linux/fs/ext2/balloc.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  linux/fs/ext2/balloc.c
   4 *
   5 * Copyright (C) 1992, 1993, 1994, 1995
   6 * Remy Card (card@masi.ibp.fr)
   7 * Laboratoire MASI - Institut Blaise Pascal
   8 * Universite Pierre et Marie Curie (Paris VI)
   9 *
  10 *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
  11 *  Big-endian to little-endian byte-swapping/bitmaps by
  12 *        David S. Miller (davem@caip.rutgers.edu), 1995
  13 */
  14
  15#include "ext2.h"
  16#include <linux/quotaops.h>
  17#include <linux/slab.h>
  18#include <linux/sched.h>
  19#include <linux/cred.h>
  20#include <linux/buffer_head.h>
  21#include <linux/capability.h>
  22
  23/*
  24 * balloc.c contains the blocks allocation and deallocation routines
  25 */
  26
  27/*
  28 * The free blocks are managed by bitmaps.  A file system contains several
  29 * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
  30 * block for inodes, N blocks for the inode table and data blocks.
  31 *
  32 * The file system contains group descriptors which are located after the
  33 * super block.  Each descriptor contains the number of the bitmap block and
  34 * the free blocks count in the block.  The descriptors are loaded in memory
  35 * when a file system is mounted (see ext2_fill_super).
  36 */
  37
  38
  39#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
  40
  41struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
  42                                             unsigned int block_group,
  43                                             struct buffer_head ** bh)
  44{
  45        unsigned long group_desc;
  46        unsigned long offset;
  47        struct ext2_group_desc * desc;
  48        struct ext2_sb_info *sbi = EXT2_SB(sb);
  49
  50        if (block_group >= sbi->s_groups_count) {
  51                ext2_error (sb, "ext2_get_group_desc",
  52                            "block_group >= groups_count - "
  53                            "block_group = %d, groups_count = %lu",
  54                            block_group, sbi->s_groups_count);
  55
  56                return NULL;
  57        }
  58
  59        group_desc = block_group >> EXT2_DESC_PER_BLOCK_BITS(sb);
  60        offset = block_group & (EXT2_DESC_PER_BLOCK(sb) - 1);
  61        if (!sbi->s_group_desc[group_desc]) {
  62                ext2_error (sb, "ext2_get_group_desc",
  63                            "Group descriptor not loaded - "
  64                            "block_group = %d, group_desc = %lu, desc = %lu",
  65                             block_group, group_desc, offset);
  66                return NULL;
  67        }
  68
  69        desc = (struct ext2_group_desc *) sbi->s_group_desc[group_desc]->b_data;
  70        if (bh)
  71                *bh = sbi->s_group_desc[group_desc];
  72        return desc + offset;
  73}
  74
  75static int ext2_valid_block_bitmap(struct super_block *sb,
  76                                        struct ext2_group_desc *desc,
  77                                        unsigned int block_group,
  78                                        struct buffer_head *bh)
  79{
  80        ext2_grpblk_t offset;
  81        ext2_grpblk_t next_zero_bit;
  82        ext2_fsblk_t bitmap_blk;
  83        ext2_fsblk_t group_first_block;
  84
  85        group_first_block = ext2_group_first_block_no(sb, block_group);
  86
  87        /* check whether block bitmap block number is set */
  88        bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
  89        offset = bitmap_blk - group_first_block;
  90        if (!ext2_test_bit(offset, bh->b_data))
  91                /* bad block bitmap */
  92                goto err_out;
  93
  94        /* check whether the inode bitmap block number is set */
  95        bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
  96        offset = bitmap_blk - group_first_block;
  97        if (!ext2_test_bit(offset, bh->b_data))
  98                /* bad block bitmap */
  99                goto err_out;
 100
 101        /* check whether the inode table block number is set */
 102        bitmap_blk = le32_to_cpu(desc->bg_inode_table);
 103        offset = bitmap_blk - group_first_block;
 104        next_zero_bit = ext2_find_next_zero_bit(bh->b_data,
 105                                offset + EXT2_SB(sb)->s_itb_per_group,
 106                                offset);
 107        if (next_zero_bit >= offset + EXT2_SB(sb)->s_itb_per_group)
 108                /* good bitmap for inode tables */
 109                return 1;
 110
 111err_out:
 112        ext2_error(sb, __func__,
 113                        "Invalid block bitmap - "
 114                        "block_group = %d, block = %lu",
 115                        block_group, bitmap_blk);
 116        return 0;
 117}
 118
 119/*
 120 * Read the bitmap for a given block_group,and validate the
 121 * bits for block/inode/inode tables are set in the bitmaps
 122 *
 123 * Return buffer_head on success or NULL in case of failure.
