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_extents.h"
  21 #include "ext4.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_ext_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 **path)
  36 {
  37         int ret = 0;
  38
  39         *path = ext4_ext_find_extent(inode, lblock, *path);
  40         if (IS_ERR(*path)) {
  41                 ret = PTR_ERR(*path);
  42                 *path = NULL;
  43         } else if ((*path)[ext_depth(inode)].p_ext == NULL)
  44                 ret = -ENODATA;
  45
  46         return ret;
  47 }
  48
  49 /**
  50  * copy_extent_status - Copy the extent's initialization status
  51  *
  52  * @src:        an extent for getting initialize status
  53  * @dest:       an extent to be set the status
  54  */
  55 static void
  56 copy_extent_status(struct ext4_extent *src, struct ext4_extent *dest)
  57 {
  58         if (ext4_ext_is_uninitialized(src))
  59                 ext4_ext_mark_uninitialized(dest);
  60         else
  61                 dest->ee_len = cpu_to_le16(ext4_ext_get_actual_len(dest));
  62 }
  63
  64 /**
  65  * mext_next_extent - Search for the next extent and set it to "extent"
  66  *
  67  * @inode:      inode which is searched
  68  * @path:       this will obtain data for the next extent
  69  * @extent:     pointer to the next extent we have just gotten
  70  *
  71  * Search the next extent in the array of ext4_ext_path structure (@path)
  72  * and set it to ext4_extent structure (@extent). In addition, the member of
  73  * @path (->p_ext) also points the next extent. Return 0 on success, 1 if
  74  * ext4_ext_path structure refers to the last extent, or a negative error
  75  * value on failure.
  76  */
  77 static int
  78 mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
  79                       struct ext4_extent **extent)
  80 {
  81         struct ext4_extent_header *eh;
  82         int ppos, leaf_ppos = path->p_depth;
  83
  84         ppos = leaf_ppos;
  85         if (EXT_LAST_EXTENT(path[ppos].p_hdr) > path[ppos].p_ext) {
  86                 /* leaf block */
  87                 *extent = ++path[ppos].p_ext;
  88                 path[ppos].p_block = ext_pblock(path[ppos].p_ext);
  89                 return 0;
  90         }
  91
  92         while (--ppos >= 0) {
  93                 if (EXT_LAST_INDEX(path[ppos].p_hdr) >
  94                     path[ppos].p_idx) {
  95                         int cur_ppos = ppos;
  96
  97                         /* index block */
  98                         path[ppos].p_idx++;
  99                         path[ppos].p_block = idx_pblock(path[ppos].p_idx);
 100                         if (path[ppos+1].p_bh)
 101                                 brelse(path[ppos+1].p_bh);
 102                         path[ppos+1].p_bh =
 103                                 sb_bread(inode->i_sb, path[ppos].p_block);
 104                         if (!path[ppos+1].p_bh)
 105                                 return -EIO;
 106                         path[ppos+1].p_hdr =
 107                                 ext_block_hdr(path[ppos+1].p_bh);
 108
 109                         /* Halfway index block */
 110                         while (++cur_ppos < leaf_ppos) {
 111                                 path[cur_ppos].p_idx =
 112                                         EXT_FIRST_INDEX(path[cur_ppos].p_hdr);
 113                                 path[cur_ppos].p_block =
 114                                         idx_pblock(path[cur_ppos].p_idx);
 115                                 if (path[cur_ppos+1].p_bh)
 116                                         brelse(path[cur_ppos+1].p_bh);
 117                                 path[cur_ppos+1].p_bh = sb_bread(inode->i_sb,
 118                                         path[cur_ppos].p_block);
 119                                 if (!path[cur_ppos+1].p_bh)
 120                                         return -EIO;
 121                                 path[cur_ppos+1].p_hdr =
 122                                         ext_block_hdr(path[cur_ppos+1].p_bh);
 123                         }
 124
 125                         path[leaf_ppos].p_ext = *extent = NULL;
 126
 127                         eh = path[leaf_ppos].p_hdr;
 128                         if (le16_to_cpu(eh->eh_entries) == 0)
 129                                 /* empty leaf is found */
 130                                 return -ENODATA;
 131
 132                         /* leaf block */
 133                         path[leaf_ppos].p_ext = *extent =
 134                                 EXT_FIRST_EXTENT(path[leaf_ppos].p_hdr);
 135                         path[leaf_ppos].p_block =
 136                                         ext_pblock(path[leaf_ppos].p_ext);
 137                         return 0;
 138                 }
 139         }
 140         /* We found the last extent */
 141         return 1;
 142 }
 143
 144 /**
 145  * mext_check_null_inode - NULL check for two inodes
 146  *
 147  * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.
 148  */
 149 static int
 150 mext_check_null_inode(struct inode *inode1, struct inode *inode2,
 151                 const char *function)
 152 {
 153         int ret = 0;
 154
 155         if (inode1 == NULL) {
 156                 __ext4_error(inode2->i_sb, function,
 157                         "Both inodes should not be NULL: "
 158                         "inode1 NULL inode2 %lu", inode2->i_ino);
 159                 ret = -EIO;
 160         } else if (inode2 == NULL) {
 161                 __ext4_error(inode1->i_sb, function,
 162                         "Both inodes should not be NULL: "
 163                         "inode1 %lu inode2 NULL", inode1->i_ino);
 164                 ret = -EIO;
 165         }
 166         return ret;
 167 }
 168
 169 /**
 170  * double_down_write_data_sem - Acquire two inodes' write lock of i_data_sem
 171  *
 172  * @orig_inode:         original inode structure
 173  * @donor_inode:        donor inode structure
 174  * Acquire write lock of i_data_sem of the two inodes (orig and donor) by
 175  * i_ino order.
 176  */
 177 static void
 178 double_down_write_data_sem(struct inode *orig_inode, struct inode *donor_inode)
 179 {
 180         struct inode *first = orig_inode, *second = donor_inode;
 181
 182         /*
 183          * Use the inode number to provide the stable locking order instead
 184          * of its address, because the C language doesn't guarantee you can
 185          * compare pointers that don't come from the same array.
 186          */
 187         if (donor_inode->i_ino < orig_inode->i_ino) {
 188                 first = donor_inode;
 189                 second = orig_inode;
 190         }
 191
 192         down_write(&EXT4_I(first)->i_data_sem);
 193         down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);
 194 }
 195
 196 /**
 197  * double_up_write_data_sem - Release two inodes' write lock of i_data_sem
 198  *
 199  * @orig_inode:         original inode structure to be released its lock first
 200  * @donor_inode:        donor inode structure to be released its lock second
 201  * Release write lock of i_data_sem of two inodes (orig and donor).
