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
  22 /**
  23  * get_ext_path - Find an extent path for designated logical block number.
  24  *
  25  * @inode:      an inode which is searched
  26  * @lblock:     logical block number to find an extent path
  27  * @path:       pointer to an extent path pointer (for output)
  28  *
  29  * ext4_ext_find_extent wrapper. Return 0 on success, or a negative error value
  30  * on failure.
  31  */
  32 static inline int
  33 get_ext_path(struct inode *inode, ext4_lblk_t lblock,
  34                 struct ext4_ext_path **path)
  35 {
  36         int ret = 0;
  37
  38         *path = ext4_ext_find_extent(inode, lblock, *path);
  39         if (IS_ERR(*path)) {
  40                 ret = PTR_ERR(*path);
  41                 *path = NULL;
  42         } else if ((*path)[ext_depth(inode)].p_ext == NULL)
  43                 ret = -ENODATA;
  44
  45         return ret;
  46 }
  47
  48 /**
  49  * copy_extent_status - Copy the extent's initialization status
  50  *
  51  * @src:        an extent for getting initialize status
  52  * @dest:       an extent to be set the status
  53  */
  54 static void
  55 copy_extent_status(struct ext4_extent *src, struct ext4_extent *dest)
  56 {
  57         if (ext4_ext_is_uninitialized(src))
  58                 ext4_ext_mark_uninitialized(dest);
  59         else
  60                 dest->ee_len = cpu_to_le16(ext4_ext_get_actual_len(dest));
  61 }
  62
  63 /**
  64  * mext_next_extent - Search for the next extent and set it to "extent"
  65  *
  66  * @inode:      inode which is searched
  67  * @path:       this will obtain data for the next extent
  68  * @extent:     pointer to the next extent we have just gotten
  69  *
  70  * Search the next extent in the array of ext4_ext_path structure (@path)
  71  * and set it to ext4_extent structure (@extent). In addition, the member of
  72  * @path (->p_ext) also points the next extent. Return 0 on success, 1 if
  73  * ext4_ext_path structure refers to the last extent, or a negative error
  74  * value on failure.
  75  */
  76 static int
  77 mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
  78                       struct ext4_extent **extent)
  79 {
  80         struct ext4_extent_header *eh;
  81         int ppos, leaf_ppos = path->p_depth;
  82
  83         ppos = leaf_ppos;
  84         if (EXT_LAST_EXTENT(path[ppos].p_hdr) > path[ppos].p_ext) {
  85                 /* leaf block */
  86                 *extent = ++path[ppos].p_ext;
  87                 path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
  88                 return 0;
  89         }
  90
  91         while (--ppos >= 0) {
  92                 if (EXT_LAST_INDEX(path[ppos].p_hdr) >
  93                     path[ppos].p_idx) {
  94                         int cur_ppos = ppos;
  95
  96                         /* index block */
  97                         path[ppos].p_idx++;
  98                         path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
  99                         if (path[ppos+1].p_bh)
 100                                 brelse(path[ppos+1].p_bh);
 101                         path[ppos+1].p_bh =
 102                                 sb_bread(inode->i_sb, path[ppos].p_block);
 103                         if (!path[ppos+1].p_bh)
 104                                 return -EIO;
 105                         path[ppos+1].p_hdr =
 106                                 ext_block_hdr(path[ppos+1].p_bh);
 107
 108                         /* Halfway index block */
 109                         while (++cur_ppos < leaf_ppos) {
 110                                 path[cur_ppos].p_idx =
 111                                         EXT_FIRST_INDEX(path[cur_ppos].p_hdr);
 112                                 path[cur_ppos].p_block =
 113                                         ext4_idx_pblock(path[cur_ppos].p_idx);
 114                                 if (path[cur_ppos+1].p_bh)
 115                                         brelse(path[cur_ppos+1].p_bh);
 116                                 path[cur_ppos+1].p_bh = sb_bread(inode->i_sb,
 117                                         path[cur_ppos].p_block);
 118                                 if (!path[cur_ppos+1].p_bh)
 119                                         return -EIO;
 120                                 path[cur_ppos+1].p_hdr =
 121                                         ext_block_hdr(path[cur_ppos+1].p_bh);
 122                         }
 123
 124                         path[leaf_ppos].p_ext = *extent = NULL;
 125
 126                         eh = path[leaf_ppos].p_hdr;
 127                         if (le16_to_cpu(eh->eh_entries) == 0)
 128                                 /* empty leaf is found */
 129                                 return -ENODATA;
 130
 131                         /* leaf block */
 132                         path[leaf_ppos].p_ext = *extent =
 133                                 EXT_FIRST_EXTENT(path[leaf_ppos].p_hdr);
 134                         path[leaf_ppos].p_block =
 135                                         ext4_ext_pblock(path[leaf_ppos].p_ext);
 136                         return 0;
 137                 }
 138         }
 139         /* We found the last extent */
 140         return 1;
 141 }
 142
 143 /**
 144  * double_down_write_data_sem - Acquire two inodes' write lock of i_data_sem
 145  *
 146  * Acquire write lock of i_data_sem of the two inodes
 147  */
 148 static void
 149 double_down_write_data_sem(struct inode *first, struct inode *second)
 150 {
 151         if (first < second) {
 152                 down_write(&EXT4_I(first)->i_data_sem);
 153                 down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);
 154         } else {
 155                 down_write(&EXT4_I(second)->i_data_sem);
 156                 down_write_nested(&EXT4_I(first)->i_data_sem, SINGLE_DEPTH_NESTING);
 157
 158         }
 159 }
 160
 161 /**
 162  * double_up_write_data_sem - Release two inodes' write lock of i_data_sem
 163  *
 164  * @orig_inode:         original inode structure to be released its lock first
 165  * @donor_inode:        donor inode structure to be released its lock second
 166  * Release write lock of i_data_sem of two inodes (orig and donor).
 167  */
 168 static void
 169 double_up_write_data_sem(struct inode *orig_inode, struct inode *donor_inode)
 170 {
 171         up_write(&EXT4_I(orig_inode)->i_data_sem);
 172         up_write(&EXT4_I(donor_inode)->i_data_sem);
 173 }
 174
 175 /**
 176  * mext_insert_across_blocks - Insert extents across leaf block
 177  *
 178  * @handle:             journal handle
 179  * @orig_inode:         original inode
 180  * @o_start:            first original extent to be changed
 181  * @o_end:              last original extent to be changed
 182  * @start_ext:          first new extent to be inserted
 183  * @new_ext:            middle of new extent to be inserted
 184  * @end_ext:            last new extent to be inserted
 185  *
 186  * Allocate a new leaf block and insert extents into it. Return 0 on success,
 187  * or a negative error value on failure.
