fs/ext4/migrate.c

   1 /*
   2  * Copyright IBM Corporation, 2007
   3  * Author Aneesh Kumar K.V <[email protected]>
   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 "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 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                 path = NULL;
  47                 goto err_out;
  48         }
  49
  50         /*
  51          * Calculate the credit needed to inserting this extent
  52          * Since we are doing this in loop we may accumalate extra
  53          * credit. But below we try to not accumalate too much
  54          * of them by restarting the journal.
  55          */
  56         needed = ext4_ext_calc_credits_for_single_extent(inode,
  57                     lb->last_block - lb->first_block + 1, path);
  58
  59         /*
  60          * Make sure the credit we accumalated is not really high
  61          */
  62         if (needed && ext4_handle_has_enough_credits(handle,
  63                                                 EXT4_RESERVE_TRANS_BLOCKS)) {
  64                 retval = ext4_journal_restart(handle, needed);
  65                 if (retval)
  66                         goto err_out;
  67         } else if (needed) {
  68                 retval = ext4_journal_extend(handle, needed);
  69                 if (retval) {
  70                         /*
  71                          * IF not able to extend the journal restart the journal
  72                          */
  73                         retval = ext4_journal_restart(handle, needed);
  74                         if (retval)
  75                                 goto err_out;
  76                 }
  77         }
  78         retval = ext4_ext_insert_extent(handle, inode, path, &newext, 0);
  79 err_out:
  80         if (path) {
  81                 ext4_ext_drop_refs(path);
  82                 kfree(path);
  83         }
  84         lb->first_pblock = 0;
  85         return retval;
  86 }
  87
  88 static int update_extent_range(handle_t *handle, struct inode *inode,
  89                                 ext4_fsblk_t pblock, ext4_lblk_t blk_num,
  90                                 struct list_blocks_struct *lb)
  91 {
  92         int retval;
  93         /*
  94          * See if we can add on to the existing range (if it exists)
  95          */
  96         if (lb->first_pblock &&
  97                 (lb->last_pblock+1 == pblock) &&
  98                 (lb->last_block+1 == blk_num)) {
  99                 lb->last_pblock = pblock;
 100                 lb->last_block = blk_num;
 101                 return 0;
 102         }
 103         /*
 104          * Start a new range.
 105          */
 106         retval = finish_range(handle, inode, lb);
 107         lb->first_pblock = lb->last_pblock = pblock;
 108         lb->first_block = lb->last_block = blk_num;
 109
 110         return retval;
 111 }
 112
 113 static int update_ind_extent_range(handle_t *handle, struct inode *inode,
 114                                    ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 115                                    struct list_blocks_struct *lb)
 116 {
 117         struct buffer_head *bh;
 118         __le32 *i_data;
 119         int i, retval = 0;
 120         ext4_lblk_t blk_count = *blk_nump;
 121         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 122
 123         if (!pblock) {
 124                 /* Only update the file block number */
 125                 *blk_nump += max_entries;
 126                 return 0;
 127         }
 128
 129         bh = sb_bread(inode->i_sb, pblock);
 130         if (!bh)
 131                 return -EIO;
 132
 133         i_data = (__le32 *)bh->b_data;
 134         for (i = 0; i < max_entries; i++, blk_count++) {
 135                 if (i_data[i]) {
 136                         retval = update_extent_range(handle, inode,
 137                                                 le32_to_cpu(i_data[i]),
 138                                                 blk_count, lb);
 139                         if (retval)
 140                                 break;
 141                 }
 142         }
 143
 144         /* Update the file block number */
 145         *blk_nump = blk_count;
 146         put_bh(bh);
 147         return retval;
 148
 149 }
 150
 151 static int update_dind_extent_range(handle_t *handle, struct inode *inode,
