linux/fs/ext4/move_extent.c
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   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 */
  32static inline int
  33get_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 */
  54static void
  55copy_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 */
  76static int
  77mext_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 */
 148static void
 149double_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 */
 168static void
 169double_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 */
 189static int
 190mext_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        }
 279out:
 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 */
 303static void
 304mext_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 */
 357static int
 358mext_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 */
 438static int
 439mext_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);
 529out:
 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 */
 544static int
 545mext_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 */
 618static int
 619mext_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
 720out:
 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 */
 754static int
 755move_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
 882out:
 883        if (unlikely(page)) {
 884                if (PageLocked(page))
 885                        unlock_page(page);
 886                page_cache_release(page);
 887                ext4_journal_stop(handle);
 888        }
 889out2:
 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 */
 911static int
 912mext_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 */
1035static void
1036mext_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
1056static void
1057mext_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 */
1104int
1105ext4_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        }
1337out:
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}
1356
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