fs/ext4/move_extent.c

   1 /*
   2  * Copyright (c) 2008,2009 NEC Software Tohoku, Ltd.
   3  * Written by Takashi Sato <t-sato@yk.jp.nec.com>
   4  *            Akira Fujita <a-fujita@rs.jp.nec.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of version 2.1 of the GNU Lesser General Public License
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  */
  15
  16 #include <linux/fs.h>
  17 #include <linux/quotaops.h>
  18 #include <linux/slab.h>
  19 #include "ext4_jbd2.h"
  20 #include "ext4.h"
  21 #include "ext4_extents.h"
  22
  23 /**
  24  * get_ext_path - Find an extent path for designated logical block number.
  25  *
  26  * @inode:      an inode which is searched
  27  * @lblock:     logical block number to find an extent path
  28  * @path:       pointer to an extent path pointer (for output)
  29  *
  30  * ext4_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 **orig_path)
  36 {
  37         int ret = 0;
  38         struct ext4_ext_path *path;
  39
  40         path = ext4_ext_find_extent(inode, lblock, *orig_path, EXT4_EX_NOCACHE);
  41         if (IS_ERR(path))
  42                 ret = PTR_ERR(path);
  43         else if (path[ext_depth(inode)].p_ext == NULL)
  44                 ret = -ENODATA;
  45         else
  46                 *orig_path = path;
  47
  48         return ret;
  49 }
  50
  51 /**
  52  * copy_extent_status - Copy the extent's initialization status
  53  *
  54  * @src:        an extent for getting initialize status
  55  * @dest:       an extent to be set the status
  56  */
  57 static void
  58 copy_extent_status(struct ext4_extent *src, struct ext4_extent *dest)
  59 {
  60         if (ext4_ext_is_uninitialized(src))
  61                 ext4_ext_mark_uninitialized(dest);
  62         else
  63                 dest->ee_len = cpu_to_le16(ext4_ext_get_actual_len(dest));
  64 }
  65
  66 /**
  67  * mext_next_extent - Search for the next extent and set it to "extent"
  68  *
  69  * @inode:      inode which is searched
  70  * @path:       this will obtain data for the next extent
  71  * @extent:     pointer to the next extent we have just gotten
  72  *
  73  * Search the next extent in the array of ext4_ext_path structure (@path)
  74  * and set it to ext4_extent structure (@extent). In addition, the member of
  75  * @path (->p_ext) also points the next extent. Return 0 on success, 1 if
  76  * ext4_ext_path structure refers to the last extent, or a negative error
  77  * value on failure.
  78  */
  79 int
  80 mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
  81                       struct ext4_extent **extent)
  82 {
  83         struct ext4_extent_header *eh;
  84         int ppos, leaf_ppos = path->p_depth;
  85
  86         ppos = leaf_ppos;
  87         if (EXT_LAST_EXTENT(path[ppos].p_hdr) > path[ppos].p_ext) {
  88                 /* leaf block */
  89                 *extent = ++path[ppos].p_ext;
  90                 path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
  91                 return 0;
  92         }
  93
  94         while (--ppos >= 0) {
  95                 if (EXT_LAST_INDEX(path[ppos].p_hdr) >
  96                     path[ppos].p_idx) {
  97                         int cur_ppos = ppos;
  98
  99                         /* index block */
 100                         path[ppos].p_idx++;
 101                         path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
 102                         if (path[ppos+1].p_bh)
 103                                 brelse(path[ppos+1].p_bh);
 104                         path[ppos+1].p_bh =
 105                                 sb_bread(inode->i_sb, path[ppos].p_block);
 106                         if (!path[ppos+1].p_bh)
 107                                 return -EIO;
 108                         path[ppos+1].p_hdr =
 109                                 ext_block_hdr(path[ppos+1].p_bh);
 110
 111                         /* Halfway index block */
 112                         while (++cur_ppos < leaf_ppos) {
 113                                 path[cur_ppos].p_idx =
 114                                         EXT_FIRST_INDEX(path[cur_ppos].p_hdr);
 115                                 path[cur_ppos].p_block =
 116                                         ext4_idx_pblock(path[cur_ppos].p_idx);
 117                                 if (path[cur_ppos+1].p_bh)
 118                                         brelse(path[cur_ppos+1].p_bh);
 119                                 path[cur_ppos+1].p_bh = sb_bread(inode->i_sb,
 120                                         path[cur_ppos].p_block);
 121                                 if (!path[cur_ppos+1].p_bh)
 122                                         return -EIO;
 123                                 path[cur_ppos+1].p_hdr =
 124                                         ext_block_hdr(path[cur_ppos+1].p_bh);
 125                         }
 126
 127                         path[leaf_ppos].p_ext = *extent = NULL;
 128
 129                         eh = path[leaf_ppos].p_hdr;
 130                         if (le16_to_cpu(eh->eh_entries) == 0)
 131                                 /* empty leaf is found */
 132                                 return -ENODATA;
 133
 134                         /* leaf block */
 135                         path[leaf_ppos].p_ext = *extent =
 136                                 EXT_FIRST_EXTENT(path[leaf_ppos].p_hdr);
 137                         path[leaf_ppos].p_block =
 138                                         ext4_ext_pblock(path[leaf_ppos].p_ext);
 139                         return 0;
 140                 }
 141         }
 142         /* We found the last extent */
 143         return 1;
 144 }
 145
 146 /**
 147  * ext4_double_down_write_data_sem - Acquire two inodes' write lock
 148  *                                   of i_data_sem
 149  *
 150  * Acquire write lock of i_data_sem of the two inodes
 151  */
 152 void
 153 ext4_double_down_write_data_sem(struct inode *first, struct inode *second)
 154 {
 155         if (first < second) {
 156                 down_write(&EXT4_I(first)->i_data_sem);
 157                 down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);
 158         } else {
 159                 down_write(&EXT4_I(second)->i_data_sem);
 160                 down_write_nested(&EXT4_I(first)->i_data_sem, SINGLE_DEPTH_NESTING);
 161
 162         }
 163 }
 164
 165 /**
 166  * ext4_double_up_write_data_sem - Release two inodes' write lock of i_data_sem
 167  *
 168  * @orig_inode:         original inode structure to be released its lock first
 169  * @donor_inode:        donor inode structure to be released its lock second
 170  * Release write lock of i_data_sem of two inodes (orig and donor).
 171  */
 172 void
 173 ext4_double_up_write_data_sem(struct inode *orig_inode,
 174                               struct inode *donor_inode)
 175 {
 176         up_write(&EXT4_I(orig_inode)->i_data_sem);
 177         up_write(&EXT4_I(donor_inode)->i_data_sem);
 178 }
 179
 180 /**
 181  * mext_insert_across_blocks - Insert extents across leaf block
 182  *
 183  * @handle:             journal handle
 184  * @orig_inode:         original inode
 185  * @o_start:            first original extent to be changed
 186  * @o_end:              last original extent to be changed
 187  * @start_ext:          first new extent to be inserted
 188  * @new_ext:            middle of new extent to be inserted
 189  * @end_ext:            last new extent to be inserted
 190  *
 191  * Allocate a new leaf block and insert extents into it. Return 0 on success,
 192  * or a negative error value on failure.
