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        le32_add_cpu(&tmp_dext->ee_block, diff);
 574        le16_add_cpu(&tmp_dext->ee_len, -diff);
 575
 576        if (max_count < ext4_ext_get_actual_len(tmp_dext))
 577                tmp_dext->ee_len = cpu_to_le16(max_count);
 578
 579        orig_diff = orig_off - le32_to_cpu(tmp_oext->ee_block);
 580        ext4_ext_store_pblock(tmp_oext, ext4_ext_pblock(tmp_oext) + orig_diff);
 581
 582        /* Adjust extent length if donor extent is larger than orig */
 583        if (ext4_ext_get_actual_len(tmp_dext) >
 584            ext4_ext_get_actual_len(tmp_oext) - orig_diff)
 585                tmp_dext->ee_len = cpu_to_le16(le16_to_cpu(tmp_oext->ee_len) -
 586                                                orig_diff);
 587
 588        tmp_oext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(tmp_dext));
 589
 590        copy_extent_status(&oext_old, tmp_dext);
 591        copy_extent_status(&dext_old, tmp_oext);
 592
 593        return 0;
 594}
 595
 596/**
 597 * mext_check_coverage - Check that all extents in range has the same type
 598 *
 599 * @inode:              inode in question
 600 * @from:               block offset of inode
 601 * @count:              block count to be checked
 602 * @uninit:             extents expected to be uninitialized
 603 * @err:                pointer to save error value
 604 *
 605 * Return 1 if all extents in range has expected type, and zero otherwise.
 606 */
 607static int
 608mext_check_coverage(struct inode *inode, ext4_lblk_t from, ext4_lblk_t count,
 609                          int uninit, int *err)
 610{
 611        struct ext4_ext_path *path = NULL;
 612        struct ext4_extent *ext;
 613        ext4_lblk_t last = from + count;
 614        while (from < last) {
 615                *err = get_ext_path(inode, from, &path);
 616                if (*err)
 617                        return 0;
 618                ext = path[ext_depth(inode)].p_ext;
 619                if (!ext) {
 620                        ext4_ext_drop_refs(path);
 621                        return 0;
 622                }
 623                if (uninit != ext4_ext_is_uninitialized(ext)) {
 624                        ext4_ext_drop_refs(path);
 625                        return 0;
 626                }
 627                from += ext4_ext_get_actual_len(ext);
 628                ext4_ext_drop_refs(path);
 629        }
 630        return 1;
 631}
 632
 633/**
 634 * mext_replace_branches - Replace original extents with new extents
 635 *
 636 * @handle:             journal handle
 637 * @orig_inode:         original inode
 638 * @donor_inode:        donor inode
 639 * @from:               block offset of orig_inode
 640 * @count:              block count to be replaced
 641 * @err:                pointer to save return value
 642 *
 643 * Replace original inode extents and donor inode extents page by page.
 644 * We implement this replacement in the following three steps:
 645 * 1. Save the block information of original and donor inodes into
 646 *    dummy extents.
 647 * 2. Change the block information of original inode to point at the
 648 *    donor inode blocks.
 649 * 3. Change the block information of donor inode to point at the saved
 650 *    original inode blocks in the dummy extents.
 651 *
 652 * Return replaced block count.
 653 */
 654static int
 655mext_replace_branches(handle_t *handle, struct inode *orig_inode,
 656                           struct inode *donor_inode, ext4_lblk_t from,
 657                           ext4_lblk_t count, int *err)
 658{
 659        struct ext4_ext_path *orig_path = NULL;
 660        struct ext4_ext_path *donor_path = NULL;
 661        struct ext4_extent *oext, *dext;
 662        struct ext4_extent tmp_dext, tmp_oext;
 663        ext4_lblk_t orig_off = from, donor_off = from;
 664        int depth;
 665        int replaced_count = 0;
 666        int dext_alen;
 667
 668        /* Get the original extent for the block "orig_off" */
 669        *err = get_ext_path(orig_inode, orig_off, &orig_path);
 670        if (*err)
 671                goto out;
 672
 673        /* Get the donor extent for the head */
 674        *err = get_ext_path(donor_inode, donor_off, &donor_path);
 675        if (*err)
 676                goto out;
 677        depth = ext_depth(orig_inode);
 678        oext = orig_path[depth].p_ext;
 679        tmp_oext = *oext;
 680
 681        depth = ext_depth(donor_inode);
 682        dext = donor_path[depth].p_ext;
 683        tmp_dext = *dext;
 684
 685        *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
 686                                      donor_off, count);
 687        if (*err)
 688                goto out;
 689
 690        /* Loop for the donor extents */
 691        while (1) {
 692                /* The extent for donor must be found. */
 693                if (!dext) {
 694                        EXT4_ERROR_INODE(donor_inode,
 695                                   "The extent for donor must be found");
 696                        *err = -EIO;
 697                        goto out;
 698                } else if (donor_off != le32_to_cpu(tmp_dext.ee_block)) {
 699                        EXT4_ERROR_INODE(donor_inode,
 700                                "Donor offset(%u) and the first block of donor "
