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/time.h>
  15#include <linux/capability.h>
  16#include <linux/fs.h>
  17#include <linux/slab.h>
  18#include <linux/jbd.h>
  19#include <linux/ext3_fs.h>
  20#include <linux/ext3_jbd.h>
  21#include <linux/quotaops.h>
  22#include <linux/buffer_head.h>
  23
  24/*
  25 * balloc.c contains the blocks allocation and deallocation routines
  26 */
  27
  28/*
  29 * The free blocks are managed by bitmaps.  A file system contains several
  30 * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
  31 * block for inodes, N blocks for the inode table and data blocks.
  32 *
  33 * The file system contains group descriptors which are located after the
  34 * super block.  Each descriptor contains the number of the bitmap block and
  35 * the free blocks count in the block.  The descriptors are loaded in memory
  36 * when a file system is mounted (see ext3_fill_super).
  37 */
  38
  39
  40#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
  41
  42/**
  43 * ext3_get_group_desc() -- load group descriptor from disk
  44 * @sb:                 super block
  45 * @block_group:        given block group
  46 * @bh:                 pointer to the buffer head to store the block
  47 *                      group descriptor
  48 */
  49struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
  50                                             unsigned int block_group,
  51                                             struct buffer_head ** bh)
  52{
  53        unsigned long group_desc;
  54        unsigned long offset;
  55        struct ext3_group_desc * desc;
  56        struct ext3_sb_info *sbi = EXT3_SB(sb);
  57
  58        if (block_group >= sbi->s_groups_count) {
  59                ext3_error (sb, "ext3_get_group_desc",
  60                            "block_group >= groups_count - "
  61                            "block_group = %d, groups_count = %lu",
  62                            block_group, sbi->s_groups_count);
  63
  64                return NULL;
  65        }
  66        smp_rmb();
  67
  68        group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb);
  69        offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1);
  70        if (!sbi->s_group_desc[group_desc]) {
  71                ext3_error (sb, "ext3_get_group_desc",
  72                            "Group descriptor not loaded - "
  73                            "block_group = %d, group_desc = %lu, desc = %lu",
  74                             block_group, group_desc, offset);
  75                return NULL;
  76        }
  77
  78        desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data;
  79        if (bh)
  80                *bh = sbi->s_group_desc[group_desc];
  81        return desc + offset;
  82}
  83
  84static int ext3_valid_block_bitmap(struct super_block *sb,
  85                                        struct ext3_group_desc *desc,
  86                                        unsigned int block_group,
  87                                        struct buffer_head *bh)
  88{
  89        ext3_grpblk_t offset;
  90        ext3_grpblk_t next_zero_bit;
  91        ext3_fsblk_t bitmap_blk;
  92        ext3_fsblk_t group_first_block;
  93
  94        group_first_block = ext3_group_first_block_no(sb, block_group);
  95
  96        /* check whether block bitmap block number is set */
  97        bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
  98        offset = bitmap_blk - group_first_block;
  99        if (!ext3_test_bit(offset, bh->b_data))
 100                /* bad block bitmap */
 101                goto err_out;
 102
 103        /* check whether the inode bitmap block number is set */
 104        bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
 105        offset = bitmap_blk - group_first_block;
 106        if (!ext3_test_bit(offset, bh->b_data))
 107                /* bad block bitmap */
 108                goto err_out;
 109
 110        /* check whether the inode table block number is set */
 111        bitmap_blk = le32_to_cpu(desc->bg_inode_table);
 112        offset = bitmap_blk - group_first_block;
 113        next_zero_bit = ext3_find_next_zero_bit(bh->b_data,
 114                                offset + EXT3_SB(sb)->s_itb_per_group,
 115                                offset);
 116        if (next_zero_bit >= offset + EXT3_SB(sb)->s_itb_per_group)
 117                /* good bitmap for inode tables */
 118                return 1;
 119
 120err_out:
 121        ext3_error(sb, __func__,
 122                        "Invalid block bitmap - "
 123                        "block_group = %d, block = %lu",
 124                        block_group, bitmap_blk);
 125        return 0;
 126}
 127
 128/**
 129 * read_block_bitmap()
 130 * @sb:                 super block
 131 * @block_group:        given block group
 132 *
 133 * Read the bitmap for a given block_group,and validate the
 134 * bits for block/inode/inode tables are set in the bitmaps
 135 *
 136 * Return buffer_head on success or NULL in case of failure.
 137 */
 138static struct buffer_head *
 139read_block_bitmap(struct super_block *sb, unsigned int block_group)
 140{
 141        struct ext3_group_desc * desc;
 142        struct buffer_head * bh = NULL;
 143        ext3_fsblk_t bitmap_blk;
 144
 145        desc = ext3_get_group_desc(sb, block_group, NULL);
 146        if (!desc)
 147                return NULL;
 148        bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
 149        bh = sb_getblk(sb, bitmap_blk);
 150        if (unlikely(!bh)) {
 151                ext3_error(sb, __func__,
 152                            "Cannot read block bitmap - "
 153                            "block_group = %d, block_bitmap = %u",
 154                            block_group, le32_to_cpu(desc->bg_block_bitmap));
 155                return NULL;
 156        }
 157        if (likely(bh_uptodate_or_lock(bh)))
 158                return bh;
 159
 160        if (bh_submit_read(bh) < 0) {
 161                brelse(bh);
 162                ext3_error(sb, __func__,
 163                            "Cannot read block bitmap - "
 164                            "block_group = %d, block_bitmap = %u",
 165                            block_group, le32_to_cpu(desc->bg_block_bitmap));
 166                return NULL;
 167        }
 168        ext3_valid_block_bitmap(sb, desc, block_group, bh);
 169        /*
 170         * file system mounted not to panic on error, continue with corrupt
 171         * bitmap
 172         */
 173        return bh;
 174}
 175/*
 176 * The reservation window structure operations
 177 * --------------------------------------------
 178 * Operations include:
 179 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
 180 *
 181 * We use a red-black tree to represent per-filesystem reservation
 182 * windows.
 183 *
 184 */
 185
 186/**
 187 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
 188 * @rb_root:            root of per-filesystem reservation rb tree
 189 * @verbose:            verbose mode
 190 * @fn:                 function which wishes to dump the reservation map
 191 *
 192 * If verbose is turned on, it will print the whole block reservation
 193 * windows(start, end). Otherwise, it will only print out the "bad" windows,
 194 * those windows that overlap with their immediate neighbors.
 195 */
 196#if 1
 197static void __rsv_window_dump(struct rb_root *root, int verbose,
 198                              const char *fn)
 199{
 200        struct rb_node *n;
 201        struct ext3_reserve_window_node *rsv, *prev;
 202        int bad;
 203
 204restart:
 205        n = rb_first(root);
 206        bad = 0;
 207        prev = NULL;
 208
 209        printk("Block Allocation Reservation Windows Map (%s):\n", fn);
 210        while (n) {
 211                rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 212                if (verbose)
 213                        printk("reservation window 0x%p "
 214                               "start:  %lu, end:  %lu\n",
 215                               rsv, rsv->rsv_start, rsv->rsv_end);
 216                if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
 217                        printk("Bad reservation %p (start >= end)\n",
 218                               rsv);
 219                        bad = 1;
 220                }
 221                if (prev && prev->rsv_end >= rsv->rsv_start) {
 222                        printk("Bad reservation %p (prev->end >= start)\n",
 223                               rsv);
 224                        bad = 1;
 225                }
 226                if (bad) {
 227                        if (!verbose) {
 228                                printk("Restarting reservation walk in verbose mode\n");
 229                                verbose = 1;
 230                                goto restart;
 231                        }
 232                }
 233                n = rb_next(n);
 234                prev = rsv;
 235        }
 236        printk("Window map complete.\n");
 237        BUG_ON(bad);
 238}
 239#define rsv_window_dump(root, verbose) \
 240        __rsv_window_dump((root), (verbose), __func__)
 241#else
 242#define rsv_window_dump(root, verbose) do {} while (0)
 243#endif
 244
 245/**
 246 * goal_in_my_reservation()
 247 * @rsv:                inode's reservation window
 248 * @grp_goal:           given goal block relative to the allocation block group
 249 * @group:              the current allocation block group
 250 * @sb:                 filesystem super block
 251 *
 252 * Test if the given goal block (group relative) is within the file's
 253 * own block reservation window range.