 202  */
 203 static void
 204 double_up_write_data_sem(struct inode *orig_inode, struct inode *donor_inode)
 205 {
 206         up_write(&EXT4_I(orig_inode)->i_data_sem);
 207         up_write(&EXT4_I(donor_inode)->i_data_sem);
 208 }
 209
 210 /**
 211  * mext_insert_across_blocks - Insert extents across leaf block
 212  *
 213  * @handle:             journal handle
 214  * @orig_inode:         original inode
 215  * @o_start:            first original extent to be changed
 216  * @o_end:              last original extent to be changed
 217  * @start_ext:          first new extent to be inserted
 218  * @new_ext:            middle of new extent to be inserted
 219  * @end_ext:            last new extent to be inserted
 220  *
 221  * Allocate a new leaf block and insert extents into it. Return 0 on success,
 222  * or a negative error value on failure.
 223  */
 224 static int
 225 mext_insert_across_blocks(handle_t *handle, struct inode *orig_inode,
 226                 struct ext4_extent *o_start, struct ext4_extent *o_end,
 227                 struct ext4_extent *start_ext, struct ext4_extent *new_ext,
 228                 struct ext4_extent *end_ext)
 229 {
 230         struct ext4_ext_path *orig_path = NULL;
 231         ext4_lblk_t eblock = 0;
 232         int new_flag = 0;
 233         int end_flag = 0;
 234         int err = 0;
 235
 236         if (start_ext->ee_len && new_ext->ee_len && end_ext->ee_len) {
 237                 if (o_start == o_end) {
 238
 239                         /*       start_ext   new_ext    end_ext
 240                          * donor |---------|-----------|--------|
 241                          * orig  |------------------------------|
 242                          */
 243                         end_flag = 1;
 244                 } else {
 245
 246                         /*       start_ext   new_ext   end_ext
 247                          * donor |---------|----------|---------|
 248                          * orig  |---------------|--------------|
 249                          */
 250                         o_end->ee_block = end_ext->ee_block;
 251                         o_end->ee_len = end_ext->ee_len;
 252                         ext4_ext_store_pblock(o_end, ext_pblock(end_ext));
 253                 }
 254
 255                 o_start->ee_len = start_ext->ee_len;
 256                 eblock = le32_to_cpu(start_ext->ee_block);
 257                 new_flag = 1;
 258
 259         } else if (start_ext->ee_len && new_ext->ee_len &&
 260                    !end_ext->ee_len && o_start == o_end) {
 261
 262                 /*       start_ext      new_ext
 263                  * donor |--------------|---------------|
 264                  * orig  |------------------------------|
 265                  */
 266                 o_start->ee_len = start_ext->ee_len;
 267                 eblock = le32_to_cpu(start_ext->ee_block);
 268                 new_flag = 1;
 269
 270         } else if (!start_ext->ee_len && new_ext->ee_len &&
 271                    end_ext->ee_len && o_start == o_end) {
 272
 273                 /*        new_ext       end_ext
 274                  * donor |--------------|---------------|
 275                  * orig  |------------------------------|
 276                  */
 277                 o_end->ee_block = end_ext->ee_block;
 278                 o_end->ee_len = end_ext->ee_len;
 279                 ext4_ext_store_pblock(o_end, ext_pblock(end_ext));
 280
 281                 /*
 282                  * Set 0 to the extent block if new_ext was
 283                  * the first block.
 284                  */
 285                 if (new_ext->ee_block)
 286                         eblock = le32_to_cpu(new_ext->ee_block);
 287
 288                 new_flag = 1;
 289         } else {
 290                 ext4_debug("ext4 move extent: Unexpected insert case\n");
 291                 return -EIO;
 292         }
 293
 294         if (new_flag) {
 295                 err = get_ext_path(orig_inode, eblock, &orig_path);
 296                 if (err)
 297                         goto out;
 298
 299                 if (ext4_ext_insert_extent(handle, orig_inode,
 300                                         orig_path, new_ext, 0))
 301                         goto out;
 302         }
 303
 304         if (end_flag) {
 305                 err = get_ext_path(orig_inode,
 306                                 le32_to_cpu(end_ext->ee_block) - 1, &orig_path);
 307                 if (err)
 308                         goto out;
 309
 310                 if (ext4_ext_insert_extent(handle, orig_inode,
 311                                            orig_path, end_ext, 0))
 312                         goto out;
 313         }
 314 out:
 315         if (orig_path) {
 316                 ext4_ext_drop_refs(orig_path);
 317                 kfree(orig_path);
 318         }
 319
 320         return err;
 321
 322 }
 323
 324 /**
 325  * mext_insert_inside_block - Insert new extent to the extent block
 326  *
 327  * @o_start:            first original extent to be moved
 328  * @o_end:              last original extent to be moved
 329  * @start_ext:          first new extent to be inserted
 330  * @new_ext:            middle of new extent to be inserted
 331  * @end_ext:            last new extent to be inserted
 332  * @eh:                 extent header of target leaf block
 333  * @range_to_move:      used to decide how to insert extent
 334  *
 335  * Insert extents into the leaf block. The extent (@o_start) is overwritten
 336  * by inserted extents.
 337  */
 338 static void
 339 mext_insert_inside_block(struct ext4_extent *o_start,
 340                               struct ext4_extent *o_end,
 341                               struct ext4_extent *start_ext,
 342                               struct ext4_extent *new_ext,
 343                               struct ext4_extent *end_ext,
 344                               struct ext4_extent_header *eh,
 345                               int range_to_move)
 346 {
 347         int i = 0;
 348         unsigned long len;
 349
 350         /* Move the existing extents */
 351         if (range_to_move && o_end < EXT_LAST_EXTENT(eh)) {
 352                 len = (unsigned long)(EXT_LAST_EXTENT(eh) + 1) -
 353                         (unsigned long)(o_end + 1);
 354                 memmove(o_end + 1 + range_to_move, o_end + 1, len);
 355         }
 356
 357         /* Insert start entry */
 358         if (start_ext->ee_len)
 359                 o_start[i++].ee_len = start_ext->ee_len;
 360
 361         /* Insert new entry */
 362         if (new_ext->ee_len) {
 363                 o_start[i] = *new_ext;
 364                 ext4_ext_store_pblock(&o_start[i++], ext_pblock(new_ext));
 365         }
 366
 367         /* Insert end entry */
 368         if (end_ext->ee_len)
 369                 o_start[i] = *end_ext;
 370
 371         /* Increment the total entries counter on the extent block */
 372         le16_add_cpu(&eh->eh_entries, range_to_move);
 373 }
 374
 375 /**
 376  * mext_insert_extents - Insert new extent
 377  *
 378  * @handle:     journal handle
 379  * @orig_inode: original inode
 380  * @orig_path:  path indicates first extent to be changed
 381  * @o_start:    first original extent to be changed
 382  * @o_end:      last original extent to be changed
 383  * @start_ext:  first new extent to be inserted
 384  * @new_ext:    middle of new extent to be inserted
 385  * @end_ext:    last new extent to be inserted
 386  *
 387  * Call the function to insert extents. If we cannot add more extents into
 388  * the leaf block, we call mext_insert_across_blocks() to create a
 389  * new leaf block. Otherwise call mext_insert_inside_block(). Return 0
 390  * on success, or a negative error value on failure.