 701                                "extent(%u) should be equal",
 702                                donor_off,
 703                                le32_to_cpu(tmp_dext.ee_block));
 704                        *err = -EIO;
 705                        goto out;
 706                }
 707
 708                /* Set donor extent to orig extent */
 709                *err = mext_leaf_block(handle, orig_inode,
 710                                           orig_path, &tmp_dext, &orig_off);
 711                if (*err)
 712                        goto out;
 713
 714                /* Set orig extent to donor extent */
 715                *err = mext_leaf_block(handle, donor_inode,
 716                                           donor_path, &tmp_oext, &donor_off);
 717                if (*err)
 718                        goto out;
 719
 720                dext_alen = ext4_ext_get_actual_len(&tmp_dext);
 721                replaced_count += dext_alen;
 722                donor_off += dext_alen;
 723                orig_off += dext_alen;
 724
 725                /* Already moved the expected blocks */
 726                if (replaced_count >= count)
 727                        break;
 728
 729                if (orig_path)
 730                        ext4_ext_drop_refs(orig_path);
 731                *err = get_ext_path(orig_inode, orig_off, &orig_path);
 732                if (*err)
 733                        goto out;
 734                depth = ext_depth(orig_inode);
 735                oext = orig_path[depth].p_ext;
 736                tmp_oext = *oext;
 737
 738                if (donor_path)
 739                        ext4_ext_drop_refs(donor_path);
 740                *err = get_ext_path(donor_inode, donor_off, &donor_path);
 741                if (*err)
 742                        goto out;
 743                depth = ext_depth(donor_inode);
 744                dext = donor_path[depth].p_ext;
 745                tmp_dext = *dext;
 746
 747                *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
 748                                           donor_off, count - replaced_count);
 749                if (*err)
 750                        goto out;
 751        }
 752
 753out:
 754        if (orig_path) {
 755                ext4_ext_drop_refs(orig_path);
 756                kfree(orig_path);
 757        }
 758        if (donor_path) {
 759                ext4_ext_drop_refs(donor_path);
 760                kfree(donor_path);
 761        }
 762
 763        ext4_ext_invalidate_cache(orig_inode);
 764        ext4_ext_invalidate_cache(donor_inode);
 765
 766        return replaced_count;
 767}
 768
 769/**
 770 * mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2
 771 *
 772 * @inode1:     the inode structure
 773 * @inode2:     the inode structure
 774 * @index:      page index
 775 * @page:       result page vector
 776 *
 777 * Grab two locked pages for inode's by inode order
 778 */
 779static int
 780mext_page_double_lock(struct inode *inode1, struct inode *inode2,
 781                      pgoff_t index, struct page *page[2])
 782{
 783        struct address_space *mapping[2];
 784        unsigned fl = AOP_FLAG_NOFS;
 785
 786        BUG_ON(!inode1 || !inode2);
 787        if (inode1 < inode2) {
 788                mapping[0] = inode1->i_mapping;
 789                mapping[1] = inode2->i_mapping;
 790        } else {
 791                mapping[0] = inode2->i_mapping;
 792                mapping[1] = inode1->i_mapping;
 793        }
 794
 795        page[0] = grab_cache_page_write_begin(mapping[0], index, fl);
 796        if (!page[0])
 797                return -ENOMEM;
 798
 799        page[1] = grab_cache_page_write_begin(mapping[1], index, fl);
 800        if (!page[1]) {
 801                unlock_page(page[0]);
 802                page_cache_release(page[0]);
 803                return -ENOMEM;
 804        }
 805
 806        if (inode1 > inode2) {
 807                struct page *tmp;
 808                tmp = page[0];
 809                page[0] = page[1];
 810                page[1] = tmp;
 811        }
 812        return 0;
 813}
 814
 815/* Force page buffers uptodate w/o dropping page's lock */
 816static int
 817mext_page_mkuptodate(struct page *page, unsigned from, unsigned to)
 818{
 819        struct inode *inode = page->mapping->host;
 820        sector_t block;
 821        struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
 822        unsigned int blocksize, block_start, block_end;
 823        int i, err,  nr = 0, partial = 0;
 824        BUG_ON(!PageLocked(page));
 825        BUG_ON(PageWriteback(page));
 826
 827        if (PageUptodate(page))
 828                return 0;
 829
 830        blocksize = 1 << inode->i_blkbits;
 831        if (!page_has_buffers(page))
 832                create_empty_buffers(page, blocksize, 0);
 833
 834        head = page_buffers(page);
 835        block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
 836        for (bh = head, block_start = 0; bh != head || !block_start;
 837             block++, block_start = block_end, bh = bh->b_this_page) {
 838                block_end = block_start + blocksize;
 839                if (block_end <= from || block_start >= to) {
 840                        if (!buffer_uptodate(bh))
 841                                partial = 1;