 254 *
 255 * If the reservation window is outside the goal allocation group, return 0;
 256 * grp_goal (given goal block) could be -1, which means no specific
 257 * goal block. In this case, always return 1.
 258 * If the goal block is within the reservation window, return 1;
 259 * otherwise, return 0;
 260 */
 261static int
 262goal_in_my_reservation(struct ext3_reserve_window *rsv, ext3_grpblk_t grp_goal,
 263                        unsigned int group, struct super_block * sb)
 264{
 265        ext3_fsblk_t group_first_block, group_last_block;
 266
 267        group_first_block = ext3_group_first_block_no(sb, group);
 268        group_last_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
 269
 270        if ((rsv->_rsv_start > group_last_block) ||
 271            (rsv->_rsv_end < group_first_block))
 272                return 0;
 273        if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
 274                || (grp_goal + group_first_block > rsv->_rsv_end)))
 275                return 0;
 276        return 1;
 277}
 278
 279/**
 280 * search_reserve_window()
 281 * @rb_root:            root of reservation tree
 282 * @goal:               target allocation block
 283 *
 284 * Find the reserved window which includes the goal, or the previous one
 285 * if the goal is not in any window.
 286 * Returns NULL if there are no windows or if all windows start after the goal.
 287 */
 288static struct ext3_reserve_window_node *
 289search_reserve_window(struct rb_root *root, ext3_fsblk_t goal)
 290{
 291        struct rb_node *n = root->rb_node;
 292        struct ext3_reserve_window_node *rsv;
 293
 294        if (!n)
 295                return NULL;
 296
 297        do {
 298                rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 299
 300                if (goal < rsv->rsv_start)
 301                        n = n->rb_left;
 302                else if (goal > rsv->rsv_end)
 303                        n = n->rb_right;
 304                else
 305                        return rsv;
 306        } while (n);
 307        /*
 308         * We've fallen off the end of the tree: the goal wasn't inside
 309         * any particular node.  OK, the previous node must be to one
 310         * side of the interval containing the goal.  If it's the RHS,
 311         * we need to back up one.
 312         */
 313        if (rsv->rsv_start > goal) {
 314                n = rb_prev(&rsv->rsv_node);
 315                rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 316        }
 317        return rsv;
 318}
 319
 320/**
 321 * ext3_rsv_window_add() -- Insert a window to the block reservation rb tree.
 322 * @sb:                 super block
 323 * @rsv:                reservation window to add
 324 *
 325 * Must be called with rsv_lock hold.
 326 */
 327void ext3_rsv_window_add(struct super_block *sb,
 328                    struct ext3_reserve_window_node *rsv)
 329{
 330        struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
 331        struct rb_node *node = &rsv->rsv_node;
 332        ext3_fsblk_t start = rsv->rsv_start;
 333
 334        struct rb_node ** p = &root->rb_node;
 335        struct rb_node * parent = NULL;
 336        struct ext3_reserve_window_node *this;
 337
 338        while (*p)
 339        {
 340                parent = *p;
 341                this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node);
 342
 343                if (start < this->rsv_start)
 344                        p = &(*p)->rb_left;
 345                else if (start > this->rsv_end)
 346                        p = &(*p)->rb_right;
 347                else {
 348                        rsv_window_dump(root, 1);
 349                        BUG();
 350                }
 351        }
 352
 353        rb_link_node(node, parent, p);
 354        rb_insert_color(node, root);
 355}
 356
 357/**
 358 * ext3_rsv_window_remove() -- unlink a window from the reservation rb tree
 359 * @sb:                 super block
 360 * @rsv:                reservation window to remove
 361 *
 362 * Mark the block reservation window as not allocated, and unlink it
 363 * from the filesystem reservation window rb tree. Must be called with
 364 * rsv_lock hold.
 365 */
 366static void rsv_window_remove(struct super_block *sb,
 367                              struct ext3_reserve_window_node *rsv)
 368{
 369        rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 370        rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 371        rsv->rsv_alloc_hit = 0;
 372        rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root);
 373}
 374
 375/*
 376 * rsv_is_empty() -- Check if the reservation window is allocated.
 377 * @rsv:                given reservation window to check
 378 *
 379 * returns 1 if the end block is EXT3_RESERVE_WINDOW_NOT_ALLOCATED.
 380 */
 381static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
 382{
 383        /* a valid reservation end block could not be 0 */
 384        return rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 385}
 386
 387/**
 388 * ext3_init_block_alloc_info()
 389 * @inode:              file inode structure
 390 *
 391 * Allocate and initialize the  reservation window structure, and
 392 * link the window to the ext3 inode structure at last
 393 *
 394 * The reservation window structure is only dynamically allocated
 395 * and linked to ext3 inode the first time the open file
 396 * needs a new block. So, before every ext3_new_block(s) call, for
 397 * regular files, we should check whether the reservation window
 398 * structure exists or not. In the latter case, this function is called.
 399 * Fail to do so will result in block reservation being turned off for that
 400 * open file.
 401 *
 402 * This function is called from ext3_get_blocks_handle(), also called
 403 * when setting the reservation window size through ioctl before the file
 404 * is open for write (needs block allocation).
 405 *
 406 * Needs truncate_mutex protection prior to call this function.
 407 */
 408void ext3_init_block_alloc_info(struct inode *inode)
 409{
 410        struct ext3_inode_info *ei = EXT3_I(inode);
 411        struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
 412        struct super_block *sb = inode->i_sb;
 413
 414        block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
 415        if (block_i) {
 416                struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node;
 417
 418                rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 419                rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 420
 421                /*
 422                 * if filesystem is mounted with NORESERVATION, the goal
 423                 * reservation window size is set to zero to indicate
 424                 * block reservation is off
 425                 */
 426                if (!test_opt(sb, RESERVATION))
 427                        rsv->rsv_goal_size = 0;
 428                else
 429                        rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS;
 430                rsv->rsv_alloc_hit = 0;
 431                block_i->last_alloc_logical_block = 0;
 432                block_i->last_alloc_physical_block = 0;
 433        }
 434        ei->i_block_alloc_info = block_i;
 435}
 436
 437/**
 438 * ext3_discard_reservation()
 439 * @inode:              inode
 440 *
 441 * Discard(free) block reservation window on last file close, or truncate
 442 * or at last iput().
 443 *
 444 * It is being called in three cases:
 445 *      ext3_release_file(): last writer close the file
 446 *      ext3_clear_inode(): last iput(), when nobody link to this file.
 447 *      ext3_truncate(): when the block indirect map is about to change.
 448 *
 449 */
 450void ext3_discard_reservation(struct inode *inode)
 451{
 452        struct ext3_inode_info *ei = EXT3_I(inode);
 453        struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
 454        struct ext3_reserve_window_node *rsv;
 455        spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
 456
 457        if (!block_i)
 458                return;
 459
 460        rsv = &block_i->rsv_window_node;
 461        if (!rsv_is_empty(&rsv->rsv_window)) {
 462                spin_lock(rsv_lock);
 463                if (!rsv_is_empty(&rsv->rsv_window))
 464                        rsv_window_remove(inode->i_sb, rsv);
 465                spin_unlock(rsv_lock);
 466        }
 467}
 468
 469/**
 470 * ext3_free_blocks_sb() -- Free given blocks and update quota
 471 * @handle:                     handle to this transaction
 472 * @sb:                         super block
 473 * @block:                      start physcial block to free
 474 * @count:                      number of blocks to free
 475 * @pdquot_freed_blocks:        pointer to quota
 476 */
 477void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
 478                         ext3_fsblk_t block, unsigned long count,
 479                         unsigned long *pdquot_freed_blocks)
 480{
 481        struct buffer_head *bitmap_bh = NULL;
 482        struct buffer_head *gd_bh;
 483        unsigned long block_group;
 484        ext3_grpblk_t bit;
 485        unsigned long i;
 486        unsigned long overflow;
 487        struct ext3_group_desc * desc;
 488        struct ext3_super_block * es;
 489        struct ext3_sb_info *sbi;
 490        int err = 0, ret;
 491        ext3_grpblk_t group_freed;
 492
 493        *pdquot_freed_blocks = 0;
 494        sbi = EXT3_SB(sb);
 495        es = sbi->s_es;
 496        if (block < le32_to_cpu(es->s_first_data_block) ||
 497            block + count < block ||
 498            block + count > le32_to_cpu(es->s_blocks_count)) {
 499                ext3_error (sb, "ext3_free_blocks",
 500                            "Freeing blocks not in datazone - "
 501                            "block = "E3FSBLK", count = %lu", block, count);
 502                goto error_return;
 503        }
 504
 505        ext3_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
 506
 507do_more:
 508        overflow = 0;
 509        block_group = (block - le32_to_cpu(es->s_first_data_block)) /
 510                      EXT3_BLOCKS_PER_GROUP(sb);
 511        bit = (block - le32_to_cpu(es->s_first_data_block)) %
 512                      EXT3_BLOCKS_PER_GROUP(sb);
 513        /*
 514         * Check to see if we are freeing blocks across a group
 515         * boundary.
