linux/fs/ext3/balloc.c
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   1/*
   2 *  linux/fs/ext3/balloc.c
   3 *
   4 * Copyright (C) 1992, 1993, 1994, 1995
   5 * Remy Card (card@masi.ibp.fr)
   6 * Laboratoire MASI - Institut Blaise Pascal
   7 * Universite Pierre et Marie Curie (Paris VI)
   8 *
   9 *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
  10 *  Big-endian to little-endian byte-swapping/bitmaps by
  11 *        David S. Miller (davem@caip.rutgers.edu), 1995
  12 */
  13
  14#include <linux/quotaops.h>
  15#include <linux/blkdev.h>
  16#include "ext3.h"
  17
  18/*
  19 * balloc.c contains the blocks allocation and deallocation routines
  20 */
  21
  22/*
  23 * The free blocks are managed by bitmaps.  A file system contains several
  24 * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
  25 * block for inodes, N blocks for the inode table and data blocks.
  26 *
  27 * The file system contains group descriptors which are located after the
  28 * super block.  Each descriptor contains the number of the bitmap block and
  29 * the free blocks count in the block.  The descriptors are loaded in memory
  30 * when a file system is mounted (see ext3_fill_super).
  31 */
  32
  33
  34#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
  35
  36/*
  37 * Calculate the block group number and offset, given a block number
  38 */
  39static void ext3_get_group_no_and_offset(struct super_block *sb,
  40        ext3_fsblk_t blocknr, unsigned long *blockgrpp, ext3_grpblk_t *offsetp)
  41{
  42        struct ext3_super_block *es = EXT3_SB(sb)->s_es;
  43
  44        blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
  45        if (offsetp)
  46                *offsetp = blocknr % EXT3_BLOCKS_PER_GROUP(sb);
  47        if (blockgrpp)
  48                *blockgrpp = blocknr / EXT3_BLOCKS_PER_GROUP(sb);
  49}
  50
  51/**
  52 * ext3_get_group_desc() -- load group descriptor from disk
  53 * @sb:                 super block
  54 * @block_group:        given block group
  55 * @bh:                 pointer to the buffer head to store the block
  56 *                      group descriptor
  57 */
  58struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
  59                                             unsigned int block_group,
  60                                             struct buffer_head ** bh)
  61{
  62        unsigned long group_desc;
  63        unsigned long offset;
  64        struct ext3_group_desc * desc;
  65        struct ext3_sb_info *sbi = EXT3_SB(sb);
  66
  67        if (block_group >= sbi->s_groups_count) {
  68                ext3_error (sb, "ext3_get_group_desc",
  69                            "block_group >= groups_count - "
  70                            "block_group = %d, groups_count = %lu",
  71                            block_group, sbi->s_groups_count);
  72
  73                return NULL;
  74        }
  75        smp_rmb();
  76
  77        group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb);
  78        offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1);
  79        if (!sbi->s_group_desc[group_desc]) {
  80                ext3_error (sb, "ext3_get_group_desc",
  81                            "Group descriptor not loaded - "
  82                            "block_group = %d, group_desc = %lu, desc = %lu",
  83                             block_group, group_desc, offset);
  84                return NULL;
  85        }
  86
  87        desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data;
  88        if (bh)
  89                *bh = sbi->s_group_desc[group_desc];
  90        return desc + offset;
  91}
  92
  93static int ext3_valid_block_bitmap(struct super_block *sb,
  94                                        struct ext3_group_desc *desc,
  95                                        unsigned int block_group,
  96                                        struct buffer_head *bh)
  97{
  98        ext3_grpblk_t offset;
  99        ext3_grpblk_t next_zero_bit;
 100        ext3_fsblk_t bitmap_blk;
 101        ext3_fsblk_t group_first_block;
 102
 103        group_first_block = ext3_group_first_block_no(sb, block_group);
 104
 105        /* check whether block bitmap block number is set */
 106        bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
 107        offset = bitmap_blk - group_first_block;
 108        if (!ext3_test_bit(offset, bh->b_data))
 109                /* bad block bitmap */
 110                goto err_out;
 111
 112        /* check whether the inode bitmap block number is set */
 113        bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
 114        offset = bitmap_blk - group_first_block;
 115        if (!ext3_test_bit(offset, bh->b_data))
 116                /* bad block bitmap */
 117                goto err_out;
 118
 119        /* check whether the inode table block number is set */
 120        bitmap_blk = le32_to_cpu(desc->bg_inode_table);
 121        offset = bitmap_blk - group_first_block;
 122        next_zero_bit = ext3_find_next_zero_bit(bh->b_data,
 123                                offset + EXT3_SB(sb)->s_itb_per_group,
 124                                offset);
 125        if (next_zero_bit >= offset + EXT3_SB(sb)->s_itb_per_group)
 126                /* good bitmap for inode tables */
 127                return 1;
 128
 129err_out:
 130        ext3_error(sb, __func__,
 131                        "Invalid block bitmap - "
 132                        "block_group = %d, block = %lu",
 133                        block_group, bitmap_blk);
 134        return 0;
 135}
 136
 137/**
 138 * read_block_bitmap()
 139 * @sb:                 super block
 140 * @block_group:        given block group
 141 *
 142 * Read the bitmap for a given block_group,and validate the
 143 * bits for block/inode/inode tables are set in the bitmaps
 144 *
 145 * Return buffer_head on success or NULL in case of failure.
 146 */
 147static struct buffer_head *
 148read_block_bitmap(struct super_block *sb, unsigned int block_group)
 149{
 150        struct ext3_group_desc * desc;
 151        struct buffer_head * bh = NULL;
 152        ext3_fsblk_t bitmap_blk;
 153
 154        desc = ext3_get_group_desc(sb, block_group, NULL);
 155        if (!desc)
 156                return NULL;
 157        trace_ext3_read_block_bitmap(sb, block_group);
 158        bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
 159        bh = sb_getblk(sb, bitmap_blk);
 160        if (unlikely(!bh)) {
 161                ext3_error(sb, __func__,
 162                            "Cannot read block bitmap - "
 163                            "block_group = %d, block_bitmap = %u",
 164                            block_group, le32_to_cpu(desc->bg_block_bitmap));
 165                return NULL;
 166        }
 167        if (likely(bh_uptodate_or_lock(bh)))
 168                return bh;
 169
 170        if (bh_submit_read(bh) < 0) {
 171                brelse(bh);
 172                ext3_error(sb, __func__,
 173                            "Cannot read block bitmap - "
 174                            "block_group = %d, block_bitmap = %u",
 175                            block_group, le32_to_cpu(desc->bg_block_bitmap));
 176                return NULL;
 177        }
 178        ext3_valid_block_bitmap(sb, desc, block_group, bh);
 179        /*
 180         * file system mounted not to panic on error, continue with corrupt
 181         * bitmap
 182         */
 183        return bh;
 184}
 185/*
 186 * The reservation window structure operations
 187 * --------------------------------------------
 188 * Operations include:
 189 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
 190 *
 191 * We use a red-black tree to represent per-filesystem reservation
 192 * windows.
 193 *
 194 */
 195
 196/**
 197 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
 198 * @rb_root:            root of per-filesystem reservation rb tree
 199 * @verbose:            verbose mode
 200 * @fn:                 function which wishes to dump the reservation map
 201 *
 202 * If verbose is turned on, it will print the whole block reservation
 203 * windows(start, end). Otherwise, it will only print out the "bad" windows,
 204 * those windows that overlap with their immediate neighbors.
 205 */
 206#if 1
 207static void __rsv_window_dump(struct rb_root *root, int verbose,
 208                              const char *fn)
 209{
 210        struct rb_node *n;
 211        struct ext3_reserve_window_node *rsv, *prev;
 212        int bad;
 213
 214restart:
 215        n = rb_first(root);
 216        bad = 0;
 217        prev = NULL;
 218
 219        printk("Block Allocation Reservation Windows Map (%s):\n", fn);
 220        while (n) {
 221                rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 222                if (verbose)
 223                        printk("reservation window 0x%p "
 224                               "start:  %lu, end:  %lu\n",
 225                               rsv, rsv->rsv_start, rsv->rsv_end);
 226                if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
 227                        printk("Bad reservation %p (start >= end)\n",
 228                               rsv);
 229                        bad = 1;
 230                }
 231                if (prev && prev->rsv_end >= rsv->rsv_start) {
 232                        printk("Bad reservation %p (prev->end >= start)\n",
 233                               rsv);
 234                        bad = 1;
 235                }
 236                if (bad) {
 237                        if (!verbose) {
 238                                printk("Restarting reservation walk in verbose mode\n");
 239                                verbose = 1;
 240                                goto restart;
 241                        }
 242                }
 243                n = rb_next(n);
 244                prev = rsv;
 245        }
 246        printk("Window map complete.\n");
 247        BUG_ON(bad);
 248}
 249#define rsv_window_dump(root, verbose) \
 250        __rsv_window_dump((root), (verbose), __func__)
 251#else
 252#define rsv_window_dump(root, verbose) do {} while (0)
 253#endif
 254
 255/**
 256 * goal_in_my_reservation()
 257 * @rsv:                inode's reservation window
 258 * @grp_goal:           given goal block relative to the allocation block group
 259 * @group:              the current allocation block group
 260 * @sb:                 filesystem super block
 261 *
 262 * Test if the given goal block (group relative) is within the file's
 263 * own block reservation window range.
 264 *
 265 * If the reservation window is outside the goal allocation group, return 0;
 266 * grp_goal (given goal block) could be -1, which means no specific
 267 * goal block. In this case, always return 1.
