fs/ext4/move_extent.c

   1 /*
   2  * Copyright (c) 2008,2009 NEC Software Tohoku, Ltd.
   3  * Written by Takashi Sato <t-sato@yk.jp.nec.com>
   4  *            Akira Fujita <a-fujita@rs.jp.nec.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of version 2.1 of the GNU Lesser General Public License
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  */
  15
  16 #include <linux/fs.h>
  17 #include <linux/quotaops.h>
  18 #include <linux/slab.h>
  19 #include "ext4_jbd2.h"
  20 #include "ext4.h"
  21 #include "ext4_extents.h"
  22
  23 /**
  24  * get_ext_path - Find an extent path for designated logical block number.
  25  *
  26  * @inode:      an inode which is searched
  27  * @lblock:     logical block number to find an extent path
  28  * @path:       pointer to an extent path pointer (for output)
  29  *
  30  * ext4_find_extent wrapper. Return 0 on success, or a negative error value
  31  * on failure.
  32  */
  33 static inline int
  34 get_ext_path(struct inode *inode, ext4_lblk_t lblock,
  35                 struct ext4_ext_path **ppath)
  36 {
  37         struct ext4_ext_path *path;
  38
  39         path = ext4_find_extent(inode, lblock, ppath, EXT4_EX_NOCACHE);
  40         if (IS_ERR(path))
  41                 return PTR_ERR(path);
  42         if (path[ext_depth(inode)].p_ext == NULL) {
  43                 ext4_ext_drop_refs(path);
  44                 kfree(path);
  45                 *ppath = NULL;
  46                 return -ENODATA;
  47         }
  48         *ppath = path;
  49         return 0;
  50 }
  51
  52 /**
  53  * ext4_double_down_write_data_sem - Acquire two inodes' write lock
  54  *                                   of i_data_sem
  55  *
  56  * Acquire write lock of i_data_sem of the two inodes
  57  */
  58 void
  59 ext4_double_down_write_data_sem(struct inode *first, struct inode *second)
  60 {
  61         if (first < second) {
  62                 down_write(&EXT4_I(first)->i_data_sem);
  63                 down_write_nested(&EXT4_I(second)->i_data_sem, I_DATA_SEM_OTHER);
  64         } else {
  65                 down_write(&EXT4_I(second)->i_data_sem);
  66                 down_write_nested(&EXT4_I(first)->i_data_sem, I_DATA_SEM_OTHER);
  67
  68         }
  69 }
  70
  71 /**
  72  * ext4_double_up_write_data_sem - Release two inodes' write lock of i_data_sem
  73  *
  74  * @orig_inode:         original inode structure to be released its lock first
  75  * @donor_inode:        donor inode structure to be released its lock second
  76  * Release write lock of i_data_sem of two inodes (orig and donor).
  77  */
  78 void
  79 ext4_double_up_write_data_sem(struct inode *orig_inode,
  80                               struct inode *donor_inode)
  81 {
  82         up_write(&EXT4_I(orig_inode)->i_data_sem);
  83         up_write(&EXT4_I(donor_inode)->i_data_sem);
  84 }
  85
  86 /**
  87  * mext_check_coverage - Check that all extents in range has the same type
  88  *
  89  * @inode:              inode in question
  90  * @from:               block offset of inode
  91  * @count:              block count to be checked
  92  * @unwritten:          extents expected to be unwritten
  93  * @err:                pointer to save error value
  94  *
  95  * Return 1 if all extents in range has expected type, and zero otherwise.
