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         /*
  54          * Make sure the credit we accumalated is not really high
  55          */
  56         if (needed && ext4_handle_has_enough_credits(handle,
  57                                                 EXT4_RESERVE_TRANS_BLOCKS)) {
  58                 up_write((&EXT4_I(inode)->i_data_sem));
  59                 retval = ext4_journal_restart(handle, needed);
  60                 down_write((&EXT4_I(inode)->i_data_sem));
  61                 if (retval)
  62                         goto err_out;
  63         } else if (needed) {
  64                 retval = ext4_journal_extend(handle, needed);
  65                 if (retval) {
  66                         /*
  67                          * IF not able to extend the journal restart the journal
  68                          */
  69                         up_write((&EXT4_I(inode)->i_data_sem));
  70                         retval = ext4_journal_restart(handle, needed);
  71                         down_write((&EXT4_I(inode)->i_data_sem));
  72                         if (retval)
  73                                 goto err_out;
  74                 }
  75         }
  76         retval = ext4_ext_insert_extent(handle, inode, &path, &newext, 0);
  77 err_out:
  78         up_write((&EXT4_I(inode)->i_data_sem));
  79         ext4_ext_drop_refs(path);
  80         kfree(path);
  81         lb->first_pblock = 0;
  82         return retval;
  83 }
  84
  85 static int update_extent_range(handle_t *handle, struct inode *inode,
  86                                ext4_fsblk_t pblock, struct migrate_struct *lb)
  87 {
  88         int retval;
  89         /*
  90          * See if we can add on to the existing range (if it exists)
  91          */
  92         if (lb->first_pblock &&
  93                 (lb->last_pblock+1 == pblock) &&
  94                 (lb->last_block+1 == lb->curr_block)) {
  95                 lb->last_pblock = pblock;
  96                 lb->last_block = lb->curr_block;
  97                 lb->curr_block++;
  98                 return 0;
  99         }
 100         /*
 101          * Start a new range.
 102          */
 103         retval = finish_range(handle, inode, lb);
 104         lb->first_pblock = lb->last_pblock = pblock;
 105         lb->first_block = lb->last_block = lb->curr_block;
 106         lb->curr_block++;
 107         return retval;
 108 }
 109
 110 static int update_ind_extent_range(handle_t *handle, struct inode *inode,
 111                                    ext4_fsblk_t pblock,
 112                                    struct migrate_struct *lb)
 113 {
 114         struct buffer_head *bh;
 115         __le32 *i_data;
 116         int i, retval = 0;
 117         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 118
 119         bh = sb_bread(inode->i_sb, pblock);
 120         if (!bh)
 121                 return -EIO;
 122
 123         i_data = (__le32 *)bh->b_data;
 124         for (i = 0; i < max_entries; i++) {
 125                 if (i_data[i]) {
 126                         retval = update_extent_range(handle, inode,
 127                                                 le32_to_cpu(i_data[i]), lb);
 128                         if (retval)
 129                                 break;
 130                 } else {
 131                         lb->curr_block++;
 132                 }
 133         }
 134         put_bh(bh);
 135         return retval;
 136
 137 }
 138
 139 static int update_dind_extent_range(handle_t *handle, struct inode *inode,
 140                                     ext4_fsblk_t pblock,
 141                                     struct migrate_struct *lb)
 142 {
 143         struct buffer_head *bh;
 144         __le32 *i_data;
 145         int i, retval = 0;
 146         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 147
 148         bh = sb_bread(inode->i_sb, pblock);
 149         if (!bh)
 150                 return -EIO;
 151
 152         i_data = (__le32 *)bh->b_data;
 153         for (i = 0; i < max_entries; i++) {
 154                 if (i_data[i]) {
 155                         retval = update_ind_extent_range(handle, inode,
 156                                                 le32_to_cpu(i_data[i]), lb);
 157                         if (retval)
 158                                 break;
 159                 } else {
 160                         /* Only update the file block number */
 161                         lb->curr_block += max_entries;
 162                 }
 163         }
 164         put_bh(bh);
 165         return retval;
 166
 167 }
 168
 169 static int update_tind_extent_range(handle_t *handle, struct inode *inode,
 170                                     ext4_fsblk_t pblock,
 171                                     struct migrate_struct *lb)
 172 {
 173         struct buffer_head *bh;
 174         __le32 *i_data;
 175         int i, retval = 0;
 176         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 177
 178         bh = sb_bread(inode->i_sb, pblock);
 179         if (!bh)
 180                 return -EIO;
 181
 182         i_data = (__le32 *)bh->b_data;
 183         for (i = 0; i < max_entries; i++) {
 184                 if (i_data[i]) {
 185                         retval = update_dind_extent_range(handle, inode,
 186                                                 le32_to_cpu(i_data[i]), lb);
 187                         if (retval)
 188                                 break;
 189                 } else {
 190                         /* Only update the file block number */
 191                         lb->curr_block += max_entries * max_entries;
 192                 }
 193         }
 194         put_bh(bh);
 195         return retval;
 196
 197 }
 198
 199 static int extend_credit_for_blkdel(handle_t *handle, struct inode *inode)
 200 {
 201         int retval = 0, needed;
 202
 203         if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
 204                 return 0;
 205         /*
 206          * We are freeing a blocks. During this we touch
 207          * superblock, group descriptor and block bitmap.