 391  */
 392 static int
 393 mext_insert_extents(handle_t *handle, struct inode *orig_inode,
 394                          struct ext4_ext_path *orig_path,
 395                          struct ext4_extent *o_start,
 396                          struct ext4_extent *o_end,
 397                          struct ext4_extent *start_ext,
 398                          struct ext4_extent *new_ext,
 399                          struct ext4_extent *end_ext)
 400 {
 401         struct  ext4_extent_header *eh;
 402         unsigned long need_slots, slots_range;
 403         int     range_to_move, depth, ret;
 404
 405         /*
 406          * The extents need to be inserted
 407          * start_extent + new_extent + end_extent.
 408          */
 409         need_slots = (start_ext->ee_len ? 1 : 0) + (end_ext->ee_len ? 1 : 0) +
 410                 (new_ext->ee_len ? 1 : 0);
 411
 412         /* The number of slots between start and end */
 413         slots_range = ((unsigned long)(o_end + 1) - (unsigned long)o_start + 1)
 414                 / sizeof(struct ext4_extent);
 415
 416         /* Range to move the end of extent */
 417         range_to_move = need_slots - slots_range;
 418         depth = orig_path->p_depth;
 419         orig_path += depth;
 420         eh = orig_path->p_hdr;
 421
 422         if (depth) {
 423                 /* Register to journal */
 424                 ret = ext4_journal_get_write_access(handle, orig_path->p_bh);
 425                 if (ret)
 426                         return ret;
 427         }
 428
 429         /* Expansion */
 430         if (range_to_move > 0 &&
 431                 (range_to_move > le16_to_cpu(eh->eh_max)
 432                         - le16_to_cpu(eh->eh_entries))) {
 433
 434                 ret = mext_insert_across_blocks(handle, orig_inode, o_start,
 435                                         o_end, start_ext, new_ext, end_ext);
 436                 if (ret < 0)
 437                         return ret;
 438         } else
 439                 mext_insert_inside_block(o_start, o_end, start_ext, new_ext,
 440                                                 end_ext, eh, range_to_move);
 441
 442         if (depth) {
 443                 ret = ext4_handle_dirty_metadata(handle, orig_inode,
 444                                                  orig_path->p_bh);
 445                 if (ret)
 446                         return ret;
 447         } else {
 448                 ret = ext4_mark_inode_dirty(handle, orig_inode);
 449                 if (ret < 0)
 450                         return ret;
 451         }
 452
 453         return 0;
 454 }
 455
 456 /**
 457  * mext_leaf_block - Move one leaf extent block into the inode.
 458  *
 459  * @handle:             journal handle
 460  * @orig_inode:         original inode
 461  * @orig_path:          path indicates first extent to be changed
 462  * @dext:               donor extent
 463  * @from:               start offset on the target file
 464  *
 465  * In order to insert extents into the leaf block, we must divide the extent
 466  * in the leaf block into three extents. The one is located to be inserted
 467  * extents, and the others are located around it.
 468  *
 469  * Therefore, this function creates structures to save extents of the leaf
 470  * block, and inserts extents by calling mext_insert_extents() with
 471  * created extents. Return 0 on success, or a negative error value on failure.
 472  */
 473 static int
 474 mext_leaf_block(handle_t *handle, struct inode *orig_inode,
 475                      struct ext4_ext_path *orig_path, struct ext4_extent *dext,
 476                      ext4_lblk_t *from)
 477 {
 478         struct ext4_extent *oext, *o_start, *o_end, *prev_ext;
 479         struct ext4_extent new_ext, start_ext, end_ext;
 480         ext4_lblk_t new_ext_end;
 481         int oext_alen, new_ext_alen, end_ext_alen;
 482         int depth = ext_depth(orig_inode);
 483         int ret;
 484
 485         o_start = o_end = oext = orig_path[depth].p_ext;
 486         oext_alen = ext4_ext_get_actual_len(oext);
 487         start_ext.ee_len = end_ext.ee_len = 0;
 488
 489         new_ext.ee_block = cpu_to_le32(*from);
 490         ext4_ext_store_pblock(&new_ext, ext_pblock(dext));
 491         new_ext.ee_len = dext->ee_len;
 492         new_ext_alen = ext4_ext_get_actual_len(&new_ext);
 493         new_ext_end = le32_to_cpu(new_ext.ee_block) + new_ext_alen - 1;
 494
 495         /*
 496          * Case: original extent is first
 497          * oext      |--------|
 498          * new_ext      |--|
 499          * start_ext |--|
 500          */
 501         if (le32_to_cpu(oext->ee_block) < le32_to_cpu(new_ext.ee_block) &&
 502                 le32_to_cpu(new_ext.ee_block) <
 503                 le32_to_cpu(oext->ee_block) + oext_alen) {
 504                 start_ext.ee_len = cpu_to_le16(le32_to_cpu(new_ext.ee_block) -
 505                                                le32_to_cpu(oext->ee_block));
 506                 start_ext.ee_block = oext->ee_block;
 507                 copy_extent_status(oext, &start_ext);
 508         } else if (oext > EXT_FIRST_EXTENT(orig_path[depth].p_hdr)) {
 509                 prev_ext = oext - 1;
 510                 /*
 511                  * We can merge new_ext into previous extent,
 512                  * if these are contiguous and same extent type.
 513                  */
 514                 if (ext4_can_extents_be_merged(orig_inode, prev_ext,
 515                                                &new_ext)) {
 516                         o_start = prev_ext;
 517                         start_ext.ee_len = cpu_to_le16(
 518                                 ext4_ext_get_actual_len(prev_ext) +
 519                                 new_ext_alen);
 520                         start_ext.ee_block = oext->ee_block;
 521                         copy_extent_status(prev_ext, &start_ext);
 522                         new_ext.ee_len = 0;
 523                 }
 524         }
 525
 526         /*
 527          * Case: new_ext_end must be less than oext
 528          * oext      |-----------|
 529          * new_ext       |-------|
 530          */
 531         if (le32_to_cpu(oext->ee_block) + oext_alen - 1 < new_ext_end) {
 532                 ext4_error(orig_inode->i_sb,
 533                         "new_ext_end(%u) should be less than or equal to "
 534                         "oext->ee_block(%u) + oext_alen(%d) - 1",
 535                         new_ext_end, le32_to_cpu(oext->ee_block),
 536                         oext_alen);
 537                 ret = -EIO;
 538                 goto out;
 539         }
 540
 541         /*
 542          * Case: new_ext is smaller than original extent
 543          * oext    |---------------|
 544          * new_ext |-----------|
 545          * end_ext             |---|
 546          */
 547         if (le32_to_cpu(oext->ee_block) <= new_ext_end &&
 548                 new_ext_end < le32_to_cpu(oext->ee_block) + oext_alen - 1) {
 549                 end_ext.ee_len =
 550                         cpu_to_le16(le32_to_cpu(oext->ee_block) +
 551                         oext_alen - 1 - new_ext_end);
 552                 copy_extent_status(oext, &end_ext);
 553                 end_ext_alen = ext4_ext_get_actual_len(&end_ext);
 554                 ext4_ext_store_pblock(&end_ext,
 555                         (ext_pblock(o_end) + oext_alen - end_ext_alen));
 556                 end_ext.ee_block =
 557                         cpu_to_le32(le32_to_cpu(o_end->ee_block) +
 558                         oext_alen - end_ext_alen);
 559         }
 560
 561         ret = mext_insert_extents(handle, orig_inode, orig_path, o_start,
 562                                 o_end, &start_ext, &new_ext, &end_ext);
 563 out:
 564         return ret;
 565 }
 566
 567 /**
 568  * mext_calc_swap_extents - Calculate extents for extent swapping.