  96  */
  97 static int
  98 mext_check_coverage(struct inode *inode, ext4_lblk_t from, ext4_lblk_t count,
  99                     int unwritten, int *err)
 100 {
 101         struct ext4_ext_path *path = NULL;
 102         struct ext4_extent *ext;
 103         int ret = 0;
 104         ext4_lblk_t last = from + count;
 105         while (from < last) {
 106                 *err = get_ext_path(inode, from, &path);
 107                 if (*err)
 108                         goto out;
 109                 ext = path[ext_depth(inode)].p_ext;
 110                 if (unwritten != ext4_ext_is_unwritten(ext))
 111                         goto out;
 112                 from += ext4_ext_get_actual_len(ext);
 113                 ext4_ext_drop_refs(path);
 114         }
 115         ret = 1;
 116 out:
 117         ext4_ext_drop_refs(path);
 118         kfree(path);
 119         return ret;
 120 }
 121
 122 /**
 123  * mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2
 124  *
 125  * @inode1:     the inode structure
 126  * @inode2:     the inode structure
 127  * @index1:     page index
 128  * @index2:     page index
 129  * @page:       result page vector
 130  *
 131  * Grab two locked pages for inode's by inode order
 132  */
 133 static int
 134 mext_page_double_lock(struct inode *inode1, struct inode *inode2,
 135                       pgoff_t index1, pgoff_t index2, struct page *page[2])
 136 {
 137         struct address_space *mapping[2];
 138         unsigned fl = AOP_FLAG_NOFS;
 139
 140         BUG_ON(!inode1 || !inode2);
 141         if (inode1 < inode2) {
 142                 mapping[0] = inode1->i_mapping;
 143                 mapping[1] = inode2->i_mapping;
 144         } else {
 145                 pgoff_t tmp = index1;
 146                 index1 = index2;
 147                 index2 = tmp;
 148                 mapping[0] = inode2->i_mapping;
 149                 mapping[1] = inode1->i_mapping;
 150         }
 151
 152         page[0] = grab_cache_page_write_begin(mapping[0], index1, fl);
 153         if (!page[0])
 154                 return -ENOMEM;
 155
 156         page[1] = grab_cache_page_write_begin(mapping[1], index2, fl);
 157         if (!page[1]) {
 158                 unlock_page(page[0]);
 159                 put_page(page[0]);
 160                 return -ENOMEM;
 161         }
 162         /*
 163          * grab_cache_page_write_begin() may not wait on page's writeback if
 164          * BDI not demand that. But it is reasonable to be very conservative
 165          * here and explicitly wait on page's writeback
 166          */
 167         wait_on_page_writeback(page[0]);
 168         wait_on_page_writeback(page[1]);
 169         if (inode1 > inode2)
 170                 swap(page[0], page[1]);
 171
 172         return 0;
 173 }
 174
 175 /* Force page buffers uptodate w/o dropping page's lock */
 176 static int
 177 mext_page_mkuptodate(struct page *page, unsigned from, unsigned to)
 178 {
 179         struct inode *inode = page->mapping->host;
 180         sector_t block;
 181         struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
 182         unsigned int blocksize, block_start, block_end;
 183         int i, err,  nr = 0, partial = 0;
 184         BUG_ON(!PageLocked(page));
 185         BUG_ON(PageWriteback(page));
 186
 187         if (PageUptodate(page))
 188                 return 0;
 189
 190         blocksize = i_blocksize(inode);
 191         if (!page_has_buffers(page))
 192                 create_empty_buffers(page, blocksize, 0);
 193
 194         head = page_buffers(page);
 195         block = (sector_t)page->index << (PAGE_SHIFT - inode->i_blkbits);
 196         for (bh = head, block_start = 0; bh != head || !block_start;
 197              block++, block_start = block_end, bh = bh->b_this_page) {
 198                 block_end = block_start + blocksize;
 199                 if (block_end <= from || block_start >= to) {
 200                         if (!buffer_uptodate(bh))
 201                                 partial = 1;
 202                         continue;
 203                 }
 204                 if (buffer_uptodate(bh))
 205                         continue;
 206                 if (!buffer_mapped(bh)) {
 207                         err = ext4_get_block(inode, block, bh, 0);
 208                         if (err) {
 209                                 SetPageError(page);
 210                                 return err;
 211                         }
 212                         if (!buffer_mapped(bh)) {
 213                                 zero_user(page, block_start, blocksize);
 214                                 set_buffer_uptodate(bh);
 215                                 continue;
 216                         }
 217                 }
 218                 BUG_ON(nr >= MAX_BUF_PER_PAGE);
 219                 arr[nr++] = bh;
 220         }
 221         /* No io required */
 222         if (!nr)
 223                 goto out;
 224
 225         for (i = 0; i < nr; i++) {
 226                 bh = arr[i];
 227                 if (!bh_uptodate_or_lock(bh)) {
 228                         err = bh_submit_read(bh);
 229                         if (err)
 230                                 return err;
 231                 }
 232         }
 233 out:
 234         if (!partial)
 235                 SetPageUptodate(page);
 236         return 0;
 237 }
 238
 239 /**
 240  * move_extent_per_page - Move extent data per page
 241  *
 242  * @o_filp:                     file structure of original file
 243  * @donor_inode:                donor inode
 244  * @orig_page_offset:           page index on original file
 245  * @donor_page_offset:          page index on donor file
 246  * @data_offset_in_page:        block index where data swapping starts
 247  * @block_len_in_page:          the number of blocks to be swapped
 248  * @unwritten:                  orig extent is unwritten or not
 249  * @err:                        pointer to save return value
 250  *
 251  * Save the data in original inode blocks and replace original inode extents
 252  * with donor inode extents by calling ext4_swap_extents().
