fs/ext4/migrate.c

   1 // SPDX-License-Identifier: LGPL-2.1
   2 /*
   3  * Copyright IBM Corporation, 2007
   4  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   5  *
   6  */
   7
   8 #include <linux/slab.h>
   9 #include "ext4_jbd2.h"
  10 #include "ext4_extents.h"
  11
  12 /*
  13  * The contiguous blocks details which can be
  14  * represented by a single extent
  15  */
  16 struct migrate_struct {
  17         ext4_lblk_t first_block, last_block, curr_block;
  18         ext4_fsblk_t first_pblock, last_pblock;
  19 };
  20
  21 static int finish_range(handle_t *handle, struct inode *inode,
  22                                 struct migrate_struct *lb)
  23
  24 {
  25         int retval = 0, needed;
  26         struct ext4_extent newext;
  27         struct ext4_ext_path *path;
  28         if (lb->first_pblock == 0)
  29                 return 0;
  30
  31         /* Add the extent to temp inode*/
  32         newext.ee_block = cpu_to_le32(lb->first_block);
  33         newext.ee_len   = cpu_to_le16(lb->last_block - lb->first_block + 1);
  34         ext4_ext_store_pblock(&newext, lb->first_pblock);
  35         /* Locking only for convinience since we are operating on temp inode */
  36         down_write(&EXT4_I(inode)->i_data_sem);
  37         path = ext4_find_extent(inode, lb->first_block, NULL, 0);
  38         if (IS_ERR(path)) {
  39                 retval = PTR_ERR(path);
  40                 path = NULL;
  41                 goto err_out;
  42         }
  43
  44         /*
  45          * Calculate the credit needed to inserting this extent
  46          * Since we are doing this in loop we may accumalate extra
  47          * credit. But below we try to not accumalate too much
  48          * of them by restarting the journal.
  49          */
  50         needed = ext4_ext_calc_credits_for_single_extent(inode,
  51                     lb->last_block - lb->first_block + 1, path);
  52
  53         retval = ext4_datasem_ensure_credits(handle, inode, needed, needed, 0);
  54         if (retval < 0)
  55                 goto err_out;
  56         retval = ext4_ext_insert_extent(handle, inode, &path, &newext, 0);
  57 err_out:
  58         up_write((&EXT4_I(inode)->i_data_sem));
  59         ext4_ext_drop_refs(path);
  60         kfree(path);
  61         lb->first_pblock = 0;
  62         return retval;
  63 }
  64
  65 static int update_extent_range(handle_t *handle, struct inode *inode,
  66                                ext4_fsblk_t pblock, struct migrate_struct *lb)
  67 {
  68         int retval;
  69         /*
  70          * See if we can add on to the existing range (if it exists)
  71          */
  72         if (lb->first_pblock &&
  73                 (lb->last_pblock+1 == pblock) &&
  74                 (lb->last_block+1 == lb->curr_block)) {
  75                 lb->last_pblock = pblock;
  76                 lb->last_block = lb->curr_block;
  77                 lb->curr_block++;
  78                 return 0;
  79         }
  80         /*
  81          * Start a new range.