 188  */
 189 static int
 190 mext_insert_across_blocks(handle_t *handle, struct inode *orig_inode,
 191                 struct ext4_extent *o_start, struct ext4_extent *o_end,
 192                 struct ext4_extent *start_ext, struct ext4_extent *new_ext,
 193                 struct ext4_extent *end_ext)
 194 {
 195         struct ext4_ext_path *orig_path = NULL;
 196         ext4_lblk_t eblock = 0;
 197         int new_flag = 0;
 198         int end_flag = 0;
 199         int err = 0;
 200
 201         if (start_ext->ee_len && new_ext->ee_len && end_ext->ee_len) {
 202                 if (o_start == o_end) {
 203
 204                         /*       start_ext   new_ext    end_ext
 205                          * donor |---------|-----------|--------|
 206                          * orig  |------------------------------|
 207                          */
 208                         end_flag = 1;
 209                 } else {
 210
 211                         /*       start_ext   new_ext   end_ext
 212                          * donor |---------|----------|---------|
 213                          * orig  |---------------|--------------|
 214                          */
 215                         o_end->ee_block = end_ext->ee_block;
 216                         o_end->ee_len = end_ext->ee_len;
 217                         ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
 218                 }
 219
 220                 o_start->ee_len = start_ext->ee_len;
 221                 eblock = le32_to_cpu(start_ext->ee_block);
 222                 new_flag = 1;
 223
 224         } else if (start_ext->ee_len && new_ext->ee_len &&
 225                    !end_ext->ee_len && o_start == o_end) {
 226
 227                 /*       start_ext      new_ext
 228                  * donor |--------------|---------------|
 229                  * orig  |------------------------------|
 230                  */
 231                 o_start->ee_len = start_ext->ee_len;
 232                 eblock = le32_to_cpu(start_ext->ee_block);
 233                 new_flag = 1;
 234
 235         } else if (!start_ext->ee_len && new_ext->ee_len &&
 236                    end_ext->ee_len && o_start == o_end) {
 237
 238                 /*        new_ext       end_ext
 239                  * donor |--------------|---------------|
 240                  * orig  |------------------------------|
 241                  */
 242                 o_end->ee_block = end_ext->ee_block;
 243                 o_end->ee_len = end_ext->ee_len;
 244                 ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
 245
 246                 /*
 247                  * Set 0 to the extent block if new_ext was
 248                  * the first block.
 249                  */
 250                 if (new_ext->ee_block)
 251                         eblock = le32_to_cpu(new_ext->ee_block);
 252
 253                 new_flag = 1;
 254         } else {
 255                 ext4_debug("ext4 move extent: Unexpected insert case\n");
 256                 return -EIO;
 257         }
 258
 259         if (new_flag) {
 260                 err = get_ext_path(orig_inode, eblock, &orig_path);
 261                 if (err)
 262                         goto out;
 263
 264                 if (ext4_ext_insert_extent(handle, orig_inode,
 265                                         orig_path, new_ext, 0))
 266                         goto out;
 267         }
 268
 269         if (end_flag) {
 270                 err = get_ext_path(orig_inode,
 271                                 le32_to_cpu(end_ext->ee_block) - 1, &orig_path);
 272                 if (err)
 273                         goto out;
 274
 275                 if (ext4_ext_insert_extent(handle, orig_inode,
 276                                            orig_path, end_ext, 0))
 277                         goto out;
 278         }
 279 out:
 280         if (orig_path) {
 281                 ext4_ext_drop_refs(orig_path);
 282                 kfree(orig_path);
 283         }
 284
 285         return err;
 286
 287 }
 288
 289 /**
 290  * mext_insert_inside_block - Insert new extent to the extent block
 291  *
 292  * @o_start:            first original extent to be moved
 293  * @o_end:              last original extent to be moved
 294  * @start_ext:          first new extent to be inserted
 295  * @new_ext:            middle of new extent to be inserted
 296  * @end_ext:            last new extent to be inserted
 297  * @eh:                 extent header of target leaf block
 298  * @range_to_move:      used to decide how to insert extent
 299  *
 300  * Insert extents into the leaf block. The extent (@o_start) is overwritten
 301  * by inserted extents.
 302  */
 303 static void
 304 mext_insert_inside_block(struct ext4_extent *o_start,
 305                               struct ext4_extent *o_end,
 306                               struct ext4_extent *start_ext,
 307                               struct ext4_extent *new_ext,
 308                               struct ext4_extent *end_ext,
 309                               struct ext4_extent_header *eh,
 310                               int range_to_move)
 311 {
 312         int i = 0;
 313         unsigned long len;
 314
 315         /* Move the existing extents */
 316         if (range_to_move && o_end < EXT_LAST_EXTENT(eh)) {
 317                 len = (unsigned long)(EXT_LAST_EXTENT(eh) + 1) -
 318                         (unsigned long)(o_end + 1);
 319                 memmove(o_end + 1 + range_to_move, o_end + 1, len);
 320         }
 321
 322         /* Insert start entry */
 323         if (start_ext->ee_len)
 324                 o_start[i++].ee_len = start_ext->ee_len;
 325
 326         /* Insert new entry */
 327         if (new_ext->ee_len) {
 328                 o_start[i] = *new_ext;
 329                 ext4_ext_store_pblock(&o_start[i++], ext4_ext_pblock(new_ext));
 330         }
 331
 332         /* Insert end entry */
 333         if (end_ext->ee_len)
 334                 o_start[i] = *end_ext;
 335
 336         /* Increment the total entries counter on the extent block */
 337         le16_add_cpu(&eh->eh_entries, range_to_move);
 338 }
 339
 340 /**
 341  * mext_insert_extents - Insert new extent
 342  *
 343  * @handle:     journal handle
 344  * @orig_inode: original inode
 345  * @orig_path:  path indicates first extent to be changed
 346  * @o_start:    first original extent to be changed
 347  * @o_end:      last original extent to be changed
 348  * @start_ext:  first new extent to be inserted
 349  * @new_ext:    middle of new extent to be inserted
 350  * @end_ext:    last new extent to be inserted
 351  *
 352  * Call the function to insert extents. If we cannot add more extents into
 353  * the leaf block, we call mext_insert_across_blocks() to create a
 354  * new leaf block. Otherwise call mext_insert_inside_block(). Return 0
 355  * on success, or a negative error value on failure.
 356  */
 357 static int
 358 mext_insert_extents(handle_t *handle, struct inode *orig_inode,
 359                          struct ext4_ext_path *orig_path,
 360                          struct ext4_extent *o_start,
 361                          struct ext4_extent *o_end,
 362                          struct ext4_extent *start_ext,
 363                          struct ext4_extent *new_ext,
 364                          struct ext4_extent *end_ext)
 365 {
 366         struct  ext4_extent_header *eh;
 367         unsigned long need_slots, slots_range;
 368         int     range_to_move, depth, ret;
 369
 370         /*
 371          * The extents need to be inserted
 372          * start_extent + new_extent + end_extent.