 253  * Finally, write out the saved data in new original inode blocks. Return
 254  * replaced block count.
 255  */
 256 static int
 257 move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
 258                      pgoff_t orig_page_offset, pgoff_t donor_page_offset,
 259                      int data_offset_in_page,
 260                      int block_len_in_page, int unwritten, int *err)
 261 {
 262         struct inode *orig_inode = file_inode(o_filp);
 263         struct page *pagep[2] = {NULL, NULL};
 264         handle_t *handle;
 265         ext4_lblk_t orig_blk_offset, donor_blk_offset;
 266         unsigned long blocksize = orig_inode->i_sb->s_blocksize;
 267         unsigned int tmp_data_size, data_size, replaced_size;
 268         int i, err2, jblocks, retries = 0;
 269         int replaced_count = 0;
 270         int from = data_offset_in_page << orig_inode->i_blkbits;
 271         int blocks_per_page = PAGE_SIZE >> orig_inode->i_blkbits;
 272         struct super_block *sb = orig_inode->i_sb;
 273         struct buffer_head *bh = NULL;
 274
 275         /*
 276          * It needs twice the amount of ordinary journal buffers because
 277          * inode and donor_inode may change each different metadata blocks.
 278          */
 279 again:
 280         *err = 0;
 281         jblocks = ext4_writepage_trans_blocks(orig_inode) * 2;
 282         handle = ext4_journal_start(orig_inode, EXT4_HT_MOVE_EXTENTS, jblocks);
 283         if (IS_ERR(handle)) {
 284                 *err = PTR_ERR(handle);
 285                 return 0;
 286         }
 287
 288         orig_blk_offset = orig_page_offset * blocks_per_page +
 289                 data_offset_in_page;
 290
 291         donor_blk_offset = donor_page_offset * blocks_per_page +
 292                 data_offset_in_page;
 293
 294         /* Calculate data_size */
 295         if ((orig_blk_offset + block_len_in_page - 1) ==
 296             ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) {
 297                 /* Replace the last block */
 298                 tmp_data_size = orig_inode->i_size & (blocksize - 1);
 299                 /*
 300                  * If data_size equal zero, it shows data_size is multiples of
 301                  * blocksize. So we set appropriate value.
 302                  */
 303                 if (tmp_data_size == 0)
 304                         tmp_data_size = blocksize;
 305
 306                 data_size = tmp_data_size +
 307                         ((block_len_in_page - 1) << orig_inode->i_blkbits);
 308         } else
 309                 data_size = block_len_in_page << orig_inode->i_blkbits;
 310
 311         replaced_size = data_size;
 312
 313         *err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset,
 314                                      donor_page_offset, pagep);
 315         if (unlikely(*err < 0))
 316                 goto stop_journal;
 317         /*
 318          * If orig extent was unwritten it can become initialized
 319          * at any time after i_data_sem was dropped, in order to
 320          * serialize with delalloc we have recheck extent while we
 321          * hold page's lock, if it is still the case data copy is not
 322          * necessary, just swap data blocks between orig and donor.
