 637         if (IS_ERR(handle))
 638                 return PTR_ERR(handle);
 639
 640         down_write(&EXT4_I(inode)->i_data_sem);
 641         ret = ext4_ext_check_inode(inode);
 642         if (ret)
 643                 goto errout;
 644
 645         eh = ext_inode_hdr(inode);
 646         ex  = EXT_FIRST_EXTENT(eh);
 647         if (ext4_blocks_count(es) > EXT4_MAX_BLOCK_FILE_PHYS ||
 648             eh->eh_depth != 0 || le16_to_cpu(eh->eh_entries) > 1) {
 649                 ret = -EOPNOTSUPP;
 650                 goto errout;
 651         }
 652         if (eh->eh_entries == 0)
 653                 blk = len = 0;
 654         else {
 655                 len = le16_to_cpu(ex->ee_len);
 656                 blk = ext4_ext_pblock(ex);
 657                 if (len > EXT4_NDIR_BLOCKS) {
 658                         ret = -EOPNOTSUPP;
 659                         goto errout;
 660                 }
 661         }
 662
 663         ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
 664         memset(ei->i_data, 0, sizeof(ei->i_data));
 665         for (i=0; i < len; i++)
 666                 ei->i_data[i] = cpu_to_le32(blk++);
 667         ext4_mark_inode_dirty(handle, inode);
 668 errout:
 669         ext4_journal_stop(handle);
 670         up_write(&EXT4_I(inode)->i_data_sem);
 671         return ret;
 672 }