 268 * If the goal block is within the reservation window, return 1;
 269 * otherwise, return 0;
 270 */
 271static int
 272goal_in_my_reservation(struct ext3_reserve_window *rsv, ext3_grpblk_t grp_goal,
 273                        unsigned int group, struct super_block * sb)
 274{
 275        ext3_fsblk_t group_first_block, group_last_block;
 276
 277        group_first_block = ext3_group_first_block_no(sb, group);
 278        group_last_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
 279
 280        if ((rsv->_rsv_start > group_last_block) ||
 281            (rsv->_rsv_end < group_first_block))
 282                return 0;
 283        if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
 284                || (grp_goal + group_first_block > rsv->_rsv_end)))
 285                return 0;
 286        return 1;
 287}
 288
 289/**
 290 * search_reserve_window()
 291 * @rb_root:            root of reservation tree
 292 * @goal:               target allocation block
 293 *
 294 * Find the reserved window which includes the goal, or the previous one
 295 * if the goal is not in any window.
 296 * Returns NULL if there are no windows or if all windows start after the goal.
 297 */
 298static struct ext3_reserve_window_node *
 299search_reserve_window(struct rb_root *root, ext3_fsblk_t goal)
 300{
 301        struct rb_node *n = root->rb_node;
 302        struct ext3_reserve_window_node *rsv;
 303
 304        if (!n)
 305                return NULL;
 306
 307        do {
 308                rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 309
 310                if (goal < rsv->rsv_start)
 311                        n = n->rb_left;
 312                else if (goal > rsv->rsv_end)
 313                        n = n->rb_right;
 314                else
 315                        return rsv;
 316        } while (n);
 317        /*
 318         * We've fallen off the end of the tree: the goal wasn't inside
 319         * any particular node.  OK, the previous node must be to one
 320         * side of the interval containing the goal.  If it's the RHS,
 321         * we need to back up one.
 322         */
 323        if (rsv->rsv_start > goal) {
 324                n = rb_prev(&rsv->rsv_node);
 325                rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 326        }
 327        return rsv;
 328}
 329
 330/**
 331 * ext3_rsv_window_add() -- Insert a window to the block reservation rb tree.
 332 * @sb:                 super block
 333 * @rsv:                reservation window to add
 334 *
 335 * Must be called with rsv_lock hold.
 336 */
 337void ext3_rsv_window_add(struct super_block *sb,
 338                    struct ext3_reserve_window_node *rsv)
 339{
 340        struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
 341        struct rb_node *node = &rsv->rsv_node;
 342        ext3_fsblk_t start = rsv->rsv_start;
 343
 344        struct rb_node ** p = &root->rb_node;
 345        struct rb_node * parent = NULL;
 346        struct ext3_reserve_window_node *this;
 347
 348        trace_ext3_rsv_window_add(sb, rsv);
 349        while (*p)
 350        {
 351                parent = *p;
 352                this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node);
 353
 354                if (start < this->rsv_start)
 355                        p = &(*p)->rb_left;
 356                else if (start > this->rsv_end)
 357                        p = &(*p)->rb_right;
 358                else {
 359                        rsv_window_dump(root, 1);
 360                        BUG();
 361                }
 362        }
 363
 364        rb_link_node(node, parent, p);
 365        rb_insert_color(node, root);
 366}
 367
 368/**
 369 * ext3_rsv_window_remove() -- unlink a window from the reservation rb tree
 370 * @sb:                 super block
 371 * @rsv:                reservation window to remove
 372 *
 373 * Mark the block reservation window as not allocated, and unlink it
 374 * from the filesystem reservation window rb tree. Must be called with
 375 * rsv_lock hold.
 376 */
 377static void rsv_window_remove(struct super_block *sb,
 378                              struct ext3_reserve_window_node *rsv)
 379{
 380        rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 381        rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 382        rsv->rsv_alloc_hit = 0;
 383        rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root);
 384}
 385
 386/*
 387 * rsv_is_empty() -- Check if the reservation window is allocated.
 388 * @rsv:                given reservation window to check
 389 *
 390 * returns 1 if the end block is EXT3_RESERVE_WINDOW_NOT_ALLOCATED.
 391 */
 392static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
 393{
 394        /* a valid reservation end block could not be 0 */
 395        return rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 396}
 397
 398/**
 399 * ext3_init_block_alloc_info()
 400 * @inode:              file inode structure
 401 *
 402 * Allocate and initialize the  reservation window structure, and
 403 * link the window to the ext3 inode structure at last
 404 *
 405 * The reservation window structure is only dynamically allocated
 406 * and linked to ext3 inode the first time the open file
 407 * needs a new block. So, before every ext3_new_block(s) call, for
 408 * regular files, we should check whether the reservation window
 409 * structure exists or not. In the latter case, this function is called.
 410 * Fail to do so will result in block reservation being turned off for that
 411 * open file.
 412 *
 413 * This function is called from ext3_get_blocks_handle(), also called
 414 * when setting the reservation window size through ioctl before the file
 415 * is open for write (needs block allocation).
 416 *
 417 * Needs truncate_mutex protection prior to call this function.
 418 */
 419void ext3_init_block_alloc_info(struct inode *inode)
 420{
 421        struct ext3_inode_info *ei = EXT3_I(inode);
 422        struct ext3_block_alloc_info *block_i;
 423        struct super_block *sb = inode->i_sb;
 424
 425        block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
 426        if (block_i) {
 427                struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node;
 428
 429                rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 430                rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 431
 432                /*
 433                 * if filesystem is mounted with NORESERVATION, the goal
 434                 * reservation window size is set to zero to indicate
 435                 * block reservation is off
 436                 */
 437                if (!test_opt(sb, RESERVATION))
 438                        rsv->rsv_goal_size = 0;
 439                else
 440                        rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS;
 441                rsv->rsv_alloc_hit = 0;
 442                block_i->last_alloc_logical_block = 0;
 443                block_i->last_alloc_physical_block = 0;
 444        }
 445        ei->i_block_alloc_info = block_i;
 446}
 447
 448/**
 449 * ext3_discard_reservation()
 450 * @inode:              inode
 451 *
 452 * Discard(free) block reservation window on last file close, or truncate
 453 * or at last iput().
 454 *
 455 * It is being called in three cases:
 456 *      ext3_release_file(): last writer close the file
 457 *      ext3_clear_inode(): last iput(), when nobody link to this file.
 458 *      ext3_truncate(): when the block indirect map is about to change.
 459 *
 460 */
 461void ext3_discard_reservation(struct inode *inode)
 462{
 463        struct ext3_inode_info *ei = EXT3_I(inode);
 464        struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
 465        struct ext3_reserve_window_node *rsv;
 466        spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
 467
 468        if (!block_i)
 469                return;
 470
 471        rsv = &block_i->rsv_window_node;
 472        if (!rsv_is_empty(&rsv->rsv_window)) {
 473                spin_lock(rsv_lock);
 474                if (!rsv_is_empty(&rsv->rsv_window)) {
 475                        trace_ext3_discard_reservation(inode, rsv);
 476                        rsv_window_remove(inode->i_sb, rsv);
 477                }
 478                spin_unlock(rsv_lock);
 479        }
 480}
 481
 482/**
 483 * ext3_free_blocks_sb() -- Free given blocks and update quota
 484 * @handle:                     handle to this transaction
 485 * @sb:                         super block
 486 * @block:                      start physical block to free
 487 * @count:                      number of blocks to free
 488 * @pdquot_freed_blocks:        pointer to quota
 489 */
 490void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
 491                         ext3_fsblk_t block, unsigned long count,
 492                         unsigned long *pdquot_freed_blocks)
 493{
 494        struct buffer_head *bitmap_bh = NULL;
 495        struct buffer_head *gd_bh;
 496        unsigned long block_group;
 497        ext3_grpblk_t bit;
 498        unsigned long i;
 499        unsigned long overflow;
 500        struct ext3_group_desc * desc;
 501        struct ext3_super_block * es;
 502        struct ext3_sb_info *sbi;
 503        int err = 0, ret;
 504        ext3_grpblk_t group_freed;
 505
 506        *pdquot_freed_blocks = 0;
 507        sbi = EXT3_SB(sb);
 508        es = sbi->s_es;
 509        if (block < le32_to_cpu(es->s_first_data_block) ||
 510            block + count < block ||
 511            block + count > le32_to_cpu(es->s_blocks_count)) {
 512                ext3_error (sb, "ext3_free_blocks",
 513                            "Freeing blocks not in datazone - "
 514                            "block = "E3FSBLK", count = %lu", block, count);
 515                goto error_return;
 516        }
 517
 518        ext3_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
 519
 520do_more:
 521        overflow = 0;
 522        block_group = (block - le32_to_cpu(es->s_first_data_block)) /
 523                      EXT3_BLOCKS_PER_GROUP(sb);
 524        bit = (block - le32_to_cpu(es->s_first_data_block)) %
 525                      EXT3_BLOCKS_PER_GROUP(sb);
 526        /*
 527         * Check to see if we are freeing blocks across a group
 528         * boundary.
 529         */
 530        if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
 531                overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
 532                count -= overflow;
 533        }
 534        brelse(bitmap_bh);
 535        bitmap_bh = read_block_bitmap(sb, block_group);
 536        if (!bitmap_bh)
 537                goto error_return;
 538        desc = ext3_get_group_desc (sb, block_group, &gd_bh);
 539        if (!desc)
 540                goto error_return;
 541
 542        if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
 543            in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
 544            in_range (block, le32_to_cpu(desc->bg_inode_table),
 545                      sbi->s_itb_per_group) ||
 546            in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
 547                      sbi->s_itb_per_group)) {
 548                ext3_error (sb, "ext3_free_blocks",
 549                            "Freeing blocks in system zones - "
 550                            "Block = "E3FSBLK", count = %lu",
 551                            block, count);
 552                goto error_return;
 553        }
 554
 555        /*
 556         * We are about to start releasing blocks in the bitmap,
 557         * so we need undo access.