  82          */
  83         retval = finish_range(handle, inode, lb);
  84         lb->first_pblock = lb->last_pblock = pblock;
  85         lb->first_block = lb->last_block = lb->curr_block;
  86         lb->curr_block++;
  87         return retval;
  88 }
  89
  90 static int update_ind_extent_range(handle_t *handle, struct inode *inode,
  91                                    ext4_fsblk_t pblock,
  92                                    struct migrate_struct *lb)
  93 {
  94         struct buffer_head *bh;
  95         __le32 *i_data;
  96         int i, retval = 0;
  97         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
  98
  99         bh = ext4_sb_bread(inode->i_sb, pblock, 0);
 100         if (IS_ERR(bh))
 101                 return PTR_ERR(bh);
 102
 103         i_data = (__le32 *)bh->b_data;
 104         for (i = 0; i < max_entries; i++) {
 105                 if (i_data[i]) {
 106                         retval = update_extent_range(handle, inode,
 107                                                 le32_to_cpu(i_data[i]), lb);
 108                         if (retval)
 109                                 break;
 110                 } else {
 111                         lb->curr_block++;
 112                 }
 113         }
 114         put_bh(bh);
 115         return retval;
 116
 117 }
 118
 119 static int update_dind_extent_range(handle_t *handle, struct inode *inode,
 120                                     ext4_fsblk_t pblock,
 121                                     struct migrate_struct *lb)
 122 {
 123         struct buffer_head *bh;
 124         __le32 *i_data;
 125         int i, retval = 0;
 126         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 127
 128         bh = ext4_sb_bread(inode->i_sb, pblock, 0);
 129         if (IS_ERR(bh))
 130                 return PTR_ERR(bh);
 131
 132         i_data = (__le32 *)bh->b_data;
 133         for (i = 0; i < max_entries; i++) {
 134                 if (i_data[i]) {
 135                         retval = update_ind_extent_range(handle, inode,
 136                                                 le32_to_cpu(i_data[i]), lb);
 137                         if (retval)
 138                                 break;
 139                 } else {
 140                         /* Only update the file block number */
 141                         lb->curr_block += max_entries;
 142                 }
 143         }
 144         put_bh(bh);
 145         return retval;
 146
 147 }
 148
 149 static int update_tind_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 = ext4_sb_bread(inode->i_sb, pblock, 0);
 159         if (IS_ERR(bh))
 160                 return PTR_ERR(bh);
 161
 162         i_data = (__le32 *)bh->b_data;
 163         for (i = 0; i < max_entries; i++) {
 164                 if (i_data[i]) {
 165                         retval = update_dind_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 * max_entries;
 172                 }
 173         }
 174         put_bh(bh);
 175         return retval;
 176
 177 }
 178
 179 static int free_dind_blocks(handle_t *handle,
 180                                 struct inode *inode, __le32 i_data)
 181 {
 182         int i;
 183         __le32 *tmp_idata;
 184         struct buffer_head *bh;
 185         struct super_block *sb = inode->i_sb;
 186         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 187         int err;
 188
 189         bh = ext4_sb_bread(sb, le32_to_cpu(i_data), 0);
 190         if (IS_ERR(bh))
 191                 return PTR_ERR(bh);
 192
 193         tmp_idata = (__le32 *)bh->b_data;
 194         for (i = 0; i < max_entries; i++) {
 195                 if (tmp_idata[i]) {
 196                         err = ext4_journal_ensure_credits(handle,
 197                                 EXT4_RESERVE_TRANS_BLOCKS,
 198                                 ext4_free_metadata_revoke_credits(sb, 1));
 199                         if (err < 0) {
 200                                 put_bh(bh);
 201                                 return err;
 202                         }
 203                         ext4_free_blocks(handle, inode, NULL,
 204                                          le32_to_cpu(tmp_idata[i]), 1,
 205                                          EXT4_FREE_BLOCKS_METADATA |
 206                                          EXT4_FREE_BLOCKS_FORGET);
 207                 }
 208         }
 209         put_bh(bh);
 210         err = ext4_journal_ensure_credits(handle, EXT4_RESERVE_TRANS_BLOCKS,
 211                                 ext4_free_metadata_revoke_credits(sb, 1));
 212         if (err < 0)
 213                 return err;
 214         ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
 215                          EXT4_FREE_BLOCKS_METADATA |