 208          * So allocate a credit of 3. We may update
 209          * quota (user and group).
 210          */
 211         needed = 3 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);
 212
 213         if (ext4_journal_extend(handle, needed) != 0)
 214                 retval = ext4_journal_restart(handle, needed);
 215
 216         return retval;
 217 }
 218
 219 static int free_dind_blocks(handle_t *handle,
 220                                 struct inode *inode, __le32 i_data)
 221 {
 222         int i;
 223         __le32 *tmp_idata;
 224         struct buffer_head *bh;
 225         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 226
 227         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 228         if (!bh)
 229                 return -EIO;
 230
 231         tmp_idata = (__le32 *)bh->b_data;
 232         for (i = 0; i < max_entries; i++) {
 233                 if (tmp_idata[i]) {
 234                         extend_credit_for_blkdel(handle, inode);
 235                         ext4_free_blocks(handle, inode, NULL,
 236                                          le32_to_cpu(tmp_idata[i]), 1,
 237                                          EXT4_FREE_BLOCKS_METADATA |
 238                                          EXT4_FREE_BLOCKS_FORGET);
 239                 }
 240         }
 241         put_bh(bh);
 242         extend_credit_for_blkdel(handle, inode);
 243         ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
 244                          EXT4_FREE_BLOCKS_METADATA |
 245                          EXT4_FREE_BLOCKS_FORGET);
 246         return 0;
 247 }
 248
 249 static int free_tind_blocks(handle_t *handle,
 250                                 struct inode *inode, __le32 i_data)
 251 {
 252         int i, retval = 0;
 253         __le32 *tmp_idata;
 254         struct buffer_head *bh;
 255         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 256
 257         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 258         if (!bh)
 259                 return -EIO;
 260
 261         tmp_idata = (__le32 *)bh->b_data;
 262         for (i = 0; i < max_entries; i++) {
 263                 if (tmp_idata[i]) {
 264                         retval = free_dind_blocks(handle,
 265                                         inode, tmp_idata[i]);
 266                         if (retval) {
 267                                 put_bh(bh);
 268                                 return retval;
 269                         }
 270                 }
 271         }
 272         put_bh(bh);
 273         extend_credit_for_blkdel(handle, inode);
 274         ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
 275                          EXT4_FREE_BLOCKS_METADATA |
 276                          EXT4_FREE_BLOCKS_FORGET);
 277         return 0;
 278 }
 279
 280 static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
 281 {
 282         int retval;
 283
 284         /* ei->i_data[EXT4_IND_BLOCK] */
 285         if (i_data[0]) {
 286                 extend_credit_for_blkdel(handle, inode);
 287                 ext4_free_blocks(handle, inode, NULL,
 288                                 le32_to_cpu(i_data[0]), 1,
 289                                  EXT4_FREE_BLOCKS_METADATA |
 290                                  EXT4_FREE_BLOCKS_FORGET);
 291         }
 292
 293         /* ei->i_data[EXT4_DIND_BLOCK] */
 294         if (i_data[1]) {
 295                 retval = free_dind_blocks(handle, inode, i_data[1]);
 296                 if (retval)
 297                         return retval;
 298         }
 299
 300         /* ei->i_data[EXT4_TIND_BLOCK] */
 301         if (i_data[2]) {
 302                 retval = free_tind_blocks(handle, inode, i_data[2]);
 303                 if (retval)
 304                         return retval;
 305         }
 306         return 0;
 307 }
 308
 309 static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
 310                                                 struct inode *tmp_inode)
 311 {
 312         int retval;
 313         __le32  i_data[3];
 314         struct ext4_inode_info *ei = EXT4_I(inode);
 315         struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);
 316
 317         /*
 318          * One credit accounted for writing the
 319          * i_data field of the original inode
 320          */
 321         retval = ext4_journal_extend(handle, 1);
 322         if (retval) {
 323                 retval = ext4_journal_restart(handle, 1);
 324                 if (retval)
 325                         goto err_out;
 326         }
 327
 328         i_data[0] = ei->i_data[EXT4_IND_BLOCK];
 329         i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
 330         i_data[2] = ei->i_data[EXT4_TIND_BLOCK];
 331
 332         down_write(&EXT4_I(inode)->i_data_sem);
 333         /*
 334          * if EXT4_STATE_EXT_MIGRATE is cleared a block allocation
 335          * happened after we started the migrate. We need to
 336          * fail the migrate
 337          */
 338         if (!ext4_test_inode_state(inode, EXT4_STATE_EXT_MIGRATE)) {
 339                 retval = -EAGAIN;
 340                 up_write(&EXT4_I(inode)->i_data_sem);
 341                 goto err_out;
 342         } else
 343                 ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 344         /*
 345          * We have the extent map build with the tmp inode.