 558         */
 559        /* @@@ check errors */
 560        BUFFER_TRACE(bitmap_bh, "getting undo access");
 561        err = ext3_journal_get_undo_access(handle, bitmap_bh);
 562        if (err)
 563                goto error_return;
 564
 565        /*
 566         * We are about to modify some metadata.  Call the journal APIs
 567         * to unshare ->b_data if a currently-committing transaction is
 568         * using it
 569         */
 570        BUFFER_TRACE(gd_bh, "get_write_access");
 571        err = ext3_journal_get_write_access(handle, gd_bh);
 572        if (err)
 573                goto error_return;
 574
 575        jbd_lock_bh_state(bitmap_bh);
 576
 577        for (i = 0, group_freed = 0; i < count; i++) {
 578                /*
 579                 * An HJ special.  This is expensive...
 580                 */
 581#ifdef CONFIG_JBD_DEBUG
 582                jbd_unlock_bh_state(bitmap_bh);
 583                {
 584                        struct buffer_head *debug_bh;
 585                        debug_bh = sb_find_get_block(sb, block + i);
 586                        if (debug_bh) {
 587                                BUFFER_TRACE(debug_bh, "Deleted!");
 588                                if (!bh2jh(bitmap_bh)->b_committed_data)
 589                                        BUFFER_TRACE(debug_bh,
 590                                                "No committed data in bitmap");
 591                                BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
 592                                __brelse(debug_bh);
 593                        }
 594                }
 595                jbd_lock_bh_state(bitmap_bh);
 596#endif
 597                if (need_resched()) {
 598                        jbd_unlock_bh_state(bitmap_bh);
 599                        cond_resched();
 600                        jbd_lock_bh_state(bitmap_bh);
 601                }
 602                /* @@@ This prevents newly-allocated data from being
 603                 * freed and then reallocated within the same
 604                 * transaction.
 605                 *
 606                 * Ideally we would want to allow that to happen, but to
 607                 * do so requires making journal_forget() capable of
 608                 * revoking the queued write of a data block, which
 609                 * implies blocking on the journal lock.  *forget()
 610                 * cannot block due to truncate races.
 611                 *
 612                 * Eventually we can fix this by making journal_forget()
 613                 * return a status indicating whether or not it was able
 614                 * to revoke the buffer.  On successful revoke, it is
 615                 * safe not to set the allocation bit in the committed
 616                 * bitmap, because we know that there is no outstanding
 617                 * activity on the buffer any more and so it is safe to
 618                 * reallocate it.
 619                 */
 620                BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
 621                J_ASSERT_BH(bitmap_bh,
 622                                bh2jh(bitmap_bh)->b_committed_data != NULL);
 623                ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
 624                                bh2jh(bitmap_bh)->b_committed_data);
 625
 626                /*
 627                 * We clear the bit in the bitmap after setting the committed
 628                 * data bit, because this is the reverse order to that which
 629                 * the allocator uses.
 630                 */
 631                BUFFER_TRACE(bitmap_bh, "clear bit");
 632                if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 633                                                bit + i, bitmap_bh->b_data)) {
 634                        jbd_unlock_bh_state(bitmap_bh);
 635                        ext3_error(sb, __func__,
 636                                "bit already cleared for block "E3FSBLK,
 637                                 block + i);
 638                        jbd_lock_bh_state(bitmap_bh);
 639                        BUFFER_TRACE(bitmap_bh, "bit already cleared");
 640                } else {
 641                        group_freed++;
 642                }
 643        }
 644        jbd_unlock_bh_state(bitmap_bh);
 645
 646        spin_lock(sb_bgl_lock(sbi, block_group));
 647        le16_add_cpu(&desc->bg_free_blocks_count, group_freed);
 648        spin_unlock(sb_bgl_lock(sbi, block_group));
 649        percpu_counter_add(&sbi->s_freeblocks_counter, count);
 650
 651        /* We dirtied the bitmap block */
 652        BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
 653        err = ext3_journal_dirty_metadata(handle, bitmap_bh);
 654
 655        /* And the group descriptor block */
 656        BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 657        ret = ext3_journal_dirty_metadata(handle, gd_bh);
 658        if (!err) err = ret;
 659        *pdquot_freed_blocks += group_freed;
 660
 661        if (overflow && !err) {
 662                block += count;
 663                count = overflow;
 664                goto do_more;
 665        }
 666
 667error_return:
 668        brelse(bitmap_bh);
 669        ext3_std_error(sb, err);
 670        return;
 671}
 672
 673/**
 674 * ext3_free_blocks() -- Free given blocks and update quota
 675 * @handle:             handle for this transaction
 676 * @inode:              inode
 677 * @block:              start physical block to free
 678 * @count:              number of blocks to count
 679 */
 680void ext3_free_blocks(handle_t *handle, struct inode *inode,
 681                        ext3_fsblk_t block, unsigned long count)
 682{
 683        struct super_block *sb = inode->i_sb;
 684        unsigned long dquot_freed_blocks;
 685
 686        trace_ext3_free_blocks(inode, block, count);
 687        ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
 688        if (dquot_freed_blocks)
 689                dquot_free_block(inode, dquot_freed_blocks);
 690        return;
 691}
 692
 693/**
 694 * ext3_test_allocatable()
 695 * @nr:                 given allocation block group
 696 * @bh:                 bufferhead contains the bitmap of the given block group
 697 *
 698 * For ext3 allocations, we must not reuse any blocks which are
 699 * allocated in the bitmap buffer's "last committed data" copy.  This
 700 * prevents deletes from freeing up the page for reuse until we have
 701 * committed the delete transaction.
 702 *
 703 * If we didn't do this, then deleting something and reallocating it as
 704 * data would allow the old block to be overwritten before the
 705 * transaction committed (because we force data to disk before commit).
 706 * This would lead to corruption if we crashed between overwriting the
 707 * data and committing the delete.
 708 *
 709 * @@@ We may want to make this allocation behaviour conditional on
 710 * data-writes at some point, and disable it for metadata allocations or
 711 * sync-data inodes.
 712 */
 713static int ext3_test_allocatable(ext3_grpblk_t nr, struct buffer_head *bh)
 714{
 715        int ret;
 716        struct journal_head *jh = bh2jh(bh);
 717
 718        if (ext3_test_bit(nr, bh->b_data))
 719                return 0;
 720
 721        jbd_lock_bh_state(bh);
 722        if (!jh->b_committed_data)
 723                ret = 1;
 724        else
 725                ret = !ext3_test_bit(nr, jh->b_committed_data);
 726        jbd_unlock_bh_state(bh);
 727        return ret;
 728}
 729
 730/**
 731 * bitmap_search_next_usable_block()
 732 * @start:              the starting block (group relative) of the search
 733 * @bh:                 bufferhead contains the block group bitmap
 734 * @maxblocks:          the ending block (group relative) of the reservation
 735 *
 736 * The bitmap search --- search forward alternately through the actual
 737 * bitmap on disk and the last-committed copy in journal, until we find a
 738 * bit free in both bitmaps.
 739 */
 740static ext3_grpblk_t
 741bitmap_search_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
 742                                        ext3_grpblk_t maxblocks)
 743{
 744        ext3_grpblk_t next;
 745        struct journal_head *jh = bh2jh(bh);
 746
 747        while (start < maxblocks) {
 748                next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
 749                if (next >= maxblocks)
 750                        return -1;
 751                if (ext3_test_allocatable(next, bh))
 752                        return next;
 753                jbd_lock_bh_state(bh);
 754                if (jh->b_committed_data)
 755                        start = ext3_find_next_zero_bit(jh->b_committed_data,
 756                                                        maxblocks, next);
 757                jbd_unlock_bh_state(bh);
 758        }
 759        return -1;
 760}
 761
 762/**
 763 * find_next_usable_block()
 764 * @start:              the starting block (group relative) to find next
 765 *                      allocatable block in bitmap.
 766 * @bh:                 bufferhead contains the block group bitmap
 767 * @maxblocks:          the ending block (group relative) for the search
 768 *
 769 * Find an allocatable block in a bitmap.  We honor both the bitmap and
 770 * its last-committed copy (if that exists), and perform the "most
 771 * appropriate allocation" algorithm of looking for a free block near
 772 * the initial goal; then for a free byte somewhere in the bitmap; then
 773 * for any free bit in the bitmap.
 774 */
 775static ext3_grpblk_t
 776find_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
 777                        ext3_grpblk_t maxblocks)
 778{
 779        ext3_grpblk_t here, next;
 780        char *p, *r;
 781
 782        if (start > 0) {
 783                /*
 784                 * The goal was occupied; search forward for a free
 785                 * block within the next XX blocks.
 786                 *
 787                 * end_goal is more or less random, but it has to be
 788                 * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
 789                 * next 64-bit boundary is simple..