 216                          EXT4_FREE_BLOCKS_FORGET);
 217         return 0;
 218 }
 219
 220 static int free_tind_blocks(handle_t *handle,
 221                                 struct inode *inode, __le32 i_data)
 222 {
 223         int i, retval = 0;
 224         __le32 *tmp_idata;
 225         struct buffer_head *bh;
 226         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 227
 228         bh = ext4_sb_bread(inode->i_sb, le32_to_cpu(i_data), 0);
 229         if (IS_ERR(bh))
 230                 return PTR_ERR(bh);
 231
 232         tmp_idata = (__le32 *)bh->b_data;
 233         for (i = 0; i < max_entries; i++) {
 234                 if (tmp_idata[i]) {
 235                         retval = free_dind_blocks(handle,
 236                                         inode, tmp_idata[i]);
 237                         if (retval) {
 238                                 put_bh(bh);
 239                                 return retval;
 240                         }
 241                 }
 242         }
 243         put_bh(bh);
 244         retval = ext4_journal_ensure_credits(handle, EXT4_RESERVE_TRANS_BLOCKS,
 245                         ext4_free_metadata_revoke_credits(inode->i_sb, 1));
 246         if (retval < 0)
 247                 return retval;
 248         ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
 249                          EXT4_FREE_BLOCKS_METADATA |
 250                          EXT4_FREE_BLOCKS_FORGET);
 251         return 0;
 252 }
 253
 254 static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
 255 {
 256         int retval;
 257
 258         /* ei->i_data[EXT4_IND_BLOCK] */
 259         if (i_data[0]) {
 260                 retval = ext4_journal_ensure_credits(handle,
 261                         EXT4_RESERVE_TRANS_BLOCKS,
 262                         ext4_free_metadata_revoke_credits(inode->i_sb, 1));
 263                 if (retval < 0)
 264                         return retval;
 265                 ext4_free_blocks(handle, inode, NULL,
 266                                 le32_to_cpu(i_data[0]), 1,
 267                                  EXT4_FREE_BLOCKS_METADATA |
 268                                  EXT4_FREE_BLOCKS_FORGET);
 269         }
 270
 271         /* ei->i_data[EXT4_DIND_BLOCK] */
 272         if (i_data[1]) {
 273                 retval = free_dind_blocks(handle, inode, i_data[1]);
 274                 if (retval)
 275                         return retval;
 276         }
 277
 278         /* ei->i_data[EXT4_TIND_BLOCK] */
 279         if (i_data[2]) {
 280                 retval = free_tind_blocks(handle, inode, i_data[2]);
 281                 if (retval)
 282                         return retval;
 283         }
 284         return 0;
 285 }
 286
 287 static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
 288                                                 struct inode *tmp_inode)
 289 {
 290         int retval;
 291         __le32  i_data[3];
 292         struct ext4_inode_info *ei = EXT4_I(inode);
 293         struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);
 294
 295         /*
 296          * One credit accounted for writing the
 297          * i_data field of the original inode
 298          */
 299         retval = ext4_journal_ensure_credits(handle, 1, 0);
 300         if (retval < 0)
 301                 goto err_out;
 302
 303         i_data[0] = ei->i_data[EXT4_IND_BLOCK];
 304         i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
 305         i_data[2] = ei->i_data[EXT4_TIND_BLOCK];
 306
 307         down_write(&EXT4_I(inode)->i_data_sem);
 308         /*
 309          * if EXT4_STATE_EXT_MIGRATE is cleared a block allocation
 310          * happened after we started the migrate. We need to
 311          * fail the migrate
 312          */
 313         if (!ext4_test_inode_state(inode, EXT4_STATE_EXT_MIGRATE)) {
 314                 retval = -EAGAIN;
 315                 up_write(&EXT4_I(inode)->i_data_sem);
 316                 goto err_out;
 317         } else
 318                 ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 319         /*
 320          * We have the extent map build with the tmp inode.
 321          * Now copy the i_data across
 322          */
 323         ext4_set_inode_flag(inode, EXT4_INODE_EXTENTS);
 324         memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));
 325
 326         /*
 327          * Update i_blocks with the new blocks that got
 328          * allocated while adding extents for extent index
 329          * blocks.
 330          *
 331          * While converting to extents we need not
 332          * update the original inode i_blocks for extent blocks
 333          * via quota APIs. The quota update happened via tmp_inode already.