 124 */
 125static struct buffer_head *
 126read_block_bitmap(struct super_block *sb, unsigned int block_group)
 127{
 128        struct ext2_group_desc * desc;
 129        struct buffer_head * bh = NULL;
 130        ext2_fsblk_t bitmap_blk;
 131
 132        desc = ext2_get_group_desc(sb, block_group, NULL);
 133        if (!desc)
 134                return NULL;
 135        bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
 136        bh = sb_getblk(sb, bitmap_blk);
 137        if (unlikely(!bh)) {
 138                ext2_error(sb, __func__,
 139                            "Cannot read block bitmap - "
 140                            "block_group = %d, block_bitmap = %u",
 141                            block_group, le32_to_cpu(desc->bg_block_bitmap));
 142                return NULL;
 143        }
 144        if (likely(bh_uptodate_or_lock(bh)))
 145                return bh;
 146
 147        if (bh_submit_read(bh) < 0) {
 148                brelse(bh);
 149                ext2_error(sb, __func__,
 150                            "Cannot read block bitmap - "
 151                            "block_group = %d, block_bitmap = %u",
 152                            block_group, le32_to_cpu(desc->bg_block_bitmap));
 153                return NULL;
 154        }
 155
 156        ext2_valid_block_bitmap(sb, desc, block_group, bh);
 157        /*
 158         * file system mounted not to panic on error, continue with corrupt
 159         * bitmap
 160         */
 161        return bh;
 162}
 163
 164static void group_adjust_blocks(struct super_block *sb, int group_no,
 165        struct ext2_group_desc *desc, struct buffer_head *bh, int count)
 166{
 167        if (count) {
 168                struct ext2_sb_info *sbi = EXT2_SB(sb);
 169                unsigned free_blocks;
 170
 171                spin_lock(sb_bgl_lock(sbi, group_no));
 172                free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
 173                desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);
 174                spin_unlock(sb_bgl_lock(sbi, group_no));
 175                mark_buffer_dirty(bh);
 176        }
 177}
 178
 179/*
 180 * The reservation window structure operations
 181 * --------------------------------------------
 182 * Operations include:
 183 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
 184 *
 185 * We use a red-black tree to represent per-filesystem reservation
 186 * windows.
 187 *
 188 */
 189
 190/**
 191 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
 192 * @rb_root:            root of per-filesystem reservation rb tree
 193 * @verbose:            verbose mode
 194 * @fn:                 function which wishes to dump the reservation map
 195 *
 196 * If verbose is turned on, it will print the whole block reservation
 197 * windows(start, end). Otherwise, it will only print out the "bad" windows,
 198 * those windows that overlap with their immediate neighbors.