 842                        continue;
 843                }
 844                if (buffer_uptodate(bh))
 845                        continue;
 846                if (!buffer_mapped(bh)) {
 847                        int err = 0;
 848                        err = ext4_get_block(inode, block, bh, 0);
 849                        if (err) {
 850                                SetPageError(page);
 851                                return err;
 852                        }
 853                        if (!buffer_mapped(bh)) {
 854                                zero_user(page, block_start, blocksize);
 855                                if (!err)
 856                                        set_buffer_uptodate(bh);
 857                                continue;
 858                        }
 859                }
 860                BUG_ON(nr >= MAX_BUF_PER_PAGE);
 861                arr[nr++] = bh;
 862        }
 863        /* No io required */
 864        if (!nr)
 865                goto out;
 866
 867        for (i = 0; i < nr; i++) {
 868                bh = arr[i];
 869                if (!bh_uptodate_or_lock(bh)) {
 870                        err = bh_submit_read(bh);
 871                        if (err)
 872                                return err;
 873                }
 874        }
 875out:
 876        if (!partial)
 877                SetPageUptodate(page);
 878        return 0;
 879}
 880
 881/**
 882 * move_extent_per_page - Move extent data per page
 883 *
 884 * @o_filp:                     file structure of original file
 885 * @donor_inode:                donor inode
 886 * @orig_page_offset:           page index on original file
 887 * @data_offset_in_page:        block index where data swapping starts
 888 * @block_len_in_page:          the number of blocks to be swapped
 889 * @uninit:                     orig extent is uninitialized or not
 890 * @err:                        pointer to save return value
 891 *
 892 * Save the data in original inode blocks and replace original inode extents
 893 * with donor inode extents by calling mext_replace_branches().
 894 * Finally, write out the saved data in new original inode blocks. Return
 895 * replaced block count.
 896 */
 897static int
 898move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
 899                  pgoff_t orig_page_offset, int data_offset_in_page,
 900                  int block_len_in_page, int uninit, int *err)
 901{
 902        struct inode *orig_inode = o_filp->f_dentry->d_inode;
 903        struct page *pagep[2] = {NULL, NULL};
 904        handle_t *handle;
 905        ext4_lblk_t orig_blk_offset;
 906        long long offs = orig_page_offset << PAGE_CACHE_SHIFT;
 907        unsigned long blocksize = orig_inode->i_sb->s_blocksize;
 908        unsigned int w_flags = 0;
 909        unsigned int tmp_data_size, data_size, replaced_size;
 910        int err2, jblocks, retries = 0;
 911        int replaced_count = 0;
 912        int from = data_offset_in_page << orig_inode->i_blkbits;
 913        int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
 914
 915        /*
 916         * It needs twice the amount of ordinary journal buffers because
 917         * inode and donor_inode may change each different metadata blocks.
 918         */
 919again:
 920        *err = 0;
 921        jblocks = ext4_writepage_trans_blocks(orig_inode) * 2;
 922        handle = ext4_journal_start(orig_inode, jblocks);
 923        if (IS_ERR(handle)) {
 924                *err = PTR_ERR(handle);
 925                return 0;
 926        }
 927
 928        if (segment_eq(get_fs(), KERNEL_DS))
 929                w_flags |= AOP_FLAG_UNINTERRUPTIBLE;
 930
 931        orig_blk_offset = orig_page_offset * blocks_per_page +
 932                data_offset_in_page;
 933
 934        offs = (long long)orig_blk_offset << orig_inode->i_blkbits;
 935
 936        /* Calculate data_size */
 937        if ((orig_blk_offset + block_len_in_page - 1) ==
 938            ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) {
 939                /* Replace the last block */
 940                tmp_data_size = orig_inode->i_size & (blocksize - 1);
 941                /*
 942                 * If data_size equal zero, it shows data_size is multiples of
 943                 * blocksize. So we set appropriate value.
 944                 */
 945                if (tmp_data_size == 0)
 946                        tmp_data_size = blocksize;
 947
 948                data_size = tmp_data_size +
 949                        ((block_len_in_page - 1) << orig_inode->i_blkbits);
 950        } else
 951                data_size = block_len_in_page << orig_inode->i_blkbits;
 952
 953        replaced_size = data_size;
 954
 955        *err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset,
 956                                     pagep);
 957        if (unlikely(*err < 0))
 958                goto stop_journal;
 959        /*
 960         * If orig extent was uninitialized it can become initialized
 961         * at any time after i_data_sem was dropped, in order to
 962         * serialize with delalloc we have recheck extent while we
 963         * hold page's lock, if it is still the case data copy is not
 964         * necessary, just swap data blocks between orig and donor.