 516         */
 517        if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
 518                overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
 519                count -= overflow;
 520        }
 521        brelse(bitmap_bh);
 522        bitmap_bh = read_block_bitmap(sb, block_group);
 523        if (!bitmap_bh)
 524                goto error_return;
 525        desc = ext3_get_group_desc (sb, block_group, &gd_bh);
 526        if (!desc)
 527                goto error_return;
 528
 529        if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
 530            in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
 531            in_range (block, le32_to_cpu(desc->bg_inode_table),
 532                      sbi->s_itb_per_group) ||
 533            in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
 534                      sbi->s_itb_per_group)) {
 535                ext3_error (sb, "ext3_free_blocks",
 536                            "Freeing blocks in system zones - "
 537                            "Block = "E3FSBLK", count = %lu",
 538                            block, count);
 539                goto error_return;
 540        }
 541
 542        /*
 543         * We are about to start releasing blocks in the bitmap,
 544         * so we need undo access.
 545         */
 546        /* @@@ check errors */
 547        BUFFER_TRACE(bitmap_bh, "getting undo access");
 548        err = ext3_journal_get_undo_access(handle, bitmap_bh);
 549        if (err)
 550                goto error_return;
 551
 552        /*
 553         * We are about to modify some metadata.  Call the journal APIs
 554         * to unshare ->b_data if a currently-committing transaction is
 555         * using it
 556         */
 557        BUFFER_TRACE(gd_bh, "get_write_access");
 558        err = ext3_journal_get_write_access(handle, gd_bh);
 559        if (err)
 560                goto error_return;
 561
 562        jbd_lock_bh_state(bitmap_bh);
 563
 564        for (i = 0, group_freed = 0; i < count; i++) {
 565                /*
 566                 * An HJ special.  This is expensive...
 567                 */
 568#ifdef CONFIG_JBD_DEBUG
 569                jbd_unlock_bh_state(bitmap_bh);
 570                {
 571                        struct buffer_head *debug_bh;
 572                        debug_bh = sb_find_get_block(sb, block + i);
 573                        if (debug_bh) {
 574                                BUFFER_TRACE(debug_bh, "Deleted!");
 575                                if (!bh2jh(bitmap_bh)->b_committed_data)
 576                                        BUFFER_TRACE(debug_bh,
 577                                                "No commited data in bitmap");
 578                                BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
 579                                __brelse(debug_bh);
 580                        }
 581                }
 582                jbd_lock_bh_state(bitmap_bh);
 583#endif
 584                if (need_resched()) {
 585                        jbd_unlock_bh_state(bitmap_bh);
 586                        cond_resched();
 587                        jbd_lock_bh_state(bitmap_bh);
 588                }
 589                /* @@@ This prevents newly-allocated data from being
 590                 * freed and then reallocated within the same
 591                 * transaction.
 592                 *
 593                 * Ideally we would want to allow that to happen, but to
 594                 * do so requires making journal_forget() capable of
 595                 * revoking the queued write of a data block, which
 596                 * implies blocking on the journal lock.  *forget()
 597                 * cannot block due to truncate races.
 598                 *
 599                 * Eventually we can fix this by making journal_forget()
 600                 * return a status indicating whether or not it was able
 601                 * to revoke the buffer.  On successful revoke, it is
 602                 * safe not to set the allocation bit in the committed
 603                 * bitmap, because we know that there is no outstanding
 604                 * activity on the buffer any more and so it is safe to
 605                 * reallocate it.
 606                 */
 607                BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
 608                J_ASSERT_BH(bitmap_bh,
 609                                bh2jh(bitmap_bh)->b_committed_data != NULL);
 610                ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
 611                                bh2jh(bitmap_bh)->b_committed_data);
 612
 613                /*
 614                 * We clear the bit in the bitmap after setting the committed
 615                 * data bit, because this is the reverse order to that which
 616                 * the allocator uses.
 617                 */
 618                BUFFER_TRACE(bitmap_bh, "clear bit");
 619                if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 620                                                bit + i, bitmap_bh->b_data)) {
 621                        jbd_unlock_bh_state(bitmap_bh);
 622                        ext3_error(sb, __func__,
 623                                "bit already cleared for block "E3FSBLK,
 624                                 block + i);
 625                        jbd_lock_bh_state(bitmap_bh);
 626                        BUFFER_TRACE(bitmap_bh, "bit already cleared");
 627                } else {
 628                        group_freed++;
 629                }
 630        }
 631        jbd_unlock_bh_state(bitmap_bh);
 632
 633        spin_lock(sb_bgl_lock(sbi, block_group));
 634        le16_add_cpu(&desc->bg_free_blocks_count, group_freed);
 635        spin_unlock(sb_bgl_lock(sbi, block_group));
 636        percpu_counter_add(&sbi->s_freeblocks_counter, count);
 637
 638        /* We dirtied the bitmap block */
 639        BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
 640        err = ext3_journal_dirty_metadata(handle, bitmap_bh);
 641
 642        /* And the group descriptor block */
 643        BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 644        ret = ext3_journal_dirty_metadata(handle, gd_bh);
 645        if (!err) err = ret;
 646        *pdquot_freed_blocks += group_freed;
 647
 648        if (overflow && !err) {
 649                block += count;
 650                count = overflow;
 651                goto do_more;
 652        }
 653
 654error_return:
 655        brelse(bitmap_bh);
 656        ext3_std_error(sb, err);
 657        return;
 658}
 659
 660/**
 661 * ext3_free_blocks() -- Free given blocks and update quota
 662 * @handle:             handle for this transaction
 663 * @inode:              inode
 664 * @block:              start physical block to free
 665 * @count:              number of blocks to count
 666 */
 667void ext3_free_blocks(handle_t *handle, struct inode *inode,
 668                        ext3_fsblk_t block, unsigned long count)
 669{
 670        struct super_block * sb;
 671        unsigned long dquot_freed_blocks;
 672
 673        sb = inode->i_sb;
 674        if (!sb) {
 675                printk ("ext3_free_blocks: nonexistent device");
 676                return;
 677        }
 678        ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
 679        if (dquot_freed_blocks)
 680                dquot_free_block(inode, dquot_freed_blocks);
 681        return;
 682}
 683
 684/**
 685 * ext3_test_allocatable()
 686 * @nr:                 given allocation block group
 687 * @bh:                 bufferhead contains the bitmap of the given block group
 688 *
 689 * For ext3 allocations, we must not reuse any blocks which are
 690 * allocated in the bitmap buffer's "last committed data" copy.  This
 691 * prevents deletes from freeing up the page for reuse until we have
 692 * committed the delete transaction.
 693 *
 694 * If we didn't do this, then deleting something and reallocating it as
 695 * data would allow the old block to be overwritten before the
 696 * transaction committed (because we force data to disk before commit).
 697 * This would lead to corruption if we crashed between overwriting the
 698 * data and committing the delete.
 699 *
 700 * @@@ We may want to make this allocation behaviour conditional on
 701 * data-writes at some point, and disable it for metadata allocations or
 702 * sync-data inodes.
