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/module.h>
  16 #include <linux/ext4_jbd2.h>
  17 #include <linux/ext4_fs_extents.h>
  18
  19 /*
  20  * The contiguous blocks details which can be
  21  * represented by a single extent
  22  */
  23 struct list_blocks_struct {
  24         ext4_lblk_t first_block, last_block;
  25         ext4_fsblk_t first_pblock, last_pblock;
  26 };
  27
  28 static int finish_range(handle_t *handle, struct inode *inode,
  29                                 struct list_blocks_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         path = ext4_ext_find_extent(inode, lb->first_block, NULL);
  43
  44         if (IS_ERR(path)) {
  45                 retval = PTR_ERR(path);
  46                 goto err_out;
  47         }
  48
  49         /*
  50          * Calculate the credit needed to inserting this extent
  51          * Since we are doing this in loop we may accumalate extra
  52          * credit. But below we try to not accumalate too much
  53          * of them by restarting the journal.
  54          */
  55         needed = ext4_ext_calc_credits_for_insert(inode, path);
  56
  57         /*
  58          * Make sure the credit we accumalated is not really high
  59          */
  60         if (needed && handle->h_buffer_credits >= EXT4_RESERVE_TRANS_BLOCKS) {
  61                 retval = ext4_journal_restart(handle, needed);
  62                 if (retval)
  63                         goto err_out;
  64         } else if (needed) {
  65                 retval = ext4_journal_extend(handle, needed);
  66                 if (retval) {
  67                         /*
  68                          * IF not able to extend the journal restart the journal
  69                          */
  70                         retval = ext4_journal_restart(handle, needed);
  71                         if (retval)
  72                                 goto err_out;
  73                 }
  74         }
  75         retval = ext4_ext_insert_extent(handle, inode, path, &newext);
  76 err_out:
  77         lb->first_pblock = 0;
  78         return retval;
  79 }
  80
  81 static int update_extent_range(handle_t *handle, struct inode *inode,
  82                                 ext4_fsblk_t pblock, ext4_lblk_t blk_num,
  83                                 struct list_blocks_struct *lb)
  84 {
  85         int retval;
  86         /*
  87          * See if we can add on to the existing range (if it exists)
  88          */
  89         if (lb->first_pblock &&
  90                 (lb->last_pblock+1 == pblock) &&
  91                 (lb->last_block+1 == blk_num)) {
  92                 lb->last_pblock = pblock;
  93                 lb->last_block = blk_num;
  94                 return 0;
  95         }
  96         /*
  97          * Start a new range.
  98          */
  99         retval = finish_range(handle, inode, lb);
 100         lb->first_pblock = lb->last_pblock = pblock;
 101         lb->first_block = lb->last_block = blk_num;
 102
 103         return retval;
 104 }
 105
 106 static int update_ind_extent_range(handle_t *handle, struct inode *inode,
 107                                    ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 108                                    struct list_blocks_struct *lb)
 109 {
 110         struct buffer_head *bh;
 111         __le32 *i_data;
 112         int i, retval = 0;
 113         ext4_lblk_t blk_count = *blk_nump;
 114         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 115
 116         if (!pblock) {
 117                 /* Only update the file block number */
 118                 *blk_nump += max_entries;
 119                 return 0;
 120         }
 121
 122         bh = sb_bread(inode->i_sb, pblock);
 123         if (!bh)
 124                 return -EIO;
 125
 126         i_data = (__le32 *)bh->b_data;
 127         for (i = 0; i < max_entries; i++, blk_count++) {
 128                 if (i_data[i]) {
 129                         retval = update_extent_range(handle, inode,