 965         */
 966        if (uninit) {
 967                double_down_write_data_sem(orig_inode, donor_inode);
 968                /* If any of extents in range became initialized we have to
 969                 * fallback to data copying */
 970                uninit = mext_check_coverage(orig_inode, orig_blk_offset,
 971                                             block_len_in_page, 1, err);
 972                if (*err)
 973                        goto drop_data_sem;
 974
 975                uninit &= mext_check_coverage(donor_inode, orig_blk_offset,
 976                                              block_len_in_page, 1, err);
 977                if (*err)
 978                        goto drop_data_sem;
 979
 980                if (!uninit) {
 981                        double_up_write_data_sem(orig_inode, donor_inode);
 982                        goto data_copy;
 983                }
 984                if ((page_has_private(pagep[0]) &&
 985                     !try_to_release_page(pagep[0], 0)) ||
 986                    (page_has_private(pagep[1]) &&
 987                     !try_to_release_page(pagep[1], 0))) {
 988                        *err = -EBUSY;
 989                        goto drop_data_sem;
 990                }
 991                replaced_count = mext_replace_branches(handle, orig_inode,
 992                                                donor_inode, orig_blk_offset,
 993                                                block_len_in_page, err);
 994        drop_data_sem:
 995                double_up_write_data_sem(orig_inode, donor_inode);
 996                goto unlock_pages;
 997        }
 998data_copy:
 999        *err = mext_page_mkuptodate(pagep[0], from, from + replaced_size);
1000        if (*err)
1001                goto unlock_pages;
1002
1003        /* At this point all buffers in range are uptodate, old mapping layout
1004         * is no longer required, try to drop it now. */
1005        if ((page_has_private(pagep[0]) && !try_to_release_page(pagep[0], 0)) ||
1006            (page_has_private(pagep[1]) && !try_to_release_page(pagep[1], 0))) {
1007                *err = -EBUSY;
1008                goto unlock_pages;
1009        }
1010
1011        replaced_count = mext_replace_branches(handle, orig_inode, donor_inode,
1012                                               orig_blk_offset,
1013                                               block_len_in_page, err);
1014        if (*err) {
1015                if (replaced_count) {
1016                        block_len_in_page = replaced_count;
1017                        replaced_size =
1018                                block_len_in_page << orig_inode->i_blkbits;
1019                } else
1020                        goto unlock_pages;
1021        }
1022        /* Perform all necessary steps similar write_begin()/write_end()
1023         * but keeping in mind that i_size will not change */
1024        *err = __block_write_begin(pagep[0], from, from + replaced_size,
1025                                   ext4_get_block);
1026        if (!*err)
1027                *err = block_commit_write(pagep[0], from, from + replaced_size);
1028
1029        if (unlikely(*err < 0))
1030                goto repair_branches;
1031
1032        /* Even in case of data=writeback it is reasonable to pin
1033         * inode to transaction, to prevent unexpected data loss */
1034        *err = ext4_jbd2_file_inode(handle, orig_inode);
1035
1036unlock_pages:
1037        unlock_page(pagep[0]);
1038        page_cache_release(pagep[0]);
1039        unlock_page(pagep[1]);
1040        page_cache_release(pagep[1]);
1041stop_journal:
1042        ext4_journal_stop(handle);
1043        /* Buffer was busy because probably is pinned to journal transaction,
1044         * force transaction commit may help to free it. */
1045        if (*err == -EBUSY && ext4_should_retry_alloc(orig_inode->i_sb,
1046                                                      &retries))
1047                goto again;
1048        return replaced_count;
1049
1050repair_branches:
1051        /*
1052         * This should never ever happen!
1053         * Extents are swapped already, but we are not able to copy data.
1054         * Try to swap extents to it's original places
1055         */
1056        double_down_write_data_sem(orig_inode, donor_inode);
1057        replaced_count = mext_replace_branches(handle, donor_inode, orig_inode,
1058                                               orig_blk_offset,
1059                                               block_len_in_page, &err2);
1060        double_up_write_data_sem(orig_inode, donor_inode);
1061        if (replaced_count != block_len_in_page) {
1062                EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset),
1063                                       "Unable to copy data block,"
1064                                       " data will be lost.");
1065                *err = -EIO;
1066        }
1067        replaced_count = 0;
1068        goto unlock_pages;
1069}
1070
1071/**
1072 * mext_check_arguments - Check whether move extent can be done
1073 *
1074 * @orig_inode:         original inode
1075 * @donor_inode:        donor inode
1076 * @orig_start:         logical start offset in block for orig
1077 * @donor_start:        logical start offset in block for donor
1078 * @len:                the number of blocks to be moved
1079 *
1080 * Check the arguments of ext4_move_extents() whether the files can be
1081 * exchanged with each other.