 703 */
 704static int ext3_test_allocatable(ext3_grpblk_t nr, struct buffer_head *bh)
 705{
 706        int ret;
 707        struct journal_head *jh = bh2jh(bh);
 708
 709        if (ext3_test_bit(nr, bh->b_data))
 710                return 0;
 711
 712        jbd_lock_bh_state(bh);
 713        if (!jh->b_committed_data)
 714                ret = 1;
 715        else
 716                ret = !ext3_test_bit(nr, jh->b_committed_data);
 717        jbd_unlock_bh_state(bh);
 718        return ret;
 719}
 720
 721/**
 722 * bitmap_search_next_usable_block()
 723 * @start:              the starting block (group relative) of the search
 724 * @bh:                 bufferhead contains the block group bitmap
 725 * @maxblocks:          the ending block (group relative) of the reservation
 726 *
 727 * The bitmap search --- search forward alternately through the actual
 728 * bitmap on disk and the last-committed copy in journal, until we find a
 729 * bit free in both bitmaps.
 730 */
 731static ext3_grpblk_t
 732bitmap_search_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
 733                                        ext3_grpblk_t maxblocks)
 734{
 735        ext3_grpblk_t next;
 736        struct journal_head *jh = bh2jh(bh);
 737
 738        while (start < maxblocks) {
 739                next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
 740                if (next >= maxblocks)
 741                        return -1;
 742                if (ext3_test_allocatable(next, bh))
 743                        return next;
 744                jbd_lock_bh_state(bh);
 745                if (jh->b_committed_data)
 746                        start = ext3_find_next_zero_bit(jh->b_committed_data,
 747                                                        maxblocks, next);
 748                jbd_unlock_bh_state(bh);
 749        }
 750        return -1;
 751}
 752
 753/**
 754 * find_next_usable_block()
 755 * @start:              the starting block (group relative) to find next
 756 *                      allocatable block in bitmap.
 757 * @bh:                 bufferhead contains the block group bitmap
 758 * @maxblocks:          the ending block (group relative) for the search
 759 *
 760 * Find an allocatable block in a bitmap.  We honor both the bitmap and
 761 * its last-committed copy (if that exists), and perform the "most
 762 * appropriate allocation" algorithm of looking for a free block near
 763 * the initial goal; then for a free byte somewhere in the bitmap; then
 764 * for any free bit in the bitmap.
 765 */
 766static ext3_grpblk_t
 767find_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
 768                        ext3_grpblk_t maxblocks)
 769{
 770        ext3_grpblk_t here, next;
 771        char *p, *r;
 772
 773        if (start > 0) {
 774                /*
 775                 * The goal was occupied; search forward for a free
 776                 * block within the next XX blocks.
 777                 *
 778                 * end_goal is more or less random, but it has to be
 779                 * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
 780                 * next 64-bit boundary is simple..
 781                 */
 782                ext3_grpblk_t end_goal = (start + 63) & ~63;
 783                if (end_goal > maxblocks)
 784                        end_goal = maxblocks;
 785                here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
 786                if (here < end_goal && ext3_test_allocatable(here, bh))
 787                        return here;
 788                ext3_debug("Bit not found near goal\n");
 789        }
 790
 791        here = start;
 792        if (here < 0)
 793                here = 0;
 794
 795        p = ((char *)bh->b_data) + (here >> 3);
 796        r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
 797        next = (r - ((char *)bh->b_data)) << 3;
 798
 799        if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
 800                return next;
 801
 802        /*
 803         * The bitmap search --- search forward alternately through the actual
 804         * bitmap and the last-committed copy until we find a bit free in
 805         * both
 806         */
 807        here = bitmap_search_next_usable_block(here, bh, maxblocks);
 808        return here;
 809}
 810
 811/**
 812 * claim_block()
 813 * @block:              the free block (group relative) to allocate
 814 * @bh:                 the bufferhead containts the block group bitmap
 815 *
 816 * We think we can allocate this block in this bitmap.  Try to set the bit.
 817 * If that succeeds then check that nobody has allocated and then freed the
 818 * block since we saw that is was not marked in b_committed_data.  If it _was_
 819 * allocated and freed then clear the bit in the bitmap again and return
 820 * zero (failure).
 821 */
 822static inline int
 823claim_block(spinlock_t *lock, ext3_grpblk_t block, struct buffer_head *bh)
 824{
 825        struct journal_head *jh = bh2jh(bh);
 826        int ret;
 827
 828        if (ext3_set_bit_atomic(lock, block, bh->b_data))
 829                return 0;
 830        jbd_lock_bh_state(bh);
 831        if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
 832                ext3_clear_bit_atomic(lock, block, bh->b_data);
 833                ret = 0;
 834        } else {
 835                ret = 1;
 836        }
 837        jbd_unlock_bh_state(bh);
 838        return ret;
 839}
 840
 841/**
 842 * ext3_try_to_allocate()
 843 * @sb:                 superblock
 844 * @handle:             handle to this transaction
 845 * @group:              given allocation block group
 846 * @bitmap_bh:          bufferhead holds the block bitmap
 847 * @grp_goal:           given target block within the group
 848 * @count:              target number of blocks to allocate
 849 * @my_rsv:             reservation window
 850 *
 851 * Attempt to allocate blocks within a give range. Set the range of allocation
 852 * first, then find the first free bit(s) from the bitmap (within the range),
 853 * and at last, allocate the blocks by claiming the found free bit as allocated.
 854 *
 855 * To set the range of this allocation:
 856 *      if there is a reservation window, only try to allocate block(s) from the
 857 *      file's own reservation window;
 858 *      Otherwise, the allocation range starts from the give goal block, ends at
 859 *      the block group's last block.
 860 *
 861 * If we failed to allocate the desired block then we may end up crossing to a
 862 * new bitmap.  In that case we must release write access to the old one via
 863 * ext3_journal_release_buffer(), else we'll run out of credits.
 864 */
 865static ext3_grpblk_t
 866ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
 867                        struct buffer_head *bitmap_bh, ext3_grpblk_t grp_goal,
 868                        unsigned long *count, struct ext3_reserve_window *my_rsv)
 869{
 870        ext3_fsblk_t group_first_block;
 871        ext3_grpblk_t start, end;
 872        unsigned long num = 0;
 873
 874        /* we do allocation within the reservation window if we have a window */
 875        if (my_rsv) {
 876                group_first_block = ext3_group_first_block_no(sb, group);
 877                if (my_rsv->_rsv_start >= group_first_block)
 878                        start = my_rsv->_rsv_start - group_first_block;
 879                else
 880                        /* reservation window cross group boundary */
 881                        start = 0;
 882                end = my_rsv->_rsv_end - group_first_block + 1;
 883                if (end > EXT3_BLOCKS_PER_GROUP(sb))
 884                        /* reservation window crosses group boundary */
 885                        end = EXT3_BLOCKS_PER_GROUP(sb);
 886                if ((start <= grp_goal) && (grp_goal < end))
 887                        start = grp_goal;
 888                else
 889                        grp_goal = -1;
 890        } else {
 891                if (grp_goal > 0)
 892                        start = grp_goal;
 893                else
 894                        start = 0;
 895                end = EXT3_BLOCKS_PER_GROUP(sb);
 896        }
 897
 898        BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
 899
 900repeat:
 901        if (grp_goal < 0 || !ext3_test_allocatable(grp_goal, bitmap_bh)) {
 902                grp_goal = find_next_usable_block(start, bitmap_bh, end);
 903                if (grp_goal < 0)
 904                        goto fail_access;
 905                if (!my_rsv) {
 906                        int i;
 907
 908                        for (i = 0; i < 7 && grp_goal > start &&
 909                                        ext3_test_allocatable(grp_goal - 1,
 910                                                                bitmap_bh);
 911                                        i++, grp_goal--)
 912                                ;
 913                }
 914        }
 915        start = grp_goal;
 916
 917        if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group),
 918                grp_goal, bitmap_bh)) {
 919                /*
 920                 * The block was allocated by another thread, or it was
 921                 * allocated and then freed by another thread
 922                 */
 923                start++;
 924                grp_goal++;
 925                if (start >= end)
 926                        goto fail_access;
 927                goto repeat;
 928        }
 929        num++;
 930        grp_goal++;
 931        while (num < *count && grp_goal < end
 932                && ext3_test_allocatable(grp_goal, bitmap_bh)
 933                && claim_block(sb_bgl_lock(EXT3_SB(sb), group),
 934                                grp_goal, bitmap_bh)) {
 935                num++;
 936                grp_goal++;
 937        }
 938        *count = num;
 939        return grp_goal - num;
 940fail_access:
 941        *count = num;
 942        return -1;
 943}
 944
 945/**
 946 *      find_next_reservable_window():
 947 *              find a reservable space within the given range.