 323          */
 324         if (unwritten) {
 325                 ext4_double_down_write_data_sem(orig_inode, donor_inode);
 326                 /* If any of extents in range became initialized we have to
 327                  * fallback to data copying */
 328                 unwritten = mext_check_coverage(orig_inode, orig_blk_offset,
 329                                                 block_len_in_page, 1, err);
 330                 if (*err)
 331                         goto drop_data_sem;
 332
 333                 unwritten &= mext_check_coverage(donor_inode, donor_blk_offset,
 334                                                  block_len_in_page, 1, err);
 335                 if (*err)
 336                         goto drop_data_sem;
 337
 338                 if (!unwritten) {
 339                         ext4_double_up_write_data_sem(orig_inode, donor_inode);
 340                         goto data_copy;
 341                 }
 342                 if ((page_has_private(pagep[0]) &&
 343                      !try_to_release_page(pagep[0], 0)) ||
 344                     (page_has_private(pagep[1]) &&
 345                      !try_to_release_page(pagep[1], 0))) {
 346                         *err = -EBUSY;
 347                         goto drop_data_sem;
 348                 }
 349                 replaced_count = ext4_swap_extents(handle, orig_inode,
 350                                                    donor_inode, orig_blk_offset,
 351                                                    donor_blk_offset,
 352                                                    block_len_in_page, 1, err);
 353         drop_data_sem:
 354                 ext4_double_up_write_data_sem(orig_inode, donor_inode);
 355                 goto unlock_pages;
 356         }
 357 data_copy:
 358         *err = mext_page_mkuptodate(pagep[0], from, from + replaced_size);
 359         if (*err)
 360                 goto unlock_pages;
 361
 362         /* At this point all buffers in range are uptodate, old mapping layout
 363          * is no longer required, try to drop it now. */
 364         if ((page_has_private(pagep[0]) && !try_to_release_page(pagep[0], 0)) ||
 365             (page_has_private(pagep[1]) && !try_to_release_page(pagep[1], 0))) {
 366                 *err = -EBUSY;
 367                 goto unlock_pages;
 368         }
 369         ext4_double_down_write_data_sem(orig_inode, donor_inode);
 370         replaced_count = ext4_swap_extents(handle, orig_inode, donor_inode,
 371                                                orig_blk_offset, donor_blk_offset,
 372                                            block_len_in_page, 1, err);
 373         ext4_double_up_write_data_sem(orig_inode, donor_inode);
 374         if (*err) {
 375                 if (replaced_count) {
 376                         block_len_in_page = replaced_count;
 377                         replaced_size =
 378                                 block_len_in_page << orig_inode->i_blkbits;
 379                 } else
 380                         goto unlock_pages;
 381         }
 382         /* Perform all necessary steps similar write_begin()/write_end()
 383          * but keeping in mind that i_size will not change */
 384         if (!page_has_buffers(pagep[0]))
 385                 create_empty_buffers(pagep[0], 1 << orig_inode->i_blkbits, 0);
 386         bh = page_buffers(pagep[0]);
 387         for (i = 0; i < data_offset_in_page; i++)
 388                 bh = bh->b_this_page;
 389         for (i = 0; i < block_len_in_page; i++) {
 390                 *err = ext4_get_block(orig_inode, orig_blk_offset + i, bh, 0);
 391                 if (*err < 0)
 392                         break;
 393                 bh = bh->b_this_page;
 394         }
 395         if (!*err)
 396                 *err = block_commit_write(pagep[0], from, from + replaced_size);
 397
 398         if (unlikely(*err < 0))
 399                 goto repair_branches;
 400
 401         /* Even in case of data=writeback it is reasonable to pin
 402          * inode to transaction, to prevent unexpected data loss */
 403         *err = ext4_jbd2_inode_add_write(handle, orig_inode,
 404                         (loff_t)orig_page_offset << PAGE_SHIFT, replaced_size);
 405
 406 unlock_pages:
 407         unlock_page(pagep[0]);
 408         put_page(pagep[0]);
 409         unlock_page(pagep[1]);
 410         put_page(pagep[1]);
 411 stop_journal:
 412         ext4_journal_stop(handle);
 413         if (*err == -ENOSPC &&
 414             ext4_should_retry_alloc(sb, &retries))
 415                 goto again;
 416         /* Buffer was busy because probably is pinned to journal transaction,
 417          * force transaction commit may help to free it. */
 418         if (*err == -EBUSY && retries++ < 4 && EXT4_SB(sb)->s_journal &&
 419             jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal))
 420                 goto again;
 421         return replaced_count;
 422
 423 repair_branches:
 424         /*
 425          * This should never ever happen!