1082 * Return 0 on success, or a negative error value on failure.
1083 */
1084static int
1085mext_check_arguments(struct inode *orig_inode,
1086                     struct inode *donor_inode, __u64 orig_start,
1087                     __u64 donor_start, __u64 *len)
1088{
1089        ext4_lblk_t orig_blocks, donor_blocks;
1090        unsigned int blkbits = orig_inode->i_blkbits;
1091        unsigned int blocksize = 1 << blkbits;
1092
1093        if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
1094                ext4_debug("ext4 move extent: suid or sgid is set"
1095                           " to donor file [ino:orig %lu, donor %lu]\n",
1096                           orig_inode->i_ino, donor_inode->i_ino);
1097                return -EINVAL;
1098        }
1099
1100        if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode))
1101                return -EPERM;
1102
1103        /* Ext4 move extent does not support swapfile */
1104        if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
1105                ext4_debug("ext4 move extent: The argument files should "
1106                        "not be swapfile [ino:orig %lu, donor %lu]\n",
1107                        orig_inode->i_ino, donor_inode->i_ino);
1108                return -EINVAL;
1109        }
1110
1111        /* Ext4 move extent supports only extent based file */
1112        if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) {
1113                ext4_debug("ext4 move extent: orig file is not extents "
1114                        "based file [ino:orig %lu]\n", orig_inode->i_ino);
1115                return -EOPNOTSUPP;
1116        } else if (!(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) {
1117                ext4_debug("ext4 move extent: donor file is not extents "
1118                        "based file [ino:donor %lu]\n", donor_inode->i_ino);
1119                return -EOPNOTSUPP;
1120        }
1121
1122        if ((!orig_inode->i_size) || (!donor_inode->i_size)) {
1123                ext4_debug("ext4 move extent: File size is 0 byte\n");
1124                return -EINVAL;
1125        }
1126
1127        /* Start offset should be same */
1128        if (orig_start != donor_start) {
1129                ext4_debug("ext4 move extent: orig and donor's start "
1130                        "offset are not same [ino:orig %lu, donor %lu]\n",
1131                        orig_inode->i_ino, donor_inode->i_ino);
1132                return -EINVAL;
1133        }
1134
1135        if ((orig_start >= EXT_MAX_BLOCKS) ||
1136            (*len > EXT_MAX_BLOCKS) ||
1137            (orig_start + *len >= EXT_MAX_BLOCKS))  {
1138                ext4_debug("ext4 move extent: Can't handle over [%u] blocks "
1139                        "[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS,
1140                        orig_inode->i_ino, donor_inode->i_ino);
1141                return -EINVAL;
1142        }
1143
1144        if (orig_inode->i_size > donor_inode->i_size) {
1145                donor_blocks = (donor_inode->i_size + blocksize - 1) >> blkbits;
1146                /* TODO: eliminate this artificial restriction */
1147                if (orig_start >= donor_blocks) {
1148                        ext4_debug("ext4 move extent: orig start offset "
1149                        "[%llu] should be less than donor file blocks "
1150                        "[%u] [ino:orig %lu, donor %lu]\n",
1151                        orig_start, donor_blocks,
1152                        orig_inode->i_ino, donor_inode->i_ino);
1153                        return -EINVAL;
1154                }
1155
1156                /* TODO: eliminate this artificial restriction */
1157                if (orig_start + *len > donor_blocks) {
1158                        ext4_debug("ext4 move extent: End offset [%llu] should "
1159                                "be less than donor file blocks [%u]."