 948 *              It does not allocate the reservation window for now:
 949 *              alloc_new_reservation() will do the work later.
 950 *
 951 *      @search_head: the head of the searching list;
 952 *              This is not necessarily the list head of the whole filesystem
 953 *
 954 *              We have both head and start_block to assist the search
 955 *              for the reservable space. The list starts from head,
 956 *              but we will shift to the place where start_block is,
 957 *              then start from there, when looking for a reservable space.
 958 *
 959 *      @size: the target new reservation window size
 960 *
 961 *      @group_first_block: the first block we consider to start
 962 *                      the real search from
 963 *
 964 *      @last_block:
 965 *              the maximum block number that our goal reservable space
 966 *              could start from. This is normally the last block in this
 967 *              group. The search will end when we found the start of next
 968 *              possible reservable space is out of this boundary.
 969 *              This could handle the cross boundary reservation window
 970 *              request.
 971 *
 972 *      basically we search from the given range, rather than the whole
 973 *      reservation double linked list, (start_block, last_block)
 974 *      to find a free region that is of my size and has not
 975 *      been reserved.
 976 *
 977 */
 978static int find_next_reservable_window(
 979                                struct ext3_reserve_window_node *search_head,
 980                                struct ext3_reserve_window_node *my_rsv,
 981                                struct super_block * sb,
 982                                ext3_fsblk_t start_block,
 983                                ext3_fsblk_t last_block)
 984{
 985        struct rb_node *next;
 986        struct ext3_reserve_window_node *rsv, *prev;
 987        ext3_fsblk_t cur;
 988        int size = my_rsv->rsv_goal_size;
 989
 990        /* TODO: make the start of the reservation window byte-aligned */
 991        /* cur = *start_block & ~7;*/
 992        cur = start_block;
 993        rsv = search_head;
 994        if (!rsv)
 995                return -1;
 996
 997        while (1) {
 998                if (cur <= rsv->rsv_end)
 999                        cur = rsv->rsv_end + 1;
1000
1001                /* TODO?
1002                 * in the case we could not find a reservable space
1003                 * that is what is expected, during the re-search, we could
1004                 * remember what's the largest reservable space we could have
1005                 * and return that one.
1006                 *
1007                 * For now it will fail if we could not find the reservable
1008                 * space with expected-size (or more)...
1009                 */
1010                if (cur > last_block)
1011                        return -1;              /* fail */
1012
1013                prev = rsv;
1014                next = rb_next(&rsv->rsv_node);
1015                rsv = rb_entry(next,struct ext3_reserve_window_node,rsv_node);
1016
1017                /*
1018                 * Reached the last reservation, we can just append to the
1019                 * previous one.
1020                 */
1021                if (!next)
1022                        break;
1023
1024                if (cur + size <= rsv->rsv_start) {
1025                        /*
1026                         * Found a reserveable space big enough.  We could
1027                         * have a reservation across the group boundary here
1028                         */
1029                        break;
1030                }
1031        }
1032        /*
1033         * we come here either :
1034         * when we reach the end of the whole list,
1035         * and there is empty reservable space after last entry in the list.
1036         * append it to the end of the list.
1037         *
1038         * or we found one reservable space in the middle of the list,
1039         * return the reservation window that we could append to.
1040         * succeed.
1041         */
1042
1043        if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
1044                rsv_window_remove(sb, my_rsv);
1045
1046        /*
1047         * Let's book the whole avaliable window for now.  We will check the
1048         * disk bitmap later and then, if there are free blocks then we adjust
1049         * the window size if it's larger than requested.
1050         * Otherwise, we will remove this node from the tree next time
1051         * call find_next_reservable_window.
1052         */
1053        my_rsv->rsv_start = cur;
1054        my_rsv->rsv_end = cur + size - 1;
1055        my_rsv->rsv_alloc_hit = 0;
1056
1057        if (prev != my_rsv)
1058                ext3_rsv_window_add(sb, my_rsv);
1059
1060        return 0;
1061}
1062
1063/**
1064 *      alloc_new_reservation()--allocate a new reservation window
1065 *
1066 *              To make a new reservation, we search part of the filesystem
1067 *              reservation list (the list that inside the group). We try to
1068 *              allocate a new reservation window near the allocation goal,
1069 *              or the beginning of the group, if there is no goal.
1070 *
1071 *              We first find a reservable space after the goal, then from
1072 *              there, we check the bitmap for the first free block after
1073 *              it. If there is no free block until the end of group, then the
1074 *              whole group is full, we failed. Otherwise, check if the free
1075 *              block is inside the expected reservable space, if so, we
1076 *              succeed.
1077 *              If the first free block is outside the reservable space, then
1078 *              start from the first free block, we search for next available
1079 *              space, and go on.
1080 *
1081 *      on succeed, a new reservation will be found and inserted into the list
1082 *      It contains at least one free block, and it does not overlap with other
1083 *      reservation windows.
1084 *
1085 *      failed: we failed to find a reservation window in this group
1086 *
1087 *      @rsv: the reservation
1088 *
1089 *      @grp_goal: The goal (group-relative).  It is where the search for a
1090 *              free reservable space should start from.
1091 *              if we have a grp_goal(grp_goal >0 ), then start from there,
1092 *              no grp_goal(grp_goal = -1), we start from the first block
1093 *              of the group.
1094 *
1095 *      @sb: the super block
1096 *      @group: the group we are trying to allocate in
1097 *      @bitmap_bh: the block group block bitmap
1098 *
1099 */
1100static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
1101                ext3_grpblk_t grp_goal, struct super_block *sb,
1102                unsigned int group, struct buffer_head *bitmap_bh)
1103{
1104        struct ext3_reserve_window_node *search_head;
1105        ext3_fsblk_t group_first_block, group_end_block, start_block;
1106        ext3_grpblk_t first_free_block;
1107        struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
1108        unsigned long size;
1109        int ret;
1110        spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1111
1112        group_first_block = ext3_group_first_block_no(sb, group);
1113        group_end_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
1114
1115        if (grp_goal < 0)
1116                start_block = group_first_block;
1117        else
1118                start_block = grp_goal + group_first_block;
1119
1120        size = my_rsv->rsv_goal_size;
1121
1122        if (!rsv_is_empty(&my_rsv->rsv_window)) {
1123                /*
1124                 * if the old reservation is cross group boundary
1125                 * and if the goal is inside the old reservation window,
1126                 * we will come here when we just failed to allocate from
1127                 * the first part of the window. We still have another part
1128                 * that belongs to the next group. In this case, there is no
1129                 * point to discard our window and try to allocate a new one
1130                 * in this group(which will fail). we should
1131                 * keep the reservation window, just simply move on.
1132                 *
1133                 * Maybe we could shift the start block of the reservation
1134                 * window to the first block of next group.
1135                 */
1136
1137                if ((my_rsv->rsv_start <= group_end_block) &&
1138                                (my_rsv->rsv_end > group_end_block) &&
1139                                (start_block >= my_rsv->rsv_start))
1140                        return -1;
1141
1142                if ((my_rsv->rsv_alloc_hit >
1143                     (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
1144                        /*
1145                         * if the previously allocation hit ratio is
1146                         * greater than 1/2, then we double the size of
1147                         * the reservation window the next time,
1148                         * otherwise we keep the same size window
1149                         */
1150                        size = size * 2;
1151                        if (size > EXT3_MAX_RESERVE_BLOCKS)
1152                                size = EXT3_MAX_RESERVE_BLOCKS;
1153                        my_rsv->rsv_goal_size= size;
1154                }
1155        }
1156
1157        spin_lock(rsv_lock);
1158        /*
1159         * shift the search start to the window near the goal block
1160         */
1161        search_head = search_reserve_window(fs_rsv_root, start_block);
1162
1163        /*
1164         * find_next_reservable_window() simply finds a reservable window
1165         * inside the given range(start_block, group_end_block).
1166         *
1167         * To make sure the reservation window has a free bit inside it, we
1168         * need to check the bitmap after we found a reservable window.