 373          */
 374         need_slots = (start_ext->ee_len ? 1 : 0) + (end_ext->ee_len ? 1 : 0) +
 375                 (new_ext->ee_len ? 1 : 0);
 376
 377         /* The number of slots between start and end */
 378         slots_range = ((unsigned long)(o_end + 1) - (unsigned long)o_start + 1)
 379                 / sizeof(struct ext4_extent);
 380
 381         /* Range to move the end of extent */
 382         range_to_move = need_slots - slots_range;
 383         depth = orig_path->p_depth;
 384         orig_path += depth;
 385         eh = orig_path->p_hdr;
 386
 387         if (depth) {
 388                 /* Register to journal */
 389                 ret = ext4_journal_get_write_access(handle, orig_path->p_bh);
 390                 if (ret)
 391                         return ret;
 392         }
 393
 394         /* Expansion */
 395         if (range_to_move > 0 &&
 396                 (range_to_move > le16_to_cpu(eh->eh_max)
 397                         - le16_to_cpu(eh->eh_entries))) {
 398
 399                 ret = mext_insert_across_blocks(handle, orig_inode, o_start,
 400                                         o_end, start_ext, new_ext, end_ext);
 401                 if (ret < 0)
 402                         return ret;
 403         } else
 404                 mext_insert_inside_block(o_start, o_end, start_ext, new_ext,
 405                                                 end_ext, eh, range_to_move);
 406
 407         if (depth) {
 408                 ret = ext4_handle_dirty_metadata(handle, orig_inode,
 409                                                  orig_path->p_bh);
 410                 if (ret)
 411                         return ret;
 412         } else {
 413                 ret = ext4_mark_inode_dirty(handle, orig_inode);
 414                 if (ret < 0)
 415                         return ret;
 416         }
 417
 418         return 0;
 419 }
 420
 421 /**
 422  * mext_leaf_block - Move one leaf extent block into the inode.
 423  *
 424  * @handle:             journal handle
 425  * @orig_inode:         original inode
 426  * @orig_path:          path indicates first extent to be changed
 427  * @dext:               donor extent
 428  * @from:               start offset on the target file
 429  *
 430  * In order to insert extents into the leaf block, we must divide the extent
 431  * in the leaf block into three extents. The one is located to be inserted
 432  * extents, and the others are located around it.
 433  *
 434  * Therefore, this function creates structures to save extents of the leaf
 435  * block, and inserts extents by calling mext_insert_extents() with
 436  * created extents. Return 0 on success, or a negative error value on failure.
 437  */
 438 static int
 439 mext_leaf_block(handle_t *handle, struct inode *orig_inode,
 440                      struct ext4_ext_path *orig_path, struct ext4_extent *dext,
 441                      ext4_lblk_t *from)
 442 {
 443         struct ext4_extent *oext, *o_start, *o_end, *prev_ext;
 444         struct ext4_extent new_ext, start_ext, end_ext;
 445         ext4_lblk_t new_ext_end;
 446         int oext_alen, new_ext_alen, end_ext_alen;
 447         int depth = ext_depth(orig_inode);
 448         int ret;
 449
 450         start_ext.ee_block = end_ext.ee_block = 0;
 451         o_start = o_end = oext = orig_path[depth].p_ext;
 452         oext_alen = ext4_ext_get_actual_len(oext);
 453         start_ext.ee_len = end_ext.ee_len = 0;
 454
 455         new_ext.ee_block = cpu_to_le32(*from);
 456         ext4_ext_store_pblock(&new_ext, ext4_ext_pblock(dext));
 457         new_ext.ee_len = dext->ee_len;
 458         new_ext_alen = ext4_ext_get_actual_len(&new_ext);
 459         new_ext_end = le32_to_cpu(new_ext.ee_block) + new_ext_alen - 1;
 460
 461         /*
 462          * Case: original extent is first
 463          * oext      |--------|
 464          * new_ext      |--|
 465          * start_ext |--|
 466          */
 467         if (le32_to_cpu(oext->ee_block) < le32_to_cpu(new_ext.ee_block) &&
 468                 le32_to_cpu(new_ext.ee_block) <
 469                 le32_to_cpu(oext->ee_block) + oext_alen) {
 470                 start_ext.ee_len = cpu_to_le16(le32_to_cpu(new_ext.ee_block) -
 471                                                le32_to_cpu(oext->ee_block));
 472                 start_ext.ee_block = oext->ee_block;
 473                 copy_extent_status(oext, &start_ext);
 474         } else if (oext > EXT_FIRST_EXTENT(orig_path[depth].p_hdr)) {
 475                 prev_ext = oext - 1;
 476                 /*
 477                  * We can merge new_ext into previous extent,
 478                  * if these are contiguous and same extent type.
 479                  */
 480                 if (ext4_can_extents_be_merged(orig_inode, prev_ext,
 481                                                &new_ext)) {
 482                         o_start = prev_ext;
 483                         start_ext.ee_len = cpu_to_le16(
 484                                 ext4_ext_get_actual_len(prev_ext) +
 485                                 new_ext_alen);
 486                         start_ext.ee_block = oext->ee_block;
 487                         copy_extent_status(prev_ext, &start_ext);
 488                         new_ext.ee_len = 0;
 489                 }
 490         }
 491
 492         /*
 493          * Case: new_ext_end must be less than oext
 494          * oext      |-----------|
 495          * new_ext       |-------|
 496          */
 497         if (le32_to_cpu(oext->ee_block) + oext_alen - 1 < new_ext_end) {
 498                 EXT4_ERROR_INODE(orig_inode,
 499                         "new_ext_end(%u) should be less than or equal to "
 500                         "oext->ee_block(%u) + oext_alen(%d) - 1",
 501                         new_ext_end, le32_to_cpu(oext->ee_block),
 502                         oext_alen);
 503                 ret = -EIO;
 504                 goto out;
 505         }
 506
 507         /*
 508          * Case: new_ext is smaller than original extent
 509          * oext    |---------------|
 510          * new_ext |-----------|
 511          * end_ext             |---|
 512          */
 513         if (le32_to_cpu(oext->ee_block) <= new_ext_end &&
 514                 new_ext_end < le32_to_cpu(oext->ee_block) + oext_alen - 1) {
 515                 end_ext.ee_len =
 516                         cpu_to_le16(le32_to_cpu(oext->ee_block) +
 517                         oext_alen - 1 - new_ext_end);
 518                 copy_extent_status(oext, &end_ext);
 519                 end_ext_alen = ext4_ext_get_actual_len(&end_ext);
 520                 ext4_ext_store_pblock(&end_ext,
 521                         (ext4_ext_pblock(o_end) + oext_alen - end_ext_alen));
 522                 end_ext.ee_block =
 523                         cpu_to_le32(le32_to_cpu(o_end->ee_block) +
 524                         oext_alen - end_ext_alen);
 525         }
 526
 527         ret = mext_insert_extents(handle, orig_inode, orig_path, o_start,
 528                                 o_end, &start_ext, &new_ext, &end_ext);
 529 out:
 530         return ret;
 531 }
 532
 533 /**
 534  * mext_calc_swap_extents - Calculate extents for extent swapping.