1160                                "So adjust length from %llu to %llu "
1161                                "[ino:orig %lu, donor %lu]\n",
1162                                orig_start + *len, donor_blocks,
1163                                *len, donor_blocks - orig_start,
1164                                orig_inode->i_ino, donor_inode->i_ino);
1165                        *len = donor_blocks - orig_start;
1166                }
1167        } else {
1168                orig_blocks = (orig_inode->i_size + blocksize - 1) >> blkbits;
1169                if (orig_start >= orig_blocks) {
1170                        ext4_debug("ext4 move extent: start offset [%llu] "
1171                                "should be less than original file blocks "
1172                                "[%u] [ino:orig %lu, donor %lu]\n",
1173                                 orig_start, orig_blocks,
1174                                orig_inode->i_ino, donor_inode->i_ino);
1175                        return -EINVAL;
1176                }
1177
1178                if (orig_start + *len > orig_blocks) {
1179                        ext4_debug("ext4 move extent: Adjust length "
1180                                "from %llu to %llu. Because it should be "
1181                                "less than original file blocks "
1182                                "[ino:orig %lu, donor %lu]\n",
1183                                *len, orig_blocks - orig_start,
1184                                orig_inode->i_ino, donor_inode->i_ino);
1185                        *len = orig_blocks - orig_start;
1186                }
1187        }
1188
1189        if (!*len) {
1190                ext4_debug("ext4 move extent: len should not be 0 "
1191                        "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino,
1192                        donor_inode->i_ino);
1193                return -EINVAL;
1194        }
1195
1196        return 0;
1197}
1198
1199/**
1200 * mext_inode_double_lock - Lock i_mutex on both @inode1 and @inode2
1201 *
1202 * @inode1:     the inode structure
1203 * @inode2:     the inode structure
1204 *
1205 * Lock two inodes' i_mutex
1206 */
1207static void
1208mext_inode_double_lock(struct inode *inode1, struct inode *inode2)
1209{
1210        BUG_ON(inode1 == inode2);
1211        if (inode1 < inode2) {
1212                mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
1213                mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
1214        } else {
1215                mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
1216                mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
1217        }
1218}
1219
1220/**
1221 * mext_inode_double_unlock - Release i_mutex on both @inode1 and @inode2
1222 *
1223 * @inode1:     the inode that is released first
1224 * @inode2:     the inode that is released second
1225 *
1226 */
1227
1228static void
1229mext_inode_double_unlock(struct inode *inode1, struct inode *inode2)
1230{
1231        mutex_unlock(&inode1->i_mutex);
1232        mutex_unlock(&inode2->i_mutex);
1233}
1234
1235/**
1236 * ext4_move_extents - Exchange the specified range of a file
1237 *
1238 * @o_filp:             file structure of the original file
1239 * @d_filp:             file structure of the donor file
1240 * @orig_start:         start offset in block for orig
1241 * @donor_start:        start offset in block for donor
1242 * @len:                the number of blocks to be moved
1243 * @moved_len:          moved block length
1244 *
1245 * This function returns 0 and moved block length is set in moved_len
1246 * if succeed, otherwise returns error value.
1247 *
1248 * Note: ext4_move_extents() proceeds the following order.
1249 * 1:ext4_move_extents() calculates the last block number of moving extent
1250 *   function by the start block number (orig_start) and the number of blocks
1251 *   to be moved (len) specified as arguments.
1252 *   If the {orig, donor}_start points a hole, the extent's start offset
1253 *   pointed by ext_cur (current extent), holecheck_path, orig_path are set
1254 *   after hole behind.
1255 * 2:Continue step 3 to step 5, until the holecheck_path points to last_extent
1256 *   or the ext_cur exceeds the block_end which is last logical block number.
1257 * 3:To get the length of continues area, call mext_next_extent()
1258 *   specified with the ext_cur (initial value is holecheck_path) re-cursive,
1259 *   until find un-continuous extent, the start logical block number exceeds
1260 *   the block_end or the extent points to the last extent.
1261 * 4:Exchange the original inode data with donor inode data
1262 *   from orig_page_offset to seq_end_page.
1263 *   The start indexes of data are specified as arguments.
1264 *   That of the original inode is orig_page_offset,
1265 *   and the donor inode is also orig_page_offset
1266 *   (To easily handle blocksize != pagesize case, the offset for the
1267 *   donor inode is block unit).
1268 * 5:Update holecheck_path and orig_path to points a next proceeding extent,
1269 *   then returns to step 2.
1270 * 6:Release holecheck_path, orig_path and set the len to moved_len
1271 *   which shows the number of moved blocks.
1272 *   The moved_len is useful for the command to calculate the file offset
1273 *   for starting next move extent ioctl.
1274 * 7:Return 0 on success, or a negative error value on failure.