 569  *
 570  * @tmp_dext:           the extent that will belong to the original inode
 571  * @tmp_oext:           the extent that will belong to the donor inode
 572  * @orig_off:           block offset of original inode
 573  * @donor_off:          block offset of donor inode
 574  * @max_count:          the maximum length of extents
 575  *
 576  * Return 0 on success, or a negative error value on failure.
 577  */
 578 static int
 579 mext_calc_swap_extents(struct ext4_extent *tmp_dext,
 580                               struct ext4_extent *tmp_oext,
 581                               ext4_lblk_t orig_off, ext4_lblk_t donor_off,
 582                               ext4_lblk_t max_count)
 583 {
 584         ext4_lblk_t diff, orig_diff;
 585         struct ext4_extent dext_old, oext_old;
 586
 587         BUG_ON(orig_off != donor_off);
 588
 589         /* original and donor extents have to cover the same block offset */
 590         if (orig_off < le32_to_cpu(tmp_oext->ee_block) ||
 591             le32_to_cpu(tmp_oext->ee_block) +
 592                         ext4_ext_get_actual_len(tmp_oext) - 1 < orig_off)
 593                 return -ENODATA;
 594
 595         if (orig_off < le32_to_cpu(tmp_dext->ee_block) ||
 596             le32_to_cpu(tmp_dext->ee_block) +
 597                         ext4_ext_get_actual_len(tmp_dext) - 1 < orig_off)
 598                 return -ENODATA;
 599
 600         dext_old = *tmp_dext;
 601         oext_old = *tmp_oext;
 602
 603         /* When tmp_dext is too large, pick up the target range. */
 604         diff = donor_off - le32_to_cpu(tmp_dext->ee_block);
 605
 606         ext4_ext_store_pblock(tmp_dext, ext_pblock(tmp_dext) + diff);
 607         tmp_dext->ee_block =
 608                         cpu_to_le32(le32_to_cpu(tmp_dext->ee_block) + diff);
 609         tmp_dext->ee_len = cpu_to_le16(le16_to_cpu(tmp_dext->ee_len) - diff);
 610
 611         if (max_count < ext4_ext_get_actual_len(tmp_dext))
 612                 tmp_dext->ee_len = cpu_to_le16(max_count);
 613
 614         orig_diff = orig_off - le32_to_cpu(tmp_oext->ee_block);
 615         ext4_ext_store_pblock(tmp_oext, ext_pblock(tmp_oext) + orig_diff);
 616
 617         /* Adjust extent length if donor extent is larger than orig */
 618         if (ext4_ext_get_actual_len(tmp_dext) >
 619             ext4_ext_get_actual_len(tmp_oext) - orig_diff)
 620                 tmp_dext->ee_len = cpu_to_le16(le16_to_cpu(tmp_oext->ee_len) -
 621                                                 orig_diff);
 622
 623         tmp_oext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(tmp_dext));
 624
 625         copy_extent_status(&oext_old, tmp_dext);
 626         copy_extent_status(&dext_old, tmp_oext);
 627
 628         return 0;
 629 }
 630
 631 /**
 632  * mext_replace_branches - Replace original extents with new extents
 633  *
 634  * @handle:             journal handle
 635  * @orig_inode:         original inode
 636  * @donor_inode:        donor inode
 637  * @from:               block offset of orig_inode
 638  * @count:              block count to be replaced
 639  * @err:                pointer to save return value
 640  *
 641  * Replace original inode extents and donor inode extents page by page.
 642  * We implement this replacement in the following three steps:
 643  * 1. Save the block information of original and donor inodes into
 644  *    dummy extents.
 645  * 2. Change the block information of original inode to point at the
 646  *    donor inode blocks.
 647  * 3. Change the block information of donor inode to point at the saved
 648  *    original inode blocks in the dummy extents.
 649  *
 650  * Return replaced block count.
 651  */
 652 static int
 653 mext_replace_branches(handle_t *handle, struct inode *orig_inode,
 654                            struct inode *donor_inode, ext4_lblk_t from,
 655                            ext4_lblk_t count, int *err)
 656 {
 657         struct ext4_ext_path *orig_path = NULL;
 658         struct ext4_ext_path *donor_path = NULL;
 659         struct ext4_extent *oext, *dext;
 660         struct ext4_extent tmp_dext, tmp_oext;
 661         ext4_lblk_t orig_off = from, donor_off = from;
 662         int depth;
 663         int replaced_count = 0;
 664         int dext_alen;
 665
 666         /* Protect extent trees against block allocations via delalloc */
 667         double_down_write_data_sem(orig_inode, donor_inode);
 668
 669         /* Get the original extent for the block "orig_off" */
 670         *err = get_ext_path(orig_inode, orig_off, &orig_path);
 671         if (*err)
 672                 goto out;
 673
 674         /* Get the donor extent for the head */
 675         *err = get_ext_path(donor_inode, donor_off, &donor_path);
 676         if (*err)
 677                 goto out;
 678         depth = ext_depth(orig_inode);
 679         oext = orig_path[depth].p_ext;
 680         tmp_oext = *oext;
 681
 682         depth = ext_depth(donor_inode);
 683         dext = donor_path[depth].p_ext;
 684         tmp_dext = *dext;
 685
 686         *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
 687                                       donor_off, count);
 688         if (*err)
 689                 goto out;
 690
 691         /* Loop for the donor extents */
 692         while (1) {
 693                 /* The extent for donor must be found. */
 694                 if (!dext) {
 695                         ext4_error(donor_inode->i_sb,
 696                                    "The extent for donor must be found");
 697                         *err = -EIO;
 698                         goto out;
 699                 } else if (donor_off != le32_to_cpu(tmp_dext.ee_block)) {
 700                         ext4_error(donor_inode->i_sb,
 701                                 "Donor offset(%u) and the first block of donor "
 702                                 "extent(%u) should be equal",
 703                                 donor_off,
 704                                 le32_to_cpu(tmp_dext.ee_block));
 705                         *err = -EIO;
 706                         goto out;
 707                 }
 708
 709                 /* Set donor extent to orig extent */
 710                 *err = mext_leaf_block(handle, orig_inode,
 711                                            orig_path, &tmp_dext, &orig_off);
 712                 if (*err)
 713                         goto out;
 714
 715                 /* Set orig extent to donor extent */
 716                 *err = mext_leaf_block(handle, donor_inode,
 717                                            donor_path, &tmp_oext, &donor_off);
 718                 if (*err)
 719                         goto out;