 199 */
 200#if 1
 201static void __rsv_window_dump(struct rb_root *root, int verbose,
 202                              const char *fn)
 203{
 204        struct rb_node *n;
 205        struct ext2_reserve_window_node *rsv, *prev;
 206        int bad;
 207
 208restart:
 209        n = rb_first(root);
 210        bad = 0;
 211        prev = NULL;
 212
 213        printk("Block Allocation Reservation Windows Map (%s):\n", fn);
 214        while (n) {
 215                rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
 216                if (verbose)
 217                        printk("reservation window 0x%p "
 218                                "start: %lu, end: %lu\n",
 219                                rsv, rsv->rsv_start, rsv->rsv_end);
 220                if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
 221                        printk("Bad reservation %p (start >= end)\n",
 222                               rsv);
 223                        bad = 1;
 224                }
 225                if (prev && prev->rsv_end >= rsv->rsv_start) {
 226                        printk("Bad reservation %p (prev->end >= start)\n",
 227                               rsv);
 228                        bad = 1;
 229                }
 230                if (bad) {
 231                        if (!verbose) {
 232                                printk("Restarting reservation walk in verbose mode\n");
 233                                verbose = 1;
 234                                goto restart;
 235                        }
 236                }
 237                n = rb_next(n);
 238                prev = rsv;
 239        }
 240        printk("Window map complete.\n");
 241        BUG_ON(bad);
 242}
 243#define rsv_window_dump(root, verbose) \
 244        __rsv_window_dump((root), (verbose), __func__)
 245#else
 246#define rsv_window_dump(root, verbose) do {} while (0)
 247#endif
 248
 249/**
 250 * goal_in_my_reservation()
 251 * @rsv:                inode's reservation window
 252 * @grp_goal:           given goal block relative to the allocation block group
 253 * @group:              the current allocation block group
 254 * @sb:                 filesystem super block
 255 *
 256 * Test if the given goal block (group relative) is within the file's
 257 * own block reservation window range.
 258 *
 259 * If the reservation window is outside the goal allocation group, return 0;
 260 * grp_goal (given goal block) could be -1, which means no specific
 261 * goal block. In this case, always return 1.
 262 * If the goal block is within the reservation window, return 1;
 263 * otherwise, return 0;
 264 */
 265static int
 266goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,
 267                        unsigned int group, struct super_block * sb)
 268{
 269        ext2_fsblk_t group_first_block, group_last_block;
 270
 271        group_first_block = ext2_group_first_block_no(sb, group);
 272        group_last_block = group_first_block + EXT2_BLOCKS_PER_GROUP(sb) - 1;
 273
 274        if ((rsv->_rsv_start > group_last_block) ||
 275            (rsv->_rsv_end < group_first_block))
 276                return 0;
 277        if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
 278                || (grp_goal + group_first_block > rsv->_rsv_end)))
 279                return 0;
 280        return 1;
 281}
 282
 283/**
 284 * search_reserve_window()
 285 * @rb_root:            root of reservation tree
 286 * @goal:               target allocation block
 287 *
 288 * Find the reserved window which includes the goal, or the previous one
 289 * if the goal is not in any window.
 290 * Returns NULL if there are no windows or if all windows start after the goal.
 291 */
 292static struct ext2_reserve_window_node *
 293search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
 294{
 295        struct rb_node *n = root->rb_node;
 296        struct ext2_reserve_window_node *rsv;
 297
 298        if (!n)
 299                return NULL;
 300
 301        do {
 302                rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
 303
 304                if (goal < rsv->rsv_start)
 305                        n = n->rb_left;
 306                else if (goal > rsv->rsv_end)
 307                        n = n->rb_right;
 308                else
 309                        return rsv;
 310        } while (n);
 311        /*
 312         * We've fallen off the end of the tree: the goal wasn't inside
 313         * any particular node.  OK, the previous node must be to one
 314         * side of the interval containing the goal.  If it's the RHS,
 315         * we need to back up one.
 316         */
 317        if (rsv->rsv_start > goal) {
 318                n = rb_prev(&rsv->rsv_node);
 319                rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
 320        }
 321        return rsv;
 322}
 323
 324/*
 325 * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.
 326 * @sb:                 super block
 327 * @rsv:                reservation window to add
 328 *
 329 * Must be called with rsv_lock held.