1275 */
1276int
1277ext4_move_extents(struct file *o_filp, struct file *d_filp,
1278                 __u64 orig_start, __u64 donor_start, __u64 len,
1279                 __u64 *moved_len)
1280{
1281        struct inode *orig_inode = o_filp->f_dentry->d_inode;
1282        struct inode *donor_inode = d_filp->f_dentry->d_inode;
1283        struct ext4_ext_path *orig_path = NULL, *holecheck_path = NULL;
1284        struct ext4_extent *ext_prev, *ext_cur, *ext_dummy;
1285        ext4_lblk_t block_start = orig_start;
1286        ext4_lblk_t block_end, seq_start, add_blocks, file_end, seq_blocks = 0;
1287        ext4_lblk_t rest_blocks;
1288        pgoff_t orig_page_offset = 0, seq_end_page;
1289        int ret, depth, last_extent = 0;
1290        int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
1291        int data_offset_in_page;
1292        int block_len_in_page;
1293        int uninit;
1294
1295        if (orig_inode->i_sb != donor_inode->i_sb) {
1296                ext4_debug("ext4 move extent: The argument files "
1297                        "should be in same FS [ino:orig %lu, donor %lu]\n",
1298                        orig_inode->i_ino, donor_inode->i_ino);
1299                return -EINVAL;
1300        }
1301
1302        /* orig and donor should be different inodes */
1303        if (orig_inode == donor_inode) {
1304                ext4_debug("ext4 move extent: The argument files should not "
1305                        "be same inode [ino:orig %lu, donor %lu]\n",
1306                        orig_inode->i_ino, donor_inode->i_ino);
1307                return -EINVAL;
1308        }
1309
1310        /* Regular file check */
1311        if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
1312                ext4_debug("ext4 move extent: The argument files should be "
1313                        "regular file [ino:orig %lu, donor %lu]\n",
1314                        orig_inode->i_ino, donor_inode->i_ino);
1315                return -EINVAL;
1316        }
1317        /* TODO: This is non obvious task to swap blocks for inodes with full
1318           jornaling enabled */
1319        if (ext4_should_journal_data(orig_inode) ||
1320            ext4_should_journal_data(donor_inode)) {
1321                return -EINVAL;
1322        }
1323        /* Protect orig and donor inodes against a truncate */
1324        mext_inode_double_lock(orig_inode, donor_inode);
1325
1326        /* Wait for all existing dio workers */
1327        ext4_inode_block_unlocked_dio(orig_inode);
1328        ext4_inode_block_unlocked_dio(donor_inode);
1329        inode_dio_wait(orig_inode);
1330        inode_dio_wait(donor_inode);
1331
1332        /* Protect extent tree against block allocations via delalloc */
1333        double_down_write_data_sem(orig_inode, donor_inode);
1334        /* Check the filesystem environment whether move_extent can be done */
1335        ret = mext_check_arguments(orig_inode, donor_inode, orig_start,
1336                                    donor_start, &len);
1337        if (ret)
1338                goto out;
1339
1340        file_end = (i_size_read(orig_inode) - 1) >> orig_inode->i_blkbits;
1341        block_end = block_start + len - 1;
1342        if (file_end < block_end)
1343                len -= block_end - file_end;
1344
1345        ret = get_ext_path(orig_inode, block_start, &orig_path);
1346        if (ret)
1347                goto out;
1348
1349        /* Get path structure to check the hole */
1350        ret = get_ext_path(orig_inode, block_start, &holecheck_path);
1351        if (ret)
1352                goto out;
1353
1354        depth = ext_depth(orig_inode);
1355        ext_cur = holecheck_path[depth].p_ext;
1356
1357        /*
1358         * Get proper starting location of block replacement if block_start was
1359         * within the hole.
1360         */
1361        if (le32_to_cpu(ext_cur->ee_block) +
1362                ext4_ext_get_actual_len(ext_cur) - 1 < block_start) {
1363                /*
1364                 * The hole exists between extents or the tail of
1365                 * original file.
1366                 */
1367                last_extent = mext_next_extent(orig_inode,
1368                                        holecheck_path, &ext_cur);
1369                if (last_extent < 0) {
1370                        ret = last_extent;
1371                        goto out;
1372                }
1373                last_extent = mext_next_extent(orig_inode, orig_path,
1374                                                        &ext_dummy);
1375                if (last_extent < 0) {
1376                        ret = last_extent;
1377                        goto out;
1378                }
1379                seq_start = le32_to_cpu(ext_cur->ee_block);
1380        } else if (le32_to_cpu(ext_cur->ee_block) > block_start)
1381                /* The hole exists at the beginning of original file. */
1382                seq_start = le32_to_cpu(ext_cur->ee_block);
1383        else
1384                seq_start = block_start;
1385
1386        /* No blocks within the specified range. */
1387        if (le32_to_cpu(ext_cur->ee_block) > block_end) {
1388                ext4_debug("ext4 move extent: The specified range of file "
1389                                                        "may be the hole\n");
1390                ret = -EINVAL;
1391                goto out;
1392        }
1393
1394        /* Adjust start blocks */
1395        add_blocks = min(le32_to_cpu(ext_cur->ee_block) +
1396                         ext4_ext_get_actual_len(ext_cur), block_end + 1) -
1397                     max(le32_to_cpu(ext_cur->ee_block), block_start);
1398
1399        while (!last_extent && le32_to_cpu(ext_cur->ee_block) <= block_end) {
1400                seq_blocks += add_blocks;
1401
1402                /* Adjust tail blocks */
1403                if (seq_start + seq_blocks - 1 > block_end)
1404                        seq_blocks = block_end - seq_start + 1;
1405
1406                ext_prev = ext_cur;
1407                last_extent = mext_next_extent(orig_inode, holecheck_path,
1408                                                &ext_cur);
1409                if (last_extent < 0) {
1410                        ret = last_extent;
1411                        break;
1412                }
1413                add_blocks = ext4_ext_get_actual_len(ext_cur);
1414
1415                /*
1416                 * Extend the length of contiguous block (seq_blocks)
1417                 * if extents are contiguous.