1169         */
1170retry:
1171        ret = find_next_reservable_window(search_head, my_rsv, sb,
1172                                                start_block, group_end_block);
1173
1174        if (ret == -1) {
1175                if (!rsv_is_empty(&my_rsv->rsv_window))
1176                        rsv_window_remove(sb, my_rsv);
1177                spin_unlock(rsv_lock);
1178                return -1;
1179        }
1180
1181        /*
1182         * On success, find_next_reservable_window() returns the
1183         * reservation window where there is a reservable space after it.
1184         * Before we reserve this reservable space, we need
1185         * to make sure there is at least a free block inside this region.
1186         *
1187         * searching the first free bit on the block bitmap and copy of
1188         * last committed bitmap alternatively, until we found a allocatable
1189         * block. Search start from the start block of the reservable space
1190         * we just found.
1191         */
1192        spin_unlock(rsv_lock);
1193        first_free_block = bitmap_search_next_usable_block(
1194                        my_rsv->rsv_start - group_first_block,
1195                        bitmap_bh, group_end_block - group_first_block + 1);
1196
1197        if (first_free_block < 0) {
1198                /*
1199                 * no free block left on the bitmap, no point
1200                 * to reserve the space. return failed.
1201                 */
1202                spin_lock(rsv_lock);
1203                if (!rsv_is_empty(&my_rsv->rsv_window))
1204                        rsv_window_remove(sb, my_rsv);
1205                spin_unlock(rsv_lock);
1206                return -1;              /* failed */
1207        }
1208
1209        start_block = first_free_block + group_first_block;
1210        /*
1211         * check if the first free block is within the
1212         * free space we just reserved
1213         */
1214        if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
1215                return 0;               /* success */
1216        /*
1217         * if the first free bit we found is out of the reservable space
1218         * continue search for next reservable space,
1219         * start from where the free block is,
1220         * we also shift the list head to where we stopped last time
1221         */
1222        search_head = my_rsv;
1223        spin_lock(rsv_lock);
1224        goto retry;
1225}
1226
1227/**
1228 * try_to_extend_reservation()
1229 * @my_rsv:             given reservation window
1230 * @sb:                 super block
1231 * @size:               the delta to extend
1232 *
1233 * Attempt to expand the reservation window large enough to have
1234 * required number of free blocks
1235 *
1236 * Since ext3_try_to_allocate() will always allocate blocks within
1237 * the reservation window range, if the window size is too small,
1238 * multiple blocks allocation has to stop at the end of the reservation
1239 * window. To make this more efficient, given the total number of
1240 * blocks needed and the current size of the window, we try to
1241 * expand the reservation window size if necessary on a best-effort
1242 * basis before ext3_new_blocks() tries to allocate blocks,
1243 */
1244static void try_to_extend_reservation(struct ext3_reserve_window_node *my_rsv,
1245                        struct super_block *sb, int size)
1246{
1247        struct ext3_reserve_window_node *next_rsv;
1248        struct rb_node *next;
1249        spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1250
1251        if (!spin_trylock(rsv_lock))
1252                return;
1253
1254        next = rb_next(&my_rsv->rsv_node);
1255
1256        if (!next)
1257                my_rsv->rsv_end += size;
1258        else {
1259                next_rsv = rb_entry(next, struct ext3_reserve_window_node, rsv_node);
1260
1261                if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1262                        my_rsv->rsv_end += size;
1263                else
1264                        my_rsv->rsv_end = next_rsv->rsv_start - 1;
1265        }
1266        spin_unlock(rsv_lock);
1267}
1268
1269/**
1270 * ext3_try_to_allocate_with_rsv()
1271 * @sb:                 superblock
1272 * @handle:             handle to this transaction
1273 * @group:              given allocation block group
1274 * @bitmap_bh:          bufferhead holds the block bitmap
1275 * @grp_goal:           given target block within the group
1276 * @count:              target number of blocks to allocate
1277 * @my_rsv:             reservation window
1278 * @errp:               pointer to store the error code
1279 *
1280 * This is the main function used to allocate a new block and its reservation
1281 * window.
1282 *
1283 * Each time when a new block allocation is need, first try to allocate from
1284 * its own reservation.  If it does not have a reservation window, instead of
1285 * looking for a free bit on bitmap first, then look up the reservation list to
1286 * see if it is inside somebody else's reservation window, we try to allocate a
1287 * reservation window for it starting from the goal first. Then do the block
1288 * allocation within the reservation window.
1289 *
1290 * This will avoid keeping on searching the reservation list again and
1291 * again when somebody is looking for a free block (without
1292 * reservation), and there are lots of free blocks, but they are all
1293 * being reserved.
1294 *
1295 * We use a red-black tree for the per-filesystem reservation list.
1296 *
1297 */
1298static ext3_grpblk_t
1299ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1300                        unsigned int group, struct buffer_head *bitmap_bh,
1301                        ext3_grpblk_t grp_goal,
1302                        struct ext3_reserve_window_node * my_rsv,
1303                        unsigned long *count, int *errp)
1304{
1305        ext3_fsblk_t group_first_block, group_last_block;
1306        ext3_grpblk_t ret = 0;
1307        int fatal;
1308        unsigned long num = *count;
1309
1310        *errp = 0;
1311
1312        /*
1313         * Make sure we use undo access for the bitmap, because it is critical
1314         * that we do the frozen_data COW on bitmap buffers in all cases even
1315         * if the buffer is in BJ_Forget state in the committing transaction.
1316         */
1317        BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1318        fatal = ext3_journal_get_undo_access(handle, bitmap_bh);
1319        if (fatal) {
1320                *errp = fatal;
1321                return -1;
1322        }
1323
1324        /*
1325         * we don't deal with reservation when
1326         * filesystem is mounted without reservation
1327         * or the file is not a regular file
1328         * or last attempt to allocate a block with reservation turned on failed
1329         */
1330        if (my_rsv == NULL ) {
1331                ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,
1332                                                grp_goal, count, NULL);
1333                goto out;
1334        }
1335        /*
1336         * grp_goal is a group relative block number (if there is a goal)
1337         * 0 <= grp_goal < EXT3_BLOCKS_PER_GROUP(sb)
1338         * first block is a filesystem wide block number
1339         * first block is the block number of the first block in this group
1340         */
1341        group_first_block = ext3_group_first_block_no(sb, group);
1342        group_last_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
1343
1344        /*
1345         * Basically we will allocate a new block from inode's reservation
1346         * window.
1347         *
1348         * We need to allocate a new reservation window, if:
1349         * a) inode does not have a reservation window; or
1350         * b) last attempt to allocate a block from existing reservation
1351         *    failed; or
1352         * c) we come here with a goal and with a reservation window
1353         *
1354         * We do not need to allocate a new reservation window if we come here
1355         * at the beginning with a goal and the goal is inside the window, or
1356         * we don't have a goal but already have a reservation window.
1357         * then we could go to allocate from the reservation window directly.
1358         */
1359        while (1) {
1360                if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1361                        !goal_in_my_reservation(&my_rsv->rsv_window,
1362                                                grp_goal, group, sb)) {
1363                        if (my_rsv->rsv_goal_size < *count)
1364                                my_rsv->rsv_goal_size = *count;
1365                        ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1366                                                        group, bitmap_bh);
1367                        if (ret < 0)
1368                                break;                  /* failed */
1369
1370                        if (!goal_in_my_reservation(&my_rsv->rsv_window,
1371                                                        grp_goal, group, sb))
1372                                grp_goal = -1;
1373                } else if (grp_goal >= 0) {
1374                        int curr = my_rsv->rsv_end -
1375                                        (grp_goal + group_first_block) + 1;
1376
1377                        if (curr < *count)
1378                                try_to_extend_reservation(my_rsv, sb,
1379                                                        *count - curr);
1380                }
1381
1382                if ((my_rsv->rsv_start > group_last_block) ||
1383                                (my_rsv->rsv_end < group_first_block)) {
1384                        rsv_window_dump(&EXT3_SB(sb)->s_rsv_window_root, 1);
1385                        BUG();
1386                }
1387                ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,
1388                                           grp_goal, &num, &my_rsv->rsv_window);
1389                if (ret >= 0) {
1390                        my_rsv->rsv_alloc_hit += num;
1391                        *count = num;
1392                        break;                          /* succeed */
1393                }
1394                num = *count;
1395        }
1396out:
1397        if (ret >= 0) {
1398                BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1399                                        "bitmap block");
1400                fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
1401                if (fatal) {
1402                        *errp = fatal;
1403                        return -1;
1404                }
1405                return ret;
1406        }
1407
1408        BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1409        ext3_journal_release_buffer(handle, bitmap_bh);
1410        return ret;
1411}
1412
1413/**
1414 * ext3_has_free_blocks()
1415 * @sbi:                in-core super block structure.