 152                                     ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 153                                     struct list_blocks_struct *lb)
 154 {
 155         struct buffer_head *bh;
 156         __le32 *i_data;
 157         int i, retval = 0;
 158         ext4_lblk_t blk_count = *blk_nump;
 159         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 160
 161         if (!pblock) {
 162                 /* Only update the file block number */
 163                 *blk_nump += max_entries * max_entries;
 164                 return 0;
 165         }
 166         bh = sb_bread(inode->i_sb, pblock);
 167         if (!bh)
 168                 return -EIO;
 169
 170         i_data = (__le32 *)bh->b_data;
 171         for (i = 0; i < max_entries; i++) {
 172                 if (i_data[i]) {
 173                         retval = update_ind_extent_range(handle, inode,
 174                                                 le32_to_cpu(i_data[i]),
 175                                                 &blk_count, lb);
 176                         if (retval)
 177                                 break;
 178                 } else {
 179                         /* Only update the file block number */
 180                         blk_count += max_entries;
 181                 }
 182         }
 183
 184         /* Update the file block number */
 185         *blk_nump = blk_count;
 186         put_bh(bh);
 187         return retval;
 188
 189 }
 190
 191 static int update_tind_extent_range(handle_t *handle, struct inode *inode,
 192                                      ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 193                                      struct list_blocks_struct *lb)
 194 {
 195         struct buffer_head *bh;
 196         __le32 *i_data;
 197         int i, retval = 0;
 198         ext4_lblk_t blk_count = *blk_nump;
 199         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 200
 201         if (!pblock) {
 202                 /* Only update the file block number */
 203                 *blk_nump += max_entries * max_entries * max_entries;
 204                 return 0;
 205         }
 206         bh = sb_bread(inode->i_sb, pblock);
 207         if (!bh)
 208                 return -EIO;
 209
 210         i_data = (__le32 *)bh->b_data;
 211         for (i = 0; i < max_entries; i++) {
 212                 if (i_data[i]) {
 213                         retval = update_dind_extent_range(handle, inode,
 214                                                 le32_to_cpu(i_data[i]),
 215                                                 &blk_count, lb);
 216                         if (retval)
 217                                 break;
 218                 } else
 219                         /* Only update the file block number */
 220                         blk_count += max_entries * max_entries;
 221         }
 222         /* Update the file block number */
 223         *blk_nump = blk_count;
 224         put_bh(bh);
 225         return retval;
 226
 227 }
 228
 229 static int extend_credit_for_blkdel(handle_t *handle, struct inode *inode)
 230 {
 231         int retval = 0, needed;
 232
 233         if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
 234                 return 0;
 235         /*
 236          * We are freeing a blocks. During this we touch
 237          * superblock, group descriptor and block bitmap.
 238          * So allocate a credit of 3. We may update
 239          * quota (user and group).
 240          */
 241         needed = 3 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);
 242
 243         if (ext4_journal_extend(handle, needed) != 0)
 244                 retval = ext4_journal_restart(handle, needed);
 245
 246         return retval;
 247 }
 248
 249 static int free_dind_blocks(handle_t *handle,
 250                                 struct inode *inode, __le32 i_data)
 251 {
 252         int i;
 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                         extend_credit_for_blkdel(handle, inode);
 265                         ext4_free_blocks(handle, inode, 0,
 266                                          le32_to_cpu(tmp_idata[i]), 1,
 267                                          EXT4_FREE_BLOCKS_METADATA |
 268                                          EXT4_FREE_BLOCKS_FORGET);
 269                 }
 270         }
 271         put_bh(bh);
 272         extend_credit_for_blkdel(handle, inode);
 273         ext4_free_blocks(handle, inode, 0, le32_to_cpu(i_data), 1,