 535  *
 536  * @tmp_dext:           the extent that will belong to the original inode
 537  * @tmp_oext:           the extent that will belong to the donor inode
 538  * @orig_off:           block offset of original inode
 539  * @donor_off:          block offset of donor inode
 540  * @max_count:          the maximum length of extents
 541  *
 542  * Return 0 on success, or a negative error value on failure.
 543  */
 544 static int
 545 mext_calc_swap_extents(struct ext4_extent *tmp_dext,
 546                               struct ext4_extent *tmp_oext,
 547                               ext4_lblk_t orig_off, ext4_lblk_t donor_off,
 548                               ext4_lblk_t max_count)
 549 {
 550         ext4_lblk_t diff, orig_diff;
 551         struct ext4_extent dext_old, oext_old;
 552
 553         BUG_ON(orig_off != donor_off);
 554
 555         /* original and donor extents have to cover the same block offset */
 556         if (orig_off < le32_to_cpu(tmp_oext->ee_block) ||
 557             le32_to_cpu(tmp_oext->ee_block) +
 558                         ext4_ext_get_actual_len(tmp_oext) - 1 < orig_off)
 559                 return -ENODATA;
 560
 561         if (orig_off < le32_to_cpu(tmp_dext->ee_block) ||
 562             le32_to_cpu(tmp_dext->ee_block) +
 563                         ext4_ext_get_actual_len(tmp_dext) - 1 < orig_off)
 564                 return -ENODATA;
 565
 566         dext_old = *tmp_dext;
 567         oext_old = *tmp_oext;
 568
 569         /* When tmp_dext is too large, pick up the target range. */
 570         diff = donor_off - le32_to_cpu(tmp_dext->ee_block);
 571
 572         ext4_ext_store_pblock(tmp_dext, ext4_ext_pblock(tmp_dext) + diff);
 573         tmp_dext->ee_block =
 574                         cpu_to_le32(le32_to_cpu(tmp_dext->ee_block) + diff);
 575         tmp_dext->ee_len = cpu_to_le16(le16_to_cpu(tmp_dext->ee_len) - diff);
 576
 577         if (max_count < ext4_ext_get_actual_len(tmp_dext))
 578                 tmp_dext->ee_len = cpu_to_le16(max_count);
 579
 580         orig_diff = orig_off - le32_to_cpu(tmp_oext->ee_block);
 581         ext4_ext_store_pblock(tmp_oext, ext4_ext_pblock(tmp_oext) + orig_diff);
 582
 583         /* Adjust extent length if donor extent is larger than orig */
 584         if (ext4_ext_get_actual_len(tmp_dext) >
 585             ext4_ext_get_actual_len(tmp_oext) - orig_diff)
 586                 tmp_dext->ee_len = cpu_to_le16(le16_to_cpu(tmp_oext->ee_len) -
 587                                                 orig_diff);
 588
 589         tmp_oext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(tmp_dext));
 590
 591         copy_extent_status(&oext_old, tmp_dext);
 592         copy_extent_status(&dext_old, tmp_oext);
 593
 594         return 0;
 595 }
 596
 597 /**
 598  * mext_replace_branches - Replace original extents with new extents
 599  *
 600  * @handle:             journal handle
 601  * @orig_inode:         original inode
 602  * @donor_inode:        donor inode
 603  * @from:               block offset of orig_inode
 604  * @count:              block count to be replaced
 605  * @err:                pointer to save return value
 606  *
 607  * Replace original inode extents and donor inode extents page by page.
 608  * We implement this replacement in the following three steps:
 609  * 1. Save the block information of original and donor inodes into
 610  *    dummy extents.
 611  * 2. Change the block information of original inode to point at the
 612  *    donor inode blocks.
 613  * 3. Change the block information of donor inode to point at the saved
 614  *    original inode blocks in the dummy extents.
 615  *
 616  * Return replaced block count.
 617  */
 618 static int
 619 mext_replace_branches(handle_t *handle, struct inode *orig_inode,
 620                            struct inode *donor_inode, ext4_lblk_t from,
 621                            ext4_lblk_t count, int *err)
 622 {
 623         struct ext4_ext_path *orig_path = NULL;
 624         struct ext4_ext_path *donor_path = NULL;
 625         struct ext4_extent *oext, *dext;
 626         struct ext4_extent tmp_dext, tmp_oext;
 627         ext4_lblk_t orig_off = from, donor_off = from;
 628         int depth;
 629         int replaced_count = 0;
 630         int dext_alen;
 631
 632         /* Protect extent trees against block allocations via delalloc */
 633         double_down_write_data_sem(orig_inode, donor_inode);
 634
 635         /* Get the original extent for the block "orig_off" */
 636         *err = get_ext_path(orig_inode, orig_off, &orig_path);
 637         if (*err)
 638                 goto out;
 639
 640         /* Get the donor extent for the head */
 641         *err = get_ext_path(donor_inode, donor_off, &donor_path);
 642         if (*err)
 643                 goto out;
 644         depth = ext_depth(orig_inode);
 645         oext = orig_path[depth].p_ext;
 646         tmp_oext = *oext;
 647
 648         depth = ext_depth(donor_inode);
 649         dext = donor_path[depth].p_ext;
 650         tmp_dext = *dext;
 651
 652         *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
 653                                       donor_off, count);
 654         if (*err)
 655                 goto out;
 656
 657         /* Loop for the donor extents */
 658         while (1) {
 659                 /* The extent for donor must be found. */
 660                 if (!dext) {
 661                         EXT4_ERROR_INODE(donor_inode,
 662                                    "The extent for donor must be found");
 663                         *err = -EIO;
 664                         goto out;
 665                 } else if (donor_off != le32_to_cpu(tmp_dext.ee_block)) {
 666                         EXT4_ERROR_INODE(donor_inode,
 667                                 "Donor offset(%u) and the first block of donor "
 668                                 "extent(%u) should be equal",
 669                                 donor_off,
 670                                 le32_to_cpu(tmp_dext.ee_block));
 671                         *err = -EIO;
 672                         goto out;
 673                 }
 674
 675                 /* Set donor extent to orig extent */
 676                 *err = mext_leaf_block(handle, orig_inode,
 677                                            orig_path, &tmp_dext, &orig_off);
 678                 if (*err)
 679                         goto out;
 680
 681                 /* Set orig extent to donor extent */
 682                 *err = mext_leaf_block(handle, donor_inode,
 683                                            donor_path, &tmp_oext, &donor_off);
 684                 if (*err)
 685                         goto out;