1416 *
1417 * Check if filesystem has at least 1 free block available for allocation.
1418 */
1419static int ext3_has_free_blocks(struct ext3_sb_info *sbi)
1420{
1421        ext3_fsblk_t free_blocks, root_blocks;
1422
1423        free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1424        root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1425        if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1426                sbi->s_resuid != current_fsuid() &&
1427                (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
1428                return 0;
1429        }
1430        return 1;
1431}
1432
1433/**
1434 * ext3_should_retry_alloc()
1435 * @sb:                 super block
1436 * @retries             number of attemps has been made
1437 *
1438 * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
1439 * it is profitable to retry the operation, this function will wait
1440 * for the current or commiting transaction to complete, and then
1441 * return TRUE.
1442 *
1443 * if the total number of retries exceed three times, return FALSE.
1444 */
1445int ext3_should_retry_alloc(struct super_block *sb, int *retries)
1446{
1447        if (!ext3_has_free_blocks(EXT3_SB(sb)) || (*retries)++ > 3)
1448                return 0;
1449
1450        jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1451
1452        return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
1453}
1454
1455/**
1456 * ext3_new_blocks() -- core block(s) allocation function
1457 * @handle:             handle to this transaction
1458 * @inode:              file inode
1459 * @goal:               given target block(filesystem wide)
1460 * @count:              target number of blocks to allocate
1461 * @errp:               error code
1462 *
1463 * ext3_new_blocks uses a goal block to assist allocation.  It tries to
1464 * allocate block(s) from the block group contains the goal block first. If that
1465 * fails, it will try to allocate block(s) from other block groups without
1466 * any specific goal block.
1467 *
1468 */
1469ext3_fsblk_t ext3_new_blocks(handle_t *handle, struct inode *inode,
1470                        ext3_fsblk_t goal, unsigned long *count, int *errp)
1471{
1472        struct buffer_head *bitmap_bh = NULL;
1473        struct buffer_head *gdp_bh;
1474        int group_no;
1475        int goal_group;
1476        ext3_grpblk_t grp_target_blk;   /* blockgroup relative goal block */
1477        ext3_grpblk_t grp_alloc_blk;    /* blockgroup-relative allocated block*/
1478        ext3_fsblk_t ret_block;         /* filesyetem-wide allocated block */
1479        int bgi;                        /* blockgroup iteration index */
1480        int fatal = 0, err;
1481        int performed_allocation = 0;
1482        ext3_grpblk_t free_blocks;      /* number of free blocks in a group */
1483        struct super_block *sb;
1484        struct ext3_group_desc *gdp;
1485        struct ext3_super_block *es;
1486        struct ext3_sb_info *sbi;
1487        struct ext3_reserve_window_node *my_rsv = NULL;
1488        struct ext3_block_alloc_info *block_i;
1489        unsigned short windowsz = 0;
1490#ifdef EXT3FS_DEBUG
1491        static int goal_hits, goal_attempts;
1492#endif
1493        unsigned long ngroups;
1494        unsigned long num = *count;
1495
1496        *errp = -ENOSPC;
1497        sb = inode->i_sb;
1498        if (!sb) {
1499                printk("ext3_new_block: nonexistent device");
1500                return 0;
1501        }
1502
1503        /*
1504         * Check quota for allocation of this block.
1505         */
1506        err = dquot_alloc_block(inode, num);
1507        if (err) {
1508                *errp = err;
1509                return 0;
1510        }
1511
1512        sbi = EXT3_SB(sb);
1513        es = EXT3_SB(sb)->s_es;
1514        ext3_debug("goal=%lu.\n", goal);
1515        /*
1516         * Allocate a block from reservation only when
1517         * filesystem is mounted with reservation(default,-o reservation), and
1518         * it's a regular file, and
1519         * the desired window size is greater than 0 (One could use ioctl
1520         * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
1521         * reservation on that particular file)
1522         */
1523        block_i = EXT3_I(inode)->i_block_alloc_info;
1524        if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
1525                my_rsv = &block_i->rsv_window_node;
1526
1527        if (!ext3_has_free_blocks(sbi)) {
1528                *errp = -ENOSPC;
1529                goto out;
1530        }
1531
1532        /*
1533         * First, test whether the goal block is free.
1534         */
1535        if (goal < le32_to_cpu(es->s_first_data_block) ||
1536            goal >= le32_to_cpu(es->s_blocks_count))
1537                goal = le32_to_cpu(es->s_first_data_block);
1538        group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1539                        EXT3_BLOCKS_PER_GROUP(sb);
1540        goal_group = group_no;
1541retry_alloc:
1542        gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1543        if (!gdp)
1544                goto io_error;
1545
1546        free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1547        /*
1548         * if there is not enough free blocks to make a new resevation
1549         * turn off reservation for this allocation
1550         */
1551        if (my_rsv && (free_blocks < windowsz)
1552                && (free_blocks > 0)
1553                && (rsv_is_empty(&my_rsv->rsv_window)))
1554                my_rsv = NULL;
1555
1556        if (free_blocks > 0) {
1557                grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1558                                EXT3_BLOCKS_PER_GROUP(sb));
1559                bitmap_bh = read_block_bitmap(sb, group_no);
1560                if (!bitmap_bh)
1561                        goto io_error;
1562                grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1563                                        group_no, bitmap_bh, grp_target_blk,
1564                                        my_rsv, &num, &fatal);
1565                if (fatal)
1566                        goto out;
1567                if (grp_alloc_blk >= 0)
1568                        goto allocated;
1569        }
1570
1571        ngroups = EXT3_SB(sb)->s_groups_count;
1572        smp_rmb();
1573
1574        /*
1575         * Now search the rest of the groups.  We assume that
1576         * group_no and gdp correctly point to the last group visited.
1577         */
1578        for (bgi = 0; bgi < ngroups; bgi++) {
1579                group_no++;
1580                if (group_no >= ngroups)
1581                        group_no = 0;
1582                gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1583                if (!gdp)
1584                        goto io_error;
1585                free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1586                /*
1587                 * skip this group (and avoid loading bitmap) if there
1588                 * are no free blocks
1589                 */
1590                if (!free_blocks)
1591                        continue;
1592                /*
1593                 * skip this group if the number of
1594                 * free blocks is less than half of the reservation
1595                 * window size.
1596                 */
1597                if (my_rsv && (free_blocks <= (windowsz/2)))
1598                        continue;
1599
1600                brelse(bitmap_bh);
1601                bitmap_bh = read_block_bitmap(sb, group_no);
1602                if (!bitmap_bh)
1603                        goto io_error;
1604                /*
1605                 * try to allocate block(s) from this group, without a goal(-1).
1606                 */
1607                grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1608                                        group_no, bitmap_bh, -1, my_rsv,
1609                                        &num, &fatal);
1610                if (fatal)
1611                        goto out;
1612                if (grp_alloc_blk >= 0)
1613                        goto allocated;
1614        }
1615        /*
1616         * We may end up a bogus ealier ENOSPC error due to
1617         * filesystem is "full" of reservations, but
1618         * there maybe indeed free blocks avaliable on disk
1619         * In this case, we just forget about the reservations
1620         * just do block allocation as without reservations.
1621         */
1622        if (my_rsv) {
1623                my_rsv = NULL;
1624                windowsz = 0;
1625                group_no = goal_group;
1626                goto retry_alloc;
1627        }
1628        /* No space left on the device */
1629        *errp = -ENOSPC;
1630        goto out;
1631
1632allocated:
1633
1634        ext3_debug("using block group %d(%d)\n",
1635                        group_no, gdp->bg_free_blocks_count);
1636
1637        BUFFER_TRACE(gdp_bh, "get_write_access");
1638        fatal = ext3_journal_get_write_access(handle, gdp_bh);
1639        if (fatal)
1640                goto out;
1641
1642        ret_block = grp_alloc_blk + ext3_group_first_block_no(sb, group_no);
1643
1644        if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1645            in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1646            in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1647                      EXT3_SB(sb)->s_itb_per_group) ||
1648            in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1649                      EXT3_SB(sb)->s_itb_per_group)) {
1650                ext3_error(sb, "ext3_new_block",
1651                            "Allocating block in system zone - "
1652                            "blocks from "E3FSBLK", length %lu",
1653                             ret_block, num);
1654                /*
1655                 * claim_block() marked the blocks we allocated as in use. So we
1656                 * may want to selectively mark some of the blocks as free.