1418                 */
1419                if (ext4_can_extents_be_merged(orig_inode,
1420                                               ext_prev, ext_cur) &&
1421                    block_end >= le32_to_cpu(ext_cur->ee_block) &&
1422                    !last_extent)
1423                        continue;
1424
1425                /* Is original extent is uninitialized */
1426                uninit = ext4_ext_is_uninitialized(ext_prev);
1427
1428                data_offset_in_page = seq_start % blocks_per_page;
1429
1430                /*
1431                 * Calculate data blocks count that should be swapped
1432                 * at the first page.
1433                 */
1434                if (data_offset_in_page + seq_blocks > blocks_per_page) {
1435                        /* Swapped blocks are across pages */
1436                        block_len_in_page =
1437                                        blocks_per_page - data_offset_in_page;
1438                } else {
1439                        /* Swapped blocks are in a page */
1440                        block_len_in_page = seq_blocks;
1441                }
1442
1443                orig_page_offset = seq_start >>
1444                                (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1445                seq_end_page = (seq_start + seq_blocks - 1) >>
1446                                (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1447                seq_start = le32_to_cpu(ext_cur->ee_block);
1448                rest_blocks = seq_blocks;
1449
1450                /*
1451                 * Up semaphore to avoid following problems:
1452                 * a. transaction deadlock among ext4_journal_start,
1453                 *    ->write_begin via pagefault, and jbd2_journal_commit
1454                 * b. racing with ->readpage, ->write_begin, and ext4_get_block
1455                 *    in move_extent_per_page
1456                 */
1457                double_up_write_data_sem(orig_inode, donor_inode);
1458
1459                while (orig_page_offset <= seq_end_page) {
1460
1461                        /* Swap original branches with new branches */
1462                        block_len_in_page = move_extent_per_page(
1463                                                o_filp, donor_inode,
1464                                                orig_page_offset,
1465                                                data_offset_in_page,
1466                                                block_len_in_page, uninit,
1467                                                &ret);
1468
1469                        /* Count how many blocks we have exchanged */
1470                        *moved_len += block_len_in_page;
1471                        if (ret < 0)
1472                                break;
1473                        if (*moved_len > len) {
1474                                EXT4_ERROR_INODE(orig_inode,
1475                                        "We replaced blocks too much! "
1476                                        "sum of replaced: %llu requested: %llu",
1477                                        *moved_len, len);
1478                                ret = -EIO;
1479                                break;
1480                        }
1481
1482                        orig_page_offset++;
1483                        data_offset_in_page = 0;
1484                        rest_blocks -= block_len_in_page;
1485                        if (rest_blocks > blocks_per_page)
1486                                block_len_in_page = blocks_per_page;
1487                        else
1488                                block_len_in_page = rest_blocks;
1489                }
1490
1491                double_down_write_data_sem(orig_inode, donor_inode);
1492                if (ret < 0)
1493                        break;
1494
1495                /* Decrease buffer counter */
1496                if (holecheck_path)
1497                        ext4_ext_drop_refs(holecheck_path);
1498                ret = get_ext_path(orig_inode, seq_start, &holecheck_path);
1499                if (ret)
1500                        break;
1501                depth = holecheck_path->p_depth;
1502
1503                /* Decrease buffer counter */
1504                if (orig_path)
1505                        ext4_ext_drop_refs(orig_path);
1506                ret = get_ext_path(orig_inode, seq_start, &orig_path);
1507                if (ret)
1508                        break;
1509
1510                ext_cur = holecheck_path[depth].p_ext;
1511                add_blocks = ext4_ext_get_actual_len(ext_cur);
1512                seq_blocks = 0;
1513
1514        }
1515out:
1516        if (*moved_len) {
1517                ext4_discard_preallocations(orig_inode);
1518                ext4_discard_preallocations(donor_inode);
1519        }
1520
1521        if (orig_path) {
1522                ext4_ext_drop_refs(orig_path);
1523                kfree(orig_path);
1524        }
1525        if (holecheck_path) {
1526                ext4_ext_drop_refs(holecheck_path);
1527                kfree(holecheck_path);
1528        }
1529        double_up_write_data_sem(orig_inode, donor_inode);
1530        ext4_inode_resume_unlocked_dio(orig_inode);
1531        ext4_inode_resume_unlocked_dio(donor_inode);
1532        mext_inode_double_unlock(orig_inode, donor_inode);
1533
1534        return ret;
1535}
1536
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