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 original 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         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 438         handle_t *handle;
 439         int retval = 0, i;
 440         __le32 *i_data;
 441         struct ext4_inode_info *ei;
 442         struct inode *tmp_inode = NULL;
 443         struct migrate_struct lb;
 444         unsigned long max_entries;
 445         __u32 goal;
 446         uid_t owner[2];
 447
 448         /*
 449          * If the filesystem does not support extents, or the inode
 450          * already is extent-based, error out.
 451          */
 452         if (!ext4_has_feature_extents(inode->i_sb) ||
 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         percpu_down_write(&sbi->s_writepages_rwsem);
 463
 464         /*
 465          * Worst case we can touch the allocation bitmaps and a block
 466          * group descriptor block.  We do need need to worry about
 467          * credits for modifying the quota inode.
 468          */
 469         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE,
 470                 3 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb));
 471
 472         if (IS_ERR(handle)) {
 473                 retval = PTR_ERR(handle);
 474                 goto out_unlock;
 475         }
 476         goal = (((inode->i_ino - 1) / EXT4_INODES_PER_GROUP(inode->i_sb)) *
 477                 EXT4_INODES_PER_GROUP(inode->i_sb)) + 1;
 478         owner[0] = i_uid_read(inode);
 479         owner[1] = i_gid_read(inode);
 480         tmp_inode = ext4_new_inode(handle, d_inode(inode->i_sb->s_root),
 481                                    S_IFREG, NULL, goal, owner);
 482         if (IS_ERR(tmp_inode)) {
 483                 retval = PTR_ERR(tmp_inode);
 484                 ext4_journal_stop(handle);
 485                 goto out_unlock;
 486         }
 487         /*
 488          * Use the correct seed for checksum (i.e. the seed from 'inode').  This
 489          * is so that the metadata blocks will have the correct checksum after
 490          * the migration.
 491          */
 492         ei = EXT4_I(inode);
 493         EXT4_I(tmp_inode)->i_csum_seed = ei->i_csum_seed;
 494         i_size_write(tmp_inode, i_size_read(inode));
 495         /*
 496          * Set the i_nlink to zero so it will be deleted later
 497          * when we drop inode reference.
 498          */
 499         clear_nlink(tmp_inode);
 500
 501         ext4_ext_tree_init(handle, tmp_inode);
 502         ext4_journal_stop(handle);
 503
 504         /*
 505          * start with one credit accounted for
 506          * superblock modification.
 507          *
 508          * For the tmp_inode we already have committed the
 509          * transaction that created the inode. Later as and
 510          * when we add extents we extent the journal
 511          */
 512         /*
 513          * Even though we take i_mutex we can still cause block
 514          * allocation via mmap write to holes. If we have allocated
 515          * new blocks we fail migrate.  New block allocation will
 516          * clear EXT4_STATE_EXT_MIGRATE flag.  The flag is updated
 517          * with i_data_sem held to prevent racing with block
 518          * allocation.
 519          */
 520         down_read(&EXT4_I(inode)->i_data_sem);
 521         ext4_set_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 522         up_read((&EXT4_I(inode)->i_data_sem));
 523
 524         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
 525         if (IS_ERR(handle)) {
 526                 retval = PTR_ERR(handle);
 527                 goto out_tmp_inode;
 528         }
 529
 530         i_data = ei->i_data;
 531         memset(&lb, 0, sizeof(lb));
 532
 533         /* 32 bit block address 4 bytes */
 534         max_entries = inode->i_sb->s_blocksize >> 2;
 535         for (i = 0; i < EXT4_NDIR_BLOCKS; i++) {
 536                 if (i_data[i]) {
 537                         retval = update_extent_range(handle, tmp_inode,
 538                                                 le32_to_cpu(i_data[i]), &lb);
 539                         if (retval)
 540                                 goto err_out;
 541                 } else
 542                         lb.curr_block++;
 543         }
 544         if (i_data[EXT4_IND_BLOCK]) {
 545                 retval = update_ind_extent_range(handle, tmp_inode,
 546                                 le32_to_cpu(i_data[EXT4_IND_BLOCK]), &lb);
 547                         if (retval)
 548                                 goto err_out;
 549         } else
 550                 lb.curr_block += max_entries;
 551         if (i_data[EXT4_DIND_BLOCK]) {
 552                 retval = update_dind_extent_range(handle, tmp_inode,
 553                                 le32_to_cpu(i_data[EXT4_DIND_BLOCK]), &lb);
 554                         if (retval)
 555                                 goto err_out;
 556         } else
 557                 lb.curr_block += max_entries * max_entries;
 558         if (i_data[EXT4_TIND_BLOCK]) {
 559                 retval = update_tind_extent_range(handle, tmp_inode,
 560                                 le32_to_cpu(i_data[EXT4_TIND_BLOCK]), &lb);
 561                         if (retval)
 562                                 goto err_out;
 563         }
 564         /*
 565          * Build the last extent
 566          */
 567         retval = finish_range(handle, tmp_inode, &lb);
 568 err_out:
 569         if (retval)
 570                 /*
 571                  * Failure case delete the extent information with the
 572                  * tmp_inode
 573                  */
 574                 free_ext_block(handle, tmp_inode);
 575         else {
 576                 retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
 577                 if (retval)
 578                         /*
 579                          * if we fail to swap inode data free the extent
 580                          * details of the tmp inode
 581                          */
 582                         free_ext_block(handle, tmp_inode);
 583         }
 584
 585         /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
 586         if (ext4_journal_extend(handle, 1) != 0)
 587                 ext4_journal_restart(handle, 1);
 588
 589         /*
 590          * Mark the tmp_inode as of size zero
 591          */
 592         i_size_write(tmp_inode, 0);
 593
 594         /*
 595          * set the  i_blocks count to zero
 596          * so that the ext4_evict_inode() does the
 597          * right job
 598          *
 599          * We don't need to take the i_lock because
 600          * the inode is not visible to user space.