 686
 687                 dext_alen = ext4_ext_get_actual_len(&tmp_dext);
 688                 replaced_count += dext_alen;
 689                 donor_off += dext_alen;
 690                 orig_off += dext_alen;
 691
 692                 /* Already moved the expected blocks */
 693                 if (replaced_count >= count)
 694                         break;
 695
 696                 if (orig_path)
 697                         ext4_ext_drop_refs(orig_path);
 698                 *err = get_ext_path(orig_inode, orig_off, &orig_path);
 699                 if (*err)
 700                         goto out;
 701                 depth = ext_depth(orig_inode);
 702                 oext = orig_path[depth].p_ext;
 703                 tmp_oext = *oext;
 704
 705                 if (donor_path)
 706                         ext4_ext_drop_refs(donor_path);
 707                 *err = get_ext_path(donor_inode, donor_off, &donor_path);
 708                 if (*err)
 709                         goto out;
 710                 depth = ext_depth(donor_inode);
 711                 dext = donor_path[depth].p_ext;
 712                 tmp_dext = *dext;
 713
 714                 *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
 715                                            donor_off, count - replaced_count);
 716                 if (*err)
 717                         goto out;
 718         }
 719
 720 out:
 721         if (orig_path) {
 722                 ext4_ext_drop_refs(orig_path);
 723                 kfree(orig_path);
 724         }
 725         if (donor_path) {
 726                 ext4_ext_drop_refs(donor_path);
 727                 kfree(donor_path);
 728         }
 729
 730         ext4_ext_invalidate_cache(orig_inode);
 731         ext4_ext_invalidate_cache(donor_inode);
 732
 733         double_up_write_data_sem(orig_inode, donor_inode);
 734
 735         return replaced_count;
 736 }
 737
 738 /**
 739  * move_extent_per_page - Move extent data per page
 740  *
 741  * @o_filp:                     file structure of original file
 742  * @donor_inode:                donor inode
 743  * @orig_page_offset:           page index on original file
 744  * @data_offset_in_page:        block index where data swapping starts
 745  * @block_len_in_page:          the number of blocks to be swapped
 746  * @uninit:                     orig extent is uninitialized or not
 747  * @err:                        pointer to save return value
 748  *
 749  * Save the data in original inode blocks and replace original inode extents
 750  * with donor inode extents by calling mext_replace_branches().
 751  * Finally, write out the saved data in new original inode blocks. Return
 752  * replaced block count.
 753  */
 754 static int
 755 move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
 756                   pgoff_t orig_page_offset, int data_offset_in_page,
 757                   int block_len_in_page, int uninit, int *err)
 758 {
 759         struct inode *orig_inode = o_filp->f_dentry->d_inode;
 760         struct address_space *mapping = orig_inode->i_mapping;
 761         struct buffer_head *bh;
 762         struct page *page = NULL;
 763         const struct address_space_operations *a_ops = mapping->a_ops;
 764         handle_t *handle;
 765         ext4_lblk_t orig_blk_offset;
 766         long long offs = orig_page_offset << PAGE_CACHE_SHIFT;
 767         unsigned long blocksize = orig_inode->i_sb->s_blocksize;
 768         unsigned int w_flags = 0;
 769         unsigned int tmp_data_size, data_size, replaced_size;
 770         void *fsdata;
 771         int i, jblocks;
 772         int err2 = 0;
 773         int replaced_count = 0;
 774         int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
 775
 776         /*
 777          * It needs twice the amount of ordinary journal buffers because
 778          * inode and donor_inode may change each different metadata blocks.
 779          */
 780         jblocks = ext4_writepage_trans_blocks(orig_inode) * 2;
 781         handle = ext4_journal_start(orig_inode, jblocks);
 782         if (IS_ERR(handle)) {
 783                 *err = PTR_ERR(handle);
 784                 return 0;
 785         }
 786
 787         if (segment_eq(get_fs(), KERNEL_DS))
 788                 w_flags |= AOP_FLAG_UNINTERRUPTIBLE;
 789
 790         orig_blk_offset = orig_page_offset * blocks_per_page +
 791                 data_offset_in_page;
 792
 793         /*
 794          * If orig extent is uninitialized one,
 795          * it's not necessary force the page into memory
 796          * and then force it to be written out again.
 797          * Just swap data blocks between orig and donor.
 798          */
 799         if (uninit) {
 800                 replaced_count = mext_replace_branches(handle, orig_inode,
 801                                                 donor_inode, orig_blk_offset,
 802                                                 block_len_in_page, err);
 803                 goto out2;
 804         }
 805
 806         offs = (long long)orig_blk_offset << orig_inode->i_blkbits;
 807
 808         /* Calculate data_size */
 809         if ((orig_blk_offset + block_len_in_page - 1) ==
 810             ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) {
 811                 /* Replace the last block */
 812                 tmp_data_size = orig_inode->i_size & (blocksize - 1);
 813                 /*
 814                  * If data_size equal zero, it shows data_size is multiples of
 815                  * blocksize. So we set appropriate value.
 816                  */
 817                 if (tmp_data_size == 0)
 818                         tmp_data_size = blocksize;
 819
 820                 data_size = tmp_data_size +
 821                         ((block_len_in_page - 1) << orig_inode->i_blkbits);
 822         } else
 823                 data_size = block_len_in_page << orig_inode->i_blkbits;
 824
 825         replaced_size = data_size;
 826
 827         *err = a_ops->write_begin(o_filp, mapping, offs, data_size, w_flags,
 828                                  &page, &fsdata);
 829         if (unlikely(*err < 0))
 830                 goto out;
 831
 832         if (!PageUptodate(page)) {
 833                 mapping->a_ops->readpage(o_filp, page);
 834                 lock_page(page);
 835         }
 836
 837         /*
 838          * try_to_release_page() doesn't call releasepage in writeback mode.
 839          * We should care about the order of writing to the same file
 840          * by multiple move extent processes.
 841          * It needs to call wait_on_page_writeback() to wait for the
 842          * writeback of the page.