 346          * Now copy the i_data across
 347          */
 348         ext4_set_inode_flag(inode, EXT4_INODE_EXTENTS);
 349         memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));
 350
 351         /*
 352          * Update i_blocks with the new blocks that got
 353          * allocated while adding extents for extent index
 354          * blocks.
 355          *
 356          * While converting to extents we need not
 357          * update the original inode i_blocks for extent blocks
 358          * via quota APIs. The quota update happened via tmp_inode already.
 359          */
 360         spin_lock(&inode->i_lock);
 361         inode->i_blocks += tmp_inode->i_blocks;
 362         spin_unlock(&inode->i_lock);
 363         up_write(&EXT4_I(inode)->i_data_sem);
 364
 365         /*
 366          * We mark the inode dirty after, because we decrement the
 367          * i_blocks when freeing the indirect meta-data blocks
 368          */
 369         retval = free_ind_block(handle, inode, i_data);
 370         ext4_mark_inode_dirty(handle, inode);
 371
 372 err_out:
 373         return retval;
 374 }
 375
 376 static int free_ext_idx(handle_t *handle, struct inode *inode,
 377                                         struct ext4_extent_idx *ix)
 378 {
 379         int i, retval = 0;
 380         ext4_fsblk_t block;
 381         struct buffer_head *bh;
 382         struct ext4_extent_header *eh;
 383
 384         block = ext4_idx_pblock(ix);
 385         bh = sb_bread(inode->i_sb, block);
 386         if (!bh)
 387                 return -EIO;
 388
 389         eh = (struct ext4_extent_header *)bh->b_data;
 390         if (eh->eh_depth != 0) {
 391                 ix = EXT_FIRST_INDEX(eh);
 392                 for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 393                         retval = free_ext_idx(handle, inode, ix);
 394                         if (retval)
 395                                 break;
 396                 }
 397         }
 398         put_bh(bh);
 399         extend_credit_for_blkdel(handle, inode);
 400         ext4_free_blocks(handle, inode, NULL, block, 1,
 401                          EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
 402         return retval;
 403 }
 404
 405 /*
 406  * Free the extent meta data blocks only
 407  */
 408 static int free_ext_block(handle_t *handle, struct inode *inode)
 409 {
 410         int i, retval = 0;
 411         struct ext4_inode_info *ei = EXT4_I(inode);
 412         struct ext4_extent_header *eh = (struct ext4_extent_header *)ei->i_data;
 413         struct ext4_extent_idx *ix;
 414         if (eh->eh_depth == 0)
 415                 /*
 416                  * No extra blocks allocated for extent meta data
 417                  */
 418                 return 0;
 419         ix = EXT_FIRST_INDEX(eh);
 420         for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 421                 retval = free_ext_idx(handle, inode, ix);
 422                 if (retval)
 423                         return retval;
 424         }
 425         return retval;
 426 }
 427
 428 int ext4_ext_migrate(struct inode *inode)
 429 {
 430         handle_t *handle;
 431         int retval = 0, i;
 432         __le32 *i_data;
 433         struct ext4_inode_info *ei;
 434         struct inode *tmp_inode = NULL;
 435         struct migrate_struct lb;
 436         unsigned long max_entries;
 437         __u32 goal;
 438         uid_t owner[2];
 439
 440         /*
 441          * If the filesystem does not support extents, or the inode
 442          * already is extent-based, error out.