 720
 721                 dext_alen = ext4_ext_get_actual_len(&tmp_dext);
 722                 replaced_count += dext_alen;
 723                 donor_off += dext_alen;
 724                 orig_off += dext_alen;
 725
 726                 /* Already moved the expected blocks */
 727                 if (replaced_count >= count)
 728                         break;
 729
 730                 if (orig_path)
 731                         ext4_ext_drop_refs(orig_path);
 732                 *err = get_ext_path(orig_inode, orig_off, &orig_path);
 733                 if (*err)
 734                         goto out;
 735                 depth = ext_depth(orig_inode);
 736                 oext = orig_path[depth].p_ext;
 737                 tmp_oext = *oext;
 738
 739                 if (donor_path)
 740                         ext4_ext_drop_refs(donor_path);
 741                 *err = get_ext_path(donor_inode, donor_off, &donor_path);
 742                 if (*err)
 743                         goto out;
 744                 depth = ext_depth(donor_inode);
 745                 dext = donor_path[depth].p_ext;
 746                 tmp_dext = *dext;
 747
 748                 *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
 749                                            donor_off, count - replaced_count);
 750                 if (*err)
 751                         goto out;
 752         }
 753
 754 out:
 755         if (orig_path) {
 756                 ext4_ext_drop_refs(orig_path);
 757                 kfree(orig_path);
 758         }
 759         if (donor_path) {
 760                 ext4_ext_drop_refs(donor_path);
 761                 kfree(donor_path);
 762         }
 763
 764         ext4_ext_invalidate_cache(orig_inode);
 765         ext4_ext_invalidate_cache(donor_inode);
 766
 767         double_up_write_data_sem(orig_inode, donor_inode);
 768
 769         return replaced_count;
 770 }
 771
 772 /**
 773  * move_extent_per_page - Move extent data per page
 774  *
 775  * @o_filp:                     file structure of original file
 776  * @donor_inode:                donor inode
 777  * @orig_page_offset:           page index on original file
 778  * @data_offset_in_page:        block index where data swapping starts
 779  * @block_len_in_page:          the number of blocks to be swapped
 780  * @uninit:                     orig extent is uninitialized or not
 781  * @err:                        pointer to save return value
 782  *
 783  * Save the data in original inode blocks and replace original inode extents
 784  * with donor inode extents by calling mext_replace_branches().
 785  * Finally, write out the saved data in new original inode blocks. Return
 786  * replaced block count.
 787  */
 788 static int
 789 move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
 790                   pgoff_t orig_page_offset, int data_offset_in_page,
 791                   int block_len_in_page, int uninit, int *err)
 792 {
 793         struct inode *orig_inode = o_filp->f_dentry->d_inode;
 794         struct address_space *mapping = orig_inode->i_mapping;
 795         struct buffer_head *bh;
 796         struct page *page = NULL;
 797         const struct address_space_operations *a_ops = mapping->a_ops;
 798         handle_t *handle;
 799         ext4_lblk_t orig_blk_offset;
 800         long long offs = orig_page_offset << PAGE_CACHE_SHIFT;
 801         unsigned long blocksize = orig_inode->i_sb->s_blocksize;
 802         unsigned int w_flags = 0;
 803         unsigned int tmp_data_size, data_size, replaced_size;
 804         void *fsdata;
 805         int i, jblocks;
 806         int err2 = 0;
 807         int replaced_count = 0;
 808         int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
 809
 810         /*
 811          * It needs twice the amount of ordinary journal buffers because
 812          * inode and donor_inode may change each different metadata blocks.
 813          */
 814         jblocks = ext4_writepage_trans_blocks(orig_inode) * 2;
 815         handle = ext4_journal_start(orig_inode, jblocks);
 816         if (IS_ERR(handle)) {
 817                 *err = PTR_ERR(handle);
 818                 return 0;
 819         }
 820
 821         if (segment_eq(get_fs(), KERNEL_DS))
 822                 w_flags |= AOP_FLAG_UNINTERRUPTIBLE;
 823
 824         orig_blk_offset = orig_page_offset * blocks_per_page +
 825                 data_offset_in_page;
 826
 827         /*
 828          * If orig extent is uninitialized one,
 829          * it's not necessary force the page into memory
 830          * and then force it to be written out again.
 831          * Just swap data blocks between orig and donor.
 832          */
 833         if (uninit) {
 834                 replaced_count = mext_replace_branches(handle, orig_inode,
 835                                                 donor_inode, orig_blk_offset,
 836                                                 block_len_in_page, err);
 837                 goto out2;
 838         }
 839
 840         offs = (long long)orig_blk_offset << orig_inode->i_blkbits;
 841
 842         /* Calculate data_size */
 843         if ((orig_blk_offset + block_len_in_page - 1) ==
 844             ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) {
 845                 /* Replace the last block */
 846                 tmp_data_size = orig_inode->i_size & (blocksize - 1);
 847                 /*
 848                  * If data_size equal zero, it shows data_size is multiples of
 849                  * blocksize. So we set appropriate value.
 850                  */
 851                 if (tmp_data_size == 0)
 852                         tmp_data_size = blocksize;
 853
 854                 data_size = tmp_data_size +
 855                         ((block_len_in_page - 1) << orig_inode->i_blkbits);
 856         } else
 857                 data_size = block_len_in_page << orig_inode->i_blkbits;
 858
 859         replaced_size = data_size;
 860
 861         *err = a_ops->write_begin(o_filp, mapping, offs, data_size, w_flags,
 862                                  &page, &fsdata);
 863         if (unlikely(*err < 0))
 864                 goto out;
 865
 866         if (!PageUptodate(page)) {
 867                 mapping->a_ops->readpage(o_filp, page);
 868                 lock_page(page);
 869         }
 870
 871         /*
 872          * try_to_release_page() doesn't call releasepage in writeback mode.
 873          * We should care about the order of writing to the same file
 874          * by multiple move extent processes.
 875          * It needs to call wait_on_page_writeback() to wait for the
 876          * writeback of the page.