 130                                                 le32_to_cpu(i_data[i]),
 131                                                 blk_count, lb);
 132                         if (retval)
 133                                 break;
 134                 }
 135         }
 136
 137         /* Update the file block number */
 138         *blk_nump = blk_count;
 139         put_bh(bh);
 140         return retval;
 141
 142 }
 143
 144 static int update_dind_extent_range(handle_t *handle, struct inode *inode,
 145                                     ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 146                                     struct list_blocks_struct *lb)
 147 {
 148         struct buffer_head *bh;
 149         __le32 *i_data;
 150         int i, retval = 0;
 151         ext4_lblk_t blk_count = *blk_nump;
 152         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 153
 154         if (!pblock) {
 155                 /* Only update the file block number */
 156                 *blk_nump += max_entries * max_entries;
 157                 return 0;
 158         }
 159         bh = sb_bread(inode->i_sb, pblock);
 160         if (!bh)
 161                 return -EIO;
 162
 163         i_data = (__le32 *)bh->b_data;
 164         for (i = 0; i < max_entries; i++) {
 165                 if (i_data[i]) {
 166                         retval = update_ind_extent_range(handle, inode,
 167                                                 le32_to_cpu(i_data[i]),
 168                                                 &blk_count, lb);
 169                         if (retval)
 170                                 break;
 171                 } else {
 172                         /* Only update the file block number */
 173                         blk_count += max_entries;
 174                 }
 175         }
 176
 177         /* Update the file block number */
 178         *blk_nump = blk_count;
 179         put_bh(bh);
 180         return retval;
 181
 182 }
 183
 184 static int update_tind_extent_range(handle_t *handle, struct inode *inode,
 185                                      ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 186                                      struct list_blocks_struct *lb)
 187 {
 188         struct buffer_head *bh;
 189         __le32 *i_data;
 190         int i, retval = 0;
 191         ext4_lblk_t blk_count = *blk_nump;
 192         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 193
 194         if (!pblock) {
 195                 /* Only update the file block number */
 196                 *blk_nump += max_entries * max_entries * max_entries;
 197                 return 0;
 198         }
 199         bh = sb_bread(inode->i_sb, pblock);
 200         if (!bh)
 201                 return -EIO;
 202
 203         i_data = (__le32 *)bh->b_data;
 204         for (i = 0; i < max_entries; i++) {
 205                 if (i_data[i]) {
 206                         retval = update_dind_extent_range(handle, inode,
 207                                                 le32_to_cpu(i_data[i]),
 208                                                 &blk_count, lb);
 209                         if (retval)
 210                                 break;
 211                 } else
 212                         /* Only update the file block number */
 213                         blk_count += max_entries * max_entries;
 214         }
 215         /* Update the file block number */
 216         *blk_nump = blk_count;
 217         put_bh(bh);
 218         return retval;
 219
 220 }
 221
 222 static int extend_credit_for_blkdel(handle_t *handle, struct inode *inode)
 223 {
 224         int retval = 0, needed;
 225
 226         if (handle->h_buffer_credits > EXT4_RESERVE_TRANS_BLOCKS)
 227                 return 0;
 228         /*
 229          * We are freeing a blocks. During this we touch
 230          * superblock, group descriptor and block bitmap.
 231          * So allocate a credit of 3. We may update
 232          * quota (user and group).
