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#include "ext4_extents.h"
  22
  23/**
  24 * get_ext_path - Find an extent path for designated logical block number.
  25 *
  26 * @inode:      an inode which is searched
  27 * @lblock:     logical block number to find an extent path
  28 * @path:       pointer to an extent path pointer (for output)
  29 *
  30 * ext4_ext_find_extent wrapper. Return 0 on success, or a negative error value
  31 * on failure.
  32 */
  33static inline int
  34get_ext_path(struct inode *inode, ext4_lblk_t lblock,
  35                struct ext4_ext_path **orig_path)
  36{
  37        int ret = 0;
  38        struct ext4_ext_path *path;
  39
  40        path = ext4_ext_find_extent(inode, lblock, *orig_path);
  41        if (IS_ERR(path))
  42                ret = PTR_ERR(path);
  43        else if (path[ext_depth(inode)].p_ext == NULL)
  44                ret = -ENODATA;
  45        else
  46                *orig_path = path;
  47
  48        return ret;
  49}
  50
  51/**
  52 * copy_extent_status - Copy the extent's initialization status
  53 *
  54 * @src:        an extent for getting initialize status
  55 * @dest:       an extent to be set the status
  56 */
  57static void
  58copy_extent_status(struct ext4_extent *src, struct ext4_extent *dest)
  59{
  60        if (ext4_ext_is_uninitialized(src))
  61                ext4_ext_mark_uninitialized(dest);
  62        else
  63                dest->ee_len = cpu_to_le16(ext4_ext_get_actual_len(dest));
  64}
  65
  66/**
  67 * mext_next_extent - Search for the next extent and set it to "extent"
  68 *
  69 * @inode:      inode which is searched
  70 * @path:       this will obtain data for the next extent
  71 * @extent:     pointer to the next extent we have just gotten
  72 *
  73 * Search the next extent in the array of ext4_ext_path structure (@path)
  74 * and set it to ext4_extent structure (@extent). In addition, the member of
  75 * @path (->p_ext) also points the next extent. Return 0 on success, 1 if
  76 * ext4_ext_path structure refers to the last extent, or a negative error
  77 * value on failure.
  78 */
  79static int
  80mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
  81                      struct ext4_extent **extent)
  82{
  83        struct ext4_extent_header *eh;
  84        int ppos, leaf_ppos = path->p_depth;
  85
  86        ppos = leaf_ppos;
  87        if (EXT_LAST_EXTENT(path[ppos].p_hdr) > path[ppos].p_ext) {
  88                /* leaf block */
  89                *extent = ++path[ppos].p_ext;
  90                path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
  91                return 0;
  92        }
  93
  94        while (--ppos >= 0) {
  95                if (EXT_LAST_INDEX(path[ppos].p_hdr) >
  96                    path[ppos].p_idx) {
  97                        int cur_ppos = ppos;
  98
  99                        /* index block */
 100                        path[ppos].p_idx++;
 101                        path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
 102                        if (path[ppos+1].p_bh)
 103                                brelse(path[ppos+1].p_bh);
 104                        path[ppos+1].p_bh =
 105                                sb_bread(inode->i_sb, path[ppos].p_block);
 106                        if (!path[ppos+1].p_bh)
 107                                return -EIO;
 108                        path[ppos+1].p_hdr =
 109                                ext_block_hdr(path[ppos+1].p_bh);
 110
 111                        /* Halfway index block */
 112                        while (++cur_ppos < leaf_ppos) {
 113                                path[cur_ppos].p_idx =
 114                                        EXT_FIRST_INDEX(path[cur_ppos].p_hdr);
 115                                path[cur_ppos].p_block =
 116                                        ext4_idx_pblock(path[cur_ppos].p_idx);
 117                                if (path[cur_ppos+1].p_bh)
 118                                        brelse(path[cur_ppos+1].p_bh);
 119                                path[cur_ppos+1].p_bh = sb_bread(inode->i_sb,
 120                                        path[cur_ppos].p_block);
 121                                if (!path[cur_ppos+1].p_bh)
 122                                        return -EIO;
 123                                path[cur_ppos+1].p_hdr =
 124                                        ext_block_hdr(path[cur_ppos+1].p_bh);
 125                        }
 126
 127                        path[leaf_ppos].p_ext = *extent = NULL;
 128
 129                        eh = path[leaf_ppos].p_hdr;
 130                        if (le16_to_cpu(eh->eh_entries) == 0)
 131                                /* empty leaf is found */
 132                                return -ENODATA;
 133
 134                        /* leaf block */
 135                        path[leaf_ppos].p_ext = *extent =
 136                                EXT_FIRST_EXTENT(path[leaf_ppos].p_hdr);
 137                        path[leaf_ppos].p_block =
 138                                        ext4_ext_pblock(path[leaf_ppos].p_ext);
 139                        return 0;
 140                }
 141        }
 142        /* We found the last extent */
 143        return 1;
 144}
 145
 146/**
 147 * ext4_double_down_write_data_sem - Acquire two inodes' write lock
 148 *                                   of i_data_sem
 149 *
 150 * Acquire write lock of i_data_sem of the two inodes
 151 */
 152void
 153ext4_double_down_write_data_sem(struct inode *first, struct inode *second)
 154{
 155        if (first < second) {
 156                down_write(&EXT4_I(first)->i_data_sem);
 157                down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);
 158        } else {
 159                down_write(&EXT4_I(second)->i_data_sem);
 160                down_write_nested(&EXT4_I(first)->i_data_sem, SINGLE_DEPTH_NESTING);
 161
 162        }
 163}
 164
 165/**
 166 * ext4_double_up_write_data_sem - Release two inodes' write lock of i_data_sem
 167 *
 168 * @orig_inode:         original inode structure to be released its lock first
 169 * @donor_inode:        donor inode structure to be released its lock second
 170 * Release write lock of i_data_sem of two inodes (orig and donor).
 171 */
 172void
 173ext4_double_up_write_data_sem(struct inode *orig_inode,
 174                              struct inode *donor_inode)
 175{
 176        up_write(&EXT4_I(orig_inode)->i_data_sem);
 177        up_write(&EXT4_I(donor_inode)->i_data_sem);
 178}
 179
 180/**
 181 * mext_insert_across_blocks - Insert extents across leaf block
 182 *
 183 * @handle:             journal handle
 184 * @orig_inode:         original inode
 185 * @o_start:            first original extent to be changed
 186 * @o_end:              last original extent to be changed
 187 * @start_ext:          first new extent to be inserted
 188 * @new_ext:            middle of new extent to be inserted
 189 * @end_ext:            last new extent to be inserted
 190 *
 191 * Allocate a new leaf block and insert extents into it. Return 0 on success,
 192 * or a negative error value on failure.