 877          */
 878         if (PageWriteback(page))
 879                 wait_on_page_writeback(page);
 880
 881         /* Release old bh and drop refs */
 882         try_to_release_page(page, 0);
 883
 884         replaced_count = mext_replace_branches(handle, orig_inode, donor_inode,
 885                                         orig_blk_offset, block_len_in_page,
 886                                         &err2);
 887         if (err2) {
 888                 if (replaced_count) {
 889                         block_len_in_page = replaced_count;
 890                         replaced_size =
 891                                 block_len_in_page << orig_inode->i_blkbits;
 892                 } else
 893                         goto out;
 894         }
 895
 896         if (!page_has_buffers(page))
 897                 create_empty_buffers(page, 1 << orig_inode->i_blkbits, 0);
 898
 899         bh = page_buffers(page);
 900         for (i = 0; i < data_offset_in_page; i++)
 901                 bh = bh->b_this_page;
 902
 903         for (i = 0; i < block_len_in_page; i++) {
 904                 *err = ext4_get_block(orig_inode,
 905                                 (sector_t)(orig_blk_offset + i), bh, 0);
 906                 if (*err < 0)
 907                         goto out;
 908
 909                 if (bh->b_this_page != NULL)
 910                         bh = bh->b_this_page;
 911         }
 912
 913         *err = a_ops->write_end(o_filp, mapping, offs, data_size, replaced_size,
 914                                page, fsdata);
 915         page = NULL;
 916
 917 out:
 918         if (unlikely(page)) {
 919                 if (PageLocked(page))
 920                         unlock_page(page);
 921                 page_cache_release(page);
 922                 ext4_journal_stop(handle);
 923         }
 924 out2:
 925         ext4_journal_stop(handle);
 926
 927         if (err2)
 928                 *err = err2;
 929
 930         return replaced_count;
 931 }
 932
 933 /**
 934  * mext_check_arguments - Check whether move extent can be done
 935  *
 936  * @orig_inode:         original inode
 937  * @donor_inode:        donor inode
 938  * @orig_start:         logical start offset in block for orig
 939  * @donor_start:        logical start offset in block for donor
 940  * @len:                the number of blocks to be moved
 941  *
 942  * Check the arguments of ext4_move_extents() whether the files can be
 943  * exchanged with each other.
 944  * Return 0 on success, or a negative error value on failure.
 945  */
 946 static int
 947 mext_check_arguments(struct inode *orig_inode,
 948                      struct inode *donor_inode, __u64 orig_start,
 949                      __u64 donor_start, __u64 *len)
 950 {
 951         ext4_lblk_t orig_blocks, donor_blocks;
 952         unsigned int blkbits = orig_inode->i_blkbits;
 953         unsigned int blocksize = 1 << blkbits;
 954
 955         if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
 956                 ext4_debug("ext4 move extent: suid or sgid is set"
 957                            " to donor file [ino:orig %lu, donor %lu]\n",
 958                            orig_inode->i_ino, donor_inode->i_ino);
 959                 return -EINVAL;
 960         }
 961
 962         /* Ext4 move extent does not support swapfile */
 963         if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
 964                 ext4_debug("ext4 move extent: The argument files should "
 965                         "not be swapfile [ino:orig %lu, donor %lu]\n",
 966                         orig_inode->i_ino, donor_inode->i_ino);
 967                 return -EINVAL;
 968         }
 969
 970         /* Files should be in the same ext4 FS */
 971         if (orig_inode->i_sb != donor_inode->i_sb) {
 972                 ext4_debug("ext4 move extent: The argument files "
 973                         "should be in same FS [ino:orig %lu, donor %lu]\n",
 974                         orig_inode->i_ino, donor_inode->i_ino);
 975                 return -EINVAL;
 976         }
 977
 978         /* Ext4 move extent supports only extent based file */
 979         if (!(EXT4_I(orig_inode)->i_flags & EXT4_EXTENTS_FL)) {
 980                 ext4_debug("ext4 move extent: orig file is not extents "
 981                         "based file [ino:orig %lu]\n", orig_inode->i_ino);
 982                 return -EOPNOTSUPP;
 983         } else if (!(EXT4_I(donor_inode)->i_flags & EXT4_EXTENTS_FL)) {
 984                 ext4_debug("ext4 move extent: donor file is not extents "
 985                         "based file [ino:donor %lu]\n", donor_inode->i_ino);
 986                 return -EOPNOTSUPP;
 987         }
 988
 989         if ((!orig_inode->i_size) || (!donor_inode->i_size)) {
 990                 ext4_debug("ext4 move extent: File size is 0 byte\n");
 991                 return -EINVAL;
 992         }
 993
 994         /* Start offset should be same */
 995         if (orig_start != donor_start) {
 996                 ext4_debug("ext4 move extent: orig and donor's start "
 997                         "offset are not same [ino:orig %lu, donor %lu]\n",
 998                         orig_inode->i_ino, donor_inode->i_ino);
 999                 return -EINVAL;
1000         }
1001
1002         if ((orig_start > EXT_MAX_BLOCK) ||
1003             (donor_start > EXT_MAX_BLOCK) ||
1004             (*len > EXT_MAX_BLOCK) ||
1005             (orig_start + *len > EXT_MAX_BLOCK))  {
1006                 ext4_debug("ext4 move extent: Can't handle over [%u] blocks "
1007                         "[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCK,
1008                         orig_inode->i_ino, donor_inode->i_ino);
1009                 return -EINVAL;
1010         }
1011
1012         if (orig_inode->i_size > donor_inode->i_size) {
1013                 donor_blocks = (donor_inode->i_size + blocksize - 1) >> blkbits;
1014                 /* TODO: eliminate this artificial restriction */
1015                 if (orig_start >= donor_blocks) {
1016                         ext4_debug("ext4 move extent: orig start offset "
1017                         "[%llu] should be less than donor file blocks "
1018                         "[%u] [ino:orig %lu, donor %lu]\n",
1019                         orig_start, donor_blocks,
1020                         orig_inode->i_ino, donor_inode->i_ino);
1021                         return -EINVAL;
1022                 }
1023
1024                 /* TODO: eliminate this artificial restriction */
1025                 if (orig_start + *len > donor_blocks) {
1026                         ext4_debug("ext4 move extent: End offset [%llu] should "
1027                                 "be less than donor file blocks [%u]."
1028                                 "So adjust length from %llu to %llu "
1029                                 "[ino:orig %lu, donor %lu]\n",
1030                                 orig_start + *len, donor_blocks,
1031                                 *len, donor_blocks - orig_start,
1032                                 orig_inode->i_ino, donor_inode->i_ino);
1033                         *len = donor_blocks - orig_start;
1034                 }
1035         } else {
1036                 orig_blocks = (orig_inode->i_size + blocksize - 1) >> blkbits;
1037                 if (orig_start >= orig_blocks) {
1038                         ext4_debug("ext4 move extent: start offset [%llu] "
1039                                 "should be less than original file blocks "
1040                                 "[%u] [ino:orig %lu, donor %lu]\n",
1041                                  orig_start, orig_blocks,
1042                                 orig_inode->i_ino, donor_inode->i_ino);
1043                         return -EINVAL;
1044                 }
1045
1046                 if (orig_start + *len > orig_blocks) {
1047                         ext4_debug("ext4 move extent: Adjust length "
1048                                 "from %llu to %llu. Because it should be "
1049                                 "less than original file blocks "
1050                                 "[ino:orig %lu, donor %lu]\n",
1051                                 *len, orig_blocks - orig_start,
1052                                 orig_inode->i_ino, donor_inode->i_ino);
1053                         *len = orig_blocks - orig_start;
1054                 }
1055         }
1056
1057         if (!*len) {
1058                 ext4_debug("ext4 move extent: len should not be 0 "
1059                         "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino,
1060                         donor_inode->i_ino);
1061                 return -EINVAL;
1062         }
1063
1064         return 0;
1065 }
1066
1067 /**
1068  * mext_inode_double_lock - Lock i_mutex on both @inode1 and @inode2
1069  *
1070  * @inode1:     the inode structure
1071  * @inode2:     the inode structure
1072  *
1073  * Lock two inodes' i_mutex by i_ino order.