 193  */
 194 static int
 195 mext_insert_across_blocks(handle_t *handle, struct inode *orig_inode,
 196                 struct ext4_extent *o_start, struct ext4_extent *o_end,
 197                 struct ext4_extent *start_ext, struct ext4_extent *new_ext,
 198                 struct ext4_extent *end_ext)
 199 {
 200         struct ext4_ext_path *orig_path = NULL;
 201         ext4_lblk_t eblock = 0;
 202         int new_flag = 0;
 203         int end_flag = 0;
 204         int err = 0;
 205
 206         if (start_ext->ee_len && new_ext->ee_len && end_ext->ee_len) {
 207                 if (o_start == o_end) {
 208
 209                         /*       start_ext   new_ext    end_ext
 210                          * donor |---------|-----------|--------|
 211                          * orig  |------------------------------|
 212                          */
 213                         end_flag = 1;
 214                 } else {
 215
 216                         /*       start_ext   new_ext   end_ext
 217                          * donor |---------|----------|---------|
 218                          * orig  |---------------|--------------|
 219                          */
 220                         o_end->ee_block = end_ext->ee_block;
 221                         o_end->ee_len = end_ext->ee_len;
 222                         ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
 223                 }
 224
 225                 o_start->ee_len = start_ext->ee_len;
 226                 eblock = le32_to_cpu(start_ext->ee_block);
 227                 new_flag = 1;
 228
 229         } else if (start_ext->ee_len && new_ext->ee_len &&
 230                    !end_ext->ee_len && o_start == o_end) {
 231
 232                 /*       start_ext      new_ext
 233                  * donor |--------------|---------------|
 234                  * orig  |------------------------------|
 235                  */
 236                 o_start->ee_len = start_ext->ee_len;
 237                 eblock = le32_to_cpu(start_ext->ee_block);
 238                 new_flag = 1;
 239
 240         } else if (!start_ext->ee_len && new_ext->ee_len &&
 241                    end_ext->ee_len && o_start == o_end) {
 242
 243                 /*        new_ext       end_ext
 244                  * donor |--------------|---------------|
 245                  * orig  |------------------------------|
 246                  */
 247                 o_end->ee_block = end_ext->ee_block;
 248                 o_end->ee_len = end_ext->ee_len;
 249                 ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
 250
 251                 /*
 252                  * Set 0 to the extent block if new_ext was
 253                  * the first block.
 254                  */
 255                 if (new_ext->ee_block)
 256                         eblock = le32_to_cpu(new_ext->ee_block);
 257
 258                 new_flag = 1;
 259         } else {
 260                 ext4_debug("ext4 move extent: Unexpected insert case\n");
 261                 return -EIO;
 262         }
 263
 264         if (new_flag) {
 265                 err = get_ext_path(orig_inode, eblock, &orig_path);
 266                 if (err)
 267                         goto out;
 268
 269                 if (ext4_ext_insert_extent(handle, orig_inode,
 270                                         orig_path, new_ext, 0))
 271                         goto out;
 272         }
 273
 274         if (end_flag) {
 275                 err = get_ext_path(orig_inode,
 276                                 le32_to_cpu(end_ext->ee_block) - 1, &orig_path);
 277                 if (err)
 278                         goto out;
 279
 280                 if (ext4_ext_insert_extent(handle, orig_inode,
 281                                            orig_path, end_ext, 0))
 282                         goto out;
 283         }
 284 out:
 285         if (orig_path) {
 286                 ext4_ext_drop_refs(orig_path);
 287                 kfree(orig_path);
 288         }
 289
 290         return err;
 291
 292 }
 293
 294 /**
 295  * mext_insert_inside_block - Insert new extent to the extent block
 296  *
 297  * @o_start:            first original extent to be moved
 298  * @o_end:              last original extent to be moved
 299  * @start_ext:          first new extent to be inserted
 300  * @new_ext:            middle of new extent to be inserted
 301  * @end_ext:            last new extent to be inserted
 302  * @eh:                 extent header of target leaf block
 303  * @range_to_move:      used to decide how to insert extent
 304  *
 305  * Insert extents into the leaf block. The extent (@o_start) is overwritten
 306  * by inserted extents.
 307  */
 308 static void
 309 mext_insert_inside_block(struct ext4_extent *o_start,
 310                               struct ext4_extent *o_end,
 311                               struct ext4_extent *start_ext,
 312                               struct ext4_extent *new_ext,
 313                               struct ext4_extent *end_ext,
 314                               struct ext4_extent_header *eh,
 315                               int range_to_move)
 316 {
 317         int i = 0;
 318         unsigned long len;
 319
 320         /* Move the existing extents */
 321         if (range_to_move && o_end < EXT_LAST_EXTENT(eh)) {
 322                 len = (unsigned long)(EXT_LAST_EXTENT(eh) + 1) -
 323                         (unsigned long)(o_end + 1);
 324                 memmove(o_end + 1 + range_to_move, o_end + 1, len);
 325         }
 326
 327         /* Insert start entry */
 328         if (start_ext->ee_len)
 329                 o_start[i++].ee_len = start_ext->ee_len;
 330
 331         /* Insert new entry */
 332         if (new_ext->ee_len) {
 333                 o_start[i] = *new_ext;
 334                 ext4_ext_store_pblock(&o_start[i++], ext4_ext_pblock(new_ext));
 335         }
 336
 337         /* Insert end entry */
 338         if (end_ext->ee_len)
 339                 o_start[i] = *end_ext;
 340
 341         /* Increment the total entries counter on the extent block */
 342         le16_add_cpu(&eh->eh_entries, range_to_move);
 343 }
 344
 345 /**
 346  * mext_insert_extents - Insert new extent
 347  *
 348  * @handle:     journal handle
 349  * @orig_inode: original inode
 350  * @orig_path:  path indicates first extent to be changed
 351  * @o_start:    first original extent to be changed
 352  * @o_end:      last original extent to be changed
 353  * @start_ext:  first new extent to be inserted
 354  * @new_ext:    middle of new extent to be inserted
 355  * @end_ext:    last new extent to be inserted
 356  *
 357  * Call the function to insert extents. If we cannot add more extents into
 358  * the leaf block, we call mext_insert_across_blocks() to create a
 359  * new leaf block. Otherwise call mext_insert_inside_block(). Return 0
 360  * on success, or a negative error value on failure.
 361  */
 362 static int
 363 mext_insert_extents(handle_t *handle, struct inode *orig_inode,
 364                          struct ext4_ext_path *orig_path,
 365                          struct ext4_extent *o_start,
 366                          struct ext4_extent *o_end,
 367                          struct ext4_extent *start_ext,
 368                          struct ext4_extent *new_ext,
 369                          struct ext4_extent *end_ext)
 370 {
 371         struct  ext4_extent_header *eh;
 372         unsigned long need_slots, slots_range;
 373         int     range_to_move, depth, ret;
 374
 375         /*
 376          * The extents need to be inserted
 377          * start_extent + new_extent + end_extent.
 378          */
 379         need_slots = (start_ext->ee_len ? 1 : 0) + (end_ext->ee_len ? 1 : 0) +
 380                 (new_ext->ee_len ? 1 : 0);
 381
 382         /* The number of slots between start and end */
 383         slots_range = ((unsigned long)(o_end + 1) - (unsigned long)o_start + 1)
 384                 / sizeof(struct ext4_extent);
 385
 386         /* Range to move the end of extent */
 387         range_to_move = need_slots - slots_range;
 388         depth = orig_path->p_depth;
 389         orig_path += depth;
 390         eh = orig_path->p_hdr;
 391
 392         if (depth) {
 393                 /* Register to journal */
 394                 ret = ext4_journal_get_write_access(handle, orig_path->p_bh);
 395                 if (ret)
 396                         return ret;
 397         }
 398
 399         /* Expansion */
 400         if (range_to_move > 0 &&
 401                 (range_to_move > le16_to_cpu(eh->eh_max)
 402                         - le16_to_cpu(eh->eh_entries))) {
 403
 404                 ret = mext_insert_across_blocks(handle, orig_inode, o_start,
 405                                         o_end, start_ext, new_ext, end_ext);
 406                 if (ret < 0)
 407                         return ret;
 408         } else
 409                 mext_insert_inside_block(o_start, o_end, start_ext, new_ext,
 410                                                 end_ext, eh, range_to_move);
 411
 412         return ext4_ext_dirty(handle, orig_inode, orig_path);
 413 }
 414
 415 /**
 416  * mext_leaf_block - Move one leaf extent block into the inode.