 274                          EXT4_FREE_BLOCKS_METADATA |
 275                          EXT4_FREE_BLOCKS_FORGET);
 276         return 0;
 277 }
 278
 279 static int free_tind_blocks(handle_t *handle,
 280                                 struct inode *inode, __le32 i_data)
 281 {
 282         int i, retval = 0;
 283         __le32 *tmp_idata;
 284         struct buffer_head *bh;
 285         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 286
 287         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 288         if (!bh)
 289                 return -EIO;
 290
 291         tmp_idata = (__le32 *)bh->b_data;
 292         for (i = 0; i < max_entries; i++) {
 293                 if (tmp_idata[i]) {
 294                         retval = free_dind_blocks(handle,
 295                                         inode, tmp_idata[i]);
 296                         if (retval) {
 297                                 put_bh(bh);
 298                                 return retval;
 299                         }
 300                 }
 301         }
 302         put_bh(bh);
 303         extend_credit_for_blkdel(handle, inode);
 304         ext4_free_blocks(handle, inode, 0, le32_to_cpu(i_data), 1,
 305                          EXT4_FREE_BLOCKS_METADATA |
 306                          EXT4_FREE_BLOCKS_FORGET);
 307         return 0;
 308 }
 309
 310 static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
 311 {
 312         int retval;
 313
 314         /* ei->i_data[EXT4_IND_BLOCK] */
 315         if (i_data[0]) {
 316                 extend_credit_for_blkdel(handle, inode);
 317                 ext4_free_blocks(handle, inode, 0,
 318                                 le32_to_cpu(i_data[0]), 1,
 319                                  EXT4_FREE_BLOCKS_METADATA |
 320                                  EXT4_FREE_BLOCKS_FORGET);
 321         }
 322
 323         /* ei->i_data[EXT4_DIND_BLOCK] */
 324         if (i_data[1]) {
 325                 retval = free_dind_blocks(handle, inode, i_data[1]);
 326                 if (retval)
 327                         return retval;
 328         }
 329
 330         /* ei->i_data[EXT4_TIND_BLOCK] */
 331         if (i_data[2]) {
 332                 retval = free_tind_blocks(handle, inode, i_data[2]);
 333                 if (retval)
 334                         return retval;
 335         }
 336         return 0;
 337 }
 338
 339 static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
 340                                                 struct inode *tmp_inode)
 341 {
 342         int retval;
 343         __le32  i_data[3];
 344         struct ext4_inode_info *ei = EXT4_I(inode);
 345         struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);
 346
 347         /*
 348          * One credit accounted for writing the
 349          * i_data field of the original inode
 350          */
 351         retval = ext4_journal_extend(handle, 1);
 352         if (retval) {
 353                 retval = ext4_journal_restart(handle, 1);
 354                 if (retval)
 355                         goto err_out;
 356         }
 357
 358         i_data[0] = ei->i_data[EXT4_IND_BLOCK];
 359         i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
 360         i_data[2] = ei->i_data[EXT4_TIND_BLOCK];
 361
 362         down_write(&EXT4_I(inode)->i_data_sem);
 363         /*
 364          * if EXT4_STATE_EXT_MIGRATE is cleared a block allocation
 365          * happened after we started the migrate. We need to
 366          * fail the migrate
 367          */
 368         if (!(EXT4_I(inode)->i_state & EXT4_STATE_EXT_MIGRATE)) {
 369                 retval = -EAGAIN;
 370                 up_write(&EXT4_I(inode)->i_data_sem);
 371                 goto err_out;
 372         } else
 373                 EXT4_I(inode)->i_state &= ~EXT4_STATE_EXT_MIGRATE;
 374         /*
 375          * We have the extent map build with the tmp inode.
 376          * Now copy the i_data across
 377          */
 378         ei->i_flags |= EXT4_EXTENTS_FL;
 379         memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));
 380
 381         /*
 382          * Update i_blocks with the new blocks that got
 383          * allocated while adding extents for extent index
 384          * blocks.
 385          *
 386          * While converting to extents we need not
 387          * update the orignal inode i_blocks for extent blocks
 388          * via quota APIs. The quota update happened via tmp_inode already.