 843          */
 844         wait_on_page_writeback(page);
 845
 846         /* Release old bh and drop refs */
 847         try_to_release_page(page, 0);
 848
 849         replaced_count = mext_replace_branches(handle, orig_inode, donor_inode,
 850                                         orig_blk_offset, block_len_in_page,
 851                                         &err2);
 852         if (err2) {
 853                 if (replaced_count) {
 854                         block_len_in_page = replaced_count;
 855                         replaced_size =
 856                                 block_len_in_page << orig_inode->i_blkbits;
 857                 } else
 858                         goto out;
 859         }
 860
 861         if (!page_has_buffers(page))
 862                 create_empty_buffers(page, 1 << orig_inode->i_blkbits, 0);
 863
 864         bh = page_buffers(page);
 865         for (i = 0; i < data_offset_in_page; i++)
 866                 bh = bh->b_this_page;
 867
 868         for (i = 0; i < block_len_in_page; i++) {
 869                 *err = ext4_get_block(orig_inode,
 870                                 (sector_t)(orig_blk_offset + i), bh, 0);
 871                 if (*err < 0)
 872                         goto out;
 873
 874                 if (bh->b_this_page != NULL)
 875                         bh = bh->b_this_page;
 876         }
 877
 878         *err = a_ops->write_end(o_filp, mapping, offs, data_size, replaced_size,
 879                                page, fsdata);
 880         page = NULL;
 881
 882 out:
 883         if (unlikely(page)) {
 884                 if (PageLocked(page))
 885                         unlock_page(page);
 886                 page_cache_release(page);
 887                 ext4_journal_stop(handle);
 888         }
 889 out2:
 890         ext4_journal_stop(handle);
 891
 892         if (err2)
 893                 *err = err2;
 894
 895         return replaced_count;
 896 }
 897
 898 /**
 899  * mext_check_arguments - Check whether move extent can be done
 900  *
 901  * @orig_inode:         original inode
 902  * @donor_inode:        donor inode
 903  * @orig_start:         logical start offset in block for orig
 904  * @donor_start:        logical start offset in block for donor
 905  * @len:                the number of blocks to be moved
 906  *
 907  * Check the arguments of ext4_move_extents() whether the files can be
 908  * exchanged with each other.
 909  * Return 0 on success, or a negative error value on failure.
 910  */
 911 static int
 912 mext_check_arguments(struct inode *orig_inode,
 913                      struct inode *donor_inode, __u64 orig_start,
 914                      __u64 donor_start, __u64 *len)
 915 {
 916         ext4_lblk_t orig_blocks, donor_blocks;
 917         unsigned int blkbits = orig_inode->i_blkbits;
 918         unsigned int blocksize = 1 << blkbits;
 919
 920         if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
 921                 ext4_debug("ext4 move extent: suid or sgid is set"
 922                            " to donor file [ino:orig %lu, donor %lu]\n",
 923                            orig_inode->i_ino, donor_inode->i_ino);
 924                 return -EINVAL;
 925         }
 926
 927         if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode))
 928                 return -EPERM;
 929
 930         /* Ext4 move extent does not support swapfile */
 931         if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
 932                 ext4_debug("ext4 move extent: The argument files should "
 933                         "not be swapfile [ino:orig %lu, donor %lu]\n",
 934                         orig_inode->i_ino, donor_inode->i_ino);
 935                 return -EINVAL;
 936         }
 937
 938         /* Ext4 move extent supports only extent based file */
 939         if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) {
 940                 ext4_debug("ext4 move extent: orig file is not extents "
 941                         "based file [ino:orig %lu]\n", orig_inode->i_ino);
 942                 return -EOPNOTSUPP;
 943         } else if (!(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) {
 944                 ext4_debug("ext4 move extent: donor file is not extents "
 945                         "based file [ino:donor %lu]\n", donor_inode->i_ino);
 946                 return -EOPNOTSUPP;
 947         }
 948
 949         if ((!orig_inode->i_size) || (!donor_inode->i_size)) {
 950                 ext4_debug("ext4 move extent: File size is 0 byte\n");
 951                 return -EINVAL;
 952         }
 953
 954         /* Start offset should be same */
 955         if (orig_start != donor_start) {
 956                 ext4_debug("ext4 move extent: orig and donor's start "
 957                         "offset are not same [ino:orig %lu, donor %lu]\n",
 958                         orig_inode->i_ino, donor_inode->i_ino);
 959                 return -EINVAL;
 960         }
 961
 962         if ((orig_start >= EXT_MAX_BLOCKS) ||
 963             (donor_start >= EXT_MAX_BLOCKS) ||
 964             (*len > EXT_MAX_BLOCKS) ||
 965             (orig_start + *len >= EXT_MAX_BLOCKS))  {
 966                 ext4_debug("ext4 move extent: Can't handle over [%u] blocks "
 967                         "[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS,
 968                         orig_inode->i_ino, donor_inode->i_ino);
 969                 return -EINVAL;
 970         }
 971
 972         if (orig_inode->i_size > donor_inode->i_size) {
 973                 donor_blocks = (donor_inode->i_size + blocksize - 1) >> blkbits;
 974                 /* TODO: eliminate this artificial restriction */
 975                 if (orig_start >= donor_blocks) {
 976                         ext4_debug("ext4 move extent: orig start offset "
 977                         "[%llu] should be less than donor file blocks "
 978                         "[%u] [ino:orig %lu, donor %lu]\n",
 979                         orig_start, donor_blocks,
 980                         orig_inode->i_ino, donor_inode->i_ino);
 981                         return -EINVAL;
 982                 }
 983
 984                 /* TODO: eliminate this artificial restriction */
 985                 if (orig_start + *len > donor_blocks) {
 986                         ext4_debug("ext4 move extent: End offset [%llu] should "
 987                                 "be less than donor file blocks [%u]."