 790                 */
 791                ext3_grpblk_t end_goal = (start + 63) & ~63;
 792                if (end_goal > maxblocks)
 793                        end_goal = maxblocks;
 794                here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
 795                if (here < end_goal && ext3_test_allocatable(here, bh))
 796                        return here;
 797                ext3_debug("Bit not found near goal\n");
 798        }
 799
 800        here = start;
 801        if (here < 0)
 802                here = 0;
 803
 804        p = bh->b_data + (here >> 3);
 805        r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
 806        next = (r - bh->b_data) << 3;
 807
 808        if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
 809                return next;
 810
 811        /*
 812         * The bitmap search --- search forward alternately through the actual
 813         * bitmap and the last-committed copy until we find a bit free in
 814         * both
 815         */
 816        here = bitmap_search_next_usable_block(here, bh, maxblocks);
 817        return here;
 818}
 819
 820/**
 821 * claim_block()
 822 * @lock:               the spin lock for this block group
 823 * @block:              the free block (group relative) to allocate
 824 * @bh:                 the buffer_head contains the block group bitmap
 825 *
 826 * We think we can allocate this block in this bitmap.  Try to set the bit.
 827 * If that succeeds then check that nobody has allocated and then freed the
 828 * block since we saw that is was not marked in b_committed_data.  If it _was_
 829 * allocated and freed then clear the bit in the bitmap again and return
 830 * zero (failure).
 831 */
 832static inline int
 833claim_block(spinlock_t *lock, ext3_grpblk_t block, struct buffer_head *bh)
 834{
 835        struct journal_head *jh = bh2jh(bh);
 836        int ret;
 837
 838        if (ext3_set_bit_atomic(lock, block, bh->b_data))
 839                return 0;
 840        jbd_lock_bh_state(bh);
 841        if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
 842                ext3_clear_bit_atomic(lock, block, bh->b_data);
 843                ret = 0;
 844        } else {
 845                ret = 1;
 846        }
 847        jbd_unlock_bh_state(bh);
 848        return ret;
 849}
 850
 851/**
 852 * ext3_try_to_allocate()
 853 * @sb:                 superblock
 854 * @handle:             handle to this transaction
 855 * @group:              given allocation block group
 856 * @bitmap_bh:          bufferhead holds the block bitmap
 857 * @grp_goal:           given target block within the group
 858 * @count:              target number of blocks to allocate
 859 * @my_rsv:             reservation window
 860 *
 861 * Attempt to allocate blocks within a give range. Set the range of allocation
 862 * first, then find the first free bit(s) from the bitmap (within the range),
 863 * and at last, allocate the blocks by claiming the found free bit as allocated.
 864 *
 865 * To set the range of this allocation:
 866 *      if there is a reservation window, only try to allocate block(s) from the
 867 *      file's own reservation window;
 868 *      Otherwise, the allocation range starts from the give goal block, ends at
 869 *      the block group's last block.
 870 *
 871 * If we failed to allocate the desired block then we may end up crossing to a
 872 * new bitmap.  In that case we must release write access to the old one via
 873 * ext3_journal_release_buffer(), else we'll run out of credits.
 874 */
 875static ext3_grpblk_t
 876ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
 877                        struct buffer_head *bitmap_bh, ext3_grpblk_t grp_goal,
 878                        unsigned long *count, struct ext3_reserve_window *my_rsv)
 879{
 880        ext3_fsblk_t group_first_block;
 881        ext3_grpblk_t start, end;
 882        unsigned long num = 0;
 883
 884        /* we do allocation within the reservation window if we have a window */
 885        if (my_rsv) {
 886                group_first_block = ext3_group_first_block_no(sb, group);
 887                if (my_rsv->_rsv_start >= group_first_block)
 888                        start = my_rsv->_rsv_start - group_first_block;
 889                else
 890                        /* reservation window cross group boundary */
 891                        start = 0;
 892                end = my_rsv->_rsv_end - group_first_block + 1;
 893                if (end > EXT3_BLOCKS_PER_GROUP(sb))
 894                        /* reservation window crosses group boundary */
 895                        end = EXT3_BLOCKS_PER_GROUP(sb);
 896                if ((start <= grp_goal) && (grp_goal < end))
 897                        start = grp_goal;
 898                else
 899                        grp_goal = -1;
 900        } else {
 901                if (grp_goal > 0)
 902                        start = grp_goal;
 903                else
 904                        start = 0;
 905                end = EXT3_BLOCKS_PER_GROUP(sb);
 906        }
 907
 908        BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
 909
 910repeat:
 911        if (grp_goal < 0 || !ext3_test_allocatable(grp_goal, bitmap_bh)) {
 912                grp_goal = find_next_usable_block(start, bitmap_bh, end);
 913                if (grp_goal < 0)
 914                        goto fail_access;
 915                if (!my_rsv) {
 916                        int i;
 917
 918                        for (i = 0; i < 7 && grp_goal > start &&
 919                                        ext3_test_allocatable(grp_goal - 1,
 920                                                                bitmap_bh);
 921                                        i++, grp_goal--)
 922                                ;
 923                }
 924        }
 925        start = grp_goal;
 926
 927        if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group),
 928                grp_goal, bitmap_bh)) {
 929                /*
 930                 * The block was allocated by another thread, or it was
 931                 * allocated and then freed by another thread
 932                 */
 933                start++;
 934                grp_goal++;
 935                if (start >= end)
 936                        goto fail_access;
 937                goto repeat;
 938        }
 939        num++;
 940        grp_goal++;
 941        while (num < *count && grp_goal < end
 942                && ext3_test_allocatable(grp_goal, bitmap_bh)
 943                && claim_block(sb_bgl_lock(EXT3_SB(sb), group),
 944                                grp_goal, bitmap_bh)) {
 945                num++;
 946                grp_goal++;
 947        }
 948        *count = num;
 949        return grp_goal - num;
 950fail_access:
 951        *count = num;
 952        return -1;
 953}
 954
 955/**
 956 *      find_next_reservable_window():
 957 *              find a reservable space within the given range.
 958 *              It does not allocate the reservation window for now:
 959 *              alloc_new_reservation() will do the work later.
 960 *
 961 *      @search_head: the head of the searching list;
 962 *              This is not necessarily the list head of the whole filesystem
 963 *
 964 *              We have both head and start_block to assist the search
 965 *              for the reservable space. The list starts from head,
 966 *              but we will shift to the place where start_block is,
 967 *              then start from there, when looking for a reservable space.
 968 *
 969 *      @my_rsv: the reservation window
 970 *
 971 *      @sb: the super block
 972 *
 973 *      @start_block: the first block we consider to start
 974 *                      the real search from
 975 *
 976 *      @last_block:
 977 *              the maximum block number that our goal reservable space
 978 *              could start from. This is normally the last block in this
 979 *              group. The search will end when we found the start of next
 980 *              possible reservable space is out of this boundary.
 981 *              This could handle the cross boundary reservation window
 982 *              request.
 983 *
 984 *      basically we search from the given range, rather than the whole
 985 *      reservation double linked list, (start_block, last_block)
 986 *      to find a free region that is of my size and has not
 987 *      been reserved.
 988 *
 989 */
 990static int find_next_reservable_window(
 991                                struct ext3_reserve_window_node *search_head,
 992                                struct ext3_reserve_window_node *my_rsv,
 993                                struct super_block * sb,
 994                                ext3_fsblk_t start_block,
 995                                ext3_fsblk_t last_block)
 996{
 997        struct rb_node *next;
 998        struct ext3_reserve_window_node *rsv, *prev;
 999        ext3_fsblk_t cur;
1000        int size = my_rsv->rsv_goal_size;
1001
1002        /* TODO: make the start of the reservation window byte-aligned */
1003        /* cur = *start_block & ~7;*/
1004        cur = start_block;
1005        rsv = search_head;
1006        if (!rsv)
1007                return -1;
1008
1009        while (1) {
1010                if (cur <= rsv->rsv_end)
1011                        cur = rsv->rsv_end + 1;
1012
1013                /* TODO?
1014                 * in the case we could not find a reservable space
1015                 * that is what is expected, during the re-search, we could
1016                 * remember what's the largest reservable space we could have
1017                 * and return that one.
1018                 *
1019                 * For now it will fail if we could not find the reservable
1020                 * space with expected-size (or more)...
1021                 */
1022                if (cur > last_block)
1023                        return -1;              /* fail */
1024
1025                prev = rsv;
1026                next = rb_next(&rsv->rsv_node);
1027                rsv = rb_entry(next,struct ext3_reserve_window_node,rsv_node);
1028
1029                /*
1030                 * Reached the last reservation, we can just append to the
1031                 * previous one.
1032                 */
1033                if (!next)
1034                        break;
1035
1036                if (cur + size <= rsv->rsv_start) {
1037                        /*
1038                         * Found a reserveable space big enough.  We could
1039                         * have a reservation across the group boundary here
1040                         */
1041                        break;
1042                }
1043        }
1044        /*
1045         * we come here either :
1046         * when we reach the end of the whole list,
1047         * and there is empty reservable space after last entry in the list.
1048         * append it to the end of the list.
1049         *
1050         * or we found one reservable space in the middle of the list,
1051         * return the reservation window that we could append to.
1052         * succeed.
1053         */
1054
1055        if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
1056                rsv_window_remove(sb, my_rsv);
1057
1058        /*
1059         * Let's book the whole available window for now.  We will check the
1060         * disk bitmap later and then, if there are free blocks then we adjust
1061         * the window size if it's larger than requested.
1062         * Otherwise, we will remove this node from the tree next time
1063         * call find_next_reservable_window.
1064         */
1065        my_rsv->rsv_start = cur;
1066        my_rsv->rsv_end = cur + size - 1;
1067        my_rsv->rsv_alloc_hit = 0;
1068
1069        if (prev != my_rsv)
1070                ext3_rsv_window_add(sb, my_rsv);
1071
1072        return 0;
1073}
1074
1075/**
1076 *      alloc_new_reservation()--allocate a new reservation window
1077 *
1078 *              To make a new reservation, we search part of the filesystem
1079 *              reservation list (the list that inside the group). We try to
1080 *              allocate a new reservation window near the allocation goal,
1081 *              or the beginning of the group, if there is no goal.