 389          */
 390         spin_lock(&inode->i_lock);
 391         inode->i_blocks += tmp_inode->i_blocks;
 392         spin_unlock(&inode->i_lock);
 393         up_write(&EXT4_I(inode)->i_data_sem);
 394
 395         /*
 396          * We mark the inode dirty after, because we decrement the
 397          * i_blocks when freeing the indirect meta-data blocks
 398          */
 399         retval = free_ind_block(handle, inode, i_data);
 400         ext4_mark_inode_dirty(handle, inode);
 401
 402 err_out:
 403         return retval;
 404 }
 405
 406 static int free_ext_idx(handle_t *handle, struct inode *inode,
 407                                         struct ext4_extent_idx *ix)
 408 {
 409         int i, retval = 0;
 410         ext4_fsblk_t block;
 411         struct buffer_head *bh;
 412         struct ext4_extent_header *eh;
 413
 414         block = idx_pblock(ix);
 415         bh = sb_bread(inode->i_sb, block);
 416         if (!bh)
 417                 return -EIO;
 418
 419         eh = (struct ext4_extent_header *)bh->b_data;
 420         if (eh->eh_depth != 0) {
 421                 ix = EXT_FIRST_INDEX(eh);
 422                 for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 423                         retval = free_ext_idx(handle, inode, ix);
 424                         if (retval)
 425                                 break;
 426                 }
 427         }
 428         put_bh(bh);
 429         extend_credit_for_blkdel(handle, inode);
 430         ext4_free_blocks(handle, inode, 0, block, 1,
 431                          EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
 432         return retval;
 433 }
 434
 435 /*
 436  * Free the extent meta data blocks only
 437  */
 438 static int free_ext_block(handle_t *handle, struct inode *inode)
 439 {
 440         int i, retval = 0;
 441         struct ext4_inode_info *ei = EXT4_I(inode);
 442         struct ext4_extent_header *eh = (struct ext4_extent_header *)ei->i_data;
 443         struct ext4_extent_idx *ix;
 444         if (eh->eh_depth == 0)
 445                 /*
 446                  * No extra blocks allocated for extent meta data
 447                  */
 448                 return 0;
 449         ix = EXT_FIRST_INDEX(eh);
 450         for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 451                 retval = free_ext_idx(handle, inode, ix);
 452                 if (retval)
 453                         return retval;
 454         }
 455         return retval;
 456
 457 }
 458
 459 int ext4_ext_migrate(struct inode *inode)
 460 {
 461         handle_t *handle;
 462         int retval = 0, i;
 463         __le32 *i_data;
 464         ext4_lblk_t blk_count = 0;
 465         struct ext4_inode_info *ei;
 466         struct inode *tmp_inode = NULL;
 467         struct list_blocks_struct lb;
 468         unsigned long max_entries;
 469         __u32 goal;
 470
 471         /*
 472          * If the filesystem does not support extents, or the inode
 473          * already is extent-based, error out.
 474          */
 475         if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
 476                                        EXT4_FEATURE_INCOMPAT_EXTENTS) ||
 477             (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
 478                 return -EINVAL;
 479
 480         if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)
 481                 /*
 482                  * don't migrate fast symlink
 483                  */
 484                 return retval;
 485
 486         handle = ext4_journal_start(inode,
 487                                         EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
 488                                         EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
 489                                         EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb)
 490                                         + 1);
 491         if (IS_ERR(handle)) {
 492                 retval = PTR_ERR(handle);
 493                 return retval;
 494         }
 495         goal = (((inode->i_ino - 1) / EXT4_INODES_PER_GROUP(inode->i_sb)) *
 496                 EXT4_INODES_PER_GROUP(inode->i_sb)) + 1;
 497         tmp_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,
 498                                    S_IFREG, 0, goal);
 499         if (IS_ERR(tmp_inode)) {
 500                 retval = -ENOMEM;
 501                 ext4_journal_stop(handle);
 502                 return retval;
 503         }
 504         i_size_write(tmp_inode, i_size_read(inode));
 505         /*
 506          * We don't want the inode to be reclaimed
 507          * if we got interrupted in between. We have
 508          * this tmp inode carrying reference to the
 509          * data blocks of the original file. We set
 510          * the i_nlink to zero at the last stage after
 511          * switching the original file to extent format
 512          */
 513         tmp_inode->i_nlink = 1;
 514
 515         ext4_ext_tree_init(handle, tmp_inode);
 516         ext4_orphan_add(handle, tmp_inode);
 517         ext4_journal_stop(handle);
 518
 519         /*
 520          * start with one credit accounted for
 521          * superblock modification.