 193 */
 194static int
 195mext_insert_across_blocks(handle_t *handle, struct inode *orig_inode,
 196                struct ext4_extent *o_start, struct ext4_extent *o_end,
 197                struct ext4_extent *start_ext, struct ext4_extent *new_ext,
 198                struct ext4_extent *end_ext)
 199{
 200        struct ext4_ext_path *orig_path = NULL;
 201        ext4_lblk_t eblock = 0;
 202        int new_flag = 0;
 203        int end_flag = 0;
 204        int err = 0;
 205
 206        if (start_ext->ee_len && new_ext->ee_len && end_ext->ee_len) {
 207                if (o_start == o_end) {
 208
 209                        /*       start_ext   new_ext    end_ext
 210                         * donor |---------|-----------|--------|
 211                         * orig  |------------------------------|
 212                         */
 213                        end_flag = 1;
 214                } else {
 215
 216                        /*       start_ext   new_ext   end_ext
 217                         * donor |---------|----------|---------|
 218                         * orig  |---------------|--------------|
 219                         */
 220                        o_end->ee_block = end_ext->ee_block;
 221                        o_end->ee_len = end_ext->ee_len;
 222                        ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
 223                }
 224
 225                o_start->ee_len = start_ext->ee_len;
 226                eblock = le32_to_cpu(start_ext->ee_block);
 227                new_flag = 1;
 228
 229        } else if (start_ext->ee_len && new_ext->ee_len &&
 230                   !end_ext->ee_len && o_start == o_end) {
 231
 232                /*       start_ext      new_ext
 233                 * donor |--------------|---------------|
 234                 * orig  |------------------------------|
 235                 */
 236                o_start->ee_len = start_ext->ee_len;
 237                eblock = le32_to_cpu(start_ext->ee_block);
 238                new_flag = 1;
 239
 240        } else if (!start_ext->ee_len && new_ext->ee_len &&
 241                   end_ext->ee_len && o_start == o_end) {
 242
 243                /*        new_ext       end_ext
 244                 * donor |--------------|---------------|
 245                 * orig  |------------------------------|
 246                 */
 247                o_end->ee_block = end_ext->ee_block;
 248                o_end->ee_len = end_ext->ee_len;
 249                ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
 250
 251                /*
 252                 * Set 0 to the extent block if new_ext was
 253                 * the first block.
 254                 */
 255                if (new_ext->ee_block)
 256                        eblock = le32_to_cpu(new_ext->ee_block);
 257
 258                new_flag = 1;
 259        } else {
 260                ext4_debug("ext4 move extent: Unexpected insert case\n");
 261                return -EIO;
 262        }
 263
 264        if (new_flag) {
 265                err = get_ext_path(orig_inode, eblock, &orig_path);
 266                if (err)
 267                        goto out;
 268
 269                if (ext4_ext_insert_extent(handle, orig_inode,
 270                                        orig_path, new_ext, 0))
 271                        goto out;
 272        }
 273
 274        if (end_flag) {
 275                err = get_ext_path(orig_inode,
 276                                le32_to_cpu(end_ext->ee_block) - 1, &orig_path);
 277                if (err)
 278                        goto out;
 279
 280                if (ext4_ext_insert_extent(handle, orig_inode,
 281                                           orig_path, end_ext, 0))
 282                        goto out;
 283        }
 284out:
 285        if (orig_path) {
 286                ext4_ext_drop_refs(orig_path);
 287                kfree(orig_path);
 288        }
 289
 290        return err;
 291
 292}
 293
 294/**
 295 * mext_insert_inside_block - Insert new extent to the extent block
 296 *
 297 * @o_start:            first original extent to be moved
 298 * @o_end:              last original extent to be moved
 299 * @start_ext:          first new extent to be inserted
 300 * @new_ext:            middle of new extent to be inserted
 301 * @end_ext:            last new extent to be inserted
 302 * @eh:                 extent header of target leaf block
 303 * @range_to_move:      used to decide how to insert extent
 304 *
 305 * Insert extents into the leaf block. The extent (@o_start) is overwritten
 306 * by inserted extents.
 307 */
 308static void
 309mext_insert_inside_block(struct ext4_extent *o_start,
 310                              struct ext4_extent *o_end,
 311                              struct ext4_extent *start_ext,
 312                              struct ext4_extent *new_ext,
 313                              struct ext4_extent *end_ext,
 314                              struct ext4_extent_header *eh,
 315                              int range_to_move)
 316{
 317        int i = 0;
 318        unsigned long len;
 319
 320        /* Move the existing extents */
 321        if (range_to_move && o_end < EXT_LAST_EXTENT(eh)) {
 322                len = (unsigned long)(EXT_LAST_EXTENT(eh) + 1) -
 323                        (unsigned long)(o_end + 1);
 324                memmove(o_end + 1 + range_to_move, o_end + 1, len);
 325        }
 326
 327        /* Insert start entry */
 328        if (start_ext->ee_len)
 329                o_start[i++].ee_len = start_ext->ee_len;
 330
 331        /* Insert new entry */
 332        if (new_ext->ee_len) {
 333                o_start[i] = *new_ext;
 334                ext4_ext_store_pblock(&o_start[i++], ext4_ext_pblock(new_ext));
 335        }
 336
 337        /* Insert end entry */
 338        if (end_ext->ee_len)
 339                o_start[i] = *end_ext;
 340
 341        /* Increment the total entries counter on the extent block */
 342        le16_add_cpu(&eh->eh_entries, range_to_move);
 343}
 344
 345/**
 346 * mext_insert_extents - Insert new extent
 347 *
 348 * @handle:     journal handle
 349 * @orig_inode: original inode
 350 * @orig_path:  path indicates first extent to be changed
 351 * @o_start:    first original extent to be changed
 352 * @o_end:      last original extent to be changed
 353 * @start_ext:  first new extent to be inserted
 354 * @new_ext:    middle of new extent to be inserted
 355 * @end_ext:    last new extent to be inserted
 356 *
 357 * Call the function to insert extents. If we cannot add more extents into
 358 * the leaf block, we call mext_insert_across_blocks() to create a
 359 * new leaf block. Otherwise call mext_insert_inside_block(). Return 0
 360 * on success, or a negative error value on failure.
 361 */
 362static int
 363mext_insert_extents(handle_t *handle, struct inode *orig_inode,
 364                         struct ext4_ext_path *orig_path,
 365                         struct ext4_extent *o_start,
 366                         struct ext4_extent *o_end,
 367                         struct ext4_extent *start_ext,
 368                         struct ext4_extent *new_ext,
 369                         struct ext4_extent *end_ext)
 370{
 371        struct  ext4_extent_header *eh;
 372        unsigned long need_slots, slots_range;
 373        int     range_to_move, depth, ret;
 374
 375        /*
 376         * The extents need to be inserted
 377         * start_extent + new_extent + end_extent.
 378         */
 379        need_slots = (start_ext->ee_len ? 1 : 0) + (end_ext->ee_len ? 1 : 0) +
 380                (new_ext->ee_len ? 1 : 0);
 381
 382        /* The number of slots between start and end */
 383        slots_range = ((unsigned long)(o_end + 1) - (unsigned long)o_start + 1)
 384                / sizeof(struct ext4_extent);
 385
 386        /* Range to move the end of extent */
 387        range_to_move = need_slots - slots_range;
 388        depth = orig_path->p_depth;
 389        orig_path += depth;
 390        eh = orig_path->p_hdr;
 391
 392        if (depth) {
 393                /* Register to journal */
 394                ret = ext4_journal_get_write_access(handle, orig_path->p_bh);
 395                if (ret)
 396                        return ret;
 397        }
 398
 399        /* Expansion */
 400        if (range_to_move > 0 &&
 401                (range_to_move > le16_to_cpu(eh->eh_max)
 402                        - le16_to_cpu(eh->eh_entries))) {
 403
 404                ret = mext_insert_across_blocks(handle, orig_inode, o_start,
 405                                        o_end, start_ext, new_ext, end_ext);
 406                if (ret < 0)
 407                        return ret;
 408        } else
 409                mext_insert_inside_block(o_start, o_end, start_ext, new_ext,
 410                                                end_ext, eh, range_to_move);
 411
 412        return ext4_ext_dirty(handle, orig_inode, orig_path);
 413}
 414
 415/**
 416 * mext_leaf_block - Move one leaf extent block into the inode.