1074  * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.
1075  */
1076 static int
1077 mext_inode_double_lock(struct inode *inode1, struct inode *inode2)
1078 {
1079         int ret = 0;
1080
1081         BUG_ON(inode1 == NULL && inode2 == NULL);
1082
1083         ret = mext_check_null_inode(inode1, inode2, __func__);
1084         if (ret < 0)
1085                 goto out;
1086
1087         if (inode1 == inode2) {
1088                 mutex_lock(&inode1->i_mutex);
1089                 goto out;
1090         }
1091
1092         if (inode1->i_ino < inode2->i_ino) {
1093                 mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
1094                 mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
1095         } else {
1096                 mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
1097                 mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
1098         }
1099
1100 out:
1101         return ret;
1102 }
1103
1104 /**
1105  * mext_inode_double_unlock - Release i_mutex on both @inode1 and @inode2
1106  *
1107  * @inode1:     the inode that is released first
1108  * @inode2:     the inode that is released second
1109  *
1110  * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.
1111  */
1112
1113 static int
1114 mext_inode_double_unlock(struct inode *inode1, struct inode *inode2)
1115 {
1116         int ret = 0;
1117
1118         BUG_ON(inode1 == NULL && inode2 == NULL);
1119
1120         ret = mext_check_null_inode(inode1, inode2, __func__);
1121         if (ret < 0)
1122                 goto out;
1123
1124         if (inode1)
1125                 mutex_unlock(&inode1->i_mutex);
1126
1127         if (inode2 && inode2 != inode1)
1128                 mutex_unlock(&inode2->i_mutex);
1129
1130 out:
1131         return ret;
1132 }
1133
1134 /**
1135  * ext4_move_extents - Exchange the specified range of a file
1136  *
1137  * @o_filp:             file structure of the original file
1138  * @d_filp:             file structure of the donor file
1139  * @orig_start:         start offset in block for orig
1140  * @donor_start:        start offset in block for donor
1141  * @len:                the number of blocks to be moved
1142  * @moved_len:          moved block length
1143  *
1144  * This function returns 0 and moved block length is set in moved_len
1145  * if succeed, otherwise returns error value.
1146  *
1147  * Note: ext4_move_extents() proceeds the following order.
1148  * 1:ext4_move_extents() calculates the last block number of moving extent
1149  *   function by the start block number (orig_start) and the number of blocks
1150  *   to be moved (len) specified as arguments.
1151  *   If the {orig, donor}_start points a hole, the extent's start offset
1152  *   pointed by ext_cur (current extent), holecheck_path, orig_path are set
1153  *   after hole behind.
1154  * 2:Continue step 3 to step 5, until the holecheck_path points to last_extent
1155  *   or the ext_cur exceeds the block_end which is last logical block number.
1156  * 3:To get the length of continues area, call mext_next_extent()
1157  *   specified with the ext_cur (initial value is holecheck_path) re-cursive,
1158  *   until find un-continuous extent, the start logical block number exceeds
1159  *   the block_end or the extent points to the last extent.
1160  * 4:Exchange the original inode data with donor inode data
1161  *   from orig_page_offset to seq_end_page.
1162  *   The start indexes of data are specified as arguments.
1163  *   That of the original inode is orig_page_offset,
1164  *   and the donor inode is also orig_page_offset
1165  *   (To easily handle blocksize != pagesize case, the offset for the
1166  *   donor inode is block unit).
1167  * 5:Update holecheck_path and orig_path to points a next proceeding extent,
1168  *   then returns to step 2.
1169  * 6:Release holecheck_path, orig_path and set the len to moved_len
1170  *   which shows the number of moved blocks.
1171  *   The moved_len is useful for the command to calculate the file offset
1172  *   for starting next move extent ioctl.
1173  * 7:Return 0 on success, or a negative error value on failure.
1174  */
1175 int
1176 ext4_move_extents(struct file *o_filp, struct file *d_filp,
1177                  __u64 orig_start, __u64 donor_start, __u64 len,
1178                  __u64 *moved_len)
1179 {
1180         struct inode *orig_inode = o_filp->f_dentry->d_inode;
1181         struct inode *donor_inode = d_filp->f_dentry->d_inode;
1182         struct ext4_ext_path *orig_path = NULL, *holecheck_path = NULL;
1183         struct ext4_extent *ext_prev, *ext_cur, *ext_dummy;
1184         ext4_lblk_t block_start = orig_start;
1185         ext4_lblk_t block_end, seq_start, add_blocks, file_end, seq_blocks = 0;
1186         ext4_lblk_t rest_blocks;
1187         pgoff_t orig_page_offset = 0, seq_end_page;
1188         int ret1, ret2, depth, last_extent = 0;
1189         int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
1190         int data_offset_in_page;
1191         int block_len_in_page;
1192         int uninit;
1193
1194         /* orig and donor should be different file */
1195         if (orig_inode->i_ino == donor_inode->i_ino) {
1196                 ext4_debug("ext4 move extent: The argument files should not "
1197                         "be same file [ino:orig %lu, donor %lu]\n",
1198                         orig_inode->i_ino, donor_inode->i_ino);
1199                 return -EINVAL;
1200         }
1201
1202         /* Regular file check */
1203         if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
1204                 ext4_debug("ext4 move extent: The argument files should be "
1205                         "regular file [ino:orig %lu, donor %lu]\n",
1206                         orig_inode->i_ino, donor_inode->i_ino);
1207                 return -EINVAL;
1208         }
1209
1210         /* Protect orig and donor inodes against a truncate */
1211         ret1 = mext_inode_double_lock(orig_inode, donor_inode);
1212         if (ret1 < 0)
1213                 return ret1;
1214
1215         /* Protect extent tree against block allocations via delalloc */
1216         double_down_write_data_sem(orig_inode, donor_inode);
1217         /* Check the filesystem environment whether move_extent can be done */
1218         ret1 = mext_check_arguments(orig_inode, donor_inode, orig_start,
1219                                     donor_start, &len);
1220         if (ret1)
1221                 goto out;
1222
1223         file_end = (i_size_read(orig_inode) - 1) >> orig_inode->i_blkbits;
1224         block_end = block_start + len - 1;
1225         if (file_end < block_end)
1226                 len -= block_end - file_end;
1227
1228         ret1 = get_ext_path(orig_inode, block_start, &orig_path);
1229         if (ret1)
1230                 goto out;
1231
1232         /* Get path structure to check the hole */
1233         ret1 = get_ext_path(orig_inode, block_start, &holecheck_path);
1234         if (ret1)
1235                 goto out;
1236
1237         depth = ext_depth(orig_inode);
1238         ext_cur = holecheck_path[depth].p_ext;
1239
1240         /*
1241          * Get proper starting location of block replacement if block_start was
1242          * within the hole.