1082 *
1083 *              We first find a reservable space after the goal, then from
1084 *              there, we check the bitmap for the first free block after
1085 *              it. If there is no free block until the end of group, then the
1086 *              whole group is full, we failed. Otherwise, check if the free
1087 *              block is inside the expected reservable space, if so, we
1088 *              succeed.
1089 *              If the first free block is outside the reservable space, then
1090 *              start from the first free block, we search for next available
1091 *              space, and go on.
1092 *
1093 *      on succeed, a new reservation will be found and inserted into the list
1094 *      It contains at least one free block, and it does not overlap with other
1095 *      reservation windows.
1096 *
1097 *      failed: we failed to find a reservation window in this group
1098 *
1099 *      @my_rsv: the reservation window
1100 *
1101 *      @grp_goal: The goal (group-relative).  It is where the search for a
1102 *              free reservable space should start from.
1103 *              if we have a grp_goal(grp_goal >0 ), then start from there,
1104 *              no grp_goal(grp_goal = -1), we start from the first block
1105 *              of the group.
1106 *
1107 *      @sb: the super block
1108 *      @group: the group we are trying to allocate in
1109 *      @bitmap_bh: the block group block bitmap
1110 *
1111 */
1112static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
1113                ext3_grpblk_t grp_goal, struct super_block *sb,
1114                unsigned int group, struct buffer_head *bitmap_bh)
1115{
1116        struct ext3_reserve_window_node *search_head;
1117        ext3_fsblk_t group_first_block, group_end_block, start_block;
1118        ext3_grpblk_t first_free_block;
1119        struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
1120        unsigned long size;
1121        int ret;
1122        spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1123
1124        group_first_block = ext3_group_first_block_no(sb, group);
1125        group_end_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
1126
1127        if (grp_goal < 0)
1128                start_block = group_first_block;
1129        else
1130                start_block = grp_goal + group_first_block;
1131
1132        trace_ext3_alloc_new_reservation(sb, start_block);
1133        size = my_rsv->rsv_goal_size;
1134
1135        if (!rsv_is_empty(&my_rsv->rsv_window)) {
1136                /*
1137                 * if the old reservation is cross group boundary
1138                 * and if the goal is inside the old reservation window,
1139                 * we will come here when we just failed to allocate from
1140                 * the first part of the window. We still have another part
1141                 * that belongs to the next group. In this case, there is no
1142                 * point to discard our window and try to allocate a new one
1143                 * in this group(which will fail). we should
1144                 * keep the reservation window, just simply move on.
1145                 *
1146                 * Maybe we could shift the start block of the reservation
1147                 * window to the first block of next group.
1148                 */
1149
1150                if ((my_rsv->rsv_start <= group_end_block) &&
1151                                (my_rsv->rsv_end > group_end_block) &&
1152                                (start_block >= my_rsv->rsv_start))
1153                        return -1;
1154
1155                if ((my_rsv->rsv_alloc_hit >
1156                     (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
1157                        /*
1158                         * if the previously allocation hit ratio is
1159                         * greater than 1/2, then we double the size of
1160                         * the reservation window the next time,
1161                         * otherwise we keep the same size window
1162                         */
1163                        size = size * 2;
1164                        if (size > EXT3_MAX_RESERVE_BLOCKS)
1165                                size = EXT3_MAX_RESERVE_BLOCKS;
1166                        my_rsv->rsv_goal_size= size;
1167                }
1168        }
1169
1170        spin_lock(rsv_lock);
1171        /*
1172         * shift the search start to the window near the goal block
1173         */
1174        search_head = search_reserve_window(fs_rsv_root, start_block);
1175
1176        /*
1177         * find_next_reservable_window() simply finds a reservable window
1178         * inside the given range(start_block, group_end_block).
1179         *
1180         * To make sure the reservation window has a free bit inside it, we
1181         * need to check the bitmap after we found a reservable window.
1182         */
1183retry:
1184        ret = find_next_reservable_window(search_head, my_rsv, sb,
1185                                                start_block, group_end_block);
1186
1187        if (ret == -1) {
1188                if (!rsv_is_empty(&my_rsv->rsv_window))
1189                        rsv_window_remove(sb, my_rsv);
1190                spin_unlock(rsv_lock);
1191                return -1;
1192        }
1193
1194        /*
1195         * On success, find_next_reservable_window() returns the
1196         * reservation window where there is a reservable space after it.
1197         * Before we reserve this reservable space, we need
1198         * to make sure there is at least a free block inside this region.
1199         *
1200         * searching the first free bit on the block bitmap and copy of
1201         * last committed bitmap alternatively, until we found a allocatable
1202         * block. Search start from the start block of the reservable space
1203         * we just found.
1204         */
1205        spin_unlock(rsv_lock);
1206        first_free_block = bitmap_search_next_usable_block(
1207                        my_rsv->rsv_start - group_first_block,
1208                        bitmap_bh, group_end_block - group_first_block + 1);
1209
1210        if (first_free_block < 0) {
1211                /*
1212                 * no free block left on the bitmap, no point
1213                 * to reserve the space. return failed.
1214                 */
1215                spin_lock(rsv_lock);
1216                if (!rsv_is_empty(&my_rsv->rsv_window))
1217                        rsv_window_remove(sb, my_rsv);
1218                spin_unlock(rsv_lock);
1219                return -1;              /* failed */
1220        }
1221
1222        start_block = first_free_block + group_first_block;
1223        /*
1224         * check if the first free block is within the
1225         * free space we just reserved
1226         */
1227        if (start_block >= my_rsv->rsv_start &&
1228            start_block <= my_rsv->rsv_end) {
1229                trace_ext3_reserved(sb, start_block, my_rsv);
1230                return 0;               /* success */
1231        }
1232        /*
1233         * if the first free bit we found is out of the reservable space
1234         * continue search for next reservable space,
1235         * start from where the free block is,
1236         * we also shift the list head to where we stopped last time
1237         */
1238        search_head = my_rsv;
1239        spin_lock(rsv_lock);
1240        goto retry;
1241}
1242
1243/**
1244 * try_to_extend_reservation()
1245 * @my_rsv:             given reservation window
1246 * @sb:                 super block
1247 * @size:               the delta to extend
1248 *
1249 * Attempt to expand the reservation window large enough to have
1250 * required number of free blocks
1251 *
1252 * Since ext3_try_to_allocate() will always allocate blocks within
1253 * the reservation window range, if the window size is too small,
1254 * multiple blocks allocation has to stop at the end of the reservation
1255 * window. To make this more efficient, given the total number of
1256 * blocks needed and the current size of the window, we try to
1257 * expand the reservation window size if necessary on a best-effort
1258 * basis before ext3_new_blocks() tries to allocate blocks,
1259 */
1260static void try_to_extend_reservation(struct ext3_reserve_window_node *my_rsv,
1261                        struct super_block *sb, int size)
1262{
1263        struct ext3_reserve_window_node *next_rsv;
1264        struct rb_node *next;
1265        spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1266
1267        if (!spin_trylock(rsv_lock))
1268                return;
1269
1270        next = rb_next(&my_rsv->rsv_node);
1271
1272        if (!next)
1273                my_rsv->rsv_end += size;
1274        else {
1275                next_rsv = rb_entry(next, struct ext3_reserve_window_node, rsv_node);
1276
1277                if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1278                        my_rsv->rsv_end += size;
1279                else
1280                        my_rsv->rsv_end = next_rsv->rsv_start - 1;
1281        }
1282        spin_unlock(rsv_lock);
1283}
1284
1285/**
1286 * ext3_try_to_allocate_with_rsv()
1287 * @sb:                 superblock
1288 * @handle:             handle to this transaction
1289 * @group:              given allocation block group
1290 * @bitmap_bh:          bufferhead holds the block bitmap
1291 * @grp_goal:           given target block within the group
1292 * @my_rsv:             reservation window
1293 * @count:              target number of blocks to allocate
1294 * @errp:               pointer to store the error code
1295 *
1296 * This is the main function used to allocate a new block and its reservation
1297 * window.
1298 *
1299 * Each time when a new block allocation is need, first try to allocate from
1300 * its own reservation.  If it does not have a reservation window, instead of
1301 * looking for a free bit on bitmap first, then look up the reservation list to
1302 * see if it is inside somebody else's reservation window, we try to allocate a
1303 * reservation window for it starting from the goal first. Then do the block
1304 * allocation within the reservation window.
1305 *
1306 * This will avoid keeping on searching the reservation list again and
1307 * again when somebody is looking for a free block (without
1308 * reservation), and there are lots of free blocks, but they are all
1309 * being reserved.
1310 *
1311 * We use a red-black tree for the per-filesystem reservation list.
1312 *
1313 */
1314static ext3_grpblk_t
1315ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1316                        unsigned int group, struct buffer_head *bitmap_bh,
1317                        ext3_grpblk_t grp_goal,
1318                        struct ext3_reserve_window_node * my_rsv,
1319                        unsigned long *count, int *errp)
1320{
1321        ext3_fsblk_t group_first_block, group_last_block;
1322        ext3_grpblk_t ret = 0;
1323        int fatal;
1324        unsigned long num = *count;
1325
1326        *errp = 0;
1327
1328        /*
1329         * Make sure we use undo access for the bitmap, because it is critical
1330         * that we do the frozen_data COW on bitmap buffers in all cases even
1331         * if the buffer is in BJ_Forget state in the committing transaction.