 417 *
 418 * @handle:             journal handle
 419 * @orig_inode:         original inode
 420 * @orig_path:          path indicates first extent to be changed
 421 * @dext:               donor extent
 422 * @from:               start offset on the target file
 423 *
 424 * In order to insert extents into the leaf block, we must divide the extent
 425 * in the leaf block into three extents. The one is located to be inserted
 426 * extents, and the others are located around it.
 427 *
 428 * Therefore, this function creates structures to save extents of the leaf
 429 * block, and inserts extents by calling mext_insert_extents() with
 430 * created extents. Return 0 on success, or a negative error value on failure.
 431 */
 432static int
 433mext_leaf_block(handle_t *handle, struct inode *orig_inode,
 434                     struct ext4_ext_path *orig_path, struct ext4_extent *dext,
 435                     ext4_lblk_t *from)
 436{
 437        struct ext4_extent *oext, *o_start, *o_end, *prev_ext;
 438        struct ext4_extent new_ext, start_ext, end_ext;
 439        ext4_lblk_t new_ext_end;
 440        int oext_alen, new_ext_alen, end_ext_alen;
 441        int depth = ext_depth(orig_inode);
 442        int ret;
 443
 444        start_ext.ee_block = end_ext.ee_block = 0;
 445        o_start = o_end = oext = orig_path[depth].p_ext;
 446        oext_alen = ext4_ext_get_actual_len(oext);
 447        start_ext.ee_len = end_ext.ee_len = 0;
 448
 449        new_ext.ee_block = cpu_to_le32(*from);
 450        ext4_ext_store_pblock(&new_ext, ext4_ext_pblock(dext));
 451        new_ext.ee_len = dext->ee_len;
 452        new_ext_alen = ext4_ext_get_actual_len(&new_ext);
 453        new_ext_end = le32_to_cpu(new_ext.ee_block) + new_ext_alen - 1;
 454
 455        /*
 456         * Case: original extent is first
 457         * oext      |--------|
 458         * new_ext      |--|
 459         * start_ext |--|
 460         */
 461        if (le32_to_cpu(oext->ee_block) < le32_to_cpu(new_ext.ee_block) &&
 462                le32_to_cpu(new_ext.ee_block) <
 463                le32_to_cpu(oext->ee_block) + oext_alen) {
 464                start_ext.ee_len = cpu_to_le16(le32_to_cpu(new_ext.ee_block) -
 465                                               le32_to_cpu(oext->ee_block));
 466                start_ext.ee_block = oext->ee_block;
 467                copy_extent_status(oext, &start_ext);
 468        } else if (oext > EXT_FIRST_EXTENT(orig_path[depth].p_hdr)) {
 469                prev_ext = oext - 1;
 470                /*
 471                 * We can merge new_ext into previous extent,
 472                 * if these are contiguous and same extent type.
 473                 */
 474                if (ext4_can_extents_be_merged(orig_inode, prev_ext,
 475                                               &new_ext)) {
 476                        o_start = prev_ext;
 477                        start_ext.ee_len = cpu_to_le16(
 478                                ext4_ext_get_actual_len(prev_ext) +
 479                                new_ext_alen);
 480                        start_ext.ee_block = oext->ee_block;
 481                        copy_extent_status(prev_ext, &start_ext);
 482                        new_ext.ee_len = 0;
 483                }
 484        }
 485
 486        /*
 487         * Case: new_ext_end must be less than oext
 488         * oext      |-----------|
 489         * new_ext       |-------|
 490         */
 491        if (le32_to_cpu(oext->ee_block) + oext_alen - 1 < new_ext_end) {
 492                EXT4_ERROR_INODE(orig_inode,
 493                        "new_ext_end(%u) should be less than or equal to "
 494                        "oext->ee_block(%u) + oext_alen(%d) - 1",
 495                        new_ext_end, le32_to_cpu(oext->ee_block),
 496                        oext_alen);
 497                ret = -EIO;
 498                goto out;
 499        }
 500
 501        /*
 502         * Case: new_ext is smaller than original extent
 503         * oext    |---------------|
 504         * new_ext |-----------|
 505         * end_ext             |---|
 506         */
 507        if (le32_to_cpu(oext->ee_block) <= new_ext_end &&
 508                new_ext_end < le32_to_cpu(oext->ee_block) + oext_alen - 1) {
 509                end_ext.ee_len =
 510                        cpu_to_le16(le32_to_cpu(oext->ee_block) +
 511                        oext_alen - 1 - new_ext_end);
 512                copy_extent_status(oext, &end_ext);
 513                end_ext_alen = ext4_ext_get_actual_len(&end_ext);
 514                ext4_ext_store_pblock(&end_ext,
 515                        (ext4_ext_pblock(o_end) + oext_alen - end_ext_alen));
 516                end_ext.ee_block =
 517                        cpu_to_le32(le32_to_cpu(o_end->ee_block) +
 518                        oext_alen - end_ext_alen);
 519        }
 520
 521        ret = mext_insert_extents(handle, orig_inode, orig_path, o_start,
 522                                o_end, &start_ext, &new_ext, &end_ext);
 523out:
 524        return ret;
 525}
 526
 527/**
 528 * mext_calc_swap_extents - Calculate extents for extent swapping.
 529 *
 530 * @tmp_dext:           the extent that will belong to the original inode
 531 * @tmp_oext:           the extent that will belong to the donor inode
 532 * @orig_off:           block offset of original inode
 533 * @donor_off:          block offset of donor inode
 534 * @max_count:          the maximum length of extents
 535 *
 536 * Return 0 on success, or a negative error value on failure.
 537 */
 538static int
 539mext_calc_swap_extents(struct ext4_extent *tmp_dext,
 540                              struct ext4_extent *tmp_oext,
 541                              ext4_lblk_t orig_off, ext4_lblk_t donor_off,
 542                              ext4_lblk_t max_count)
 543{
 544        ext4_lblk_t diff, orig_diff;
 545        struct ext4_extent dext_old, oext_old;
 546
 547        BUG_ON(orig_off != donor_off);
 548
 549        /* original and donor extents have to cover the same block offset */
 550        if (orig_off < le32_to_cpu(tmp_oext->ee_block) ||
 551            le32_to_cpu(tmp_oext->ee_block) +
 552                        ext4_ext_get_actual_len(tmp_oext) - 1 < orig_off)
 553                return -ENODATA;
 554
 555        if (orig_off < le32_to_cpu(tmp_dext->ee_block) ||
 556            le32_to_cpu(tmp_dext->ee_block) +
 557                        ext4_ext_get_actual_len(tmp_dext) - 1 < orig_off)
 558                return -ENODATA;
 559
 560        dext_old = *tmp_dext;
 561        oext_old = *tmp_oext;
 562
 563        /* When tmp_dext is too large, pick up the target range. */
 564        diff = donor_off - le32_to_cpu(tmp_dext->ee_block);
 565
 566        ext4_ext_store_pblock(tmp_dext, ext4_ext_pblock(tmp_dext) + diff);
 567        le32_add_cpu(&tmp_dext->ee_block, diff);
 568        le16_add_cpu(&tmp_dext->ee_len, -diff);
 569
 570        if (max_count < ext4_ext_get_actual_len(tmp_dext))
 571                tmp_dext->ee_len = cpu_to_le16(max_count);
 572
 573        orig_diff = orig_off - le32_to_cpu(tmp_oext->ee_block);
 574        ext4_ext_store_pblock(tmp_oext, ext4_ext_pblock(tmp_oext) + orig_diff);
 575
 576        /* Adjust extent length if donor extent is larger than orig */
 577        if (ext4_ext_get_actual_len(tmp_dext) >
 578            ext4_ext_get_actual_len(tmp_oext) - orig_diff)
 579                tmp_dext->ee_len = cpu_to_le16(le16_to_cpu(tmp_oext->ee_len) -
 580                                                orig_diff);
 581
 582        tmp_oext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(tmp_dext));
 583
 584        copy_extent_status(&oext_old, tmp_dext);
 585        copy_extent_status(&dext_old, tmp_oext);
 586
 587        return 0;
 588}
 589
 590/**
 591 * mext_check_coverage - Check that all extents in range has the same type
 592 *
 593 * @inode:              inode in question
 594 * @from:               block offset of inode
 595 * @count:              block count to be checked
 596 * @uninit:             extents expected to be uninitialized
 597 * @err:                pointer to save error value
 598 *
 599 * Return 1 if all extents in range has expected type, and zero otherwise.