 988                                 "So adjust length from %llu to %llu "
 989                                 "[ino:orig %lu, donor %lu]\n",
 990                                 orig_start + *len, donor_blocks,
 991                                 *len, donor_blocks - orig_start,
 992                                 orig_inode->i_ino, donor_inode->i_ino);
 993                         *len = donor_blocks - orig_start;
 994                 }
 995         } else {
 996                 orig_blocks = (orig_inode->i_size + blocksize - 1) >> blkbits;
 997                 if (orig_start >= orig_blocks) {
 998                         ext4_debug("ext4 move extent: start offset [%llu] "
 999                                 "should be less than original file blocks "
1000                                 "[%u] [ino:orig %lu, donor %lu]\n",
1001                                  orig_start, orig_blocks,
1002                                 orig_inode->i_ino, donor_inode->i_ino);
1003                         return -EINVAL;
1004                 }
1005
1006                 if (orig_start + *len > orig_blocks) {
1007                         ext4_debug("ext4 move extent: Adjust length "
1008                                 "from %llu to %llu. Because it should be "
1009                                 "less than original file blocks "
1010                                 "[ino:orig %lu, donor %lu]\n",
1011                                 *len, orig_blocks - orig_start,
1012                                 orig_inode->i_ino, donor_inode->i_ino);
1013                         *len = orig_blocks - orig_start;
1014                 }
1015         }
1016
1017         if (!*len) {
1018                 ext4_debug("ext4 move extent: len should not be 0 "
1019                         "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino,
1020                         donor_inode->i_ino);
1021                 return -EINVAL;
1022         }
1023
1024         return 0;
1025 }
1026
1027 /**
1028  * mext_inode_double_lock - Lock i_mutex on both @inode1 and @inode2
1029  *
1030  * @inode1:     the inode structure
1031  * @inode2:     the inode structure
1032  *
1033  * Lock two inodes' i_mutex
1034  */
1035 static void
1036 mext_inode_double_lock(struct inode *inode1, struct inode *inode2)
1037 {
1038         BUG_ON(inode1 == inode2);
1039         if (inode1 < inode2) {
1040                 mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
1041                 mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
1042         } else {
1043                 mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
1044                 mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
1045         }
1046 }
1047
1048 /**
1049  * mext_inode_double_unlock - Release i_mutex on both @inode1 and @inode2
1050  *
1051  * @inode1:     the inode that is released first
1052  * @inode2:     the inode that is released second
1053  *
1054  */
1055
1056 static void
1057 mext_inode_double_unlock(struct inode *inode1, struct inode *inode2)
1058 {
1059         mutex_unlock(&inode1->i_mutex);
1060         mutex_unlock(&inode2->i_mutex);
1061 }
1062
1063 /**
1064  * ext4_move_extents - Exchange the specified range of a file
1065  *
1066  * @o_filp:             file structure of the original file
1067  * @d_filp:             file structure of the donor file
1068  * @orig_start:         start offset in block for orig
1069  * @donor_start:        start offset in block for donor
1070  * @len:                the number of blocks to be moved
1071  * @moved_len:          moved block length
1072  *
1073  * This function returns 0 and moved block length is set in moved_len
1074  * if succeed, otherwise returns error value.
1075  *
1076  * Note: ext4_move_extents() proceeds the following order.
1077  * 1:ext4_move_extents() calculates the last block number of moving extent
1078  *   function by the start block number (orig_start) and the number of blocks
1079  *   to be moved (len) specified as arguments.
1080  *   If the {orig, donor}_start points a hole, the extent's start offset
1081  *   pointed by ext_cur (current extent), holecheck_path, orig_path are set
1082  *   after hole behind.
1083  * 2:Continue step 3 to step 5, until the holecheck_path points to last_extent
1084  *   or the ext_cur exceeds the block_end which is last logical block number.
1085  * 3:To get the length of continues area, call mext_next_extent()
1086  *   specified with the ext_cur (initial value is holecheck_path) re-cursive,
1087  *   until find un-continuous extent, the start logical block number exceeds
1088  *   the block_end or the extent points to the last extent.
1089  * 4:Exchange the original inode data with donor inode data
1090  *   from orig_page_offset to seq_end_page.
1091  *   The start indexes of data are specified as arguments.
1092  *   That of the original inode is orig_page_offset,
1093  *   and the donor inode is also orig_page_offset
1094  *   (To easily handle blocksize != pagesize case, the offset for the
1095  *   donor inode is block unit).
1096  * 5:Update holecheck_path and orig_path to points a next proceeding extent,
1097  *   then returns to step 2.
1098  * 6:Release holecheck_path, orig_path and set the len to moved_len
1099  *   which shows the number of moved blocks.
1100  *   The moved_len is useful for the command to calculate the file offset
1101  *   for starting next move extent ioctl.
1102  * 7:Return 0 on success, or a negative error value on failure.
1103  */
1104 int
1105 ext4_move_extents(struct file *o_filp, struct file *d_filp,
1106                  __u64 orig_start, __u64 donor_start, __u64 len,
1107                  __u64 *moved_len)
1108 {
1109         struct inode *orig_inode = o_filp->f_dentry->d_inode;
1110         struct inode *donor_inode = d_filp->f_dentry->d_inode;
1111         struct ext4_ext_path *orig_path = NULL, *holecheck_path = NULL;
1112         struct ext4_extent *ext_prev, *ext_cur, *ext_dummy;
1113         ext4_lblk_t block_start = orig_start;
1114         ext4_lblk_t block_end, seq_start, add_blocks, file_end, seq_blocks = 0;
1115         ext4_lblk_t rest_blocks;
1116         pgoff_t orig_page_offset = 0, seq_end_page;
1117         int ret, depth, last_extent = 0;
1118         int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
1119         int data_offset_in_page;
1120         int block_len_in_page;
1121         int uninit;
1122
1123         if (orig_inode->i_sb != donor_inode->i_sb) {
1124                 ext4_debug("ext4 move extent: The argument files "
1125                         "should be in same FS [ino:orig %lu, donor %lu]\n",
1126                         orig_inode->i_ino, donor_inode->i_ino);
1127                 return -EINVAL;
1128         }
1129
1130         /* orig and donor should be different inodes */
1131         if (orig_inode == donor_inode) {
1132                 ext4_debug("ext4 move extent: The argument files should not "
1133                         "be same inode [ino:orig %lu, donor %lu]\n",
1134                         orig_inode->i_ino, donor_inode->i_ino);
1135                 return -EINVAL;
1136         }
1137
1138         /* Regular file check */
1139         if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
1140                 ext4_debug("ext4 move extent: The argument files should be "
1141                         "regular file [ino:orig %lu, donor %lu]\n",
1142                         orig_inode->i_ino, donor_inode->i_ino);
1143                 return -EINVAL;
1144         }
1145         /* TODO: This is non obvious task to swap blocks for inodes with full
1146            jornaling enabled */
1147         if (ext4_should_journal_data(orig_inode) ||
1148             ext4_should_journal_data(donor_inode)) {
1149                 return -EINVAL;
1150         }
1151         /* Protect orig and donor inodes against a truncate */
1152         mext_inode_double_lock(orig_inode, donor_inode);
1153
1154         /* Protect extent tree against block allocations via delalloc */
1155         double_down_write_data_sem(orig_inode, donor_inode);
1156         /* Check the filesystem environment whether move_extent can be done */
1157         ret = mext_check_arguments(orig_inode, donor_inode, orig_start,
1158                                     donor_start, &len);
1159         if (ret)
1160                 goto out;
1161
1162         file_end = (i_size_read(orig_inode) - 1) >> orig_inode->i_blkbits;
1163         block_end = block_start + len - 1;
1164         if (file_end < block_end)
1165                 len -= block_end - file_end;
1166
1167         ret = get_ext_path(orig_inode, block_start, &orig_path);
1168         if (ret)
1169                 goto out;
1170
1171         /* Get path structure to check the hole */
1172         ret = get_ext_path(orig_inode, block_start, &holecheck_path);
1173         if (ret)
1174                 goto out;
1175
1176         depth = ext_depth(orig_inode);
1177         ext_cur = holecheck_path[depth].p_ext;
1178
1179         /*
1180          * Get proper starting location of block replacement if block_start was
1181          * within the hole.