 417  *
 418  * @handle:             journal handle
 419  * @orig_inode:         original inode
 420  * @orig_path:          path indicates first extent to be changed
 421  * @dext:               donor extent
 422  * @from:               start offset on the target file
 423  *
 424  * In order to insert extents into the leaf block, we must divide the extent
 425  * in the leaf block into three extents. The one is located to be inserted
 426  * extents, and the others are located around it.
 427  *
 428  * Therefore, this function creates structures to save extents of the leaf
 429  * block, and inserts extents by calling mext_insert_extents() with
 430  * created extents. Return 0 on success, or a negative error value on failure.
 431  */
 432 static int
 433 mext_leaf_block(handle_t *handle, struct inode *orig_inode,
 434                      struct ext4_ext_path *orig_path, struct ext4_extent *dext,
 435                      ext4_lblk_t *from)
 436 {
 437         struct ext4_extent *oext, *o_start, *o_end, *prev_ext;
 438         struct ext4_extent new_ext, start_ext, end_ext;
 439         ext4_lblk_t new_ext_end;
 440         int oext_alen, new_ext_alen, end_ext_alen;
 441         int depth = ext_depth(orig_inode);
 442         int ret;
 443
 444         start_ext.ee_block = end_ext.ee_block = 0;
 445         o_start = o_end = oext = orig_path[depth].p_ext;
 446         oext_alen = ext4_ext_get_actual_len(oext);
 447         start_ext.ee_len = end_ext.ee_len = 0;
 448
 449         new_ext.ee_block = cpu_to_le32(*from);
 450         ext4_ext_store_pblock(&new_ext, ext4_ext_pblock(dext));
 451         new_ext.ee_len = dext->ee_len;
 452         new_ext_alen = ext4_ext_get_actual_len(&new_ext);
 453         new_ext_end = le32_to_cpu(new_ext.ee_block) + new_ext_alen - 1;
 454
 455         /*
 456          * Case: original extent is first
 457          * oext      |--------|
 458          * new_ext      |--|
 459          * start_ext |--|
 460          */
 461         if (le32_to_cpu(oext->ee_block) < le32_to_cpu(new_ext.ee_block) &&
 462                 le32_to_cpu(new_ext.ee_block) <
 463                 le32_to_cpu(oext->ee_block) + oext_alen) {
 464                 start_ext.ee_len = cpu_to_le16(le32_to_cpu(new_ext.ee_block) -
 465                                                le32_to_cpu(oext->ee_block));
 466                 start_ext.ee_block = oext->ee_block;
 467                 copy_extent_status(oext, &start_ext);
 468         } else if (oext > EXT_FIRST_EXTENT(orig_path[depth].p_hdr)) {
 469                 prev_ext = oext - 1;
 470                 /*
 471                  * We can merge new_ext into previous extent,
 472                  * if these are contiguous and same extent type.
 473                  */
 474                 if (ext4_can_extents_be_merged(orig_inode, prev_ext,
 475                                                &new_ext)) {
 476                         o_start = prev_ext;
 477                         start_ext.ee_len = cpu_to_le16(
 478                                 ext4_ext_get_actual_len(prev_ext) +
 479                                 new_ext_alen);
 480                         start_ext.ee_block = oext->ee_block;
 481                         copy_extent_status(prev_ext, &start_ext);
 482                         new_ext.ee_len = 0;
 483                 }
 484         }
 485
 486         /*
 487          * Case: new_ext_end must be less than oext
 488          * oext      |-----------|
 489          * new_ext       |-------|
 490          */
 491         if (le32_to_cpu(oext->ee_block) + oext_alen - 1 < new_ext_end) {
 492                 EXT4_ERROR_INODE(orig_inode,
 493                         "new_ext_end(%u) should be less than or equal to "
 494                         "oext->ee_block(%u) + oext_alen(%d) - 1",
 495                         new_ext_end, le32_to_cpu(oext->ee_block),
 496                         oext_alen);
 497                 ret = -EIO;
 498                 goto out;
 499         }
 500
 501         /*
 502          * Case: new_ext is smaller than original extent
 503          * oext    |---------------|
 504          * new_ext |-----------|
 505          * end_ext             |---|
 506          */
 507         if (le32_to_cpu(oext->ee_block) <= new_ext_end &&
 508                 new_ext_end < le32_to_cpu(oext->ee_block) + oext_alen - 1) {
 509                 end_ext.ee_len =
 510                         cpu_to_le16(le32_to_cpu(oext->ee_block) +
 511                         oext_alen - 1 - new_ext_end);
 512                 copy_extent_status(oext, &end_ext);
 513                 end_ext_alen = ext4_ext_get_actual_len(&end_ext);
 514                 ext4_ext_store_pblock(&end_ext,
 515                         (ext4_ext_pblock(o_end) + oext_alen - end_ext_alen));
 516                 end_ext.ee_block =
 517                         cpu_to_le32(le32_to_cpu(o_end->ee_block) +
 518                         oext_alen - end_ext_alen);
 519         }
 520
 521         ret = mext_insert_extents(handle, orig_inode, orig_path, o_start,
 522                                 o_end, &start_ext, &new_ext, &end_ext);
 523 out:
 524         return ret;
 525 }
 526
 527 /**
 528  * mext_calc_swap_extents - Calculate extents for extent swapping.
 529  *
 530  * @tmp_dext:           the extent that will belong to the original inode
 531  * @tmp_oext:           the extent that will belong to the donor inode
 532  * @orig_off:           block offset of original inode
 533  * @donor_off:          block offset of donor inode
 534  * @max_count:          the maximum length of extents
 535  *
 536  * Return 0 on success, or a negative error value on failure.