1332         */
1333        BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1334        fatal = ext3_journal_get_undo_access(handle, bitmap_bh);
1335        if (fatal) {
1336                *errp = fatal;
1337                return -1;
1338        }
1339
1340        /*
1341         * we don't deal with reservation when
1342         * filesystem is mounted without reservation
1343         * or the file is not a regular file
1344         * or last attempt to allocate a block with reservation turned on failed
1345         */
1346        if (my_rsv == NULL ) {
1347                ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,
1348                                                grp_goal, count, NULL);
1349                goto out;
1350        }
1351        /*
1352         * grp_goal is a group relative block number (if there is a goal)
1353         * 0 <= grp_goal < EXT3_BLOCKS_PER_GROUP(sb)
1354         * first block is a filesystem wide block number
1355         * first block is the block number of the first block in this group
1356         */
1357        group_first_block = ext3_group_first_block_no(sb, group);
1358        group_last_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
1359
1360        /*
1361         * Basically we will allocate a new block from inode's reservation
1362         * window.
1363         *
1364         * We need to allocate a new reservation window, if:
1365         * a) inode does not have a reservation window; or
1366         * b) last attempt to allocate a block from existing reservation
1367         *    failed; or
1368         * c) we come here with a goal and with a reservation window
1369         *
1370         * We do not need to allocate a new reservation window if we come here
1371         * at the beginning with a goal and the goal is inside the window, or
1372         * we don't have a goal but already have a reservation window.
1373         * then we could go to allocate from the reservation window directly.
1374         */
1375        while (1) {
1376                if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1377                        !goal_in_my_reservation(&my_rsv->rsv_window,
1378                                                grp_goal, group, sb)) {
1379                        if (my_rsv->rsv_goal_size < *count)
1380                                my_rsv->rsv_goal_size = *count;
1381                        ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1382                                                        group, bitmap_bh);
1383                        if (ret < 0)
1384                                break;                  /* failed */
1385
1386                        if (!goal_in_my_reservation(&my_rsv->rsv_window,
1387                                                        grp_goal, group, sb))
1388                                grp_goal = -1;
1389                } else if (grp_goal >= 0) {
1390                        int curr = my_rsv->rsv_end -
1391                                        (grp_goal + group_first_block) + 1;
1392
1393                        if (curr < *count)
1394                                try_to_extend_reservation(my_rsv, sb,
1395                                                        *count - curr);
1396                }
1397
1398                if ((my_rsv->rsv_start > group_last_block) ||
1399                                (my_rsv->rsv_end < group_first_block)) {
1400                        rsv_window_dump(&EXT3_SB(sb)->s_rsv_window_root, 1);
1401                        BUG();
1402                }
1403                ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,
1404                                           grp_goal, &num, &my_rsv->rsv_window);
1405                if (ret >= 0) {
1406                        my_rsv->rsv_alloc_hit += num;
1407                        *count = num;
1408                        break;                          /* succeed */
1409                }
1410                num = *count;
1411        }
1412out:
1413        if (ret >= 0) {
1414                BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1415                                        "bitmap block");
1416                fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
1417                if (fatal) {
1418                        *errp = fatal;
1419                        return -1;
1420                }
1421                return ret;
1422        }
1423
1424        BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1425        ext3_journal_release_buffer(handle, bitmap_bh);
1426        return ret;
1427}
1428
1429/**
1430 * ext3_has_free_blocks()
1431 * @sbi:                in-core super block structure.
1432 *
1433 * Check if filesystem has at least 1 free block available for allocation.
1434 */
1435static int ext3_has_free_blocks(struct ext3_sb_info *sbi, int use_reservation)
1436{
1437        ext3_fsblk_t free_blocks, root_blocks;
1438
1439        free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1440        root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1441        if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1442                !use_reservation && !uid_eq(sbi->s_resuid, current_fsuid()) &&
1443                (gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
1444                 !in_group_p (sbi->s_resgid))) {
1445                return 0;
1446        }
1447        return 1;
1448}
1449
1450/**
1451 * ext3_should_retry_alloc()
1452 * @sb:                 super block
1453 * @retries             number of attemps has been made
1454 *
1455 * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
1456 * it is profitable to retry the operation, this function will wait
1457 * for the current or committing transaction to complete, and then
1458 * return TRUE.
1459 *
1460 * if the total number of retries exceed three times, return FALSE.
1461 */
1462int ext3_should_retry_alloc(struct super_block *sb, int *retries)
1463{
1464        if (!ext3_has_free_blocks(EXT3_SB(sb), 0) || (*retries)++ > 3)
1465                return 0;
1466
1467        jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1468
1469        return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
1470}
1471
1472/**
1473 * ext3_new_blocks() -- core block(s) allocation function
1474 * @handle:             handle to this transaction
1475 * @inode:              file inode
1476 * @goal:               given target block(filesystem wide)
1477 * @count:              target number of blocks to allocate
1478 * @errp:               error code
1479 *
1480 * ext3_new_blocks uses a goal block to assist allocation.  It tries to
1481 * allocate block(s) from the block group contains the goal block first. If that
1482 * fails, it will try to allocate block(s) from other block groups without
1483 * any specific goal block.
1484 *
1485 */
1486ext3_fsblk_t ext3_new_blocks(handle_t *handle, struct inode *inode,
1487                        ext3_fsblk_t goal, unsigned long *count, int *errp)
1488{
1489        struct buffer_head *bitmap_bh = NULL;
1490        struct buffer_head *gdp_bh;
1491        int group_no;
1492        int goal_group;
1493        ext3_grpblk_t grp_target_blk;   /* blockgroup relative goal block */
1494        ext3_grpblk_t grp_alloc_blk;    /* blockgroup-relative allocated block*/
1495        ext3_fsblk_t ret_block;         /* filesyetem-wide allocated block */
1496        int bgi;                        /* blockgroup iteration index */
1497        int fatal = 0, err;
1498        int performed_allocation = 0;
1499        ext3_grpblk_t free_blocks;      /* number of free blocks in a group */
1500        struct super_block *sb;
1501        struct ext3_group_desc *gdp;
1502        struct ext3_super_block *es;
1503        struct ext3_sb_info *sbi;
1504        struct ext3_reserve_window_node *my_rsv = NULL;
1505        struct ext3_block_alloc_info *block_i;
1506        unsigned short windowsz = 0;
1507#ifdef EXT3FS_DEBUG
1508        static int goal_hits, goal_attempts;
1509#endif
1510        unsigned long ngroups;
1511        unsigned long num = *count;
1512
1513        *errp = -ENOSPC;
1514        sb = inode->i_sb;
1515
1516        /*
1517         * Check quota for allocation of this block.
1518         */
1519        err = dquot_alloc_block(inode, num);
1520        if (err) {
1521                *errp = err;
1522                return 0;
1523        }
1524
1525        trace_ext3_request_blocks(inode, goal, num);
1526
1527        sbi = EXT3_SB(sb);
1528        es = sbi->s_es;
1529        ext3_debug("goal=%lu.\n", goal);
1530        /*
1531         * Allocate a block from reservation only when
1532         * filesystem is mounted with reservation(default,-o reservation), and
1533         * it's a regular file, and
1534         * the desired window size is greater than 0 (One could use ioctl
1535         * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
1536         * reservation on that particular file)
1537         */
1538        block_i = EXT3_I(inode)->i_block_alloc_info;
1539        if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
1540                my_rsv = &block_i->rsv_window_node;
1541
1542        if (!ext3_has_free_blocks(sbi, IS_NOQUOTA(inode))) {
1543                *errp = -ENOSPC;
1544                goto out;
1545        }
1546
1547        /*
1548         * First, test whether the goal block is free.
1549         */
1550        if (goal < le32_to_cpu(es->s_first_data_block) ||
1551            goal >= le32_to_cpu(es->s_blocks_count))
1552                goal = le32_to_cpu(es->s_first_data_block);
1553        group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1554                        EXT3_BLOCKS_PER_GROUP(sb);
1555        goal_group = group_no;
1556retry_alloc:
1557        gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1558        if (!gdp)
1559                goto io_error;
1560
1561        free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1562        /*
1563         * if there is not enough free blocks to make a new resevation
1564         * turn off reservation for this allocation
1565         */
1566        if (my_rsv && (free_blocks < windowsz)
1567                && (free_blocks > 0)
1568                && (rsv_is_empty(&my_rsv->rsv_window)))
1569                my_rsv = NULL;
1570
1571        if (free_blocks > 0) {
1572                grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1573                                EXT3_BLOCKS_PER_GROUP(sb));
1574                bitmap_bh = read_block_bitmap(sb, group_no);
1575                if (!bitmap_bh)
1576                        goto io_error;
1577                grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1578                                        group_no, bitmap_bh, grp_target_blk,
1579                                        my_rsv, &num, &fatal);
1580                if (fatal)
1581                        goto out;
1582                if (grp_alloc_blk >= 0)
1583                        goto allocated;
1584        }
1585
1586        ngroups = EXT3_SB(sb)->s_groups_count;
1587        smp_rmb();
1588
1589        /*
1590         * Now search the rest of the groups.  We assume that
1591         * group_no and gdp correctly point to the last group visited.
1592         */
1593        for (bgi = 0; bgi < ngroups; bgi++) {
1594                group_no++;
1595                if (group_no >= ngroups)
1596                        group_no = 0;
1597                gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1598                if (!gdp)
1599                        goto io_error;
1600                free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1601                /*
1602                 * skip this group (and avoid loading bitmap) if there
1603                 * are no free blocks
1604                 */
1605                if (!free_blocks)
1606                        continue;
1607                /*
1608                 * skip this group if the number of
1609                 * free blocks is less than half of the reservation
1610                 * window size.
