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 "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_insert(inode, path);
  57
  58         /*
  59          * Make sure the credit we accumalated is not really high
  60          */
  61         if (needed && handle->h_buffer_credits >= EXT4_RESERVE_TRANS_BLOCKS) {
  62                 retval = ext4_journal_restart(handle, needed);
  63                 if (retval)
  64                         goto err_out;
  65         } else if (needed) {
  66                 retval = ext4_journal_extend(handle, needed);
  67                 if (retval) {
  68                         /*
  69                          * IF not able to extend the journal restart the journal
  70                          */
  71                         retval = ext4_journal_restart(handle, needed);
  72                         if (retval)
  73                                 goto err_out;
  74                 }
  75         }
  76         retval = ext4_ext_insert_extent(handle, inode, path, &newext);
  77 err_out:
  78         if (path) {
  79                 ext4_ext_drop_refs(path);
  80                 kfree(path);
  81         }
  82         lb->first_pblock = 0;
  83         return retval;
  84 }
  85
  86 static int update_extent_range(handle_t *handle, struct inode *inode,
  87                                 ext4_fsblk_t pblock, ext4_lblk_t blk_num,
  88                                 struct list_blocks_struct *lb)
  89 {
  90         int retval;
  91         /*
  92          * See if we can add on to the existing range (if it exists)
  93          */
  94         if (lb->first_pblock &&
  95                 (lb->last_pblock+1 == pblock) &&
  96                 (lb->last_block+1 == blk_num)) {
  97                 lb->last_pblock = pblock;
  98                 lb->last_block = blk_num;
  99                 return 0;
 100         }
 101         /*
 102          * Start a new range.
 103          */
 104         retval = finish_range(handle, inode, lb);
 105         lb->first_pblock = lb->last_pblock = pblock;
 106         lb->first_block = lb->last_block = blk_num;
 107
 108         return retval;
 109 }
 110
 111 static int update_ind_extent_range(handle_t *handle, struct inode *inode,
 112                                    ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 113                                    struct list_blocks_struct *lb)
 114 {
 115         struct buffer_head *bh;
 116         __le32 *i_data;
 117         int i, retval = 0;
 118         ext4_lblk_t blk_count = *blk_nump;
 119         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 120
 121         if (!pblock) {
 122                 /* Only update the file block number */
 123                 *blk_nump += max_entries;
 124                 return 0;
 125         }
 126
 127         bh = sb_bread(inode->i_sb, pblock);
 128         if (!bh)
 129                 return -EIO;
 130
 131         i_data = (__le32 *)bh->b_data;
 132         for (i = 0; i < max_entries; i++, blk_count++) {
 133                 if (i_data[i]) {
 134                         retval = update_extent_range(handle, inode,
 135                                                 le32_to_cpu(i_data[i]),
 136                                                 blk_count, lb);
 137                         if (retval)
 138                                 break;
 139                 }
 140         }
 141
 142         /* Update the file block number */
 143         *blk_nump = blk_count;
 144         put_bh(bh);
 145         return retval;
 146
 147 }
 148
 149 static int update_dind_extent_range(handle_t *handle, struct inode *inode,
 150                                     ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 151                                     struct list_blocks_struct *lb)
 152 {
 153         struct buffer_head *bh;
 154         __le32 *i_data;
 155         int i, retval = 0;
 156         ext4_lblk_t blk_count = *blk_nump;
 157         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 158
 159         if (!pblock) {
 160                 /* Only update the file block number */
 161                 *blk_nump += max_entries * max_entries;