 537  */
 538 static int
 539 mext_calc_swap_extents(struct ext4_extent *tmp_dext,
 540                               struct ext4_extent *tmp_oext,
 541                               ext4_lblk_t orig_off, ext4_lblk_t donor_off,
 542                               ext4_lblk_t max_count)
 543 {
 544         ext4_lblk_t diff, orig_diff;
 545         struct ext4_extent dext_old, oext_old;
 546
 547         BUG_ON(orig_off != donor_off);
 548
 549         /* original and donor extents have to cover the same block offset */
 550         if (orig_off < le32_to_cpu(tmp_oext->ee_block) ||
 551             le32_to_cpu(tmp_oext->ee_block) +
 552                         ext4_ext_get_actual_len(tmp_oext) - 1 < orig_off)
 553                 return -ENODATA;
 554
 555         if (orig_off < le32_to_cpu(tmp_dext->ee_block) ||
 556             le32_to_cpu(tmp_dext->ee_block) +
 557                         ext4_ext_get_actual_len(tmp_dext) - 1 < orig_off)
 558                 return -ENODATA;
 559
 560         dext_old = *tmp_dext;
 561         oext_old = *tmp_oext;
 562
 563         /* When tmp_dext is too large, pick up the target range. */
 564         diff = donor_off - le32_to_cpu(tmp_dext->ee_block);
 565
 566         ext4_ext_store_pblock(tmp_dext, ext4_ext_pblock(tmp_dext) + diff);
 567         le32_add_cpu(&tmp_dext->ee_block, diff);
 568         le16_add_cpu(&tmp_dext->ee_len, -diff);
 569
 570         if (max_count < ext4_ext_get_actual_len(tmp_dext))
 571                 tmp_dext->ee_len = cpu_to_le16(max_count);
 572
 573         orig_diff = orig_off - le32_to_cpu(tmp_oext->ee_block);
 574         ext4_ext_store_pblock(tmp_oext, ext4_ext_pblock(tmp_oext) + orig_diff);
 575
 576         /* Adjust extent length if donor extent is larger than orig */
 577         if (ext4_ext_get_actual_len(tmp_dext) >
 578             ext4_ext_get_actual_len(tmp_oext) - orig_diff)
 579                 tmp_dext->ee_len = cpu_to_le16(le16_to_cpu(tmp_oext->ee_len) -
 580                                                 orig_diff);
 581
 582         tmp_oext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(tmp_dext));
 583
 584         copy_extent_status(&oext_old, tmp_dext);
 585         copy_extent_status(&dext_old, tmp_oext);
 586
 587         return 0;
 588 }
 589
 590 /**
 591  * mext_check_coverage - Check that all extents in range has the same type
 592  *
 593  * @inode:              inode in question
 594  * @from:               block offset of inode
 595  * @count:              block count to be checked
 596  * @uninit:             extents expected to be uninitialized
 597  * @err:                pointer to save error value
 598  *
 599  * Return 1 if all extents in range has expected type, and zero otherwise.
 600  */
 601 static int
 602 mext_check_coverage(struct inode *inode, ext4_lblk_t from, ext4_lblk_t count,
 603                           int uninit, int *err)
 604 {
 605         struct ext4_ext_path *path = NULL;
 606         struct ext4_extent *ext;
 607         int ret = 0;
 608         ext4_lblk_t last = from + count;
 609         while (from < last) {
 610                 *err = get_ext_path(inode, from, &path);
 611                 if (*err)
 612                         goto out;
 613                 ext = path[ext_depth(inode)].p_ext;
 614                 if (uninit != ext4_ext_is_uninitialized(ext))
 615                         goto out;
 616                 from += ext4_ext_get_actual_len(ext);
 617                 ext4_ext_drop_refs(path);
 618         }
 619         ret = 1;
 620 out:
 621         if (path) {
 622                 ext4_ext_drop_refs(path);
 623                 kfree(path);
 624         }
 625         return ret;
 626 }
 627
 628 /**
 629  * mext_replace_branches - Replace original extents with new extents
 630  *
 631  * @handle:             journal handle
 632  * @orig_inode:         original inode
 633  * @donor_inode:        donor inode
 634  * @from:               block offset of orig_inode
 635  * @count:              block count to be replaced
 636  * @err:                pointer to save return value
 637  *
 638  * Replace original inode extents and donor inode extents page by page.
 639  * We implement this replacement in the following three steps:
 640  * 1. Save the block information of original and donor inodes into
 641  *    dummy extents.
 642  * 2. Change the block information of original inode to point at the
 643  *    donor inode blocks.
 644  * 3. Change the block information of donor inode to point at the saved
 645  *    original inode blocks in the dummy extents.
 646  *
 647  * Return replaced block count.
 648  */
 649 static int
 650 mext_replace_branches(handle_t *handle, struct inode *orig_inode,
 651                            struct inode *donor_inode, ext4_lblk_t from,
 652                            ext4_lblk_t count, int *err)
 653 {
 654         struct ext4_ext_path *orig_path = NULL;
 655         struct ext4_ext_path *donor_path = NULL;
 656         struct ext4_extent *oext, *dext;
 657         struct ext4_extent tmp_dext, tmp_oext;
 658         ext4_lblk_t orig_off = from, donor_off = from;
 659         int depth;
 660         int replaced_count = 0;
 661         int dext_alen;
 662
 663         *err = ext4_es_remove_extent(orig_inode, from, count);
 664         if (*err)
 665                 goto out;
 666
 667         *err = ext4_es_remove_extent(donor_inode, from, count);
 668         if (*err)
 669                 goto out;
 670
 671         /* Get the original extent for the block "orig_off" */
 672         *err = get_ext_path(orig_inode, orig_off, &orig_path);
 673         if (*err)
 674                 goto out;
 675
 676         /* Get the donor extent for the head */
 677         *err = get_ext_path(donor_inode, donor_off, &donor_path);
 678         if (*err)
 679                 goto out;
 680         depth = ext_depth(orig_inode);
 681         oext = orig_path[depth].p_ext;
 682         tmp_oext = *oext;
 683
 684         depth = ext_depth(donor_inode);
 685         dext = donor_path[depth].p_ext;
 686         if (unlikely(!dext))
 687                 goto missing_donor_extent;
 688         tmp_dext = *dext;
 689
 690         *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
 691                                       donor_off, count);
 692         if (*err)
 693                 goto out;
 694
 695         /* Loop for the donor extents */
 696         while (1) {
 697                 /* The extent for donor must be found. */
 698                 if (unlikely(!dext)) {
 699                 missing_donor_extent:
 700                         EXT4_ERROR_INODE(donor_inode,
 701                                    "The extent for donor must be found");
 702                         *err = -EIO;
 703                         goto out;
 704                 } else if (donor_off != le32_to_cpu(tmp_dext.ee_block)) {
 705                         EXT4_ERROR_INODE(donor_inode,
 706                                 "Donor offset(%u) and the first block of donor "
 707                                 "extent(%u) should be equal",
 708                                 donor_off,
 709                                 le32_to_cpu(tmp_dext.ee_block));
 710                         *err = -EIO;
 711                         goto out;
 712                 }
 713
 714                 /* Set donor extent to orig extent */
 715                 *err = mext_leaf_block(handle, orig_inode,
 716                                            orig_path, &tmp_dext, &orig_off);
 717                 if (*err)
 718                         goto out;
 719
 720                 /* Set orig extent to donor extent */
 721                 *err = mext_leaf_block(handle, donor_inode,
 722                                            donor_path, &tmp_oext, &donor_off);
 723                 if (*err)
 724                         goto out;
 725
 726                 dext_alen = ext4_ext_get_actual_len(&tmp_dext);
 727                 replaced_count += dext_alen;
 728                 donor_off += dext_alen;
 729                 orig_off += dext_alen;
 730
 731                 BUG_ON(replaced_count > count);
 732                 /* Already moved the expected blocks */
 733                 if (replaced_count >= count)
 734                         break;
 735
 736                 if (orig_path)
 737                         ext4_ext_drop_refs(orig_path);
 738                 *err = get_ext_path(orig_inode, orig_off, &orig_path);
 739                 if (*err)
 740                         goto out;
 741                 depth = ext_depth(orig_inode);
 742                 oext = orig_path[depth].p_ext;
 743                 tmp_oext = *oext;
 744
 745                 if (donor_path)
 746                         ext4_ext_drop_refs(donor_path);
 747                 *err = get_ext_path(donor_inode, donor_off, &donor_path);
 748                 if (*err)
 749                         goto out;
 750                 depth = ext_depth(donor_inode);