 330 */
 331void ext2_rsv_window_add(struct super_block *sb,
 332                    struct ext2_reserve_window_node *rsv)
 333{
 334        struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
 335        struct rb_node *node = &rsv->rsv_node;
 336        ext2_fsblk_t start = rsv->rsv_start;
 337
 338        struct rb_node ** p = &root->rb_node;
 339        struct rb_node * parent = NULL;
 340        struct ext2_reserve_window_node *this;
 341
 342        while (*p)
 343        {
 344                parent = *p;
 345                this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);
 346
 347                if (start < this->rsv_start)
 348                        p = &(*p)->rb_left;
 349                else if (start > this->rsv_end)
 350                        p = &(*p)->rb_right;
 351                else {
 352                        rsv_window_dump(root, 1);
 353                        BUG();
 354                }
 355        }
 356
 357        rb_link_node(node, parent, p);
 358        rb_insert_color(node, root);
 359}
 360
 361/**
 362 * rsv_window_remove() -- unlink a window from the reservation rb tree
 363 * @sb:                 super block
 364 * @rsv:                reservation window to remove
 365 *
 366 * Mark the block reservation window as not allocated, and unlink it
 367 * from the filesystem reservation window rb tree. Must be called with
 368 * rsv_lock held.
 369 */
 370static void rsv_window_remove(struct super_block *sb,
 371                              struct ext2_reserve_window_node *rsv)
 372{
 373        rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
 374        rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
 375        rsv->rsv_alloc_hit = 0;
 376        rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);
 377}
 378
 379/*
 380 * rsv_is_empty() -- Check if the reservation window is allocated.
 381 * @rsv:                given reservation window to check
 382 *
 383 * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.
 384 */
 385static inline int rsv_is_empty(struct ext2_reserve_window *rsv)
 386{
 387        /* a valid reservation end block could not be 0 */
 388        return (rsv->_rsv_end == EXT2_RESERVE_WINDOW_NOT_ALLOCATED);
 389}
 390
 391/**
 392 * ext2_init_block_alloc_info()
 393 * @inode:              file inode structure
 394 *
 395 * Allocate and initialize the  reservation window structure, and
 396 * link the window to the ext2 inode structure at last
 397 *
 398 * The reservation window structure is only dynamically allocated
 399 * and linked to ext2 inode the first time the open file
 400 * needs a new block. So, before every ext2_new_block(s) call, for
 401 * regular files, we should check whether the reservation window
 402 * structure exists or not. In the latter case, this function is called.
 403 * Fail to do so will result in block reservation being turned off for that
 404 * open file.
 405 *
 406 * This function is called from ext2_get_blocks_handle(), also called
 407 * when setting the reservation window size through ioctl before the file
 408 * is open for write (needs block allocation).
 409 *
 410 * Needs truncate_mutex protection prior to calling this function.
 411 */
 412void ext2_init_block_alloc_info(struct inode *inode)
 413{
 414        struct ext2_inode_info *ei = EXT2_I(inode);
 415        struct ext2_block_alloc_info *block_i;
 416        struct super_block *sb = inode->i_sb;
 417
 418        block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
 419        if (block_i) {
 420                struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;
 421
 422                rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
 423                rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
 424
 425                /*
 426                 * if filesystem is mounted with NORESERVATION, the goal
 427                 * reservation window size is set to zero to indicate
 428                 * block reservation is off
 429                 */
 430                if (!test_opt(sb, RESERVATION))
 431                        rsv->rsv_goal_size = 0;
 432                else
 433                        rsv->rsv_goal_size = EXT2_DEFAULT_RESERVE_BLOCKS;
 434                rsv->rsv_alloc_hit = 0;
 435                block_i->last_alloc_logical_block = 0;
 436                block_i->last_alloc_physical_block = 0;
 437        }
 438        ei->i_block_alloc_info = block_i;
 439}
 440
 441/**
 442 * ext2_discard_reservation()
 443 * @inode:              inode
 444 *
 445 * Discard(free) block reservation window on last file close, or truncate
 446 * or at last iput().
 447 *
 448 * It is being called in three cases:
 449 *      ext2_release_file(): last writer closes the file
 450 *      ext2_clear_inode(): last iput(), when nobody links to this file.
 451 *      ext2_truncate(): when the block indirect map is about to change.