 426          * Extents are swapped already, but we are not able to copy data.
 427          * Try to swap extents to it's original places
 428          */
 429         ext4_double_down_write_data_sem(orig_inode, donor_inode);
 430         replaced_count = ext4_swap_extents(handle, donor_inode, orig_inode,
 431                                                orig_blk_offset, donor_blk_offset,
 432                                            block_len_in_page, 0, &err2);
 433         ext4_double_up_write_data_sem(orig_inode, donor_inode);
 434         if (replaced_count != block_len_in_page) {
 435                 EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset),
 436                                        "Unable to copy data block,"
 437                                        " data will be lost.");
 438                 *err = -EIO;
 439         }
 440         replaced_count = 0;
 441         goto unlock_pages;
 442 }
 443
 444 /**
 445  * mext_check_arguments - Check whether move extent can be done
 446  *
 447  * @orig_inode:         original inode
 448  * @donor_inode:        donor inode
 449  * @orig_start:         logical start offset in block for orig
 450  * @donor_start:        logical start offset in block for donor
 451  * @len:                the number of blocks to be moved
 452  *
 453  * Check the arguments of ext4_move_extents() whether the files can be
 454  * exchanged with each other.
 455  * Return 0 on success, or a negative error value on failure.
 456  */
 457 static int
 458 mext_check_arguments(struct inode *orig_inode,
 459                      struct inode *donor_inode, __u64 orig_start,
 460                      __u64 donor_start, __u64 *len)
 461 {
 462         __u64 orig_eof, donor_eof;
 463         unsigned int blkbits = orig_inode->i_blkbits;
 464         unsigned int blocksize = 1 << blkbits;
 465
 466         orig_eof = (i_size_read(orig_inode) + blocksize - 1) >> blkbits;
 467         donor_eof = (i_size_read(donor_inode) + blocksize - 1) >> blkbits;
 468
 469
 470         if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
 471                 ext4_debug("ext4 move extent: suid or sgid is set"
 472                            " to donor file [ino:orig %lu, donor %lu]\n",
 473                            orig_inode->i_ino, donor_inode->i_ino);
 474                 return -EINVAL;
 475         }
 476
 477         if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode))
 478                 return -EPERM;
 479
 480         /* Ext4 move extent does not support swapfile */
 481         if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
 482                 ext4_debug("ext4 move extent: The argument files should "
 483                         "not be swapfile [ino:orig %lu, donor %lu]\n",
 484                         orig_inode->i_ino, donor_inode->i_ino);
 485                 return -EBUSY;
 486         }
 487
 488         if (ext4_is_quota_file(orig_inode) && ext4_is_quota_file(donor_inode)) {
 489                 ext4_debug("ext4 move extent: The argument files should "
 490                         "not be quota files [ino:orig %lu, donor %lu]\n",
 491                         orig_inode->i_ino, donor_inode->i_ino);
 492                 return -EBUSY;
 493         }
 494
 495         /* Ext4 move extent supports only extent based file */
 496         if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) {
 497                 ext4_debug("ext4 move extent: orig file is not extents "
 498                         "based file [ino:orig %lu]\n", orig_inode->i_ino);
 499                 return -EOPNOTSUPP;
 500         } else if (!(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) {
 501                 ext4_debug("ext4 move extent: donor file is not extents "
 502                         "based file [ino:donor %lu]\n", donor_inode->i_ino);
 503                 return -EOPNOTSUPP;
 504         }
 505
 506         if ((!orig_inode->i_size) || (!donor_inode->i_size)) {
 507                 ext4_debug("ext4 move extent: File size is 0 byte\n");
 508                 return -EINVAL;
 509         }
 510
 511         /* Start offset should be same */
 512         if ((orig_start & ~(PAGE_MASK >> orig_inode->i_blkbits)) !=
 513             (donor_start & ~(PAGE_MASK >> orig_inode->i_blkbits))) {
 514                 ext4_debug("ext4 move extent: orig and donor's start "
 515                         "offsets are not aligned [ino:orig %lu, donor %lu]\n",
 516                         orig_inode->i_ino, donor_inode->i_ino);
 517                 return -EINVAL;
 518         }
 519