 162                 return 0;
 163         }
 164         bh = sb_bread(inode->i_sb, pblock);
 165         if (!bh)
 166                 return -EIO;
 167
 168         i_data = (__le32 *)bh->b_data;
 169         for (i = 0; i < max_entries; i++) {
 170                 if (i_data[i]) {
 171                         retval = update_ind_extent_range(handle, inode,
 172                                                 le32_to_cpu(i_data[i]),
 173                                                 &blk_count, lb);
 174                         if (retval)
 175                                 break;
 176                 } else {
 177                         /* Only update the file block number */
 178                         blk_count += max_entries;
 179                 }
 180         }
 181
 182         /* Update the file block number */
 183         *blk_nump = blk_count;
 184         put_bh(bh);
 185         return retval;
 186
 187 }
 188
 189 static int update_tind_extent_range(handle_t *handle, struct inode *inode,
 190                                      ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
 191                                      struct list_blocks_struct *lb)
 192 {
 193         struct buffer_head *bh;
 194         __le32 *i_data;
 195         int i, retval = 0;
 196         ext4_lblk_t blk_count = *blk_nump;
 197         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 198
 199         if (!pblock) {
 200                 /* Only update the file block number */
 201                 *blk_nump += max_entries * max_entries * max_entries;
 202                 return 0;
 203         }
 204         bh = sb_bread(inode->i_sb, pblock);
 205         if (!bh)
 206                 return -EIO;
 207
 208         i_data = (__le32 *)bh->b_data;
 209         for (i = 0; i < max_entries; i++) {
 210                 if (i_data[i]) {
 211                         retval = update_dind_extent_range(handle, inode,
 212                                                 le32_to_cpu(i_data[i]),
 213                                                 &blk_count, lb);
 214                         if (retval)
 215                                 break;
 216                 } else
 217                         /* Only update the file block number */
 218                         blk_count += max_entries * max_entries;
 219         }
 220         /* Update the file block number */
 221         *blk_nump = blk_count;
 222         put_bh(bh);
 223         return retval;
 224
 225 }
 226
 227 static int extend_credit_for_blkdel(handle_t *handle, struct inode *inode)
 228 {
 229         int retval = 0, needed;
 230
 231         if (handle->h_buffer_credits > EXT4_RESERVE_TRANS_BLOCKS)
 232                 return 0;
 233         /*
 234          * We are freeing a blocks. During this we touch
 235          * superblock, group descriptor and block bitmap.
 236          * So allocate a credit of 3. We may update
 237          * quota (user and group).
 238          */
 239         needed = 3 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
 240
 241         if (ext4_journal_extend(handle, needed) != 0)
 242                 retval = ext4_journal_restart(handle, needed);
 243
 244         return retval;
 245 }
 246
 247 static int free_dind_blocks(handle_t *handle,
 248                                 struct inode *inode, __le32 i_data)
 249 {
 250         int i;
 251         __le32 *tmp_idata;
 252         struct buffer_head *bh;
 253         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 254
 255         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 256         if (!bh)
 257                 return -EIO;
 258
 259         tmp_idata = (__le32 *)bh->b_data;
 260         for (i = 0; i < max_entries; i++) {
 261                 if (tmp_idata[i]) {
 262                         extend_credit_for_blkdel(handle, inode);
 263                         ext4_free_blocks(handle, inode,
 264                                         le32_to_cpu(tmp_idata[i]), 1, 1);
 265                 }
 266         }
 267         put_bh(bh);
 268         extend_credit_for_blkdel(handle, inode);
 269         ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