 452 */
 453void ext2_discard_reservation(struct inode *inode)
 454{
 455        struct ext2_inode_info *ei = EXT2_I(inode);
 456        struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
 457        struct ext2_reserve_window_node *rsv;
 458        spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;
 459
 460        if (!block_i)
 461                return;
 462
 463        rsv = &block_i->rsv_window_node;
 464        if (!rsv_is_empty(&rsv->rsv_window)) {
 465                spin_lock(rsv_lock);
 466                if (!rsv_is_empty(&rsv->rsv_window))
 467                        rsv_window_remove(inode->i_sb, rsv);
 468                spin_unlock(rsv_lock);
 469        }
 470}
 471
 472/**
 473 * ext2_free_blocks() -- Free given blocks and update quota and i_blocks
 474 * @inode:              inode
 475 * @block:              start physical block to free
 476 * @count:              number of blocks to free
 477 */
 478void ext2_free_blocks (struct inode * inode, unsigned long block,
 479                       unsigned long count)
 480{
 481        struct buffer_head *bitmap_bh = NULL;
 482        struct buffer_head * bh2;
 483        unsigned long block_group;
 484        unsigned long bit;
 485        unsigned long i;
 486        unsigned long overflow;
 487        struct super_block * sb = inode->i_sb;
 488        struct ext2_sb_info * sbi = EXT2_SB(sb);
 489        struct ext2_group_desc * desc;
 490        struct ext2_super_block * es = sbi->s_es;
 491        unsigned freed = 0, group_freed;
 492
 493        if (block < le32_to_cpu(es->s_first_data_block) ||
 494            block + count < block ||
 495            block + count > le32_to_cpu(es->s_blocks_count)) {
 496                ext2_error (sb, "ext2_free_blocks",
 497                            "Freeing blocks not in datazone - "
 498                            "block = %lu, count = %lu", block, count);
 499                goto error_return;
 500        }
 501
 502        ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
 503
 504do_more:
 505        overflow = 0;
 506        block_group = (block - le32_to_cpu(es->s_first_data_block)) /
 507                      EXT2_BLOCKS_PER_GROUP(sb);
 508        bit = (block - le32_to_cpu(es->s_first_data_block)) %
 509                      EXT2_BLOCKS_PER_GROUP(sb);
 510        /*
 511         * Check to see if we are freeing blocks across a group
 512         * boundary.
 513         */
 514        if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
 515                overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
 516                count -= overflow;
 517        }
 518        brelse(bitmap_bh);
 519        bitmap_bh = read_block_bitmap(sb, block_group);
 520        if (!bitmap_bh)
 521                goto error_return;
 522
 523        desc = ext2_get_group_desc (sb, block_group, &bh2);
 524        if (!desc)
 525                goto error_return;
 526
 527        if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
 528            in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
 529            in_range (block, le32_to_cpu(desc->bg_inode_table),
 530                      sbi->s_itb_per_group) ||
 531            in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
 532                      sbi->s_itb_per_group)) {
 533                ext2_error (sb, "ext2_free_blocks",
 534                            "Freeing blocks in system zones - "
 535                            "Block = %lu, count = %lu",
 536                            block, count);
 537                goto error_return;
 538        }
 539
 540        for (i = 0, group_freed = 0; i < count; i++) {
 541                if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 542                                                bit + i, bitmap_bh->b_data)) {
 543                        ext2_error(sb, __func__,
 544                                "bit already cleared for block %lu", block + i);
 545                } else {
 546                        group_freed++;
 547                }
 548        }
 549
 550        mark_buffer_dirty(bitmap_bh);
 551        if (sb->s_flags & SB_SYNCHRONOUS)
 552                sync_dirty_buffer(bitmap_bh);
 553
 554        group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
 555        freed += group_freed;
 556
 557        if (overflow) {
 558                block += count;
 559                count = overflow;
 560                goto do_more;
 561        }
 562error_return:
 563        brelse(bitmap_bh);
 564        if (freed) {
 565                percpu_counter_add(&sbi->s_freeblocks_counter, freed);
 566                dquot_free_block_nodirty(inode, freed);
 567                mark_inode_dirty(inode);
 568        }
 569}
 570
 571/**
 572 * bitmap_search_next_usable_block()
 573 * @start:              the starting block (group relative) of the search
 574 * @bh:                 bufferhead contains the block group bitmap
 575 * @maxblocks:          the ending block (group relative) of the reservation
 576 *
 577 * The bitmap search --- search forward through the actual bitmap on disk until
 578 * we find a bit free.