 751                 dext = donor_path[depth].p_ext;
 752                 tmp_dext = *dext;
 753
 754                 *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
 755                                            donor_off, count - replaced_count);
 756                 if (*err)
 757                         goto out;
 758         }
 759
 760 out:
 761         if (orig_path) {
 762                 ext4_ext_drop_refs(orig_path);
 763                 kfree(orig_path);
 764         }
 765         if (donor_path) {
 766                 ext4_ext_drop_refs(donor_path);
 767                 kfree(donor_path);
 768         }
 769
 770         return replaced_count;
 771 }
 772
 773 /**
 774  * mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2
 775  *
 776  * @inode1:     the inode structure
 777  * @inode2:     the inode structure
 778  * @index:      page index
 779  * @page:       result page vector
 780  *
 781  * Grab two locked pages for inode's by inode order
 782  */
 783 static int
 784 mext_page_double_lock(struct inode *inode1, struct inode *inode2,
 785                       pgoff_t index, struct page *page[2])
 786 {
 787         struct address_space *mapping[2];
 788         unsigned fl = AOP_FLAG_NOFS;
 789
 790         BUG_ON(!inode1 || !inode2);
 791         if (inode1 < inode2) {
 792                 mapping[0] = inode1->i_mapping;
 793                 mapping[1] = inode2->i_mapping;
 794         } else {
 795                 mapping[0] = inode2->i_mapping;
 796                 mapping[1] = inode1->i_mapping;
 797         }
 798
 799         page[0] = grab_cache_page_write_begin(mapping[0], index, fl);
 800         if (!page[0])
 801                 return -ENOMEM;
 802
 803         page[1] = grab_cache_page_write_begin(mapping[1], index, fl);
 804         if (!page[1]) {
 805                 unlock_page(page[0]);
 806                 page_cache_release(page[0]);
 807                 return -ENOMEM;
 808         }
 809         /*
 810          * grab_cache_page_write_begin() may not wait on page's writeback if
 811          * BDI not demand that. But it is reasonable to be very conservative
 812          * here and explicitly wait on page's writeback
 813          */
 814         wait_on_page_writeback(page[0]);
 815         wait_on_page_writeback(page[1]);
 816         if (inode1 > inode2) {
 817                 struct page *tmp;
 818                 tmp = page[0];
 819                 page[0] = page[1];
 820                 page[1] = tmp;
 821         }
 822         return 0;
 823 }
 824
 825 /* Force page buffers uptodate w/o dropping page's lock */
 826 static int
 827 mext_page_mkuptodate(struct page *page, unsigned from, unsigned to)
 828 {
 829         struct inode *inode = page->mapping->host;
 830         sector_t block;
 831         struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
 832         unsigned int blocksize, block_start, block_end;
 833         int i, err,  nr = 0, partial = 0;
 834         BUG_ON(!PageLocked(page));
 835         BUG_ON(PageWriteback(page));
 836
 837         if (PageUptodate(page))
 838                 return 0;
 839
 840         blocksize = 1 << inode->i_blkbits;
 841         if (!page_has_buffers(page))
 842                 create_empty_buffers(page, blocksize, 0);
 843
 844         head = page_buffers(page);
 845         block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
 846         for (bh = head, block_start = 0; bh != head || !block_start;
 847              block++, block_start = block_end, bh = bh->b_this_page) {
 848                 block_end = block_start + blocksize;
 849                 if (block_end <= from || block_start >= to) {
 850                         if (!buffer_uptodate(bh))
 851                                 partial = 1;
 852                         continue;
 853                 }
 854                 if (buffer_uptodate(bh))
 855                         continue;
 856                 if (!buffer_mapped(bh)) {
 857                         err = ext4_get_block(inode, block, bh, 0);
 858                         if (err) {
 859                                 SetPageError(page);
 860                                 return err;
 861                         }
 862                         if (!buffer_mapped(bh)) {
 863                                 zero_user(page, block_start, blocksize);
 864                                 set_buffer_uptodate(bh);
 865                                 continue;
 866                         }
 867                 }
 868                 BUG_ON(nr >= MAX_BUF_PER_PAGE);
 869                 arr[nr++] = bh;
 870         }
 871         /* No io required */
 872         if (!nr)
 873                 goto out;
 874
 875         for (i = 0; i < nr; i++) {
 876                 bh = arr[i];
 877                 if (!bh_uptodate_or_lock(bh)) {
 878                         err = bh_submit_read(bh);
 879                         if (err)
 880                                 return err;
 881                 }
 882         }
 883 out:
 884         if (!partial)
 885                 SetPageUptodate(page);
 886         return 0;
 887 }
 888
 889 /**
 890  * move_extent_per_page - Move extent data per page
 891  *
 892  * @o_filp:                     file structure of original file
 893  * @donor_inode:                donor inode
 894  * @orig_page_offset:           page index on original file
 895  * @data_offset_in_page:        block index where data swapping starts
 896  * @block_len_in_page:          the number of blocks to be swapped
 897  * @uninit:                     orig extent is uninitialized or not
 898  * @err:                        pointer to save return value
 899  *
 900  * Save the data in original inode blocks and replace original inode extents
 901  * with donor inode extents by calling mext_replace_branches().
 902  * Finally, write out the saved data in new original inode blocks. Return
 903  * replaced block count.
 904  */
 905 static int
 906 move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
 907                   pgoff_t orig_page_offset, int data_offset_in_page,
 908                   int block_len_in_page, int uninit, int *err)
 909 {
 910         struct inode *orig_inode = file_inode(o_filp);
 911         struct page *pagep[2] = {NULL, NULL};
 912         handle_t *handle;
 913         ext4_lblk_t orig_blk_offset;
 914         unsigned long blocksize = orig_inode->i_sb->s_blocksize;
 915         unsigned int w_flags = 0;
 916         unsigned int tmp_data_size, data_size, replaced_size;
 917         int err2, jblocks, retries = 0;
 918         int replaced_count = 0;
 919         int from = data_offset_in_page << orig_inode->i_blkbits;
 920         int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
 921
 922         /*
 923          * It needs twice the amount of ordinary journal buffers because
 924          * inode and donor_inode may change each different metadata blocks.
 925          */
 926 again:
 927         *err = 0;
 928         jblocks = ext4_writepage_trans_blocks(orig_inode) * 2;
 929         handle = ext4_journal_start(orig_inode, EXT4_HT_MOVE_EXTENTS, jblocks);
 930         if (IS_ERR(handle)) {
 931                 *err = PTR_ERR(handle);
 932                 return 0;
 933         }
 934
 935         if (segment_eq(get_fs(), KERNEL_DS))
 936                 w_flags |= AOP_FLAG_UNINTERRUPTIBLE;
 937
 938         orig_blk_offset = orig_page_offset * blocks_per_page +
 939                 data_offset_in_page;
 940
 941         /* Calculate data_size */
 942         if ((orig_blk_offset + block_len_in_page - 1) ==
 943             ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) {
 944                 /* Replace the last block */
 945                 tmp_data_size = orig_inode->i_size & (blocksize - 1);
 946                 /*
 947                  * If data_size equal zero, it shows data_size is multiples of
 948                  * blocksize. So we set appropriate value.
 949                  */
 950                 if (tmp_data_size == 0)
 951                         tmp_data_size = blocksize;
 952
 953                 data_size = tmp_data_size +
 954                         ((block_len_in_page - 1) << orig_inode->i_blkbits);
 955         } else
 956                 data_size = block_len_in_page << orig_inode->i_blkbits;
 957
 958         replaced_size = data_size;
 959
 960         *err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset,
 961                                      pagep);
 962         if (unlikely(*err < 0))
 963                 goto stop_journal;
 964         /*
 965          * If orig extent was uninitialized it can become initialized
 966          * at any time after i_data_sem was dropped, in order to
 967          * serialize with delalloc we have recheck extent while we
 968          * hold page's lock, if it is still the case data copy is not
 969          * necessary, just swap data blocks between orig and donor.