1182          */
1183         if (le32_to_cpu(ext_cur->ee_block) +
1184                 ext4_ext_get_actual_len(ext_cur) - 1 < block_start) {
1185                 /*
1186                  * The hole exists between extents or the tail of
1187                  * original file.
1188                  */
1189                 last_extent = mext_next_extent(orig_inode,
1190                                         holecheck_path, &ext_cur);
1191                 if (last_extent < 0) {
1192                         ret = last_extent;
1193                         goto out;
1194                 }
1195                 last_extent = mext_next_extent(orig_inode, orig_path,
1196                                                         &ext_dummy);
1197                 if (last_extent < 0) {
1198                         ret = last_extent;
1199                         goto out;
1200                 }
1201                 seq_start = le32_to_cpu(ext_cur->ee_block);
1202         } else if (le32_to_cpu(ext_cur->ee_block) > block_start)
1203                 /* The hole exists at the beginning of original file. */
1204                 seq_start = le32_to_cpu(ext_cur->ee_block);
1205         else
1206                 seq_start = block_start;
1207
1208         /* No blocks within the specified range. */
1209         if (le32_to_cpu(ext_cur->ee_block) > block_end) {
1210                 ext4_debug("ext4 move extent: The specified range of file "
1211                                                         "may be the hole\n");
1212                 ret = -EINVAL;
1213                 goto out;
1214         }
1215
1216         /* Adjust start blocks */
1217         add_blocks = min(le32_to_cpu(ext_cur->ee_block) +
1218                          ext4_ext_get_actual_len(ext_cur), block_end + 1) -
1219                      max(le32_to_cpu(ext_cur->ee_block), block_start);
1220
1221         while (!last_extent && le32_to_cpu(ext_cur->ee_block) <= block_end) {
1222                 seq_blocks += add_blocks;
1223
1224                 /* Adjust tail blocks */
1225                 if (seq_start + seq_blocks - 1 > block_end)
1226                         seq_blocks = block_end - seq_start + 1;
1227
1228                 ext_prev = ext_cur;
1229                 last_extent = mext_next_extent(orig_inode, holecheck_path,
1230                                                 &ext_cur);
1231                 if (last_extent < 0) {
1232                         ret = last_extent;
1233                         break;
1234                 }
1235                 add_blocks = ext4_ext_get_actual_len(ext_cur);
1236
1237                 /*
1238                  * Extend the length of contiguous block (seq_blocks)
1239                  * if extents are contiguous.
1240                  */
1241                 if (ext4_can_extents_be_merged(orig_inode,
1242                                                ext_prev, ext_cur) &&
1243                     block_end >= le32_to_cpu(ext_cur->ee_block) &&
1244                     !last_extent)
1245                         continue;
1246
1247                 /* Is original extent is uninitialized */
1248                 uninit = ext4_ext_is_uninitialized(ext_prev);
1249
1250                 data_offset_in_page = seq_start % blocks_per_page;
1251
1252                 /*
1253                  * Calculate data blocks count that should be swapped
1254                  * at the first page.
1255                  */
1256                 if (data_offset_in_page + seq_blocks > blocks_per_page) {
1257                         /* Swapped blocks are across pages */
1258                         block_len_in_page =
1259                                         blocks_per_page - data_offset_in_page;
1260                 } else {
1261                         /* Swapped blocks are in a page */
1262                         block_len_in_page = seq_blocks;
1263                 }
1264
1265                 orig_page_offset = seq_start >>
1266                                 (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1267                 seq_end_page = (seq_start + seq_blocks - 1) >>
1268                                 (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1269                 seq_start = le32_to_cpu(ext_cur->ee_block);
1270                 rest_blocks = seq_blocks;
1271
1272                 /*
1273                  * Up semaphore to avoid following problems:
1274                  * a. transaction deadlock among ext4_journal_start,
1275                  *    ->write_begin via pagefault, and jbd2_journal_commit
1276                  * b. racing with ->readpage, ->write_begin, and ext4_get_block
1277                  *    in move_extent_per_page
1278                  */
1279                 double_up_write_data_sem(orig_inode, donor_inode);
1280
1281                 while (orig_page_offset <= seq_end_page) {
1282
1283                         /* Swap original branches with new branches */
1284                         block_len_in_page = move_extent_per_page(
1285                                                 o_filp, donor_inode,
1286                                                 orig_page_offset,
1287                                                 data_offset_in_page,
1288                                                 block_len_in_page, uninit,
1289                                                 &ret);
1290
1291                         /* Count how many blocks we have exchanged */
1292                         *moved_len += block_len_in_page;
1293                         if (ret < 0)
1294                                 break;
1295                         if (*moved_len > len) {
1296                                 EXT4_ERROR_INODE(orig_inode,
1297                                         "We replaced blocks too much! "
1298                                         "sum of replaced: %llu requested: %llu",
1299                                         *moved_len, len);
1300                                 ret = -EIO;
1301                                 break;
1302                         }
1303
1304                         orig_page_offset++;
1305                         data_offset_in_page = 0;
1306                         rest_blocks -= block_len_in_page;
1307                         if (rest_blocks > blocks_per_page)
1308                                 block_len_in_page = blocks_per_page;
1309                         else
1310                                 block_len_in_page = rest_blocks;
1311                 }
1312
1313                 double_down_write_data_sem(orig_inode, donor_inode);
1314                 if (ret < 0)
1315                         break;
1316
1317                 /* Decrease buffer counter */
1318                 if (holecheck_path)
1319                         ext4_ext_drop_refs(holecheck_path);
1320                 ret = get_ext_path(orig_inode, seq_start, &holecheck_path);
1321                 if (ret)
1322                         break;
1323                 depth = holecheck_path->p_depth;
1324
1325                 /* Decrease buffer counter */
1326                 if (orig_path)
1327                         ext4_ext_drop_refs(orig_path);
1328                 ret = get_ext_path(orig_inode, seq_start, &orig_path);
1329                 if (ret)
1330                         break;
1331
1332                 ext_cur = holecheck_path[depth].p_ext;
1333                 add_blocks = ext4_ext_get_actual_len(ext_cur);
1334                 seq_blocks = 0;
1335
1336         }
1337 out:
1338         if (*moved_len) {
1339                 ext4_discard_preallocations(orig_inode);
1340                 ext4_discard_preallocations(donor_inode);
1341         }
1342
1343         if (orig_path) {
1344                 ext4_ext_drop_refs(orig_path);
1345                 kfree(orig_path);
1346         }
1347         if (holecheck_path) {
1348                 ext4_ext_drop_refs(holecheck_path);
1349                 kfree(holecheck_path);
1350         }
1351         double_up_write_data_sem(orig_inode, donor_inode);
1352         mext_inode_double_unlock(orig_inode, donor_inode);
1353
1354         return ret;
1355 }