 579 */
 580static ext2_grpblk_t
 581bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
 582                                        ext2_grpblk_t maxblocks)
 583{
 584        ext2_grpblk_t next;
 585
 586        next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
 587        if (next >= maxblocks)
 588                return -1;
 589        return next;
 590}
 591
 592/**
 593 * find_next_usable_block()
 594 * @start:              the starting block (group relative) to find next
 595 *                      allocatable block in bitmap.
 596 * @bh:                 bufferhead contains the block group bitmap
 597 * @maxblocks:          the ending block (group relative) for the search
 598 *
 599 * Find an allocatable block in a bitmap.  We perform the "most
 600 * appropriate allocation" algorithm of looking for a free block near
 601 * the initial goal; then for a free byte somewhere in the bitmap;
 602 * then for any free bit in the bitmap.
 603 */
 604static ext2_grpblk_t
 605find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
 606{
 607        ext2_grpblk_t here, next;
 608        char *p, *r;
 609
 610        if (start > 0) {
 611                /*
 612                 * The goal was occupied; search forward for a free 
 613                 * block within the next XX blocks.
 614                 *
 615                 * end_goal is more or less random, but it has to be
 616                 * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
 617                 * next 64-bit boundary is simple..
 618                 */
 619                ext2_grpblk_t end_goal = (start + 63) & ~63;
 620                if (end_goal > maxblocks)
 621                        end_goal = maxblocks;
 622                here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
 623                if (here < end_goal)
 624                        return here;
 625                ext2_debug("Bit not found near goal\n");
 626        }
 627
 628        here = start;
 629        if (here < 0)
 630                here = 0;
 631
 632        p = ((char *)bh->b_data) + (here >> 3);
 633        r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
 634        next = (r - ((char *)bh->b_data)) << 3;
 635
 636        if (next < maxblocks && next >= here)
 637                return next;
 638
 639        here = bitmap_search_next_usable_block(here, bh, maxblocks);
 640        return here;
 641}
 642
 643/**
 644 * ext2_try_to_allocate()
 645 * @sb:                 superblock
 646 * @group:              given allocation block group
 647 * @bitmap_bh:          bufferhead holds the block bitmap
 648 * @grp_goal:           given target block within the group
 649 * @count:              target number of blocks to allocate
 650 * @my_rsv:             reservation window
 651 *
 652 * Attempt to allocate blocks within a give range. Set the range of allocation
 653 * first, then find the first free bit(s) from the bitmap (within the range),
 654 * and at last, allocate the blocks by claiming the found free bit as allocated.
 655 *
 656 * To set the range of this allocation:
 657 *      if there is a reservation window, only try to allocate block(s)
 658 *      from the file's own reservation window;
 659 *      Otherwise, the allocation range starts from the give goal block,
 660 *      ends at the block group's last block.
 661 *
 662 * If we failed to allocate the desired block then we may end up crossing to a
 663 * new bitmap.