 522          *
 523          * For the tmp_inode we already have commited the
 524          * trascation that created the inode. Later as and
 525          * when we add extents we extent the journal
 526          */
 527         /*
 528          * Even though we take i_mutex we can still cause block
 529          * allocation via mmap write to holes. If we have allocated
 530          * new blocks we fail migrate.  New block allocation will
 531          * clear EXT4_STATE_EXT_MIGRATE flag.  The flag is updated
 532          * with i_data_sem held to prevent racing with block
 533          * allocation.
 534          */
 535         down_read((&EXT4_I(inode)->i_data_sem));
 536         EXT4_I(inode)->i_state |= EXT4_STATE_EXT_MIGRATE;
 537         up_read((&EXT4_I(inode)->i_data_sem));
 538
 539         handle = ext4_journal_start(inode, 1);
 540
 541         ei = EXT4_I(inode);
 542         i_data = ei->i_data;
 543         memset(&lb, 0, sizeof(lb));
 544
 545         /* 32 bit block address 4 bytes */
 546         max_entries = inode->i_sb->s_blocksize >> 2;
 547         for (i = 0; i < EXT4_NDIR_BLOCKS; i++, blk_count++) {
 548                 if (i_data[i]) {
 549                         retval = update_extent_range(handle, tmp_inode,
 550                                                 le32_to_cpu(i_data[i]),
 551                                                 blk_count, &lb);
 552                         if (retval)
 553                                 goto err_out;
 554                 }
 555         }
 556         if (i_data[EXT4_IND_BLOCK]) {
 557                 retval = update_ind_extent_range(handle, tmp_inode,
 558                                         le32_to_cpu(i_data[EXT4_IND_BLOCK]),
 559                                         &blk_count, &lb);
 560                         if (retval)
 561                                 goto err_out;
 562         } else
 563                 blk_count +=  max_entries;
 564         if (i_data[EXT4_DIND_BLOCK]) {
 565                 retval = update_dind_extent_range(handle, tmp_inode,
 566                                         le32_to_cpu(i_data[EXT4_DIND_BLOCK]),
 567                                         &blk_count, &lb);
 568                         if (retval)
 569                                 goto err_out;
 570         } else
 571                 blk_count += max_entries * max_entries;
 572         if (i_data[EXT4_TIND_BLOCK]) {
 573                 retval = update_tind_extent_range(handle, tmp_inode,
 574                                         le32_to_cpu(i_data[EXT4_TIND_BLOCK]),
 575                                         &blk_count, &lb);
 576                         if (retval)
 577                                 goto err_out;
 578         }
 579         /*
 580          * Build the last extent
 581          */
 582         retval = finish_range(handle, tmp_inode, &lb);
 583 err_out:
 584         if (retval)
 585                 /*
 586                  * Failure case delete the extent information with the
 587                  * tmp_inode
 588                  */
 589                 free_ext_block(handle, tmp_inode);
 590         else {
 591                 retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
 592                 if (retval)
 593                         /*
 594                          * if we fail to swap inode data free the extent
 595                          * details of the tmp inode
 596                          */
 597                         free_ext_block(handle, tmp_inode);
 598         }
 599
 600         /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
 601         if (ext4_journal_extend(handle, 1) != 0)
 602                 ext4_journal_restart(handle, 1);
 603
 604         /*
 605          * Mark the tmp_inode as of size zero
 606          */
 607         i_size_write(tmp_inode, 0);
 608
 609         /*
 610          * set the  i_blocks count to zero
 611          * so that the ext4_delete_inode does the
 612          * right job
 613          *
 614          * We don't need to take the i_lock because
 615          * the inode is not visible to user space.
 616          */
 617         tmp_inode->i_blocks = 0;
 618
 619         /* Reset the extent details */
 620         ext4_ext_tree_init(handle, tmp_inode);
 621
 622         /*
 623          * Set the i_nlink to zero so that
 624          * generic_drop_inode really deletes the
 625          * inode
 626          */
 627         tmp_inode->i_nlink = 0;
 628
 629         ext4_journal_stop(handle);
 630         unlock_new_inode(tmp_inode);
 631         iput(tmp_inode);
 632
 633         return retval;
 634 }