 970          */
 971         if (uninit) {
 972                 ext4_double_down_write_data_sem(orig_inode, donor_inode);
 973                 /* If any of extents in range became initialized we have to
 974                  * fallback to data copying */
 975                 uninit = mext_check_coverage(orig_inode, orig_blk_offset,
 976                                              block_len_in_page, 1, err);
 977                 if (*err)
 978                         goto drop_data_sem;
 979
 980                 uninit &= mext_check_coverage(donor_inode, orig_blk_offset,
 981                                               block_len_in_page, 1, err);
 982                 if (*err)
 983                         goto drop_data_sem;
 984
 985                 if (!uninit) {
 986                         ext4_double_up_write_data_sem(orig_inode, donor_inode);
 987                         goto data_copy;
 988                 }
 989                 if ((page_has_private(pagep[0]) &&
 990                      !try_to_release_page(pagep[0], 0)) ||
 991                     (page_has_private(pagep[1]) &&
 992                      !try_to_release_page(pagep[1], 0))) {
 993                         *err = -EBUSY;
 994                         goto drop_data_sem;
 995                 }
 996                 replaced_count = mext_replace_branches(handle, orig_inode,
 997                                                 donor_inode, orig_blk_offset,
 998                                                 block_len_in_page, err);
 999         drop_data_sem:
1000                 ext4_double_up_write_data_sem(orig_inode, donor_inode);
1001                 goto unlock_pages;
1002         }
1003 data_copy:
1004         *err = mext_page_mkuptodate(pagep[0], from, from + replaced_size);
1005         if (*err)
1006                 goto unlock_pages;
1007
1008         /* At this point all buffers in range are uptodate, old mapping layout
1009          * is no longer required, try to drop it now. */
1010         if ((page_has_private(pagep[0]) && !try_to_release_page(pagep[0], 0)) ||
1011             (page_has_private(pagep[1]) && !try_to_release_page(pagep[1], 0))) {
1012                 *err = -EBUSY;
1013                 goto unlock_pages;
1014         }
1015
1016         replaced_count = mext_replace_branches(handle, orig_inode, donor_inode,
1017                                                orig_blk_offset,
1018                                                block_len_in_page, err);
1019         if (*err) {
1020                 if (replaced_count) {
1021                         block_len_in_page = replaced_count;
1022                         replaced_size =
1023                                 block_len_in_page << orig_inode->i_blkbits;
1024                 } else
1025                         goto unlock_pages;
1026         }
1027         /* Perform all necessary steps similar write_begin()/write_end()
1028          * but keeping in mind that i_size will not change */
1029         *err = __block_write_begin(pagep[0], from, replaced_size,
1030                                    ext4_get_block);
1031         if (!*err)
1032                 *err = block_commit_write(pagep[0], from, from + replaced_size);
1033
1034         if (unlikely(*err < 0))
1035                 goto repair_branches;
1036
1037         /* Even in case of data=writeback it is reasonable to pin
1038          * inode to transaction, to prevent unexpected data loss */
1039         *err = ext4_jbd2_file_inode(handle, orig_inode);
1040
1041 unlock_pages:
1042         unlock_page(pagep[0]);
1043         page_cache_release(pagep[0]);
1044         unlock_page(pagep[1]);
1045         page_cache_release(pagep[1]);
1046 stop_journal:
1047         ext4_journal_stop(handle);
1048         /* Buffer was busy because probably is pinned to journal transaction,
1049          * force transaction commit may help to free it. */
1050         if (*err == -EBUSY && ext4_should_retry_alloc(orig_inode->i_sb,
1051                                                       &retries))
1052                 goto again;
1053         return replaced_count;
1054
1055 repair_branches:
1056         /*
1057          * This should never ever happen!
1058          * Extents are swapped already, but we are not able to copy data.
1059          * Try to swap extents to it's original places
1060          */
1061         ext4_double_down_write_data_sem(orig_inode, donor_inode);
1062         replaced_count = mext_replace_branches(handle, donor_inode, orig_inode,
1063                                                orig_blk_offset,
1064                                                block_len_in_page, &err2);
1065         ext4_double_up_write_data_sem(orig_inode, donor_inode);
1066         if (replaced_count != block_len_in_page) {
1067                 EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset),
1068                                        "Unable to copy data block,"
1069                                        " data will be lost.");
1070                 *err = -EIO;
1071         }
1072         replaced_count = 0;
1073         goto unlock_pages;
1074 }
1075
1076 /**
1077  * mext_check_arguments - Check whether move extent can be done
1078  *
1079  * @orig_inode:         original inode
1080  * @donor_inode:        donor inode
1081  * @orig_start:         logical start offset in block for orig
1082  * @donor_start:        logical start offset in block for donor
1083  * @len:                the number of blocks to be moved
1084  *
1085  * Check the arguments of ext4_move_extents() whether the files can be
1086  * exchanged with each other.
1087  * Return 0 on success, or a negative error value on failure.
1088  */
1089 static int
1090 mext_check_arguments(struct inode *orig_inode,
1091                      struct inode *donor_inode, __u64 orig_start,
1092                      __u64 donor_start, __u64 *len)
1093 {
1094         ext4_lblk_t orig_blocks, donor_blocks;
1095         unsigned int blkbits = orig_inode->i_blkbits;
1096         unsigned int blocksize = 1 << blkbits;
1097
1098         if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
1099                 ext4_debug("ext4 move extent: suid or sgid is set"
1100                            " to donor file [ino:orig %lu, donor %lu]\n",
1101                            orig_inode->i_ino, donor_inode->i_ino);
1102                 return -EINVAL;
1103         }
1104
1105         if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode))
1106                 return -EPERM;
1107
1108         /* Ext4 move extent does not support swapfile */
1109         if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
1110                 ext4_debug("ext4 move extent: The argument files should "
1111                         "not be swapfile [ino:orig %lu, donor %lu]\n",
1112                         orig_inode->i_ino, donor_inode->i_ino);
1113                 return -EINVAL;
1114         }
1115
1116         /* Ext4 move extent supports only extent based file */
1117         if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) {
1118                 ext4_debug("ext4 move extent: orig file is not extents "
1119                         "based file [ino:orig %lu]\n", orig_inode->i_ino);
1120                 return -EOPNOTSUPP;
1121         } else if (!(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) {
1122                 ext4_debug("ext4 move extent: donor file is not extents "
1123                         "based file [ino:donor %lu]\n", donor_inode->i_ino);
1124                 return -EOPNOTSUPP;
1125         }
1126
1127         if ((!orig_inode->i_size) || (!donor_inode->i_size)) {
1128                 ext4_debug("ext4 move extent: File size is 0 byte\n");
1129                 return -EINVAL;
1130         }
1131
1132         /* Start offset should be same */
1133         if (orig_start != donor_start) {
1134                 ext4_debug("ext4 move extent: orig and donor's start "
1135                         "offset are not same [ino:orig %lu, donor %lu]\n",
1136                         orig_inode->i_ino, donor_inode->i_ino);
1137                 return -EINVAL;
1138         }
1139
1140         if ((orig_start >= EXT_MAX_BLOCKS) ||
1141             (*len > EXT_MAX_BLOCKS) ||
1142             (orig_start + *len >= EXT_MAX_BLOCKS))  {
1143                 ext4_debug("ext4 move extent: Can't handle over [%u] blocks "
1144                         "[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS,
1145                         orig_inode->i_ino, donor_inode->i_ino);
1146                 return -EINVAL;
1147         }
1148
1149         if (orig_inode->i_size > donor_inode->i_size) {
1150                 donor_blocks = (donor_inode->i_size + blocksize - 1) >> blkbits;
1151                 /* TODO: eliminate this artificial restriction */
1152                 if (orig_start >= donor_blocks) {
1153                         ext4_debug("ext4 move extent: orig start offset "
1154                         "[%llu] should be less than donor file blocks "
1155                         "[%u] [ino:orig %lu, donor %lu]\n",
1156                         orig_start, donor_blocks,
1157                         orig_inode->i_ino, donor_inode->i_ino);
1158                         return -EINVAL;
1159                 }
1160
1161                 /* TODO: eliminate this artificial restriction */
1162                 if (orig_start + *len > donor_blocks) {
1163                         ext4_debug("ext4 move extent: End offset [%llu] should "
1164                                 "be less than donor file blocks [%u]."