 600 */
 601static int
 602mext_check_coverage(struct inode *inode, ext4_lblk_t from, ext4_lblk_t count,
 603                          int uninit, int *err)
 604{
 605        struct ext4_ext_path *path = NULL;
 606        struct ext4_extent *ext;
 607        int ret = 0;
 608        ext4_lblk_t last = from + count;
 609        while (from < last) {
 610                *err = get_ext_path(inode, from, &path);
 611                if (*err)
 612                        goto out;
 613                ext = path[ext_depth(inode)].p_ext;
 614                if (uninit != ext4_ext_is_uninitialized(ext))
 615                        goto out;
 616                from += ext4_ext_get_actual_len(ext);
 617                ext4_ext_drop_refs(path);
 618        }
 619        ret = 1;
 620out:
 621        if (path) {
 622                ext4_ext_drop_refs(path);
 623                kfree(path);
 624        }
 625        return ret;
 626}
 627
 628/**
 629 * mext_replace_branches - Replace original extents with new extents
 630 *
 631 * @handle:             journal handle
 632 * @orig_inode:         original inode
 633 * @donor_inode:        donor inode
 634 * @from:               block offset of orig_inode
 635 * @count:              block count to be replaced
 636 * @err:                pointer to save return value
 637 *
 638 * Replace original inode extents and donor inode extents page by page.
 639 * We implement this replacement in the following three steps:
 640 * 1. Save the block information of original and donor inodes into
 641 *    dummy extents.
 642 * 2. Change the block information of original inode to point at the
 643 *    donor inode blocks.
 644 * 3. Change the block information of donor inode to point at the saved
 645 *    original inode blocks in the dummy extents.
 646 *
 647 * Return replaced block count.
 648 */
 649static int
 650mext_replace_branches(handle_t *handle, struct inode *orig_inode,
 651                           struct inode *donor_inode, ext4_lblk_t from,
 652                           ext4_lblk_t count, int *err)
 653{
 654        struct ext4_ext_path *orig_path = NULL;
 655        struct ext4_ext_path *donor_path = NULL;
 656        struct ext4_extent *oext, *dext;
 657        struct ext4_extent tmp_dext, tmp_oext;
 658        ext4_lblk_t orig_off = from, donor_off = from;
 659        int depth;
 660        int replaced_count = 0;
 661        int dext_alen;
 662
 663        *err = ext4_es_remove_extent(orig_inode, from, count);
 664        if (*err)
 665                goto out;
 666
 667        *err = ext4_es_remove_extent(donor_inode, from, count);
 668        if (*err)
 669                goto out;
 670
 671        /* Get the original extent for the block "orig_off" */
 672        *err = get_ext_path(orig_inode, orig_off, &orig_path);
 673        if (*err)
 674                goto out;
 675
 676        /* Get the donor extent for the head */
 677        *err = get_ext_path(donor_inode, donor_off, &donor_path);
 678        if (*err)
 679                goto out;
 680        depth = ext_depth(orig_inode);
 681        oext = orig_path[depth].p_ext;
 682        tmp_oext = *oext;
 683
 684        depth = ext_depth(donor_inode);
 685        dext = donor_path[depth].p_ext;
 686        if (unlikely(!dext))
 687                goto missing_donor_extent;
 688        tmp_dext = *dext;
 689
 690        *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
 691                                      donor_off, count);
 692        if (*err)
 693                goto out;
 694
 695        /* Loop for the donor extents */
 696        while (1) {
 697                /* The extent for donor must be found. */
 698                if (unlikely(!dext)) {
 699                missing_donor_extent:
 700                        EXT4_ERROR_INODE(donor_inode,
 701                                   "The extent for donor must be found");
 702                        *err = -EIO;
 703                        goto out;
 704                } else if (donor_off != le32_to_cpu(tmp_dext.ee_block)) {
 705                        EXT4_ERROR_INODE(donor_inode,
 706                                "Donor offset(%u) and the first block of donor "
 707                                "extent(%u) should be equal",
 708                                donor_off,
 709                                le32_to_cpu(tmp_dext.ee_block));
 710                        *err = -EIO;
 711                        goto out;
 712                }
 713
 714                /* Set donor extent to orig extent */
 715                *err = mext_leaf_block(handle, orig_inode,
 716                                           orig_path, &tmp_dext, &orig_off);
 717                if (*err)
 718                        goto out;
 719
 720                /* Set orig extent to donor extent */
 721                *err = mext_leaf_block(handle, donor_inode,
 722                                           donor_path, &tmp_oext, &donor_off);
 723                if (*err)
 724                        goto out;
 725
 726                dext_alen = ext4_ext_get_actual_len(&tmp_dext);
 727                replaced_count += dext_alen;
 728                donor_off += dext_alen;
 729                orig_off += dext_alen;
 730
 731                BUG_ON(replaced_count > count);
 732                /* Already moved the expected blocks */
 733                if (replaced_count >= count)
 734                        break;
 735
 736                if (orig_path)
 737                        ext4_ext_drop_refs(orig_path);
 738                *err = get_ext_path(orig_inode, orig_off, &orig_path);
 739                if (*err)
 740                        goto out;
 741                depth = ext_depth(orig_inode);
 742                oext = orig_path[depth].p_ext;
 743                tmp_oext = *oext;
 744
 745                if (donor_path)
 746                        ext4_ext_drop_refs(donor_path);
 747                *err = get_ext_path(donor_inode, donor_off, &donor_path);
 748                if (*err)
 749                        goto out;
 750                depth = ext_depth(donor_inode);
 751                dext = donor_path[depth].p_ext;
 752                tmp_dext = *dext;
 753
 754                *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
 755                                           donor_off, count - replaced_count);
 756                if (*err)
 757                        goto out;
 758        }
 759
 760out:
 761        if (orig_path) {
 762                ext4_ext_drop_refs(orig_path);
 763                kfree(orig_path);
 764        }
 765        if (donor_path) {
 766                ext4_ext_drop_refs(donor_path);
 767                kfree(donor_path);
 768        }
 769
 770        return replaced_count;
 771}
 772
 773/**
 774 * mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2
 775 *
 776 * @inode1:     the inode structure
 777 * @inode2:     the inode structure
 778 * @index:      page index
 779 * @page:       result page vector
 780 *
 781 * Grab two locked pages for inode's by inode order
 782 */
 783static int
 784mext_page_double_lock(struct inode *inode1, struct inode *inode2,
 785                      pgoff_t index, struct page *page[2])
 786{
 787        struct address_space *mapping[2];
 788        unsigned fl = AOP_FLAG_NOFS;
 789
 790        BUG_ON(!inode1 || !inode2);
 791        if (inode1 < inode2) {
 792                mapping[0] = inode1->i_mapping;