 270         return 0;
 271 }
 272
 273 static int free_tind_blocks(handle_t *handle,
 274                                 struct inode *inode, __le32 i_data)
 275 {
 276         int i, retval = 0;
 277         __le32 *tmp_idata;
 278         struct buffer_head *bh;
 279         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
 280
 281         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
 282         if (!bh)
 283                 return -EIO;
 284
 285         tmp_idata = (__le32 *)bh->b_data;
 286         for (i = 0; i < max_entries; i++) {
 287                 if (tmp_idata[i]) {
 288                         retval = free_dind_blocks(handle,
 289                                         inode, tmp_idata[i]);
 290                         if (retval) {
 291                                 put_bh(bh);
 292                                 return retval;
 293                         }
 294                 }
 295         }
 296         put_bh(bh);
 297         extend_credit_for_blkdel(handle, inode);
 298         ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
 299         return 0;
 300 }
 301
 302 static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
 303 {
 304         int retval;
 305
 306         /* ei->i_data[EXT4_IND_BLOCK] */
 307         if (i_data[0]) {
 308                 extend_credit_for_blkdel(handle, inode);
 309                 ext4_free_blocks(handle, inode,
 310                                 le32_to_cpu(i_data[0]), 1, 1);
 311         }
 312
 313         /* ei->i_data[EXT4_DIND_BLOCK] */
 314         if (i_data[1]) {
 315                 retval = free_dind_blocks(handle, inode, i_data[1]);
 316                 if (retval)
 317                         return retval;
 318         }
 319
 320         /* ei->i_data[EXT4_TIND_BLOCK] */
 321         if (i_data[2]) {
 322                 retval = free_tind_blocks(handle, inode, i_data[2]);
 323                 if (retval)
 324                         return retval;
 325         }
 326         return 0;
 327 }
 328
 329 static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
 330                                                 struct inode *tmp_inode)
 331 {
 332         int retval;
 333         __le32  i_data[3];
 334         struct ext4_inode_info *ei = EXT4_I(inode);
 335         struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);
 336
 337         /*
 338          * One credit accounted for writing the
 339          * i_data field of the original inode
 340          */
 341         retval = ext4_journal_extend(handle, 1);
 342         if (retval) {
 343                 retval = ext4_journal_restart(handle, 1);
 344                 if (retval)
 345                         goto err_out;
 346         }
 347
 348         i_data[0] = ei->i_data[EXT4_IND_BLOCK];
 349         i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
 350         i_data[2] = ei->i_data[EXT4_TIND_BLOCK];
 351
 352         down_write(&EXT4_I(inode)->i_data_sem);
 353         /*
 354          * if EXT4_EXT_MIGRATE is cleared a block allocation
 355          * happened after we started the migrate. We need to
 356          * fail the migrate
 357          */
 358         if (!(EXT4_I(inode)->i_flags & EXT4_EXT_MIGRATE)) {
 359                 retval = -EAGAIN;
 360                 up_write(&EXT4_I(inode)->i_data_sem);
 361                 goto err_out;
 362         } else
 363                 EXT4_I(inode)->i_flags = EXT4_I(inode)->i_flags &
 364                                                         ~EXT4_EXT_MIGRATE;
 365         /*
 366          * We have the extent map build with the tmp inode.
 367          * Now copy the i_data across
 368          */
 369         ei->i_flags |= EXT4_EXTENTS_FL;
 370         memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));
 371
 372         /*
 373          * Update i_blocks with the new blocks that got
 374          * allocated while adding extents for extent index
 375          * blocks.
 376          *
 377          * While converting to extents we need not
 378          * update the orignal inode i_blocks for extent blocks
 379          * via quota APIs. The quota update happened via tmp_inode already.