 334          */
 335         spin_lock(&inode->i_lock);
 336         inode->i_blocks += tmp_inode->i_blocks;
 337         spin_unlock(&inode->i_lock);
 338         up_write(&EXT4_I(inode)->i_data_sem);
 339
 340         /*
 341          * We mark the inode dirty after, because we decrement the
 342          * i_blocks when freeing the indirect meta-data blocks
 343          */
 344         retval = free_ind_block(handle, inode, i_data);
 345         ext4_mark_inode_dirty(handle, inode);
 346
 347 err_out:
 348         return retval;
 349 }
 350
 351 static int free_ext_idx(handle_t *handle, struct inode *inode,
 352                                         struct ext4_extent_idx *ix)
 353 {
 354         int i, retval = 0;
 355         ext4_fsblk_t block;
 356         struct buffer_head *bh;
 357         struct ext4_extent_header *eh;
 358
 359         block = ext4_idx_pblock(ix);
 360         bh = ext4_sb_bread(inode->i_sb, block, 0);
 361         if (IS_ERR(bh))
 362                 return PTR_ERR(bh);
 363
 364         eh = (struct ext4_extent_header *)bh->b_data;
 365         if (eh->eh_depth != 0) {
 366                 ix = EXT_FIRST_INDEX(eh);
 367                 for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 368                         retval = free_ext_idx(handle, inode, ix);
 369                         if (retval) {
 370                                 put_bh(bh);
 371                                 return retval;
 372                         }
 373                 }
 374         }
 375         put_bh(bh);
 376         retval = ext4_journal_ensure_credits(handle, EXT4_RESERVE_TRANS_BLOCKS,
 377                         ext4_free_metadata_revoke_credits(inode->i_sb, 1));
 378         if (retval < 0)
 379                 return retval;
 380         ext4_free_blocks(handle, inode, NULL, block, 1,
 381                          EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
 382         return 0;
 383 }
 384
 385 /*
 386  * Free the extent meta data blocks only
 387  */
 388 static int free_ext_block(handle_t *handle, struct inode *inode)
 389 {
 390         int i, retval = 0;
 391         struct ext4_inode_info *ei = EXT4_I(inode);
 392         struct ext4_extent_header *eh = (struct ext4_extent_header *)ei->i_data;
 393         struct ext4_extent_idx *ix;
 394         if (eh->eh_depth == 0)
 395                 /*
 396                  * No extra blocks allocated for extent meta data
 397                  */
 398                 return 0;
 399         ix = EXT_FIRST_INDEX(eh);
 400         for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 401                 retval = free_ext_idx(handle, inode, ix);
 402                 if (retval)
 403                         return retval;
 404         }
 405         return retval;
 406 }
 407
 408 int ext4_ext_migrate(struct inode *inode)
 409 {
 410         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 411         handle_t *handle;
 412         int retval = 0, i;
 413         __le32 *i_data;
 414         struct ext4_inode_info *ei;
 415         struct inode *tmp_inode = NULL;
 416         struct migrate_struct lb;
 417         unsigned long max_entries;
 418         __u32 goal;
 419         uid_t owner[2];
 420
 421         /*
 422          * If the filesystem does not support extents, or the inode
 423          * already is extent-based, error out.
 424          */
 425         if (!ext4_has_feature_extents(inode->i_sb) ||
 426             (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 427                 return -EINVAL;
 428
 429         if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)
 430                 /*
 431                  * don't migrate fast symlink
 432                  */
 433                 return retval;
 434
 435         percpu_down_write(&sbi->s_writepages_rwsem);
 436
 437         /*
 438          * Worst case we can touch the allocation bitmaps, a bgd
 439          * block, and a block to link in the orphan list.  We do need
 440          * need to worry about credits for modifying the quota inode.
 441          */
 442         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE,
 443                 4 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb));
 444
 445         if (IS_ERR(handle)) {
 446                 retval = PTR_ERR(handle);
 447                 goto out_unlock;
 448         }
 449         goal = (((inode->i_ino - 1) / EXT4_INODES_PER_GROUP(inode->i_sb)) *
 450                 EXT4_INODES_PER_GROUP(inode->i_sb)) + 1;
 451         owner[0] = i_uid_read(inode);
 452         owner[1] = i_gid_read(inode);
 453         tmp_inode = ext4_new_inode(handle, d_inode(inode->i_sb->s_root),
 454                                    S_IFREG, NULL, goal, owner, 0);
 455         if (IS_ERR(tmp_inode)) {
 456                 retval = PTR_ERR(tmp_inode);
 457                 ext4_journal_stop(handle);
 458                 goto out_unlock;
 459         }
 460         i_size_write(tmp_inode, i_size_read(inode));
 461         /*
 462          * Set the i_nlink to zero so it will be deleted later
 463          * when we drop inode reference.