 520         if ((orig_start >= EXT_MAX_BLOCKS) ||
 521             (donor_start >= EXT_MAX_BLOCKS) ||
 522             (*len > EXT_MAX_BLOCKS) ||
 523             (donor_start + *len >= EXT_MAX_BLOCKS) ||
 524             (orig_start + *len >= EXT_MAX_BLOCKS))  {
 525                 ext4_debug("ext4 move extent: Can't handle over [%u] blocks "
 526                         "[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS,
 527                         orig_inode->i_ino, donor_inode->i_ino);
 528                 return -EINVAL;
 529         }
 530         if (orig_eof <= orig_start)
 531                 *len = 0;
 532         else if (orig_eof < orig_start + *len - 1)
 533                 *len = orig_eof - orig_start;
 534         if (donor_eof <= donor_start)
 535                 *len = 0;
 536         else if (donor_eof < donor_start + *len - 1)
 537                 *len = donor_eof - donor_start;
 538         if (!*len) {
 539                 ext4_debug("ext4 move extent: len should not be 0 "
 540                         "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino,
 541                         donor_inode->i_ino);
 542                 return -EINVAL;
 543         }
 544
 545         return 0;
 546 }
 547
 548 /**
 549  * ext4_move_extents - Exchange the specified range of a file
 550  *
 551  * @o_filp:             file structure of the original file
 552  * @d_filp:             file structure of the donor file
 553  * @orig_blk:           start offset in block for orig
 554  * @donor_blk:          start offset in block for donor
 555  * @len:                the number of blocks to be moved
 556  * @moved_len:          moved block length
 557  *
 558  * This function returns 0 and moved block length is set in moved_len
 559  * if succeed, otherwise returns error value.
 560  *
 561  */
 562 int
 563 ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
 564                   __u64 donor_blk, __u64 len, __u64 *moved_len)
 565 {
 566         struct inode *orig_inode = file_inode(o_filp);
 567         struct inode *donor_inode = file_inode(d_filp);
 568         struct ext4_ext_path *path = NULL;
 569         int blocks_per_page = PAGE_SIZE >> orig_inode->i_blkbits;
 570         ext4_lblk_t o_end, o_start = orig_blk;
 571         ext4_lblk_t d_start = donor_blk;
 572         int ret;
 573
 574         if (orig_inode->i_sb != donor_inode->i_sb) {
 575                 ext4_debug("ext4 move extent: The argument files "
 576                         "should be in same FS [ino:orig %lu, donor %lu]\n",
 577                         orig_inode->i_ino, donor_inode->i_ino);
 578                 return -EINVAL;
 579         }
 580
 581         /* orig and donor should be different inodes */
 582         if (orig_inode == donor_inode) {
 583                 ext4_debug("ext4 move extent: The argument files should not "
 584                         "be same inode [ino:orig %lu, donor %lu]\n",
 585                         orig_inode->i_ino, donor_inode->i_ino);
 586                 return -EINVAL;
 587         }
 588
 589         /* Regular file check */
 590         if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
 591                 ext4_debug("ext4 move extent: The argument files should be "
 592                         "regular file [ino:orig %lu, donor %lu]\n",
 593                         orig_inode->i_ino, donor_inode->i_ino);
 594                 return -EINVAL;
 595         }
 596
 597         /* TODO: it's not obvious how to swap blocks for inodes with full
 598            journaling enabled */
 599         if (ext4_should_journal_data(orig_inode) ||
 600             ext4_should_journal_data(donor_inode)) {
 601                 ext4_msg(orig_inode->i_sb, KERN_ERR,
 602                          "Online defrag not supported with data journaling");
 603                 return -EOPNOTSUPP;
 604         }
 605
 606         if (ext4_encrypted_inode(orig_inode) ||
 607             ext4_encrypted_inode(donor_inode)) {
 608                 ext4_msg(orig_inode->i_sb, KERN_ERR,
 609                          "Online defrag not supported for encrypted files");
 610                 return -EOPNOTSUPP;
 611         }
 612
 613         /* Protect orig and donor inodes against a truncate */
 614         lock_two_nondirectories(orig_inode, donor_inode);
 615
 616         /* Wait for all existing dio workers */
 617         ext4_inode_block_unlocked_dio(orig_inode);
 618         ext4_inode_block_unlocked_dio(donor_inode);
 619         inode_dio_wait(orig_inode);
 620         inode_dio_wait(donor_inode);
 621