 380          */
 381         spin_lock(&inode->i_lock);
 382         inode->i_blocks += tmp_inode->i_blocks;
 383         spin_unlock(&inode->i_lock);
 384         up_write(&EXT4_I(inode)->i_data_sem);
 385
 386         /*
 387          * We mark the inode dirty after, because we decrement the
 388          * i_blocks when freeing the indirect meta-data blocks
 389          */
 390         retval = free_ind_block(handle, inode, i_data);
 391         ext4_mark_inode_dirty(handle, inode);
 392
 393 err_out:
 394         return retval;
 395 }
 396
 397 static int free_ext_idx(handle_t *handle, struct inode *inode,
 398                                         struct ext4_extent_idx *ix)
 399 {
 400         int i, retval = 0;
 401         ext4_fsblk_t block;
 402         struct buffer_head *bh;
 403         struct ext4_extent_header *eh;
 404
 405         block = idx_pblock(ix);
 406         bh = sb_bread(inode->i_sb, block);
 407         if (!bh)
 408                 return -EIO;
 409
 410         eh = (struct ext4_extent_header *)bh->b_data;
 411         if (eh->eh_depth != 0) {
 412                 ix = EXT_FIRST_INDEX(eh);
 413                 for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 414                         retval = free_ext_idx(handle, inode, ix);
 415                         if (retval)
 416                                 break;
 417                 }
 418         }
 419         put_bh(bh);
 420         extend_credit_for_blkdel(handle, inode);
 421         ext4_free_blocks(handle, inode, block, 1, 1);
 422         return retval;
 423 }
 424
 425 /*
 426  * Free the extent meta data blocks only
 427  */
 428 static int free_ext_block(handle_t *handle, struct inode *inode)
 429 {
 430         int i, retval = 0;
 431         struct ext4_inode_info *ei = EXT4_I(inode);
 432         struct ext4_extent_header *eh = (struct ext4_extent_header *)ei->i_data;
 433         struct ext4_extent_idx *ix;
 434         if (eh->eh_depth == 0)
 435                 /*
 436                  * No extra blocks allocated for extent meta data
 437                  */
 438                 return 0;
 439         ix = EXT_FIRST_INDEX(eh);
 440         for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
 441                 retval = free_ext_idx(handle, inode, ix);
 442                 if (retval)
 443                         return retval;
 444         }
 445         return retval;
 446
 447 }
 448
 449 int ext4_ext_migrate(struct inode *inode, struct file *filp,
 450                                 unsigned int cmd, unsigned long arg)
 451 {
 452         handle_t *handle;
 453         int retval = 0, i;
 454         __le32 *i_data;
 455         ext4_lblk_t blk_count = 0;
 456         struct ext4_inode_info *ei;
 457         struct inode *tmp_inode = NULL;
 458         struct list_blocks_struct lb;
 459         unsigned long max_entries;
 460
 461         if (!test_opt(inode->i_sb, EXTENTS))
 462                 /*
 463                  * if mounted with noextents we don't allow the migrate
 464                  */
 465                 return -EINVAL;
 466
 467         if ((EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
 468                 return -EINVAL;
 469
 470         if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)
 471                 /*
 472                  * don't migrate fast symlink
 473                  */
 474                 return retval;
 475
 476         handle = ext4_journal_start(inode,
 477                                         EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
 478                                         EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
 479                                         2 * EXT4_QUOTA_INIT_BLOCKS(inode->i_sb)
 480                                         + 1);
 481         if (IS_ERR(handle)) {
 482                 retval = PTR_ERR(handle);
 483                 goto err_out;
 484         }
 485         tmp_inode = ext4_new_inode(handle,
 486                                 inode->i_sb->s_root->d_inode,
 487                                 S_IFREG);
 488         if (IS_ERR(tmp_inode)) {
 489                 retval = -ENOMEM;
 490                 ext4_journal_stop(handle);
 491                 tmp_inode = NULL;
 492                 goto err_out;
 493         }
 494         i_size_write(tmp_inode, i_size_read(inode));
 495         /*
 496          * We don't want the inode to be reclaimed
 497          * if we got interrupted in between. We have
 498          * this tmp inode carrying reference to the
 499          * data blocks of the original file. We set
 500          * the i_nlink to zero at the last stage after
 501          * switching the original file to extent format
 502          */
 503         tmp_inode->i_nlink = 1;
 504
 505         ext4_ext_tree_init(handle, tmp_inode);
 506         ext4_orphan_add(handle, tmp_inode);
 507         ext4_journal_stop(handle);
 508
 509         /*
 510          * start with one credit accounted for
 511          * superblock modification.
 512          *
 513          * For the tmp_inode we already have commited the
 514          * trascation that created the inode. Later as and
 515          * when we add extents we extent the journal
 516          */
 517         /*
 518          * inode_mutex prevent write and truncate on the file. Read still goes
 519          * through. We take i_data_sem in ext4_ext_swap_inode_data before we
 520          * switch the inode format to prevent read.
 521          */
 522         mutex_lock(&(inode->i_mutex));
 523         /*
 524          * Even though we take i_mutex we can still cause block allocation
 525          * via mmap write to holes. If we have allocated new blocks we fail
 526          * migrate.  New block allocation will clear EXT4_EXT_MIGRATE flag.