 464          */
 465         clear_nlink(tmp_inode);
 466
 467         ext4_ext_tree_init(handle, tmp_inode);
 468         ext4_orphan_add(handle, tmp_inode);
 469         ext4_journal_stop(handle);
 470
 471         /*
 472          * start with one credit accounted for
 473          * superblock modification.
 474          *
 475          * For the tmp_inode we already have committed the
 476          * transaction that created the inode. Later as and
 477          * when we add extents we extent the journal
 478          */
 479         /*
 480          * Even though we take i_mutex we can still cause block
 481          * allocation via mmap write to holes. If we have allocated
 482          * new blocks we fail migrate.  New block allocation will
 483          * clear EXT4_STATE_EXT_MIGRATE flag.  The flag is updated
 484          * with i_data_sem held to prevent racing with block
 485          * allocation.
 486          */
 487         down_read(&EXT4_I(inode)->i_data_sem);
 488         ext4_set_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 489         up_read((&EXT4_I(inode)->i_data_sem));
 490
 491         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
 492         if (IS_ERR(handle)) {
 493                 /*
 494                  * It is impossible to update on-disk structures without
 495                  * a handle, so just rollback in-core changes and live other
 496                  * work to orphan_list_cleanup()
 497                  */
 498                 ext4_orphan_del(NULL, tmp_inode);
 499                 retval = PTR_ERR(handle);
 500                 goto out_tmp_inode;
 501         }
 502
 503         ei = EXT4_I(inode);
 504         i_data = ei->i_data;
 505         memset(&lb, 0, sizeof(lb));
 506
 507         /* 32 bit block address 4 bytes */
 508         max_entries = inode->i_sb->s_blocksize >> 2;
 509         for (i = 0; i < EXT4_NDIR_BLOCKS; i++) {
 510                 if (i_data[i]) {
 511                         retval = update_extent_range(handle, tmp_inode,
 512                                                 le32_to_cpu(i_data[i]), &lb);
 513                         if (retval)
 514                                 goto err_out;
 515                 } else
 516                         lb.curr_block++;
 517         }
 518         if (i_data[EXT4_IND_BLOCK]) {
 519                 retval = update_ind_extent_range(handle, tmp_inode,
 520                                 le32_to_cpu(i_data[EXT4_IND_BLOCK]), &lb);
 521                 if (retval)
 522                         goto err_out;
 523         } else
 524                 lb.curr_block += max_entries;
 525         if (i_data[EXT4_DIND_BLOCK]) {
 526                 retval = update_dind_extent_range(handle, tmp_inode,
 527                                 le32_to_cpu(i_data[EXT4_DIND_BLOCK]), &lb);
 528                 if (retval)
 529                         goto err_out;
 530         } else
 531                 lb.curr_block += max_entries * max_entries;
 532         if (i_data[EXT4_TIND_BLOCK]) {
 533                 retval = update_tind_extent_range(handle, tmp_inode,
 534                                 le32_to_cpu(i_data[EXT4_TIND_BLOCK]), &lb);
 535                 if (retval)
 536                         goto err_out;
 537         }
 538         /*
 539          * Build the last extent
 540          */
 541         retval = finish_range(handle, tmp_inode, &lb);
 542 err_out:
 543         if (retval)
 544                 /*
 545                  * Failure case delete the extent information with the
 546                  * tmp_inode
 547                  */
 548                 free_ext_block(handle, tmp_inode);
 549         else {
 550                 retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
 551                 if (retval)
 552                         /*
 553                          * if we fail to swap inode data free the extent
 554                          * details of the tmp inode
 555                          */
 556                         free_ext_block(handle, tmp_inode);
 557         }
 558
 559         /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
 560         retval = ext4_journal_ensure_credits(handle, 1, 0);
 561         if (retval < 0)
 562                 goto out_stop;
 563         /*
 564          * Mark the tmp_inode as of size zero
 565          */
 566         i_size_write(tmp_inode, 0);
 567
 568         /*
 569          * set the  i_blocks count to zero
 570          * so that the ext4_evict_inode() does the
 571          * right job
 572          *
 573          * We don't need to take the i_lock because
 574          * the inode is not visible to user space.