 622         /* Protect extent tree against block allocations via delalloc */
 623         ext4_double_down_write_data_sem(orig_inode, donor_inode);
 624         /* Check the filesystem environment whether move_extent can be done */
 625         ret = mext_check_arguments(orig_inode, donor_inode, orig_blk,
 626                                     donor_blk, &len);
 627         if (ret)
 628                 goto out;
 629         o_end = o_start + len;
 630
 631         while (o_start < o_end) {
 632                 struct ext4_extent *ex;
 633                 ext4_lblk_t cur_blk, next_blk;
 634                 pgoff_t orig_page_index, donor_page_index;
 635                 int offset_in_page;
 636                 int unwritten, cur_len;
 637
 638                 ret = get_ext_path(orig_inode, o_start, &path);
 639                 if (ret)
 640                         goto out;
 641                 ex = path[path->p_depth].p_ext;
 642                 next_blk = ext4_ext_next_allocated_block(path);
 643                 cur_blk = le32_to_cpu(ex->ee_block);
 644                 cur_len = ext4_ext_get_actual_len(ex);
 645                 /* Check hole before the start pos */
 646                 if (cur_blk + cur_len - 1 < o_start) {
 647                         if (next_blk == EXT_MAX_BLOCKS) {
 648                                 o_start = o_end;
 649                                 ret = -ENODATA;
 650                                 goto out;
 651                         }
 652                         d_start += next_blk - o_start;
 653                         o_start = next_blk;
 654                         continue;
 655                 /* Check hole after the start pos */
 656                 } else if (cur_blk > o_start) {
 657                         /* Skip hole */
 658                         d_start += cur_blk - o_start;
 659                         o_start = cur_blk;
 660                         /* Extent inside requested range ?*/
 661                         if (cur_blk >= o_end)
 662                                 goto out;
 663                 } else { /* in_range(o_start, o_blk, o_len) */
 664                         cur_len += cur_blk - o_start;
 665                 }
 666                 unwritten = ext4_ext_is_unwritten(ex);
 667                 if (o_end - o_start < cur_len)
 668                         cur_len = o_end - o_start;
 669
 670                 orig_page_index = o_start >> (PAGE_SHIFT -
 671                                                orig_inode->i_blkbits);
 672                 donor_page_index = d_start >> (PAGE_SHIFT -
 673                                                donor_inode->i_blkbits);
 674                 offset_in_page = o_start % blocks_per_page;
 675                 if (cur_len > blocks_per_page- offset_in_page)
 676                         cur_len = blocks_per_page - offset_in_page;
 677                 /*
 678                  * Up semaphore to avoid following problems:
 679                  * a. transaction deadlock among ext4_journal_start,
 680                  *    ->write_begin via pagefault, and jbd2_journal_commit
 681                  * b. racing with ->readpage, ->write_begin, and ext4_get_block
 682                  *    in move_extent_per_page
 683                  */
 684                 ext4_double_up_write_data_sem(orig_inode, donor_inode);
 685                 /* Swap original branches with new branches */
 686                 move_extent_per_page(o_filp, donor_inode,
 687                                      orig_page_index, donor_page_index,
 688                                      offset_in_page, cur_len,
 689                                      unwritten, &ret);
 690                 ext4_double_down_write_data_sem(orig_inode, donor_inode);
 691                 if (ret < 0)
 692                         break;
 693                 o_start += cur_len;
 694                 d_start += cur_len;
 695         }
 696         *moved_len = o_start - orig_blk;
 697         if (*moved_len > len)
 698                 *moved_len = len;
 699
 700 out:
 701         if (*moved_len) {
 702                 ext4_discard_preallocations(orig_inode);
 703                 ext4_discard_preallocations(donor_inode);
 704         }
 705
 706         ext4_ext_drop_refs(path);
 707         kfree(path);
 708         ext4_double_up_write_data_sem(orig_inode, donor_inode);
 709         ext4_inode_resume_unlocked_dio(orig_inode);
 710         ext4_inode_resume_unlocked_dio(donor_inode);
 711         unlock_two_nondirectories(orig_inode, donor_inode);
 712
 713         return ret;
 714 }