 601          */
 602         tmp_inode->i_blocks = 0;
 603
 604         /* Reset the extent details */
 605         ext4_ext_tree_init(handle, tmp_inode);
 606         ext4_journal_stop(handle);
 607 out_tmp_inode:
 608         unlock_new_inode(tmp_inode);
 609         iput(tmp_inode);
 610 out_unlock:
 611         percpu_up_write(&sbi->s_writepages_rwsem);
 612         return retval;
 613 }
 614
 615 /*
 616  * Migrate a simple extent-based inode to use the i_blocks[] array
 617  */
 618 int ext4_ind_migrate(struct inode *inode)
 619 {
 620         struct ext4_extent_header       *eh;
 621         struct ext4_sb_info             *sbi = EXT4_SB(inode->i_sb);
 622         struct ext4_super_block         *es = sbi->s_es;
 623         struct ext4_inode_info          *ei = EXT4_I(inode);
 624         struct ext4_extent              *ex;
 625         unsigned int                    i, len;
 626         ext4_lblk_t                     start, end;
 627         ext4_fsblk_t                    blk;
 628         handle_t                        *handle;
 629         int                             ret;
 630
 631         if (!ext4_has_feature_extents(inode->i_sb) ||
 632             (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 633                 return -EINVAL;
 634
 635         if (ext4_has_feature_bigalloc(inode->i_sb))
 636                 return -EOPNOTSUPP;
 637
 638         /*
 639          * In order to get correct extent info, force all delayed allocation
 640          * blocks to be allocated, otherwise delayed allocation blocks may not
 641          * be reflected and bypass the checks on extent header.
 642          */
 643         if (test_opt(inode->i_sb, DELALLOC))
 644                 ext4_alloc_da_blocks(inode);
 645
 646         percpu_down_write(&sbi->s_writepages_rwsem);
 647
 648         handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
 649         if (IS_ERR(handle)) {
 650                 ret = PTR_ERR(handle);
 651                 goto out_unlock;
 652         }
 653
 654         down_write(&EXT4_I(inode)->i_data_sem);
 655         ret = ext4_ext_check_inode(inode);
 656         if (ret)
 657                 goto errout;
 658
 659         eh = ext_inode_hdr(inode);
 660         ex  = EXT_FIRST_EXTENT(eh);
 661         if (ext4_blocks_count(es) > EXT4_MAX_BLOCK_FILE_PHYS ||
 662             eh->eh_depth != 0 || le16_to_cpu(eh->eh_entries) > 1) {
 663                 ret = -EOPNOTSUPP;
 664                 goto errout;
 665         }
 666         if (eh->eh_entries == 0)
 667                 blk = len = start = end = 0;
 668         else {
 669                 len = le16_to_cpu(ex->ee_len);
 670                 blk = ext4_ext_pblock(ex);
 671                 start = le32_to_cpu(ex->ee_block);
 672                 end = start + len - 1;
 673                 if (end >= EXT4_NDIR_BLOCKS) {
 674                         ret = -EOPNOTSUPP;
 675                         goto errout;
 676                 }
 677         }
 678
 679         ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
 680         memset(ei->i_data, 0, sizeof(ei->i_data));
 681         for (i = start; i <= end; i++)
 682                 ei->i_data[i] = cpu_to_le32(blk++);
 683         ext4_mark_inode_dirty(handle, inode);
 684 errout:
 685         ext4_journal_stop(handle);
 686         up_write(&EXT4_I(inode)->i_data_sem);
 687 out_unlock:
 688         percpu_up_write(&sbi->s_writepages_rwsem);
 689         return ret;
 690 }