 443          */
 444         if (!ext4_has_feature_extents(inode->i_sb) ||
 445             (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 446                 return -EINVAL;
 447
 448         if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)
 449                 /*
 450                  * don't migrate fast symlink
 451                  */
 452                 return retval;
 453
 454         /*
 455          * Worst case we can touch the allocation bitmaps, a bgd
 456          * block, and a block to link in the orphan list.  We do need
 457          * need to worry about credits for modifying the quota inode.
 458          */
 459         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE,
 460                 4 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb));
 461
 462         if (IS_ERR(handle)) {
 463                 retval = PTR_ERR(handle);
 464                 return retval;
 465         }
 466         goal = (((inode->i_ino - 1) / EXT4_INODES_PER_GROUP(inode->i_sb)) *
 467                 EXT4_INODES_PER_GROUP(inode->i_sb)) + 1;
 468         owner[0] = i_uid_read(inode);
 469         owner[1] = i_gid_read(inode);
 470         tmp_inode = ext4_new_inode(handle, d_inode(inode->i_sb->s_root),
 471                                    S_IFREG, NULL, goal, owner, 0);
 472         if (IS_ERR(tmp_inode)) {
 473                 retval = PTR_ERR(tmp_inode);
 474                 ext4_journal_stop(handle);
 475                 return retval;
 476         }
 477         i_size_write(tmp_inode, i_size_read(inode));
 478         /*
 479          * Set the i_nlink to zero so it will be deleted later
 480          * when we drop inode reference.
 481          */
 482         clear_nlink(tmp_inode);
 483
 484         ext4_ext_tree_init(handle, tmp_inode);
 485         ext4_orphan_add(handle, tmp_inode);
 486         ext4_journal_stop(handle);
 487
 488         /*
 489          * start with one credit accounted for
 490          * superblock modification.
 491          *
 492          * For the tmp_inode we already have committed the
 493          * transaction that created the inode. Later as and
 494          * when we add extents we extent the journal
 495          */
 496         /*
 497          * Even though we take i_mutex we can still cause block
 498          * allocation via mmap write to holes. If we have allocated
 499          * new blocks we fail migrate.  New block allocation will
 500          * clear EXT4_STATE_EXT_MIGRATE flag.  The flag is updated
 501          * with i_data_sem held to prevent racing with block
 502          * allocation.
 503          */
 504         down_read(&EXT4_I(inode)->i_data_sem);
 505         ext4_set_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 506         up_read((&EXT4_I(inode)->i_data_sem));
 507
 508         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
 509         if (IS_ERR(handle)) {
 510                 /*
 511                  * It is impossible to update on-disk structures without
 512                  * a handle, so just rollback in-core changes and live other
 513                  * work to orphan_list_cleanup()
 514                  */
 515                 ext4_orphan_del(NULL, tmp_inode);
 516                 retval = PTR_ERR(handle);
 517                 goto out;
 518         }
 519
 520         ei = EXT4_I(inode);
 521         i_data = ei->i_data;
 522         memset(&lb, 0, sizeof(lb));
 523
 524         /* 32 bit block address 4 bytes */
 525         max_entries = inode->i_sb->s_blocksize >> 2;
 526         for (i = 0; i < EXT4_NDIR_BLOCKS; i++) {
 527                 if (i_data[i]) {
 528                         retval = update_extent_range(handle, tmp_inode,
 529                                                 le32_to_cpu(i_data[i]), &lb);
 530                         if (retval)
 531                                 goto err_out;
 532                 } else
 533                         lb.curr_block++;
 534         }
 535         if (i_data[EXT4_IND_BLOCK]) {
 536                 retval = update_ind_extent_range(handle, tmp_inode,
 537                                 le32_to_cpu(i_data[EXT4_IND_BLOCK]), &lb);
 538                         if (retval)
 539                                 goto err_out;
 540         } else
 541                 lb.curr_block += max_entries;
 542         if (i_data[EXT4_DIND_BLOCK]) {
 543                 retval = update_dind_extent_range(handle, tmp_inode,
 544                                 le32_to_cpu(i_data[EXT4_DIND_BLOCK]), &lb);
 545                         if (retval)
 546                                 goto err_out;
 547         } else
 548                 lb.curr_block += max_entries * max_entries;
 549         if (i_data[EXT4_TIND_BLOCK]) {
 550                 retval = update_tind_extent_range(handle, tmp_inode,
 551                                 le32_to_cpu(i_data[EXT4_TIND_BLOCK]), &lb);
 552                         if (retval)
 553                                 goto err_out;
 554         }
 555         /*
 556          * Build the last extent
 557          */
 558         retval = finish_range(handle, tmp_inode, &lb);
 559 err_out:
 560         if (retval)
 561                 /*
 562                  * Failure case delete the extent information with the
 563                  * tmp_inode
 564                  */
 565                 free_ext_block(handle, tmp_inode);
 566         else {
 567                 retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
 568                 if (retval)
 569                         /*
 570                          * if we fail to swap inode data free the extent
 571                          * details of the tmp inode
 572                          */
 573                         free_ext_block(handle, tmp_inode);
 574         }
 575
 576         /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
 577         if (ext4_journal_extend(handle, 1) != 0)
 578                 ext4_journal_restart(handle, 1);
 579
 580         /*
 581          * Mark the tmp_inode as of size zero
 582          */
 583         i_size_write(tmp_inode, 0);
 584
 585         /*
 586          * set the  i_blocks count to zero
 587          * so that the ext4_evict_inode() does the
 588          * right job
 589          *
 590          * We don't need to take the i_lock because
 591          * the inode is not visible to user space.