 664 */
 665static int
 666ext2_try_to_allocate(struct super_block *sb, int group,
 667                        struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
 668                        unsigned long *count,
 669                        struct ext2_reserve_window *my_rsv)
 670{
 671        ext2_fsblk_t group_first_block;
 672        ext2_grpblk_t start, end;
 673        unsigned long num = 0;
 674
 675        /* we do allocation within the reservation window if we have a window */
 676        if (my_rsv) {
 677                group_first_block = ext2_group_first_block_no(sb, group);
 678                if (my_rsv->_rsv_start >= group_first_block)
 679                        start = my_rsv->_rsv_start - group_first_block;
 680                else
 681                        /* reservation window cross group boundary */
 682                        start = 0;
 683                end = my_rsv->_rsv_end - group_first_block + 1;
 684                if (end > EXT2_BLOCKS_PER_GROUP(sb))
 685                        /* reservation window crosses group boundary */
 686                        end = EXT2_BLOCKS_PER_GROUP(sb);
 687                if ((start <= grp_goal) && (grp_goal < end))
 688                        start = grp_goal;
 689                else
 690                        grp_goal = -1;
 691        } else {
 692                if (grp_goal > 0)
 693                        start = grp_goal;
 694                else
 695                        start = 0;
 696                end = EXT2_BLOCKS_PER_GROUP(sb);
 697        }
 698
 699        BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
 700
 701repeat:
 702        if (grp_goal < 0) {
 703                grp_goal = find_next_usable_block(start, bitmap_bh, end);
 704                if (grp_goal < 0)
 705                        goto fail_access;
 706                if (!my_rsv) {
 707                        int i;
 708
 709                        for (i = 0; i < 7 && grp_goal > start &&
 710                                        !ext2_test_bit(grp_goal - 1,
 711                                                        bitmap_bh->b_data);
 712                                        i++, grp_goal--)
 713                                ;
 714                }
 715        }
 716        start = grp_goal;
 717
 718        if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group), grp_goal,
 719                                                        bitmap_bh->b_data)) {
 720                /*
 721                 * The block was allocated by another thread, or it was
 722                 * allocated and then freed by another thread
 723                 */
 724                start++;
 725                grp_goal++;
 726                if (start >= end)
 727                        goto fail_access;
 728                goto repeat;
 729        }
 730        num++;
 731        grp_goal++;
 732        while (num < *count && grp_goal < end
 733                && !ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
 734                                        grp_goal, bitmap_bh->b_data)) {
 735                num++;
 736                grp_goal++;
 737        }
 738        *count = num;
 739        return grp_goal - num;
 740fail_access:
 741        *count = num;
 742        return -1;
 743}
 744
 745/**
 746 *      find_next_reservable_window():
 747 *              find a reservable space within the given range.
 748 *              It does not allocate the reservation window for now:
 749 *              alloc_new_reservation() will do the work later.
 750 *
 751 *      @search_head: the head of the searching list;
 752 *              This is not necessarily the list head of the whole filesystem
 753 *
 754 *              We have both head and start_block to assist the search
 755 *              for the reservable space. The list starts from head,
 756 *              but we will shift to the place where start_block is,
 757 *              then start from there, when looking for a reservable space.
 758 *
 759 *      @size: the target new reservation window size
 760 *
 761 *      @group_first_block: the first block we consider to start
 762 *                      the real search from
 763 *
 764 *      @last_block:
 765 *              the maximum block number that our goal reservable space
 766 *              could start from. This is normally the last block in this
 767 *              group. The search will end when we found the start of next
 768 *              possible reservable space is out of this boundary.
 769 *              This could handle the cross boundary reservation window
 770 *              request.
 771 *
 772 *      basically we search from the given range, rather than the whole
 773 *      reservation double linked list, (start_block, last_block)
 774 *      to find a free region that is of my size and has not
 775 *      been reserved.
 776 *
 777 */
 778static int find_next_reservable_window(
 779                                struct ext2_reserve_window_node *search_head,
 780                                struct ext2_reserve_window_node *my_rsv,
 781                                struct super_block * sb,
 782                                ext2_fsblk_t start_block,
 783                                ext2_fsblk_t last_block)
 784{
 785        struct rb_node *next;
 786        struct ext2_reserve_window_node *rsv, *prev;
 787        ext2_fsblk_t cur;
 788        int size = my_rsv->rsv_goal_size;
 789
 790        /* TODO: make the start of the reservation window byte-aligned */
 791        /* cur = *start_block & ~7;*/
 792        cur = start_block;
 793        rsv = search_head;
 794        if (!rsv)
 795                return -1;
 796
 797        while (1) {
 798                if (cur <= rsv->rsv_end)
 799                        cur = rsv->rsv_end + 1;
 800
 801                /* TODO?