1611                 */
1612                if (my_rsv && (free_blocks <= (windowsz/2)))
1613                        continue;
1614
1615                brelse(bitmap_bh);
1616                bitmap_bh = read_block_bitmap(sb, group_no);
1617                if (!bitmap_bh)
1618                        goto io_error;
1619                /*
1620                 * try to allocate block(s) from this group, without a goal(-1).
1621                 */
1622                grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1623                                        group_no, bitmap_bh, -1, my_rsv,
1624                                        &num, &fatal);
1625                if (fatal)
1626                        goto out;
1627                if (grp_alloc_blk >= 0)
1628                        goto allocated;
1629        }
1630        /*
1631         * We may end up a bogus earlier ENOSPC error due to
1632         * filesystem is "full" of reservations, but
1633         * there maybe indeed free blocks available on disk
1634         * In this case, we just forget about the reservations
1635         * just do block allocation as without reservations.
1636         */
1637        if (my_rsv) {
1638                my_rsv = NULL;
1639                windowsz = 0;
1640                group_no = goal_group;
1641                goto retry_alloc;
1642        }
1643        /* No space left on the device */
1644        *errp = -ENOSPC;
1645        goto out;
1646
1647allocated:
1648
1649        ext3_debug("using block group %d(%d)\n",
1650                        group_no, gdp->bg_free_blocks_count);
1651
1652        BUFFER_TRACE(gdp_bh, "get_write_access");
1653        fatal = ext3_journal_get_write_access(handle, gdp_bh);
1654        if (fatal)
1655                goto out;
1656
1657        ret_block = grp_alloc_blk + ext3_group_first_block_no(sb, group_no);
1658
1659        if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1660            in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1661            in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1662                      EXT3_SB(sb)->s_itb_per_group) ||
1663            in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1664                      EXT3_SB(sb)->s_itb_per_group)) {
1665                ext3_error(sb, "ext3_new_block",
1666                            "Allocating block in system zone - "
1667                            "blocks from "E3FSBLK", length %lu",
1668                             ret_block, num);
1669                /*
1670                 * claim_block() marked the blocks we allocated as in use. So we
1671                 * may want to selectively mark some of the blocks as free.
1672                 */
1673                goto retry_alloc;
1674        }
1675
1676        performed_allocation = 1;
1677
1678#ifdef CONFIG_JBD_DEBUG
1679        {
1680                struct buffer_head *debug_bh;
1681
1682                /* Record bitmap buffer state in the newly allocated block */
1683                debug_bh = sb_find_get_block(sb, ret_block);
1684                if (debug_bh) {
1685                        BUFFER_TRACE(debug_bh, "state when allocated");
1686                        BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1687                        brelse(debug_bh);
1688                }
1689        }
1690        jbd_lock_bh_state(bitmap_bh);
1691        spin_lock(sb_bgl_lock(sbi, group_no));
1692        if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1693                int i;
1694
1695                for (i = 0; i < num; i++) {
1696                        if (ext3_test_bit(grp_alloc_blk+i,
1697                                        bh2jh(bitmap_bh)->b_committed_data)) {
1698                                printk("%s: block was unexpectedly set in "
1699                                        "b_committed_data\n", __func__);
1700                        }
1701                }
1702        }
1703        ext3_debug("found bit %d\n", grp_alloc_blk);
1704        spin_unlock(sb_bgl_lock(sbi, group_no));
1705        jbd_unlock_bh_state(bitmap_bh);
1706#endif
1707
1708        if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1709                ext3_error(sb, "ext3_new_block",
1710                            "block("E3FSBLK") >= blocks count(%d) - "
1711                            "block_group = %d, es == %p ", ret_block,
1712                        le32_to_cpu(es->s_blocks_count), group_no, es);
1713                goto out;
1714        }
1715
1716        /*
1717         * It is up to the caller to add the new buffer to a journal
1718         * list of some description.  We don't know in advance whether
1719         * the caller wants to use it as metadata or data.
1720         */
1721        ext3_debug("allocating block %lu. Goal hits %d of %d.\n",
1722                        ret_block, goal_hits, goal_attempts);
1723
1724        spin_lock(sb_bgl_lock(sbi, group_no));
1725        le16_add_cpu(&gdp->bg_free_blocks_count, -num);
1726        spin_unlock(sb_bgl_lock(sbi, group_no));
1727        percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1728
1729        BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1730        err = ext3_journal_dirty_metadata(handle, gdp_bh);
1731        if (!fatal)
1732                fatal = err;
1733
1734        if (fatal)
1735                goto out;
1736
1737        *errp = 0;
1738        brelse(bitmap_bh);
1739
1740        if (num < *count) {
1741                dquot_free_block(inode, *count-num);
1742                *count = num;
1743        }
1744
1745        trace_ext3_allocate_blocks(inode, goal, num,
1746                                   (unsigned long long)ret_block);
1747
1748        return ret_block;
1749
1750io_error:
1751        *errp = -EIO;
1752out:
1753        if (fatal) {
1754                *errp = fatal;
1755                ext3_std_error(sb, fatal);
1756        }
1757        /*
1758         * Undo the block allocation
1759         */
1760        if (!performed_allocation)
1761                dquot_free_block(inode, *count);
1762        brelse(bitmap_bh);
1763        return 0;
1764}
1765
1766ext3_fsblk_t ext3_new_block(handle_t *handle, struct inode *inode,
1767                        ext3_fsblk_t goal, int *errp)
1768{
1769        unsigned long count = 1;
1770
1771        return ext3_new_blocks(handle, inode, goal, &count, errp);
1772}
1773
1774/**
1775 * ext3_count_free_blocks() -- count filesystem free blocks
1776 * @sb:         superblock
1777 *
1778 * Adds up the number of free blocks from each block group.
1779 */
1780ext3_fsblk_t ext3_count_free_blocks(struct super_block *sb)
1781{
1782        ext3_fsblk_t desc_count;
1783        struct ext3_group_desc *gdp;
1784        int i;
1785        unsigned long ngroups = EXT3_SB(sb)->s_groups_count;
1786#ifdef EXT3FS_DEBUG
1787        struct ext3_super_block *es;
1788        ext3_fsblk_t bitmap_count;
1789        unsigned long x;
1790        struct buffer_head *bitmap_bh = NULL;
1791
1792        es = EXT3_SB(sb)->s_es;
1793        desc_count = 0;
1794        bitmap_count = 0;
1795        gdp = NULL;
1796
1797        smp_rmb();
1798        for (i = 0; i < ngroups; i++) {
1799                gdp = ext3_get_group_desc(sb, i, NULL);
1800                if (!gdp)
1801                        continue;
1802                desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1803                brelse(bitmap_bh);
1804                bitmap_bh = read_block_bitmap(sb, i);
1805                if (bitmap_bh == NULL)
1806                        continue;
1807
1808                x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1809                printk("group %d: stored = %d, counted = %lu\n",
1810                        i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1811                bitmap_count += x;
1812        }
1813        brelse(bitmap_bh);
1814        printk("ext3_count_free_blocks: stored = "E3FSBLK
1815                ", computed = "E3FSBLK", "E3FSBLK"\n",
1816               (ext3_fsblk_t)le32_to_cpu(es->s_free_blocks_count),
1817                desc_count, bitmap_count);
1818        return bitmap_count;
1819#else
1820        desc_count = 0;
1821        smp_rmb();
1822        for (i = 0; i < ngroups; i++) {
1823                gdp = ext3_get_group_desc(sb, i, NULL);
1824                if (!gdp)
1825                        continue;
1826                desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1827        }
1828
1829        return desc_count;
1830#endif
1831}
1832
1833static inline int test_root(int a, int b)
1834{
1835        int num = b;
1836
1837        while (a > num)
1838                num *= b;
1839        return num == a;
1840}
1841
1842static int ext3_group_sparse(int group)
1843{
1844        if (group <= 1)
1845                return 1;
1846        if (!(group & 1))
1847                return 0;
1848        return (test_root(group, 7) || test_root(group, 5) ||
1849                test_root(group, 3));
1850}
1851
1852/**
1853 *      ext3_bg_has_super - number of blocks used by the superblock in group
1854 *      @sb: superblock for filesystem
1855 *      @group: group number to check
1856 *
1857 *      Return the number of blocks used by the superblock (primary or backup)
1858 *      in this group.  Currently this will be only 0 or 1.
1859 */
1860int ext3_bg_has_super(struct super_block *sb, int group)
1861{
1862        if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
1863                                EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1864                        !ext3_group_sparse(group))
1865                return 0;
1866        return 1;
1867}
1868
1869static unsigned long ext3_bg_num_gdb_meta(struct super_block *sb, int group)
1870{
1871        unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1872        unsigned long first = metagroup * EXT3_DESC_PER_BLOCK(sb);
1873        unsigned long last = first + EXT3_DESC_PER_BLOCK(sb) - 1;
1874
1875        if (group == first || group == first + 1 || group == last)
1876                return 1;
1877        return 0;
1878}
1879
1880static unsigned long ext3_bg_num_gdb_nometa(struct super_block *sb, int group)
1881{
1882        return ext3_bg_has_super(sb, group) ? EXT3_SB(sb)->s_gdb_count : 0;
1883}
1884
1885/**
1886 *      ext3_bg_num_gdb - number of blocks used by the group table in group
1887 *      @sb: superblock for filesystem
1888 *      @group: group number to check
1889 *
1890 *      Return the number of blocks used by the group descriptor table
1891 *      (primary or backup) in this group.  In the future there may be a
1892 *      different number of descriptor blocks in each group.