 793                mapping[1] = inode2->i_mapping;
 794        } else {
 795                mapping[0] = inode2->i_mapping;
 796                mapping[1] = inode1->i_mapping;
 797        }
 798
 799        page[0] = grab_cache_page_write_begin(mapping[0], index, fl);
 800        if (!page[0])
 801                return -ENOMEM;
 802
 803        page[1] = grab_cache_page_write_begin(mapping[1], index, fl);
 804        if (!page[1]) {
 805                unlock_page(page[0]);
 806                page_cache_release(page[0]);
 807                return -ENOMEM;
 808        }
 809        /*
 810         * grab_cache_page_write_begin() may not wait on page's writeback if
 811         * BDI not demand that. But it is reasonable to be very conservative
 812         * here and explicitly wait on page's writeback
 813         */
 814        wait_on_page_writeback(page[0]);
 815        wait_on_page_writeback(page[1]);
 816        if (inode1 > inode2) {
 817                struct page *tmp;
 818                tmp = page[0];
 819                page[0] = page[1];
 820                page[1] = tmp;
 821        }
 822        return 0;
 823}
 824
 825/* Force page buffers uptodate w/o dropping page's lock */
 826static int
 827mext_page_mkuptodate(struct page *page, unsigned from, unsigned to)
 828{
 829        struct inode *inode = page->mapping->host;
 830        sector_t block;
 831        struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
 832        unsigned int blocksize, block_start, block_end;
 833        int i, err,  nr = 0, partial = 0;
 834        BUG_ON(!PageLocked(page));
 835        BUG_ON(PageWriteback(page));
 836
 837        if (PageUptodate(page))
 838                return 0;
 839
 840        blocksize = 1 << inode->i_blkbits;
 841        if (!page_has_buffers(page))
 842                create_empty_buffers(page, blocksize, 0);
 843
 844        head = page_buffers(page);
 845        block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
 846        for (bh = head, block_start = 0; bh != head || !block_start;
 847             block++, block_start = block_end, bh = bh->b_this_page) {
 848                block_end = block_start + blocksize;
 849                if (block_end <= from || block_start >= to) {
 850                        if (!buffer_uptodate(bh))
 851                                partial = 1;
 852                        continue;
 853                }
 854                if (buffer_uptodate(bh))
 855                        continue;
 856                if (!buffer_mapped(bh)) {
 857                        err = ext4_get_block(inode, block, bh, 0);
 858                        if (err) {
 859                                SetPageError(page);
 860                                return err;
 861                        }
 862                        if (!buffer_mapped(bh)) {
 863                                zero_user(page, block_start, blocksize);
 864                                if (!err)
 865                                        set_buffer_uptodate(bh);
 866                                continue;
 867                        }
 868                }
 869                BUG_ON(nr >= MAX_BUF_PER_PAGE);
 870                arr[nr++] = bh;
 871        }
 872        /* No io required */
 873        if (!nr)
 874                goto out;
 875
 876        for (i = 0; i < nr; i++) {
 877                bh = arr[i];
 878                if (!bh_uptodate_or_lock(bh)) {
 879                        err = bh_submit_read(bh);
 880                        if (err)
 881                                return err;
 882                }
 883        }
 884out:
 885        if (!partial)
 886                SetPageUptodate(page);
 887        return 0;
 888}
 889
 890/**
 891 * move_extent_per_page - Move extent data per page
 892 *
 893 * @o_filp:                     file structure of original file
 894 * @donor_inode:                donor inode
 895 * @orig_page_offset:           page index on original file
 896 * @data_offset_in_page:        block index where data swapping starts
 897 * @block_len_in_page:          the number of blocks to be swapped
 898 * @uninit:                     orig extent is uninitialized or not
 899 * @err:                        pointer to save return value
 900 *
 901 * Save the data in original inode blocks and replace original inode extents
 902 * with donor inode extents by calling mext_replace_branches().
 903 * Finally, write out the saved data in new original inode blocks. Return
 904 * replaced block count.
 905 */
 906static int
 907move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
 908                  pgoff_t orig_page_offset, int data_offset_in_page,
 909                  int block_len_in_page, int uninit, int *err)
 910{
 911        struct inode *orig_inode = file_inode(o_filp);
 912        struct page *pagep[2] = {NULL, NULL};
 913        handle_t *handle;
 914        ext4_lblk_t orig_blk_offset;
 915        unsigned long blocksize = orig_inode->i_sb->s_blocksize;
 916        unsigned int w_flags = 0;
 917        unsigned int tmp_data_size, data_size, replaced_size;
 918        int err2, jblocks, retries = 0;
 919        int replaced_count = 0;
 920        int from = data_offset_in_page << orig_inode->i_blkbits;
 921        int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
 922
 923        /*
 924         * It needs twice the amount of ordinary journal buffers because
 925         * inode and donor_inode may change each different metadata blocks.
 926         */
 927again:
 928        *err = 0;
 929        jblocks = ext4_writepage_trans_blocks(orig_inode) * 2;
 930        handle = ext4_journal_start(orig_inode, EXT4_HT_MOVE_EXTENTS, jblocks);
 931        if (IS_ERR(handle)) {
 932                *err = PTR_ERR(handle);
 933                return 0;
 934        }
 935
 936        if (segment_eq(get_fs(), KERNEL_DS))
 937                w_flags |= AOP_FLAG_UNINTERRUPTIBLE;
 938
 939        orig_blk_offset = orig_page_offset * blocks_per_page +
 940                data_offset_in_page;
 941
 942        /* Calculate data_size */
 943        if ((orig_blk_offset + block_len_in_page - 1) ==
 944            ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) {
 945                /* Replace the last block */
 946                tmp_data_size = orig_inode->i_size & (blocksize - 1);
 947                /*
 948                 * If data_size equal zero, it shows data_size is multiples of
 949                 * blocksize. So we set appropriate value.
 950                 */
 951                if (tmp_data_size == 0)
 952                        tmp_data_size = blocksize;
 953
 954                data_size = tmp_data_size +
 955                        ((block_len_in_page - 1) << orig_inode->i_blkbits);
 956        } else
 957                data_size = block_len_in_page << orig_inode->i_blkbits;
 958
 959        replaced_size = data_size;
 960
 961        *err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset,
 962                                     pagep);
 963        if (unlikely(*err < 0))
 964                goto stop_journal;
 965        /*
 966         * If orig extent was uninitialized it can become initialized
 967         * at any time after i_data_sem was dropped, in order to
 968         * serialize with delalloc we have recheck extent while we
 969         * hold page's lock, if it is still the case data copy is not
 970         * necessary, just swap data blocks between orig and donor.