 233          */
 234         needed = 3 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
 235
 236         if (ext4_journal_extend(handle, needed) != 0)
 237                 retval = ext4_journal_restart(handle, needed);
 238
 239         return retval;
 240 }
 241
 242 static int free_dind_blocks(handle_t *handle,
 243                                 struct inode *inode, __le32 i_data)
 244 {
 245         int i;
 246         __le32 *tmp_idata;
 247         struct buffer_head *bh;
 248         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 249
 250         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 251         if (!bh)
 252                 return -EIO;
 253
 254         tmp_idata = (__le32 *)bh->b_data;
 255         for (i = 0; i < max_entries; i++) {
 256                 if (tmp_idata[i]) {
 257                         extend_credit_for_blkdel(handle, inode);
 258                         ext4_free_blocks(handle, inode,
 259                                         le32_to_cpu(tmp_idata[i]), 1, 1);
 260                 }
 261         }
 262         put_bh(bh);
 263         extend_credit_for_blkdel(handle, inode);
 264         ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
 265         return 0;
 266 }
 267
 268 static int free_tind_blocks(handle_t *handle,
 269                                 struct inode *inode, __le32 i_data)
 270 {
 271         int i, retval = 0;
 272         __le32 *tmp_idata;
 273         struct buffer_head *bh;
 274         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 275
 276         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 277         if (!bh)
 278                 return -EIO;
 279
 280         tmp_idata = (__le32 *)bh->b_data;
 281         for (i = 0; i < max_entries; i++) {
 282                 if (tmp_idata[i]) {
 283                         retval = free_dind_blocks(handle,
 284                                         inode, tmp_idata[i]);
 285                         if (retval) {
 286                                 put_bh(bh);
 287                                 return retval;
 288                         }
 289                 }
 290         }
 291         put_bh(bh);
 292         extend_credit_for_blkdel(handle, inode);
 293         ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
 294         return 0;
 295 }
 296
 297 static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
 298 {
 299         int retval;
 300
 301         /* ei->i_data[EXT4_IND_BLOCK] */
 302         if (i_data[0]) {
 303                 extend_credit_for_blkdel(handle, inode);
 304                 ext4_free_blocks(handle, inode,
 305                                 le32_to_cpu(i_data[0]), 1, 1);
 306         }
 307
 308         /* ei->i_data[EXT4_DIND_BLOCK] */
 309         if (i_data[1]) {
 310                 retval = free_dind_blocks(handle, inode, i_data[1]);
 311                 if (retval)
 312                         return retval;
 313         }
 314
 315         /* ei->i_data[EXT4_TIND_BLOCK] */
 316         if (i_data[2]) {
 317                 retval = free_tind_blocks(handle, inode, i_data[2]);
 318                 if (retval)
 319                         return retval;
 320         }
 321         return 0;
 322 }
 323
 324 static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
 325                                 struct inode *tmp_inode)
 326 {
 327         int retval;
 328         __le32  i_data[3];
 329         struct ext4_inode_info *ei = EXT4_I(inode);
 330         struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);
 331
 332         /*
 333          * One credit accounted for writing the
 334          * i_data field of the original inode
 335          */
 336         retval = ext4_journal_extend(handle, 1);
 337         if (retval != 0) {
 338                 retval = ext4_journal_restart(handle, 1);
 339                 if (retval)
 340                         goto err_out;
 341         }
 342
 343         i_data[0] = ei->i_data[EXT4_IND_BLOCK];
 344         i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
 345         i_data[2] = ei->i_data[EXT4_TIND_BLOCK];
 346
 347         down_write(&EXT4_I(inode)->i_data_sem);
 348         /*
 349          * We have the extent map build with the tmp inode.
 350          * Now copy the i_data across
 351          */
 352         ei->i_flags |= EXT4_EXTENTS_FL;
 353         memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));
 354
 355         /*
 356          * Update i_blocks with the new blocks that got
 357          * allocated while adding extents for extent index
 358          * blocks.
 359          *
 360          * While converting to extents we need not
 361          * update the orignal inode i_blocks for extent blocks
 362          * via quota APIs. The quota update happened via tmp_inode already.