1893 */
1894unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
1895{
1896        unsigned long first_meta_bg =
1897                        le32_to_cpu(EXT3_SB(sb)->s_es->s_first_meta_bg);
1898        unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1899
1900        if (!EXT3_HAS_INCOMPAT_FEATURE(sb,EXT3_FEATURE_INCOMPAT_META_BG) ||
1901                        metagroup < first_meta_bg)
1902                return ext3_bg_num_gdb_nometa(sb,group);
1903
1904        return ext3_bg_num_gdb_meta(sb,group);
1905
1906}
1907
1908/**
1909 * ext3_trim_all_free -- function to trim all free space in alloc. group
1910 * @sb:                 super block for file system
1911 * @group:              allocation group to trim
1912 * @start:              first group block to examine
1913 * @max:                last group block to examine
1914 * @gdp:                allocation group description structure
1915 * @minblocks:          minimum extent block count
1916 *
1917 * ext3_trim_all_free walks through group's block bitmap searching for free
1918 * blocks. When the free block is found, it tries to allocate this block and
1919 * consequent free block to get the biggest free extent possible, until it
1920 * reaches any used block. Then issue a TRIM command on this extent and free
1921 * the extent in the block bitmap. This is done until whole group is scanned.
1922 */
1923static ext3_grpblk_t ext3_trim_all_free(struct super_block *sb,
1924                                        unsigned int group,
1925                                        ext3_grpblk_t start, ext3_grpblk_t max,
1926                                        ext3_grpblk_t minblocks)
1927{
1928        handle_t *handle;
1929        ext3_grpblk_t next, free_blocks, bit, freed, count = 0;
1930        ext3_fsblk_t discard_block;
1931        struct ext3_sb_info *sbi;
1932        struct buffer_head *gdp_bh, *bitmap_bh = NULL;
1933        struct ext3_group_desc *gdp;
1934        int err = 0, ret = 0;
1935
1936        /*
1937         * We will update one block bitmap, and one group descriptor
1938         */
1939        handle = ext3_journal_start_sb(sb, 2);
1940        if (IS_ERR(handle))
1941                return PTR_ERR(handle);
1942
1943        bitmap_bh = read_block_bitmap(sb, group);
1944        if (!bitmap_bh) {
1945                err = -EIO;
1946                goto err_out;
1947        }
1948
1949        BUFFER_TRACE(bitmap_bh, "getting undo access");
1950        err = ext3_journal_get_undo_access(handle, bitmap_bh);
1951        if (err)
1952                goto err_out;
1953
1954        gdp = ext3_get_group_desc(sb, group, &gdp_bh);
1955        if (!gdp) {
1956                err = -EIO;
1957                goto err_out;
1958        }
1959
1960        BUFFER_TRACE(gdp_bh, "get_write_access");
1961        err = ext3_journal_get_write_access(handle, gdp_bh);
1962        if (err)
1963                goto err_out;
1964
1965        free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1966        sbi = EXT3_SB(sb);
1967
1968         /* Walk through the whole group */
1969        while (start <= max) {
1970                start = bitmap_search_next_usable_block(start, bitmap_bh, max);
1971                if (start < 0)
1972                        break;
1973                next = start;
1974
1975                /*
1976                 * Allocate contiguous free extents by setting bits in the
1977                 * block bitmap
1978                 */
1979                while (next <= max
1980                        && claim_block(sb_bgl_lock(sbi, group),
1981                                        next, bitmap_bh)) {
1982                        next++;
1983                }
1984
1985                 /* We did not claim any blocks */
1986                if (next == start)
1987                        continue;
1988
1989                discard_block = (ext3_fsblk_t)start +
1990                                ext3_group_first_block_no(sb, group);
1991
1992                /* Update counters */
1993                spin_lock(sb_bgl_lock(sbi, group));
1994                le16_add_cpu(&gdp->bg_free_blocks_count, start - next);
1995                spin_unlock(sb_bgl_lock(sbi, group));
1996                percpu_counter_sub(&sbi->s_freeblocks_counter, next - start);
1997
1998                free_blocks -= next - start;
1999                /* Do not issue a TRIM on extents smaller than minblocks */
2000                if ((next - start) < minblocks)
2001                        goto free_extent;
2002
2003                trace_ext3_discard_blocks(sb, discard_block, next - start);
2004                 /* Send the TRIM command down to the device */
2005                err = sb_issue_discard(sb, discard_block, next - start,
2006                                       GFP_NOFS, 0);
2007                count += (next - start);
2008free_extent:
2009                freed = 0;
2010
2011                /*
2012                 * Clear bits in the bitmap
2013                 */
2014                for (bit = start; bit < next; bit++) {
2015                        BUFFER_TRACE(bitmap_bh, "clear bit");
2016                        if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, group),
2017                                                bit, bitmap_bh->b_data)) {
2018                                ext3_error(sb, __func__,
2019                                        "bit already cleared for block "E3FSBLK,
2020                                         (unsigned long)bit);
2021                                BUFFER_TRACE(bitmap_bh, "bit already cleared");
2022                        } else {
2023                                freed++;
2024                        }
2025                }
2026
2027                /* Update couters */
2028                spin_lock(sb_bgl_lock(sbi, group));
2029                le16_add_cpu(&gdp->bg_free_blocks_count, freed);
2030                spin_unlock(sb_bgl_lock(sbi, group));
2031                percpu_counter_add(&sbi->s_freeblocks_counter, freed);
2032
2033                start = next;
2034                if (err < 0) {
2035                        if (err != -EOPNOTSUPP)
2036                                ext3_warning(sb, __func__, "Discard command "
2037                                             "returned error %d\n", err);
2038                        break;
2039                }
2040
2041                if (fatal_signal_pending(current)) {
2042                        err = -ERESTARTSYS;
2043                        break;
2044                }
2045
2046                cond_resched();
2047
2048                /* No more suitable extents */
2049                if (free_blocks < minblocks)
2050                        break;
2051        }
2052
2053        /* We dirtied the bitmap block */
2054        BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
2055        ret = ext3_journal_dirty_metadata(handle, bitmap_bh);
2056        if (!err)
2057                err = ret;
2058
2059        /* And the group descriptor block */
2060        BUFFER_TRACE(gdp_bh, "dirtied group descriptor block");
2061        ret = ext3_journal_dirty_metadata(handle, gdp_bh);
2062        if (!err)
2063                err = ret;
2064
2065        ext3_debug("trimmed %d blocks in the group %d\n",
2066                count, group);
2067
2068err_out:
2069        if (err)
2070                count = err;
2071        ext3_journal_stop(handle);
2072        brelse(bitmap_bh);
2073
2074        return count;
2075}
2076
2077/**
2078 * ext3_trim_fs() -- trim ioctl handle function
2079 * @sb:                 superblock for filesystem
2080 * @start:              First Byte to trim
2081 * @len:                number of Bytes to trim from start
2082 * @minlen:             minimum extent length in Bytes
2083 *
2084 * ext3_trim_fs goes through all allocation groups containing Bytes from
2085 * start to start+len. For each such a group ext3_trim_all_free function
2086 * is invoked to trim all free space.
2087 */
2088int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range)
2089{
2090        ext3_grpblk_t last_block, first_block;
2091        unsigned long group, first_group, last_group;
2092        struct ext3_group_desc *gdp;
2093        struct ext3_super_block *es = EXT3_SB(sb)->s_es;
2094        uint64_t start, minlen, end, trimmed = 0;
2095        ext3_fsblk_t first_data_blk =
2096                        le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block);
2097        ext3_fsblk_t max_blks = le32_to_cpu(es->s_blocks_count);
2098        int ret = 0;
2099
2100        start = range->start >> sb->s_blocksize_bits;
2101        end = start + (range->len >> sb->s_blocksize_bits) - 1;
2102        minlen = range->minlen >> sb->s_blocksize_bits;
2103
2104        if (minlen > EXT3_BLOCKS_PER_GROUP(sb) ||
2105            start >= max_blks ||
2106            range->len < sb->s_blocksize)
2107                return -EINVAL;
2108        if (end >= max_blks)
2109                end = max_blks - 1;
2110        if (end <= first_data_blk)
2111                goto out;
2112        if (start < first_data_blk)
2113                start = first_data_blk;
2114
2115        smp_rmb();
2116
2117        /* Determine first and last group to examine based on start and len */
2118        ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) start,
2119                                     &first_group, &first_block);
2120        ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) end,
2121                                     &last_group, &last_block);
2122
2123        /* end now represents the last block to discard in this group */
2124        end = EXT3_BLOCKS_PER_GROUP(sb) - 1;
2125
2126        for (group = first_group; group <= last_group; group++) {
2127                gdp = ext3_get_group_desc(sb, group, NULL);
2128                if (!gdp)
2129                        break;
2130
2131                /*
2132                 * For all the groups except the last one, last block will
2133                 * always be EXT3_BLOCKS_PER_GROUP(sb)-1, so we only need to
2134                 * change it for the last group, note that last_block is
2135                 * already computed earlier by ext3_get_group_no_and_offset()
2136                 */
2137                if (group == last_group)
2138                        end = last_block;
2139
2140                if (le16_to_cpu(gdp->bg_free_blocks_count) >= minlen) {
2141                        ret = ext3_trim_all_free(sb, group, first_block,
2142                                                 end, minlen);
2143                        if (ret < 0)
2144                                break;
2145                        trimmed += ret;
2146                }
2147
2148                /*
2149                 * For every group except the first one, we are sure
2150                 * that the first block to discard will be block #0.
2151                 */
2152                first_block = 0;
2153        }
2154
2155        if (ret > 0)
2156                ret = 0;
2157
2158out:
2159        range->len = trimmed * sb->s_blocksize;
2160        return ret;
2161}
2162
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