1243          */
1244         if (le32_to_cpu(ext_cur->ee_block) +
1245                 ext4_ext_get_actual_len(ext_cur) - 1 < block_start) {
1246                 /*
1247                  * The hole exists between extents or the tail of
1248                  * original file.
1249                  */
1250                 last_extent = mext_next_extent(orig_inode,
1251                                         holecheck_path, &ext_cur);
1252                 if (last_extent < 0) {
1253                         ret1 = last_extent;
1254                         goto out;
1255                 }
1256                 last_extent = mext_next_extent(orig_inode, orig_path,
1257                                                         &ext_dummy);
1258                 if (last_extent < 0) {
1259                         ret1 = last_extent;
1260                         goto out;
1261                 }
1262                 seq_start = le32_to_cpu(ext_cur->ee_block);
1263         } else if (le32_to_cpu(ext_cur->ee_block) > block_start)
1264                 /* The hole exists at the beginning of original file. */
1265                 seq_start = le32_to_cpu(ext_cur->ee_block);
1266         else
1267                 seq_start = block_start;
1268
1269         /* No blocks within the specified range. */
1270         if (le32_to_cpu(ext_cur->ee_block) > block_end) {
1271                 ext4_debug("ext4 move extent: The specified range of file "
1272                                                         "may be the hole\n");
1273                 ret1 = -EINVAL;
1274                 goto out;
1275         }
1276
1277         /* Adjust start blocks */
1278         add_blocks = min(le32_to_cpu(ext_cur->ee_block) +
1279                          ext4_ext_get_actual_len(ext_cur), block_end + 1) -
1280                      max(le32_to_cpu(ext_cur->ee_block), block_start);
1281
1282         while (!last_extent && le32_to_cpu(ext_cur->ee_block) <= block_end) {
1283                 seq_blocks += add_blocks;
1284
1285                 /* Adjust tail blocks */
1286                 if (seq_start + seq_blocks - 1 > block_end)
1287                         seq_blocks = block_end - seq_start + 1;
1288
1289                 ext_prev = ext_cur;
1290                 last_extent = mext_next_extent(orig_inode, holecheck_path,
1291                                                 &ext_cur);
1292                 if (last_extent < 0) {
1293                         ret1 = last_extent;
1294                         break;
1295                 }
1296                 add_blocks = ext4_ext_get_actual_len(ext_cur);
1297
1298                 /*
1299                  * Extend the length of contiguous block (seq_blocks)
1300                  * if extents are contiguous.
1301                  */
1302                 if (ext4_can_extents_be_merged(orig_inode,
1303                                                ext_prev, ext_cur) &&
1304                     block_end >= le32_to_cpu(ext_cur->ee_block) &&
1305                     !last_extent)
1306                         continue;
1307
1308                 /* Is original extent is uninitialized */
1309                 uninit = ext4_ext_is_uninitialized(ext_prev);
1310
1311                 data_offset_in_page = seq_start % blocks_per_page;
1312
1313                 /*
1314                  * Calculate data blocks count that should be swapped
1315                  * at the first page.
1316                  */
1317                 if (data_offset_in_page + seq_blocks > blocks_per_page) {
1318                         /* Swapped blocks are across pages */
1319                         block_len_in_page =
1320                                         blocks_per_page - data_offset_in_page;
1321                 } else {
1322                         /* Swapped blocks are in a page */
1323                         block_len_in_page = seq_blocks;
1324                 }
1325
1326                 orig_page_offset = seq_start >>
1327                                 (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1328                 seq_end_page = (seq_start + seq_blocks - 1) >>
1329                                 (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1330                 seq_start = le32_to_cpu(ext_cur->ee_block);
1331                 rest_blocks = seq_blocks;
1332
1333                 /*
1334                  * Up semaphore to avoid following problems:
1335                  * a. transaction deadlock among ext4_journal_start,
1336                  *    ->write_begin via pagefault, and jbd2_journal_commit
1337                  * b. racing with ->readpage, ->write_begin, and ext4_get_block
1338                  *    in move_extent_per_page
1339                  */
1340                 double_up_write_data_sem(orig_inode, donor_inode);
1341
1342                 while (orig_page_offset <= seq_end_page) {
1343
1344                         /* Swap original branches with new branches */
1345                         block_len_in_page = move_extent_per_page(
1346                                                 o_filp, donor_inode,
1347                                                 orig_page_offset,
1348                                                 data_offset_in_page,
1349                                                 block_len_in_page, uninit,
1350                                                 &ret1);
1351
1352                         /* Count how many blocks we have exchanged */
1353                         *moved_len += block_len_in_page;
1354                         if (ret1 < 0)
1355                                 break;
1356                         if (*moved_len > len) {
1357                                 ext4_error(orig_inode->i_sb,
1358                                         "We replaced blocks too much! "
1359                                         "sum of replaced: %llu requested: %llu",
1360                                         *moved_len, len);
1361                                 ret1 = -EIO;
1362                                 break;
1363                         }
1364
1365                         orig_page_offset++;
1366                         data_offset_in_page = 0;
1367                         rest_blocks -= block_len_in_page;
1368                         if (rest_blocks > blocks_per_page)
1369                                 block_len_in_page = blocks_per_page;
1370                         else
1371                                 block_len_in_page = rest_blocks;
1372                 }
1373
1374                 double_down_write_data_sem(orig_inode, donor_inode);
1375                 if (ret1 < 0)
1376                         break;
1377
1378                 /* Decrease buffer counter */
1379                 if (holecheck_path)
1380                         ext4_ext_drop_refs(holecheck_path);
1381                 ret1 = get_ext_path(orig_inode, seq_start, &holecheck_path);
1382                 if (ret1)
1383                         break;
1384                 depth = holecheck_path->p_depth;
1385
1386                 /* Decrease buffer counter */
1387                 if (orig_path)
1388                         ext4_ext_drop_refs(orig_path);
1389                 ret1 = get_ext_path(orig_inode, seq_start, &orig_path);
1390                 if (ret1)
1391                         break;
1392
1393                 ext_cur = holecheck_path[depth].p_ext;
1394                 add_blocks = ext4_ext_get_actual_len(ext_cur);
1395                 seq_blocks = 0;
1396
1397         }
1398 out:
1399         if (*moved_len) {
1400                 ext4_discard_preallocations(orig_inode);
1401                 ext4_discard_preallocations(donor_inode);
1402         }
1403
1404         if (orig_path) {
1405                 ext4_ext_drop_refs(orig_path);
1406                 kfree(orig_path);
1407         }
1408         if (holecheck_path) {
1409                 ext4_ext_drop_refs(holecheck_path);
1410                 kfree(holecheck_path);
1411         }
1412         double_up_write_data_sem(orig_inode, donor_inode);
1413         ret2 = mext_inode_double_unlock(orig_inode, donor_inode);
1414
1415         if (ret1)
1416                 return ret1;
1417         else if (ret2)
1418                 return ret2;
1419
1420         return 0;
1421 }