 575          */
 576         tmp_inode->i_blocks = 0;
 577
 578         /* Reset the extent details */
 579         ext4_ext_tree_init(handle, tmp_inode);
 580 out_stop:
 581         ext4_journal_stop(handle);
 582 out_tmp_inode:
 583         unlock_new_inode(tmp_inode);
 584         iput(tmp_inode);
 585 out_unlock:
 586         percpu_up_write(&sbi->s_writepages_rwsem);
 587         return retval;
 588 }
 589
 590 /*
 591  * Migrate a simple extent-based inode to use the i_blocks[] array
 592  */
 593 int ext4_ind_migrate(struct inode *inode)
 594 {
 595         struct ext4_extent_header       *eh;
 596         struct ext4_sb_info             *sbi = EXT4_SB(inode->i_sb);
 597         struct ext4_super_block         *es = sbi->s_es;
 598         struct ext4_inode_info          *ei = EXT4_I(inode);
 599         struct ext4_extent              *ex;
 600         unsigned int                    i, len;
 601         ext4_lblk_t                     start, end;
 602         ext4_fsblk_t                    blk;
 603         handle_t                        *handle;
 604         int                             ret;
 605
 606         if (!ext4_has_feature_extents(inode->i_sb) ||
 607             (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 608                 return -EINVAL;
 609
 610         if (ext4_has_feature_bigalloc(inode->i_sb))
 611                 return -EOPNOTSUPP;
 612
 613         /*
 614          * In order to get correct extent info, force all delayed allocation
 615          * blocks to be allocated, otherwise delayed allocation blocks may not
 616          * be reflected and bypass the checks on extent header.
 617          */
 618         if (test_opt(inode->i_sb, DELALLOC))
 619                 ext4_alloc_da_blocks(inode);
 620
 621         percpu_down_write(&sbi->s_writepages_rwsem);
 622
 623         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
 624         if (IS_ERR(handle)) {
 625                 ret = PTR_ERR(handle);
 626                 goto out_unlock;
 627         }
 628
 629         down_write(&EXT4_I(inode)->i_data_sem);
 630         ret = ext4_ext_check_inode(inode);
 631         if (ret)
 632                 goto errout;
 633
 634         eh = ext_inode_hdr(inode);
 635         ex  = EXT_FIRST_EXTENT(eh);
 636         if (ext4_blocks_count(es) > EXT4_MAX_BLOCK_FILE_PHYS ||
 637             eh->eh_depth != 0 || le16_to_cpu(eh->eh_entries) > 1) {
 638                 ret = -EOPNOTSUPP;
 639                 goto errout;
 640         }
 641         if (eh->eh_entries == 0)
 642                 blk = len = start = end = 0;
 643         else {
 644                 len = le16_to_cpu(ex->ee_len);
 645                 blk = ext4_ext_pblock(ex);
 646                 start = le32_to_cpu(ex->ee_block);
 647                 end = start + len - 1;
 648                 if (end >= EXT4_NDIR_BLOCKS) {
 649                         ret = -EOPNOTSUPP;
 650                         goto errout;
 651                 }
 652         }
 653
 654         ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
 655         memset(ei->i_data, 0, sizeof(ei->i_data));
 656         for (i = start; i <= end; i++)
 657                 ei->i_data[i] = cpu_to_le32(blk++);
 658         ext4_mark_inode_dirty(handle, inode);
 659 errout:
 660         ext4_journal_stop(handle);
 661         up_write(&EXT4_I(inode)->i_data_sem);
 662 out_unlock:
 663         percpu_up_write(&sbi->s_writepages_rwsem);
 664         return ret;
 665 }