 971         */
 972        if (uninit) {
 973                ext4_double_down_write_data_sem(orig_inode, donor_inode);
 974                /* If any of extents in range became initialized we have to
 975                 * fallback to data copying */
 976                uninit = mext_check_coverage(orig_inode, orig_blk_offset,
 977                                             block_len_in_page, 1, err);
 978                if (*err)
 979                        goto drop_data_sem;
 980
 981                uninit &= mext_check_coverage(donor_inode, orig_blk_offset,
 982                                              block_len_in_page, 1, err);
 983                if (*err)
 984                        goto drop_data_sem;
 985
 986                if (!uninit) {
 987                        ext4_double_up_write_data_sem(orig_inode, donor_inode);
 988                        goto data_copy;
 989                }
 990                if ((page_has_private(pagep[0]) &&
 991                     !try_to_release_page(pagep[0], 0)) ||
 992                    (page_has_private(pagep[1]) &&
 993                     !try_to_release_page(pagep[1], 0))) {
 994                        *err = -EBUSY;
 995                        goto drop_data_sem;
 996                }
 997                replaced_count = mext_replace_branches(handle, orig_inode,
 998                                                donor_inode, orig_blk_offset,
 999                                                block_len_in_page, err);
1000        drop_data_sem:
1001                ext4_double_up_write_data_sem(orig_inode, donor_inode);
1002                goto unlock_pages;
1003        }
1004data_copy:
1005        *err = mext_page_mkuptodate(pagep[0], from, from + replaced_size);
1006        if (*err)
1007                goto unlock_pages;
1008
1009        /* At this point all buffers in range are uptodate, old mapping layout
1010         * is no longer required, try to drop it now. */
1011        if ((page_has_private(pagep[0]) && !try_to_release_page(pagep[0], 0)) ||
1012            (page_has_private(pagep[1]) && !try_to_release_page(pagep[1], 0))) {
1013                *err = -EBUSY;
1014                goto unlock_pages;
1015        }
1016
1017        replaced_count = mext_replace_branches(handle, orig_inode, donor_inode,
1018                                               orig_blk_offset,
1019                                               block_len_in_page, err);
1020        if (*err) {
1021                if (replaced_count) {
1022                        block_len_in_page = replaced_count;
1023                        replaced_size =
1024                                block_len_in_page << orig_inode->i_blkbits;
1025                } else
1026                        goto unlock_pages;
1027        }
1028        /* Perform all necessary steps similar write_begin()/write_end()
1029         * but keeping in mind that i_size will not change */
1030        *err = __block_write_begin(pagep[0], from, replaced_size,
1031                                   ext4_get_block);
1032        if (!*err)
1033                *err = block_commit_write(pagep[0], from, from + replaced_size);
1034
1035        if (unlikely(*err < 0))
1036                goto repair_branches;
1037
1038        /* Even in case of data=writeback it is reasonable to pin
1039         * inode to transaction, to prevent unexpected data loss */
1040        *err = ext4_jbd2_file_inode(handle, orig_inode);
1041
1042unlock_pages:
1043        unlock_page(pagep[0]);
1044        page_cache_release(pagep[0]);
1045        unlock_page(pagep[1]);
1046        page_cache_release(pagep[1]);
1047stop_journal:
1048        ext4_journal_stop(handle);
1049        /* Buffer was busy because probably is pinned to journal transaction,
1050         * force transaction commit may help to free it. */
1051        if (*err == -EBUSY && ext4_should_retry_alloc(orig_inode->i_sb,
1052                                                      &retries))
1053                goto again;
1054        return replaced_count;
1055
1056repair_branches:
1057        /*
1058         * This should never ever happen!
1059         * Extents are swapped already, but we are not able to copy data.
1060         * Try to swap extents to it's original places
1061         */
1062        ext4_double_down_write_data_sem(orig_inode, donor_inode);
1063        replaced_count = mext_replace_branches(handle, donor_inode, orig_inode,
1064                                               orig_blk_offset,
1065                                               block_len_in_page, &err2);
1066        ext4_double_up_write_data_sem(orig_inode, donor_inode);
1067        if (replaced_count != block_len_in_page) {
1068                EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset),
1069                                       "Unable to copy data block,"
1070                                       " data will be lost.");
1071                *err = -EIO;
1072        }
1073        replaced_count = 0;
1074        goto unlock_pages;
1075}
1076
1077/**
1078 * mext_check_arguments - Check whether move extent can be done
1079 *
1080 * @orig_inode:         original inode
1081 * @donor_inode:        donor inode
1082 * @orig_start:         logical start offset in block for orig
1083 * @donor_start:        logical start offset in block for donor
1084 * @len:                the number of blocks to be moved
1085 *
1086 * Check the arguments of ext4_move_extents() whether the files can be
1087 * exchanged with each other.
1088 * Return 0 on success, or a negative error value on failure.
1089 */
1090static int
1091mext_check_arguments(struct inode *orig_inode,
1092                     struct inode *donor_inode, __u64 orig_start,
1093                     __u64 donor_start, __u64 *len)
1094{
1095        ext4_lblk_t orig_blocks, donor_blocks;
1096        unsigned int blkbits = orig_inode->i_blkbits;
1097        unsigned int blocksize = 1 << blkbits;
1098
1099        if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
1100                ext4_debug("ext4 move extent: suid or sgid is set"
1101                           " to donor file [ino:orig %lu, donor %lu]\n",
1102                           orig_inode->i_ino, donor_inode->i_ino);
1103                return -EINVAL;
1104        }
1105
1106        if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode))
1107                return -EPERM;
1108
1109        /* Ext4 move extent does not support swapfile */
1110        if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
1111                ext4_debug("ext4 move extent: The argument files should "
1112                        "not be swapfile [ino:orig %lu, donor %lu]\n",
1113                        orig_inode->i_ino, donor_inode->i_ino);
1114                return -EINVAL;
1115        }
1116
1117        /* Ext4 move extent supports only extent based file */
1118        if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) {
1119                ext4_debug("ext4 move extent: orig file is not extents "
1120                        "based file [ino:orig %lu]\n", orig_inode->i_ino);
1121                return -EOPNOTSUPP;
1122        } else if (!(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) {
1123                ext4_debug("ext4 move extent: donor file is not extents "
1124                        "based file [ino:donor %lu]\n", donor_inode->i_ino);
1125                return -EOPNOTSUPP;
1126        }
1127
1128        if ((!orig_inode->i_size) || (!donor_inode->i_size)) {
1129                ext4_debug("ext4 move extent: File size is 0 byte\n");
1130                return -EINVAL;
1131        }
1132
1133        /* Start offset should be same */
1134        if (orig_start != donor_start) {
1135                ext4_debug("ext4 move extent: orig and donor's start "
1136                        "offset are not same [ino:orig %lu, donor %lu]\n",
1137                        orig_inode->i_ino, donor_inode->i_ino);
1138                return -EINVAL;
1139        }
1140
1141        if ((orig_start >= EXT_MAX_BLOCKS) ||
1142            (*len > EXT_MAX_BLOCKS) ||
1143            (orig_start + *len >= EXT_MAX_BLOCKS))  {
1144                ext4_debug("ext4 move extent: Can't handle over [%u] blocks "
1145                        "[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS,
1146                        orig_inode->i_ino, donor_inode->i_ino);
1147                return -EINVAL;
1148        }
1149
1150        if (orig_inode->i_size > donor_inode->i_size) {
1151                donor_blocks = (donor_inode->i_size + blocksize - 1) >> blkbits;
1152                /* TODO: eliminate this artificial restriction */
1153                if (orig_start >= donor_blocks) {
1154                        ext4_debug("ext4 move extent: orig start offset "
1155                        "[%llu] should be less than donor file blocks "
1156                        "[%u] [ino:orig %lu, donor %lu]\n",
1157                        orig_start, donor_blocks,
1158                        orig_inode->i_ino, donor_inode->i_ino);
1159                        return -EINVAL;
1160                }
1161
1162                /* TODO: eliminate this artificial restriction */
1163                if (orig_start + *len > donor_blocks) {
1164                        ext4_debug("ext4 move extent: End offset [%llu] should "
1165                                "be less than donor file blocks [%u]."