 363          */
 364         spin_lock(&inode->i_lock);
 365         inode->i_blocks += tmp_inode->i_blocks;
 366         spin_unlock(&inode->i_lock);
 367         up_write(&EXT4_I(inode)->i_data_sem);
 368
 369         /*
 370          * We mark the inode dirty after, because we decrement the
 371          * i_blocks when freeing the indirect meta-data blocks
 372          */
 373         retval = free_ind_block(handle, inode, i_data);
 374         ext4_mark_inode_dirty(handle, inode);
 375
 376 err_out:
 377         return retval;
 378 }
 379
 380 static int free_ext_idx(handle_t *handle, struct inode *inode,
 381                                         struct ext4_extent_idx *ix)
 382 {
 383         int i, retval = 0;
 384         ext4_fsblk_t block;
 385         struct buffer_head *bh;
 386         struct ext4_extent_header *eh;
 387
 388         block = idx_pblock(ix);
 389         bh = sb_bread(inode->i_sb, block);
 390         if (!bh)
 391                 return -EIO;
 392
 393         eh = (struct ext4_extent_header *)bh->b_data;
 394         if (eh->eh_depth != 0) {
 395                 ix = EXT_FIRST_INDEX(eh);
 396                 for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 397                         retval = free_ext_idx(handle, inode, ix);
 398                         if (retval)
 399                                 break;
 400                 }
 401         }
 402         put_bh(bh);
 403         extend_credit_for_blkdel(handle, inode);
 404         ext4_free_blocks(handle, inode, block, 1, 1);
 405         return retval;
 406 }
 407
 408 /*
 409  * Free the extent meta data blocks only
 410  */
 411 static int free_ext_block(handle_t *handle, struct inode *inode)
 412 {
 413         int i, retval = 0;
 414         struct ext4_inode_info *ei = EXT4_I(inode);
 415         struct ext4_extent_header *eh = (struct ext4_extent_header *)ei->i_data;
 416         struct ext4_extent_idx *ix;
 417         if (eh->eh_depth == 0)
 418                 /*
 419                  * No extra blocks allocated for extent meta data
 420                  */
 421                 return 0;
 422         ix = EXT_FIRST_INDEX(eh);
 423         for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 424                 retval = free_ext_idx(handle, inode, ix);
 425                 if (retval)
 426                         return retval;
 427         }
 428         return retval;
 429
 430 }
 431
 432 int ext4_ext_migrate(struct inode *inode, struct file *filp,
 433                                 unsigned int cmd, unsigned long arg)
 434 {
 435         handle_t *handle;
 436         int retval = 0, i;
 437         __le32 *i_data;
 438         ext4_lblk_t blk_count = 0;
 439         struct ext4_inode_info *ei;
 440         struct inode *tmp_inode = NULL;
 441         struct list_blocks_struct lb;
 442         unsigned long max_entries;
 443
 444         if (!test_opt(inode->i_sb, EXTENTS))
 445                 /*
 446                  * if mounted with noextents we don't allow the migrate
 447                  */
 448                 return -EINVAL;
 449
 450         if ((EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
 451                 return -EINVAL;
 452
 453         if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)
 454                 /*
 455                  * don't migrate fast symlink
 456                  */
 457                 return retval;
 458
 459         handle = ext4_journal_start(inode,
 460                                         EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
 461                                         EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
 462                                         2 * EXT4_QUOTA_INIT_BLOCKS(inode->i_sb)
 463                                         + 1);
 464         if (IS_ERR(handle)) {
 465                 retval = PTR_ERR(handle);
 466                 goto err_out;
 467         }
 468         tmp_inode = ext4_new_inode(handle,
 469                                 inode->i_sb->s_root->d_inode,
 470                                 S_IFREG);
 471         if (IS_ERR(tmp_inode)) {
 472                 retval = -ENOMEM;
 473                 ext4_journal_stop(handle);
 474                 tmp_inode = NULL;
 475                 goto err_out;
 476         }
 477         i_size_write(tmp_inode, i_size_read(inode));
 478         /*
 479          * We don't want the inode to be reclaimed
 480          * if we got interrupted in between. We have
 481          * this tmp inode carrying reference to the
 482          * data blocks of the original file. We set
 483          * the i_nlink to zero at the last stage after
 484          * switching the original file to extent format
 485          */
 486         tmp_inode->i_nlink = 1;
 487
 488         ext4_ext_tree_init(handle, tmp_inode);
 489         ext4_orphan_add(handle, tmp_inode);
 490         ext4_journal_stop(handle);
 491
 492         /*
 493          * start with one credit accounted for
 494          * superblock modification.