1165                                 "So adjust length from %llu to %llu "
1166                                 "[ino:orig %lu, donor %lu]\n",
1167                                 orig_start + *len, donor_blocks,
1168                                 *len, donor_blocks - orig_start,
1169                                 orig_inode->i_ino, donor_inode->i_ino);
1170                         *len = donor_blocks - orig_start;
1171                 }
1172         } else {
1173                 orig_blocks = (orig_inode->i_size + blocksize - 1) >> blkbits;
1174                 if (orig_start >= orig_blocks) {
1175                         ext4_debug("ext4 move extent: start offset [%llu] "
1176                                 "should be less than original file blocks "
1177                                 "[%u] [ino:orig %lu, donor %lu]\n",
1178                                  orig_start, orig_blocks,
1179                                 orig_inode->i_ino, donor_inode->i_ino);
1180                         return -EINVAL;
1181                 }
1182
1183                 if (orig_start + *len > orig_blocks) {
1184                         ext4_debug("ext4 move extent: Adjust length "
1185                                 "from %llu to %llu. Because it should be "
1186                                 "less than original file blocks "
1187                                 "[ino:orig %lu, donor %lu]\n",
1188                                 *len, orig_blocks - orig_start,
1189                                 orig_inode->i_ino, donor_inode->i_ino);
1190                         *len = orig_blocks - orig_start;
1191                 }
1192         }
1193
1194         if (!*len) {
1195                 ext4_debug("ext4 move extent: len should not be 0 "
1196                         "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino,
1197                         donor_inode->i_ino);
1198                 return -EINVAL;
1199         }
1200
1201         return 0;
1202 }
1203
1204 /**
1205  * ext4_move_extents - Exchange the specified range of a file
1206  *
1207  * @o_filp:             file structure of the original file
1208  * @d_filp:             file structure of the donor file
1209  * @orig_start:         start offset in block for orig
1210  * @donor_start:        start offset in block for donor
1211  * @len:                the number of blocks to be moved
1212  * @moved_len:          moved block length
1213  *
1214  * This function returns 0 and moved block length is set in moved_len
1215  * if succeed, otherwise returns error value.
1216  *
1217  * Note: ext4_move_extents() proceeds the following order.
1218  * 1:ext4_move_extents() calculates the last block number of moving extent
1219  *   function by the start block number (orig_start) and the number of blocks
1220  *   to be moved (len) specified as arguments.
1221  *   If the {orig, donor}_start points a hole, the extent's start offset
1222  *   pointed by ext_cur (current extent), holecheck_path, orig_path are set
1223  *   after hole behind.
1224  * 2:Continue step 3 to step 5, until the holecheck_path points to last_extent
1225  *   or the ext_cur exceeds the block_end which is last logical block number.
1226  * 3:To get the length of continues area, call mext_next_extent()
1227  *   specified with the ext_cur (initial value is holecheck_path) re-cursive,
1228  *   until find un-continuous extent, the start logical block number exceeds
1229  *   the block_end or the extent points to the last extent.
1230  * 4:Exchange the original inode data with donor inode data
1231  *   from orig_page_offset to seq_end_page.
1232  *   The start indexes of data are specified as arguments.
1233  *   That of the original inode is orig_page_offset,
1234  *   and the donor inode is also orig_page_offset
1235  *   (To easily handle blocksize != pagesize case, the offset for the
1236  *   donor inode is block unit).
1237  * 5:Update holecheck_path and orig_path to points a next proceeding extent,
1238  *   then returns to step 2.
1239  * 6:Release holecheck_path, orig_path and set the len to moved_len
1240  *   which shows the number of moved blocks.
1241  *   The moved_len is useful for the command to calculate the file offset
1242  *   for starting next move extent ioctl.
1243  * 7:Return 0 on success, or a negative error value on failure.
1244  */
1245 int
1246 ext4_move_extents(struct file *o_filp, struct file *d_filp,
1247                  __u64 orig_start, __u64 donor_start, __u64 len,
1248                  __u64 *moved_len)
1249 {
1250         struct inode *orig_inode = file_inode(o_filp);
1251         struct inode *donor_inode = file_inode(d_filp);
1252         struct ext4_ext_path *orig_path = NULL, *holecheck_path = NULL;
1253         struct ext4_extent *ext_prev, *ext_cur, *ext_dummy;
1254         ext4_lblk_t block_start = orig_start;
1255         ext4_lblk_t block_end, seq_start, add_blocks, file_end, seq_blocks = 0;
1256         ext4_lblk_t rest_blocks;
1257         pgoff_t orig_page_offset = 0, seq_end_page;
1258         int ret, depth, last_extent = 0;
1259         int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
1260         int data_offset_in_page;
1261         int block_len_in_page;
1262         int uninit;
1263
1264         if (orig_inode->i_sb != donor_inode->i_sb) {
1265                 ext4_debug("ext4 move extent: The argument files "
1266                         "should be in same FS [ino:orig %lu, donor %lu]\n",
1267                         orig_inode->i_ino, donor_inode->i_ino);
1268                 return -EINVAL;
1269         }
1270
1271         /* orig and donor should be different inodes */
1272         if (orig_inode == donor_inode) {
1273                 ext4_debug("ext4 move extent: The argument files should not "
1274                         "be same inode [ino:orig %lu, donor %lu]\n",
1275                         orig_inode->i_ino, donor_inode->i_ino);
1276                 return -EINVAL;
1277         }
1278
1279         /* Regular file check */
1280         if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
1281                 ext4_debug("ext4 move extent: The argument files should be "
1282                         "regular file [ino:orig %lu, donor %lu]\n",
1283                         orig_inode->i_ino, donor_inode->i_ino);
1284                 return -EINVAL;
1285         }
1286         /* TODO: This is non obvious task to swap blocks for inodes with full
1287            jornaling enabled */
1288         if (ext4_should_journal_data(orig_inode) ||
1289             ext4_should_journal_data(donor_inode)) {
1290                 return -EINVAL;
1291         }
1292         /* Protect orig and donor inodes against a truncate */
1293         lock_two_nondirectories(orig_inode, donor_inode);
1294
1295         /* Wait for all existing dio workers */
1296         ext4_inode_block_unlocked_dio(orig_inode);
1297         ext4_inode_block_unlocked_dio(donor_inode);
1298         inode_dio_wait(orig_inode);
1299         inode_dio_wait(donor_inode);
1300
1301         /* Protect extent tree against block allocations via delalloc */
1302         ext4_double_down_write_data_sem(orig_inode, donor_inode);
1303         /* Check the filesystem environment whether move_extent can be done */
1304         ret = mext_check_arguments(orig_inode, donor_inode, orig_start,
1305                                     donor_start, &len);
1306         if (ret)
1307                 goto out;
1308
1309         file_end = (i_size_read(orig_inode) - 1) >> orig_inode->i_blkbits;
1310         block_end = block_start + len - 1;
1311         if (file_end < block_end)
1312                 len -= block_end - file_end;
1313
1314         ret = get_ext_path(orig_inode, block_start, &orig_path);
1315         if (ret)
1316                 goto out;
1317
1318         /* Get path structure to check the hole */
1319         ret = get_ext_path(orig_inode, block_start, &holecheck_path);
1320         if (ret)
1321                 goto out;
1322
1323         depth = ext_depth(orig_inode);
1324         ext_cur = holecheck_path[depth].p_ext;
1325
1326         /*
1327          * Get proper starting location of block replacement if block_start was
1328          * within the hole.