1166                                "So adjust length from %llu to %llu "
1167                                "[ino:orig %lu, donor %lu]\n",
1168                                orig_start + *len, donor_blocks,
1169                                *len, donor_blocks - orig_start,
1170                                orig_inode->i_ino, donor_inode->i_ino);
1171                        *len = donor_blocks - orig_start;
1172                }
1173        } else {
1174                orig_blocks = (orig_inode->i_size + blocksize - 1) >> blkbits;
1175                if (orig_start >= orig_blocks) {
1176                        ext4_debug("ext4 move extent: start offset [%llu] "
1177                                "should be less than original file blocks "
1178                                "[%u] [ino:orig %lu, donor %lu]\n",
1179                                 orig_start, orig_blocks,
1180                                orig_inode->i_ino, donor_inode->i_ino);
1181                        return -EINVAL;
1182                }
1183
1184                if (orig_start + *len > orig_blocks) {
1185                        ext4_debug("ext4 move extent: Adjust length "
1186                                "from %llu to %llu. Because it should be "
1187                                "less than original file blocks "
1188                                "[ino:orig %lu, donor %lu]\n",
1189                                *len, orig_blocks - orig_start,
1190                                orig_inode->i_ino, donor_inode->i_ino);
1191                        *len = orig_blocks - orig_start;
1192                }
1193        }
1194
1195        if (!*len) {
1196                ext4_debug("ext4 move extent: len should not be 0 "
1197                        "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino,
1198                        donor_inode->i_ino);
1199                return -EINVAL;
1200        }
1201
1202        return 0;
1203}
1204
1205/**
1206 * ext4_inode_double_lock - Lock i_mutex on both @inode1 and @inode2
1207 *
1208 * @inode1:     the inode structure
1209 * @inode2:     the inode structure
1210 *
1211 * Lock two inodes' i_mutex
1212 */
1213void
1214ext4_inode_double_lock(struct inode *inode1, struct inode *inode2)
1215{
1216        BUG_ON(inode1 == inode2);
1217        if (inode1 < inode2) {
1218                mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
1219                mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
1220        } else {
1221                mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
1222                mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
1223        }
1224}
1225
1226/**
1227 * ext4_inode_double_unlock - Release i_mutex on both @inode1 and @inode2
1228 *
1229 * @inode1:     the inode that is released first
1230 * @inode2:     the inode that is released second
1231 *
1232 */
1233
1234void
1235ext4_inode_double_unlock(struct inode *inode1, struct inode *inode2)
1236{
1237        mutex_unlock(&inode1->i_mutex);
1238        mutex_unlock(&inode2->i_mutex);
1239}
1240
1241/**
1242 * ext4_move_extents - Exchange the specified range of a file
1243 *
1244 * @o_filp:             file structure of the original file
1245 * @d_filp:             file structure of the donor file
1246 * @orig_start:         start offset in block for orig
1247 * @donor_start:        start offset in block for donor
1248 * @len:                the number of blocks to be moved
1249 * @moved_len:          moved block length
1250 *
1251 * This function returns 0 and moved block length is set in moved_len
1252 * if succeed, otherwise returns error value.
1253 *
1254 * Note: ext4_move_extents() proceeds the following order.
1255 * 1:ext4_move_extents() calculates the last block number of moving extent
1256 *   function by the start block number (orig_start) and the number of blocks
1257 *   to be moved (len) specified as arguments.
1258 *   If the {orig, donor}_start points a hole, the extent's start offset
1259 *   pointed by ext_cur (current extent), holecheck_path, orig_path are set
1260 *   after hole behind.
1261 * 2:Continue step 3 to step 5, until the holecheck_path points to last_extent
1262 *   or the ext_cur exceeds the block_end which is last logical block number.
1263 * 3:To get the length of continues area, call mext_next_extent()
1264 *   specified with the ext_cur (initial value is holecheck_path) re-cursive,
1265 *   until find un-continuous extent, the start logical block number exceeds
1266 *   the block_end or the extent points to the last extent.
1267 * 4:Exchange the original inode data with donor inode data
1268 *   from orig_page_offset to seq_end_page.
1269 *   The start indexes of data are specified as arguments.
1270 *   That of the original inode is orig_page_offset,
1271 *   and the donor inode is also orig_page_offset
1272 *   (To easily handle blocksize != pagesize case, the offset for the
1273 *   donor inode is block unit).
1274 * 5:Update holecheck_path and orig_path to points a next proceeding extent,
1275 *   then returns to step 2.
1276 * 6:Release holecheck_path, orig_path and set the len to moved_len
1277 *   which shows the number of moved blocks.
1278 *   The moved_len is useful for the command to calculate the file offset
1279 *   for starting next move extent ioctl.
1280 * 7:Return 0 on success, or a negative error value on failure.
1281 */
1282int
1283ext4_move_extents(struct file *o_filp, struct file *d_filp,
1284                 __u64 orig_start, __u64 donor_start, __u64 len,
1285                 __u64 *moved_len)
1286{
1287        struct inode *orig_inode = file_inode(o_filp);
1288        struct inode *donor_inode = file_inode(d_filp);
1289        struct ext4_ext_path *orig_path = NULL, *holecheck_path = NULL;
1290        struct ext4_extent *ext_prev, *ext_cur, *ext_dummy;
1291        ext4_lblk_t block_start = orig_start;
1292        ext4_lblk_t block_end, seq_start, add_blocks, file_end, seq_blocks = 0;
1293        ext4_lblk_t rest_blocks;
1294        pgoff_t orig_page_offset = 0, seq_end_page;
1295        int ret, depth, last_extent = 0;
1296        int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
1297        int data_offset_in_page;
1298        int block_len_in_page;
1299        int uninit;
1300
1301        if (orig_inode->i_sb != donor_inode->i_sb) {
1302                ext4_debug("ext4 move extent: The argument files "
1303                        "should be in same FS [ino:orig %lu, donor %lu]\n",
1304                        orig_inode->i_ino, donor_inode->i_ino);
1305                return -EINVAL;
1306        }
1307
1308        /* orig and donor should be different inodes */
1309        if (orig_inode == donor_inode) {
1310                ext4_debug("ext4 move extent: The argument files should not "
1311                        "be same inode [ino:orig %lu, donor %lu]\n",
1312                        orig_inode->i_ino, donor_inode->i_ino);
1313                return -EINVAL;
1314        }
1315
1316        /* Regular file check */
1317        if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
1318                ext4_debug("ext4 move extent: The argument files should be "
1319                        "regular file [ino:orig %lu, donor %lu]\n",
1320                        orig_inode->i_ino, donor_inode->i_ino);
1321                return -EINVAL;
1322        }
1323        /* TODO: This is non obvious task to swap blocks for inodes with full
1324           jornaling enabled */
1325        if (ext4_should_journal_data(orig_inode) ||
1326            ext4_should_journal_data(donor_inode)) {
1327                return -EINVAL;
1328        }
1329        /* Protect orig and donor inodes against a truncate */
1330        ext4_inode_double_lock(orig_inode, donor_inode);
1331
1332        /* Wait for all existing dio workers */
1333        ext4_inode_block_unlocked_dio(orig_inode);
1334        ext4_inode_block_unlocked_dio(donor_inode);
1335        inode_dio_wait(orig_inode);
1336        inode_dio_wait(donor_inode);
1337
1338        /* Protect extent tree against block allocations via delalloc */
1339        ext4_double_down_write_data_sem(orig_inode, donor_inode);
1340        /* Check the filesystem environment whether move_extent can be done */
1341        ret = mext_check_arguments(orig_inode, donor_inode, orig_start,
1342                                    donor_start, &len);
1343        if (ret)
1344                goto out;
1345
1346        file_end = (i_size_read(orig_inode) - 1) >> orig_inode->i_blkbits;
1347        block_end = block_start + len - 1;
1348        if (file_end < block_end)
1349                len -= block_end - file_end;
1350
1351        ret = get_ext_path(orig_inode, block_start, &orig_path);
1352        if (ret)
1353                goto out;
1354
1355        /* Get path structure to check the hole */
1356        ret = get_ext_path(orig_inode, block_start, &holecheck_path);
1357        if (ret)
1358                goto out;
1359
1360        depth = ext_depth(orig_inode);
1361        ext_cur = holecheck_path[depth].p_ext;
1362
1363        /*
1364         * Get proper starting location of block replacement if block_start was
1365         * within the hole.
