root/fs/ext4/move_extent.c

DEFINITIONS

1. get_ext_path
2. ext4_double_down_write_data_sem
3. ext4_double_up_write_data_sem
4. mext_check_coverage
5. mext_page_double_lock
6. mext_page_mkuptodate
7. move_extent_per_page
8. mext_check_arguments
9. ext4_move_extents

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