1329          */
1330         if (le32_to_cpu(ext_cur->ee_block) +
1331                 ext4_ext_get_actual_len(ext_cur) - 1 < block_start) {
1332                 /*
1333                  * The hole exists between extents or the tail of
1334                  * original file.
1335                  */
1336                 last_extent = mext_next_extent(orig_inode,
1337                                         holecheck_path, &ext_cur);
1338                 if (last_extent < 0) {
1339                         ret = last_extent;
1340                         goto out;
1341                 }
1342                 last_extent = mext_next_extent(orig_inode, orig_path,
1343                                                         &ext_dummy);
1344                 if (last_extent < 0) {
1345                         ret = last_extent;
1346                         goto out;
1347                 }
1348                 seq_start = le32_to_cpu(ext_cur->ee_block);
1349         } else if (le32_to_cpu(ext_cur->ee_block) > block_start)
1350                 /* The hole exists at the beginning of original file. */
1351                 seq_start = le32_to_cpu(ext_cur->ee_block);
1352         else
1353                 seq_start = block_start;
1354
1355         /* No blocks within the specified range. */
1356         if (le32_to_cpu(ext_cur->ee_block) > block_end) {
1357                 ext4_debug("ext4 move extent: The specified range of file "
1358                                                         "may be the hole\n");
1359                 ret = -EINVAL;
1360                 goto out;
1361         }
1362
1363         /* Adjust start blocks */
1364         add_blocks = min(le32_to_cpu(ext_cur->ee_block) +
1365                          ext4_ext_get_actual_len(ext_cur), block_end + 1) -
1366                      max(le32_to_cpu(ext_cur->ee_block), block_start);
1367
1368         while (!last_extent && le32_to_cpu(ext_cur->ee_block) <= block_end) {
1369                 seq_blocks += add_blocks;
1370
1371                 /* Adjust tail blocks */
1372                 if (seq_start + seq_blocks - 1 > block_end)
1373                         seq_blocks = block_end - seq_start + 1;
1374
1375                 ext_prev = ext_cur;
1376                 last_extent = mext_next_extent(orig_inode, holecheck_path,
1377                                                 &ext_cur);
1378                 if (last_extent < 0) {
1379                         ret = last_extent;
1380                         break;
1381                 }
1382                 add_blocks = ext4_ext_get_actual_len(ext_cur);
1383
1384                 /*
1385                  * Extend the length of contiguous block (seq_blocks)
1386                  * if extents are contiguous.
1387                  */
1388                 if (ext4_can_extents_be_merged(orig_inode,
1389                                                ext_prev, ext_cur) &&
1390                     block_end >= le32_to_cpu(ext_cur->ee_block) &&
1391                     !last_extent)
1392                         continue;
1393
1394                 /* Is original extent is uninitialized */
1395                 uninit = ext4_ext_is_uninitialized(ext_prev);
1396
1397                 data_offset_in_page = seq_start % blocks_per_page;
1398
1399                 /*
1400                  * Calculate data blocks count that should be swapped
1401                  * at the first page.
1402                  */
1403                 if (data_offset_in_page + seq_blocks > blocks_per_page) {
1404                         /* Swapped blocks are across pages */
1405                         block_len_in_page =
1406                                         blocks_per_page - data_offset_in_page;
1407                 } else {
1408                         /* Swapped blocks are in a page */
1409                         block_len_in_page = seq_blocks;
1410                 }
1411
1412                 orig_page_offset = seq_start >>
1413                                 (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1414                 seq_end_page = (seq_start + seq_blocks - 1) >>
1415                                 (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1416                 seq_start = le32_to_cpu(ext_cur->ee_block);
1417                 rest_blocks = seq_blocks;
1418
1419                 /*
1420                  * Up semaphore to avoid following problems:
1421                  * a. transaction deadlock among ext4_journal_start,
1422                  *    ->write_begin via pagefault, and jbd2_journal_commit
1423                  * b. racing with ->readpage, ->write_begin, and ext4_get_block
1424                  *    in move_extent_per_page
1425                  */
1426                 ext4_double_up_write_data_sem(orig_inode, donor_inode);
1427
1428                 while (orig_page_offset <= seq_end_page) {
1429
1430                         /* Swap original branches with new branches */
1431                         block_len_in_page = move_extent_per_page(
1432                                                 o_filp, donor_inode,
1433                                                 orig_page_offset,
1434                                                 data_offset_in_page,
1435                                                 block_len_in_page, uninit,
1436                                                 &ret);
1437
1438                         /* Count how many blocks we have exchanged */
1439                         *moved_len += block_len_in_page;
1440                         if (ret < 0)
1441                                 break;
1442                         if (*moved_len > len) {
1443                                 EXT4_ERROR_INODE(orig_inode,
1444                                         "We replaced blocks too much! "
1445                                         "sum of replaced: %llu requested: %llu",
1446                                         *moved_len, len);
1447                                 ret = -EIO;
1448                                 break;
1449                         }
1450
1451                         orig_page_offset++;
1452                         data_offset_in_page = 0;
1453                         rest_blocks -= block_len_in_page;
1454                         if (rest_blocks > blocks_per_page)
1455                                 block_len_in_page = blocks_per_page;
1456                         else
1457                                 block_len_in_page = rest_blocks;
1458                 }
1459
1460                 ext4_double_down_write_data_sem(orig_inode, donor_inode);
1461                 if (ret < 0)
1462                         break;
1463
1464                 /* Decrease buffer counter */
1465                 if (holecheck_path)
1466                         ext4_ext_drop_refs(holecheck_path);
1467                 ret = get_ext_path(orig_inode, seq_start, &holecheck_path);
1468                 if (ret)
1469                         break;
1470                 depth = holecheck_path->p_depth;
1471
1472                 /* Decrease buffer counter */
1473                 if (orig_path)
1474                         ext4_ext_drop_refs(orig_path);
1475                 ret = get_ext_path(orig_inode, seq_start, &orig_path);
1476                 if (ret)
1477                         break;
1478
1479                 ext_cur = holecheck_path[depth].p_ext;
1480                 add_blocks = ext4_ext_get_actual_len(ext_cur);
1481                 seq_blocks = 0;
1482
1483         }
1484 out:
1485         if (*moved_len) {
1486                 ext4_discard_preallocations(orig_inode);
1487                 ext4_discard_preallocations(donor_inode);
1488         }
1489
1490         if (orig_path) {
1491                 ext4_ext_drop_refs(orig_path);
1492                 kfree(orig_path);
1493         }
1494         if (holecheck_path) {
1495                 ext4_ext_drop_refs(holecheck_path);
1496                 kfree(holecheck_path);
1497         }
1498         ext4_double_up_write_data_sem(orig_inode, donor_inode);
1499         ext4_inode_resume_unlocked_dio(orig_inode);
1500         ext4_inode_resume_unlocked_dio(donor_inode);
1501         unlock_two_nondirectories(orig_inode, donor_inode);
1502
1503         return ret;
1504 }