1657                 */
1658                goto retry_alloc;
1659        }
1660
1661        performed_allocation = 1;
1662
1663#ifdef CONFIG_JBD_DEBUG
1664        {
1665                struct buffer_head *debug_bh;
1666
1667                /* Record bitmap buffer state in the newly allocated block */
1668                debug_bh = sb_find_get_block(sb, ret_block);
1669                if (debug_bh) {
1670                        BUFFER_TRACE(debug_bh, "state when allocated");
1671                        BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1672                        brelse(debug_bh);
1673                }
1674        }
1675        jbd_lock_bh_state(bitmap_bh);
1676        spin_lock(sb_bgl_lock(sbi, group_no));
1677        if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1678                int i;
1679
1680                for (i = 0; i < num; i++) {
1681                        if (ext3_test_bit(grp_alloc_blk+i,
1682                                        bh2jh(bitmap_bh)->b_committed_data)) {
1683                                printk("%s: block was unexpectedly set in "
1684                                        "b_committed_data\n", __func__);
1685                        }
1686                }
1687        }
1688        ext3_debug("found bit %d\n", grp_alloc_blk);
1689        spin_unlock(sb_bgl_lock(sbi, group_no));
1690        jbd_unlock_bh_state(bitmap_bh);
1691#endif
1692
1693        if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1694                ext3_error(sb, "ext3_new_block",
1695                            "block("E3FSBLK") >= blocks count(%d) - "
1696                            "block_group = %d, es == %p ", ret_block,
1697                        le32_to_cpu(es->s_blocks_count), group_no, es);
1698                goto out;
1699        }
1700
1701        /*
1702         * It is up to the caller to add the new buffer to a journal
1703         * list of some description.  We don't know in advance whether
1704         * the caller wants to use it as metadata or data.
1705         */
1706        ext3_debug("allocating block %lu. Goal hits %d of %d.\n",
1707                        ret_block, goal_hits, goal_attempts);
1708
1709        spin_lock(sb_bgl_lock(sbi, group_no));
1710        le16_add_cpu(&gdp->bg_free_blocks_count, -num);
1711        spin_unlock(sb_bgl_lock(sbi, group_no));
1712        percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1713
1714        BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1715        err = ext3_journal_dirty_metadata(handle, gdp_bh);
1716        if (!fatal)
1717                fatal = err;
1718
1719        if (fatal)
1720                goto out;
1721
1722        *errp = 0;
1723        brelse(bitmap_bh);
1724        dquot_free_block(inode, *count-num);
1725        *count = num;
1726        return ret_block;
1727
1728io_error:
1729        *errp = -EIO;
1730out:
1731        if (fatal) {
1732                *errp = fatal;
1733                ext3_std_error(sb, fatal);
1734        }
1735        /*
1736         * Undo the block allocation
1737         */
1738        if (!performed_allocation)
1739                dquot_free_block(inode, *count);
1740        brelse(bitmap_bh);
1741        return 0;
1742}
1743
1744ext3_fsblk_t ext3_new_block(handle_t *handle, struct inode *inode,
1745                        ext3_fsblk_t goal, int *errp)
1746{
1747        unsigned long count = 1;
1748
1749        return ext3_new_blocks(handle, inode, goal, &count, errp);
1750}
1751
1752/**
1753 * ext3_count_free_blocks() -- count filesystem free blocks
1754 * @sb:         superblock
1755 *
1756 * Adds up the number of free blocks from each block group.
1757 */
1758ext3_fsblk_t ext3_count_free_blocks(struct super_block *sb)
1759{
1760        ext3_fsblk_t desc_count;
1761        struct ext3_group_desc *gdp;
1762        int i;
1763        unsigned long ngroups = EXT3_SB(sb)->s_groups_count;
1764#ifdef EXT3FS_DEBUG
1765        struct ext3_super_block *es;
1766        ext3_fsblk_t bitmap_count;
1767        unsigned long x;
1768        struct buffer_head *bitmap_bh = NULL;
1769
1770        es = EXT3_SB(sb)->s_es;
1771        desc_count = 0;
1772        bitmap_count = 0;
1773        gdp = NULL;
1774
1775        smp_rmb();
1776        for (i = 0; i < ngroups; i++) {
1777                gdp = ext3_get_group_desc(sb, i, NULL);
1778                if (!gdp)
1779                        continue;
1780                desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1781                brelse(bitmap_bh);
1782                bitmap_bh = read_block_bitmap(sb, i);
1783                if (bitmap_bh == NULL)
1784                        continue;
1785
1786                x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1787                printk("group %d: stored = %d, counted = %lu\n",
1788                        i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1789                bitmap_count += x;
1790        }
1791        brelse(bitmap_bh);
1792        printk("ext3_count_free_blocks: stored = "E3FSBLK
1793                ", computed = "E3FSBLK", "E3FSBLK"\n",
1794               le32_to_cpu(es->s_free_blocks_count),
1795                desc_count, bitmap_count);
1796        return bitmap_count;
1797#else
1798        desc_count = 0;
1799        smp_rmb();
1800        for (i = 0; i < ngroups; i++) {
1801                gdp = ext3_get_group_desc(sb, i, NULL);
1802                if (!gdp)
1803                        continue;
1804                desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1805        }
1806
1807        return desc_count;
1808#endif
1809}
1810
1811static inline int test_root(int a, int b)
1812{
1813        int num = b;
1814
1815        while (a > num)
1816                num *= b;
1817        return num == a;
1818}
1819
1820static int ext3_group_sparse(int group)
1821{
1822        if (group <= 1)
1823                return 1;
1824        if (!(group & 1))
1825                return 0;
1826        return (test_root(group, 7) || test_root(group, 5) ||
1827                test_root(group, 3));
1828}
1829
1830/**
1831 *      ext3_bg_has_super - number of blocks used by the superblock in group
1832 *      @sb: superblock for filesystem
1833 *      @group: group number to check
1834 *
1835 *      Return the number of blocks used by the superblock (primary or backup)
1836 *      in this group.  Currently this will be only 0 or 1.
1837 */
1838int ext3_bg_has_super(struct super_block *sb, int group)
1839{
1840        if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
1841                                EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1842                        !ext3_group_sparse(group))
1843                return 0;
1844        return 1;
1845}
1846
1847static unsigned long ext3_bg_num_gdb_meta(struct super_block *sb, int group)
1848{
1849        unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1850        unsigned long first = metagroup * EXT3_DESC_PER_BLOCK(sb);
1851        unsigned long last = first + EXT3_DESC_PER_BLOCK(sb) - 1;
1852
1853        if (group == first || group == first + 1 || group == last)
1854                return 1;
1855        return 0;
1856}
1857
1858static unsigned long ext3_bg_num_gdb_nometa(struct super_block *sb, int group)
1859{
1860        return ext3_bg_has_super(sb, group) ? EXT3_SB(sb)->s_gdb_count : 0;
1861}
1862
1863/**
1864 *      ext3_bg_num_gdb - number of blocks used by the group table in group
1865 *      @sb: superblock for filesystem
1866 *      @group: group number to check
1867 *
1868 *      Return the number of blocks used by the group descriptor table
1869 *      (primary or backup) in this group.  In the future there may be a
1870 *      different number of descriptor blocks in each group.
1871 */
1872unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
1873{
1874        unsigned long first_meta_bg =
1875                        le32_to_cpu(EXT3_SB(sb)->s_es->s_first_meta_bg);
1876        unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1877
1878        if (!EXT3_HAS_INCOMPAT_FEATURE(sb,EXT3_FEATURE_INCOMPAT_META_BG) ||
1879                        metagroup < first_meta_bg)
1880                return ext3_bg_num_gdb_nometa(sb,group);
1881
1882        return ext3_bg_num_gdb_meta(sb,group);
1883
1884}
1885
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