 592          */
 593         tmp_inode->i_blocks = 0;
 594
 595         /* Reset the extent details */
 596         ext4_ext_tree_init(handle, tmp_inode);
 597         ext4_journal_stop(handle);
 598 out:
 599         unlock_new_inode(tmp_inode);
 600         iput(tmp_inode);
 601
 602         return retval;
 603 }
 604
 605 /*
 606  * Migrate a simple extent-based inode to use the i_blocks[] array
 607  */
 608 int ext4_ind_migrate(struct inode *inode)
 609 {
 610         struct ext4_extent_header       *eh;
 611         struct ext4_super_block         *es = EXT4_SB(inode->i_sb)->s_es;
 612         struct ext4_inode_info          *ei = EXT4_I(inode);
 613         struct ext4_extent              *ex;
 614         unsigned int                    i, len;
 615         ext4_lblk_t                     start, end;
 616         ext4_fsblk_t                    blk;
 617         handle_t                        *handle;
 618         int                             ret;
 619
 620         if (!ext4_has_feature_extents(inode->i_sb) ||
 621             (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 622                 return -EINVAL;
 623
 624         if (ext4_has_feature_bigalloc(inode->i_sb))
 625                 return -EOPNOTSUPP;
 626
 627         /*
 628          * In order to get correct extent info, force all delayed allocation
 629          * blocks to be allocated, otherwise delayed allocation blocks may not
 630          * be reflected and bypass the checks on extent header.
 631          */
 632         if (test_opt(inode->i_sb, DELALLOC))
 633                 ext4_alloc_da_blocks(inode);
 634
 635         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
 636         if (IS_ERR(handle))
 637                 return PTR_ERR(handle);
 638
 639         down_write(&EXT4_I(inode)->i_data_sem);
 640         ret = ext4_ext_check_inode(inode);
 641         if (ret)
 642                 goto errout;
 643
 644         eh = ext_inode_hdr(inode);
 645         ex  = EXT_FIRST_EXTENT(eh);
 646         if (ext4_blocks_count(es) > EXT4_MAX_BLOCK_FILE_PHYS ||
 647             eh->eh_depth != 0 || le16_to_cpu(eh->eh_entries) > 1) {
 648                 ret = -EOPNOTSUPP;
 649                 goto errout;
 650         }
 651         if (eh->eh_entries == 0)
 652                 blk = len = start = end = 0;
 653         else {
 654                 len = le16_to_cpu(ex->ee_len);
 655                 blk = ext4_ext_pblock(ex);
 656                 start = le32_to_cpu(ex->ee_block);
 657                 end = start + len - 1;
 658                 if (end >= EXT4_NDIR_BLOCKS) {
 659                         ret = -EOPNOTSUPP;
 660                         goto errout;
 661                 }
 662         }
 663
 664         ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
 665         memset(ei->i_data, 0, sizeof(ei->i_data));
 666         for (i = start; i <= end; i++)
 667                 ei->i_data[i] = cpu_to_le32(blk++);
 668         ext4_mark_inode_dirty(handle, inode);
 669 errout:
 670         ext4_journal_stop(handle);
 671         up_write(&EXT4_I(inode)->i_data_sem);
 672         return ret;
 673 }