 527          * The flag is updated with i_data_sem held to prevent racing with
 528          * block allocation.
 529          */
 530         down_read((&EXT4_I(inode)->i_data_sem));
 531         EXT4_I(inode)->i_flags = EXT4_I(inode)->i_flags | EXT4_EXT_MIGRATE;
 532         up_read((&EXT4_I(inode)->i_data_sem));
 533
 534         handle = ext4_journal_start(inode, 1);
 535
 536         ei = EXT4_I(inode);
 537         i_data = ei->i_data;
 538         memset(&lb, 0, sizeof(lb));
 539
 540         /* 32 bit block address 4 bytes */
 541         max_entries = inode->i_sb->s_blocksize >> 2;
 542         for (i = 0; i < EXT4_NDIR_BLOCKS; i++, blk_count++) {
 543                 if (i_data[i]) {
 544                         retval = update_extent_range(handle, tmp_inode,
 545                                                 le32_to_cpu(i_data[i]),
 546                                                 blk_count, &lb);
 547                         if (retval)
 548                                 goto err_out;
 549                 }
 550         }
 551         if (i_data[EXT4_IND_BLOCK]) {
 552                 retval = update_ind_extent_range(handle, tmp_inode,
 553                                         le32_to_cpu(i_data[EXT4_IND_BLOCK]),
 554                                         &blk_count, &lb);
 555                         if (retval)
 556                                 goto err_out;
 557         } else
 558                 blk_count +=  max_entries;
 559         if (i_data[EXT4_DIND_BLOCK]) {
 560                 retval = update_dind_extent_range(handle, tmp_inode,
 561                                         le32_to_cpu(i_data[EXT4_DIND_BLOCK]),
 562                                         &blk_count, &lb);
 563                         if (retval)
 564                                 goto err_out;
 565         } else
 566                 blk_count += max_entries * max_entries;
 567         if (i_data[EXT4_TIND_BLOCK]) {
 568                 retval = update_tind_extent_range(handle, tmp_inode,
 569                                         le32_to_cpu(i_data[EXT4_TIND_BLOCK]),
 570                                         &blk_count, &lb);
 571                         if (retval)
 572                                 goto err_out;
 573         }
 574         /*
 575          * Build the last extent
 576          */
 577         retval = finish_range(handle, tmp_inode, &lb);
 578 err_out:
 579         if (retval)
 580                 /*
 581                  * Failure case delete the extent information with the
 582                  * tmp_inode
 583                  */
 584                 free_ext_block(handle, tmp_inode);
 585         else {
 586                 retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
 587                 if (retval)
 588                         /*
 589                          * if we fail to swap inode data free the extent
 590                          * details of the tmp inode
 591                          */
 592                         free_ext_block(handle, tmp_inode);
 593         }
 594
 595         /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
 596         if (ext4_journal_extend(handle, 1) != 0)
 597                 ext4_journal_restart(handle, 1);
 598
 599         /*
 600          * Mark the tmp_inode as of size zero
 601          */
 602         i_size_write(tmp_inode, 0);
 603
 604         /*
 605          * set the  i_blocks count to zero
 606          * so that the ext4_delete_inode does the
 607          * right job
 608          *
 609          * We don't need to take the i_lock because
 610          * the inode is not visible to user space.
 611          */
 612         tmp_inode->i_blocks = 0;
 613
 614         /* Reset the extent details */
 615         ext4_ext_tree_init(handle, tmp_inode);
 616
 617         /*
 618          * Set the i_nlink to zero so that
 619          * generic_drop_inode really deletes the
 620          * inode
 621          */
 622         tmp_inode->i_nlink = 0;
 623
 624         ext4_journal_stop(handle);
 625         mutex_unlock(&(inode->i_mutex));
 626
 627         if (tmp_inode)
 628                 iput(tmp_inode);
 629
 630         return retval;
 631 }