 495          *
 496          * For the tmp_inode we already have commited the
 497          * trascation that created the inode. Later as and
 498          * when we add extents we extent the journal
 499          */
 500         /*
 501          * inode_mutex prevent write and truncate on the file. Read still goes
 502          * through. We take i_data_sem in ext4_ext_swap_inode_data before we
 503          * switch the inode format to prevent read.
 504          */
 505         mutex_lock(&(inode->i_mutex));
 506         handle = ext4_journal_start(inode, 1);
 507
 508         ei = EXT4_I(inode);
 509         i_data = ei->i_data;
 510         memset(&lb, 0, sizeof(lb));
 511
 512         /* 32 bit block address 4 bytes */
 513         max_entries = inode->i_sb->s_blocksize >> 2;
 514         for (i = 0; i < EXT4_NDIR_BLOCKS; i++, blk_count++) {
 515                 if (i_data[i]) {
 516                         retval = update_extent_range(handle, tmp_inode,
 517                                                 le32_to_cpu(i_data[i]),
 518                                                 blk_count, &lb);
 519                         if (retval)
 520                                 goto err_out;
 521                 }
 522         }
 523         if (i_data[EXT4_IND_BLOCK]) {
 524                 retval = update_ind_extent_range(handle, tmp_inode,
 525                                         le32_to_cpu(i_data[EXT4_IND_BLOCK]),
 526                                         &blk_count, &lb);
 527                         if (retval)
 528                                 goto err_out;
 529         } else
 530                 blk_count +=  max_entries;
 531         if (i_data[EXT4_DIND_BLOCK]) {
 532                 retval = update_dind_extent_range(handle, tmp_inode,
 533                                         le32_to_cpu(i_data[EXT4_DIND_BLOCK]),
 534                                         &blk_count, &lb);
 535                         if (retval)
 536                                 goto err_out;
 537         } else
 538                 blk_count += max_entries * max_entries;
 539         if (i_data[EXT4_TIND_BLOCK]) {
 540                 retval = update_tind_extent_range(handle, tmp_inode,
 541                                         le32_to_cpu(i_data[EXT4_TIND_BLOCK]),
 542                                         &blk_count, &lb);
 543                         if (retval)
 544                                 goto err_out;
 545         }
 546         /*
 547          * Build the last extent
 548          */
 549         retval = finish_range(handle, tmp_inode, &lb);
 550 err_out:
 551         if (retval)
 552                 /*
 553                  * Failure case delete the extent information with the
 554                  * tmp_inode
 555                  */
 556                 free_ext_block(handle, tmp_inode);
 557         else
 558                 retval = ext4_ext_swap_inode_data(handle, inode,
 559                                                         tmp_inode);
 560
 561         /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
 562         if (ext4_journal_extend(handle, 1) != 0)
 563                 ext4_journal_restart(handle, 1);
 564
 565         /*
 566          * Mark the tmp_inode as of size zero
 567          */
 568         i_size_write(tmp_inode, 0);
 569
 570         /*
 571          * set the  i_blocks count to zero
 572          * so that the ext4_delete_inode does the
 573          * right job
 574          *
 575          * We don't need to take the i_lock because
 576          * the inode is not visible to user space.
 577          */
 578         tmp_inode->i_blocks = 0;
 579
 580         /* Reset the extent details */
 581         ext4_ext_tree_init(handle, tmp_inode);
 582
 583         /*
 584          * Set the i_nlink to zero so that
 585          * generic_drop_inode really deletes the
 586          * inode
 587          */
 588         tmp_inode->i_nlink = 0;
 589
 590         ext4_journal_stop(handle);
 591         mutex_unlock(&(inode->i_mutex));
 592
 593         if (tmp_inode)
 594                 iput(tmp_inode);
 595
 596         return retval;
 597 }