1366         */
1367        if (le32_to_cpu(ext_cur->ee_block) +
1368                ext4_ext_get_actual_len(ext_cur) - 1 < block_start) {
1369                /*
1370                 * The hole exists between extents or the tail of
1371                 * original file.
1372                 */
1373                last_extent = mext_next_extent(orig_inode,
1374                                        holecheck_path, &ext_cur);
1375                if (last_extent < 0) {
1376                        ret = last_extent;
1377                        goto out;
1378                }
1379                last_extent = mext_next_extent(orig_inode, orig_path,
1380                                                        &ext_dummy);
1381                if (last_extent < 0) {
1382                        ret = last_extent;
1383                        goto out;
1384                }
1385                seq_start = le32_to_cpu(ext_cur->ee_block);
1386        } else if (le32_to_cpu(ext_cur->ee_block) > block_start)
1387                /* The hole exists at the beginning of original file. */
1388                seq_start = le32_to_cpu(ext_cur->ee_block);
1389        else
1390                seq_start = block_start;
1391
1392        /* No blocks within the specified range. */
1393        if (le32_to_cpu(ext_cur->ee_block) > block_end) {
1394                ext4_debug("ext4 move extent: The specified range of file "
1395                                                        "may be the hole\n");
1396                ret = -EINVAL;
1397                goto out;
1398        }
1399
1400        /* Adjust start blocks */
1401        add_blocks = min(le32_to_cpu(ext_cur->ee_block) +
1402                         ext4_ext_get_actual_len(ext_cur), block_end + 1) -
1403                     max(le32_to_cpu(ext_cur->ee_block), block_start);
1404
1405        while (!last_extent && le32_to_cpu(ext_cur->ee_block) <= block_end) {
1406                seq_blocks += add_blocks;
1407
1408                /* Adjust tail blocks */
1409                if (seq_start + seq_blocks - 1 > block_end)
1410                        seq_blocks = block_end - seq_start + 1;
1411
1412                ext_prev = ext_cur;
1413                last_extent = mext_next_extent(orig_inode, holecheck_path,
1414                                                &ext_cur);
1415                if (last_extent < 0) {
1416                        ret = last_extent;
1417                        break;
1418                }
1419                add_blocks = ext4_ext_get_actual_len(ext_cur);
1420
1421                /*
1422                 * Extend the length of contiguous block (seq_blocks)
1423                 * if extents are contiguous.
1424                 */
1425                if (ext4_can_extents_be_merged(orig_inode,
1426                                               ext_prev, ext_cur) &&
1427                    block_end >= le32_to_cpu(ext_cur->ee_block) &&
1428                    !last_extent)
1429                        continue;
1430
1431                /* Is original extent is uninitialized */
1432                uninit = ext4_ext_is_uninitialized(ext_prev);
1433
1434                data_offset_in_page = seq_start % blocks_per_page;
1435
1436                /*
1437                 * Calculate data blocks count that should be swapped
1438                 * at the first page.
1439                 */
1440                if (data_offset_in_page + seq_blocks > blocks_per_page) {
1441                        /* Swapped blocks are across pages */
1442                        block_len_in_page =
1443                                        blocks_per_page - data_offset_in_page;
1444                } else {
1445                        /* Swapped blocks are in a page */
1446                        block_len_in_page = seq_blocks;
1447                }
1448
1449                orig_page_offset = seq_start >>
1450                                (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1451                seq_end_page = (seq_start + seq_blocks - 1) >>
1452                                (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1453                seq_start = le32_to_cpu(ext_cur->ee_block);
1454                rest_blocks = seq_blocks;
1455
1456                /*
1457                 * Up semaphore to avoid following problems:
1458                 * a. transaction deadlock among ext4_journal_start,
1459                 *    ->write_begin via pagefault, and jbd2_journal_commit
1460                 * b. racing with ->readpage, ->write_begin, and ext4_get_block
1461                 *    in move_extent_per_page
1462                 */
1463                ext4_double_up_write_data_sem(orig_inode, donor_inode);
1464
1465                while (orig_page_offset <= seq_end_page) {
1466
1467                        /* Swap original branches with new branches */
1468                        block_len_in_page = move_extent_per_page(
1469                                                o_filp, donor_inode,
1470                                                orig_page_offset,
1471                                                data_offset_in_page,
1472                                                block_len_in_page, uninit,
1473                                                &ret);
1474
1475                        /* Count how many blocks we have exchanged */
1476                        *moved_len += block_len_in_page;
1477                        if (ret < 0)
1478                                break;
1479                        if (*moved_len > len) {
1480                                EXT4_ERROR_INODE(orig_inode,
1481                                        "We replaced blocks too much! "
1482                                        "sum of replaced: %llu requested: %llu",
1483                                        *moved_len, len);
1484                                ret = -EIO;
1485                                break;
1486                        }
1487
1488                        orig_page_offset++;
1489                        data_offset_in_page = 0;
1490                        rest_blocks -= block_len_in_page;
1491                        if (rest_blocks > blocks_per_page)
1492                                block_len_in_page = blocks_per_page;
1493                        else
1494                                block_len_in_page = rest_blocks;
1495                }
1496
1497                ext4_double_down_write_data_sem(orig_inode, donor_inode);
1498                if (ret < 0)
1499                        break;
1500
1501                /* Decrease buffer counter */
1502                if (holecheck_path)
1503                        ext4_ext_drop_refs(holecheck_path);
1504                ret = get_ext_path(orig_inode, seq_start, &holecheck_path);
1505                if (ret)
1506                        break;
1507                depth = holecheck_path->p_depth;
1508
1509                /* Decrease buffer counter */
1510                if (orig_path)
1511                        ext4_ext_drop_refs(orig_path);
1512                ret = get_ext_path(orig_inode, seq_start, &orig_path);
1513                if (ret)
1514                        break;
1515
1516                ext_cur = holecheck_path[depth].p_ext;
1517                add_blocks = ext4_ext_get_actual_len(ext_cur);
1518                seq_blocks = 0;
1519
1520        }
1521out:
1522        if (*moved_len) {
1523                ext4_discard_preallocations(orig_inode);
1524                ext4_discard_preallocations(donor_inode);
1525        }
1526
1527        if (orig_path) {
1528                ext4_ext_drop_refs(orig_path);
1529                kfree(orig_path);
1530        }
1531        if (holecheck_path) {
1532                ext4_ext_drop_refs(holecheck_path);
1533                kfree(holecheck_path);
1534        }
1535        ext4_double_up_write_data_sem(orig_inode, donor_inode);
1536        ext4_inode_resume_unlocked_dio(orig_inode);
1537        ext4_inode_resume_unlocked_dio(donor_inode);
1538        ext4_inode_double_unlock(orig_inode, donor_inode);
1539
1540        return ret;
1541}
1542