 802                 * in the case we could not find a reservable space
 803                 * that is what is expected, during the re-search, we could
 804                 * remember what's the largest reservable space we could have
 805                 * and return that one.
 806                 *
 807                 * For now it will fail if we could not find the reservable
 808                 * space with expected-size (or more)...
 809                 */
 810                if (cur > last_block)
 811                        return -1;              /* fail */
 812
 813                prev = rsv;
 814                next = rb_next(&rsv->rsv_node);
 815                rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
 816
 817                /*
 818                 * Reached the last reservation, we can just append to the
 819                 * previous one.
 820                 */
 821                if (!next)
 822                        break;
 823
 824                if (cur + size <= rsv->rsv_start) {
 825                        /*
 826                         * Found a reserveable space big enough.  We could
 827                         * have a reservation across the group boundary here
 828                         */
 829                        break;
 830                }
 831        }
 832        /*
 833         * we come here either :
 834         * when we reach the end of the whole list,
 835         * and there is empty reservable space after last entry in the list.
 836         * append it to the end of the list.
 837         *
 838         * or we found one reservable space in the middle of the list,
 839         * return the reservation window that we could append to.
 840         * succeed.
 841         */
 842
 843        if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
 844                rsv_window_remove(sb, my_rsv);
 845
 846        /*
 847         * Let's book the whole available window for now.  We will check the
 848         * disk bitmap later and then, if there are free blocks then we adjust
 849         * the window size if it's larger than requested.
 850         * Otherwise, we will remove this node from the tree next time
 851         * call find_next_reservable_window.
 852         */
 853        my_rsv->rsv_start = cur;
 854        my_rsv->rsv_end = cur + size - 1;
 855        my_rsv->rsv_alloc_hit = 0;
 856
 857        if (prev != my_rsv)
 858                ext2_rsv_window_add(sb, my_rsv);
 859
 860        return 0;
 861}
 862
 863/**
 864 *      alloc_new_reservation()--allocate a new reservation window
 865 *
 866 *              To make a new reservation, we search part of the filesystem
 867 *              reservation list (the list that inside the group). We try to
 868 *              allocate a new reservation window near the allocation goal,
 869 *              or the beginning of the group, if there is no goal.
 870 *
 871 *              We first find a reservable space after the goal, then from
 872 *              there, we check the bitmap for the first free block after
 873 *              it. If there is no free block until the end of group, then the
 874 *              whole group is full, we failed. Otherwise, check if the free
 875 *              block is inside the expected reservable space, if so, we
 876 *              succeed.
 877 *              If the first free block is outside the reservable space, then
 878 *              start from the first free block, we search for next available
 879 *              space, and go on.
 880 *
 881 *      on succeed, a new reservation will be found and inserted into the list
 882 *      It contains at least one free block, and it does not overlap with other
 883 *      reservation windows.
 884 *
 885 *      failed: we failed to find a reservation window in this group
 886 *
 887 *      @rsv: the reservation
 888 *
 889 *      @grp_goal: The goal (group-relative).  It is where the search for a
 890 *              free reservable space should start from.
 891 *              if we have a goal(goal >0 ), then start from there,
 892 *              no goal(goal = -1), we start from the first block
 893 *              of the group.
 894 *
 895 *      @sb: the super block
 896 *      @group: the group we are trying to allocate in
 897 *      @bitmap_bh: the block group block bitmap
 898 *
 899 */
 900static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
 901                ext2_grpblk_t grp_goal, struct super_block *sb,
 902                unsigned int group, struct buffer_head *bitmap_bh)
 903{
 904        struct ext2_reserve_window_node *search_head;
 905        ext2_fsblk_t group_first_block, group_end_block, start_block;
 906        ext2_grpblk_t first_free_block;
 907        struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
 908        unsigned long size;
 909        int ret;
 910        spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
 911
 912        group_first_block = ext2_group_first_block_no(sb, group);
 913        group_end_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
 914
 915        if (grp_goal < 0)
 916                start_block = group_first_block;
 917        else
 918                start_block = grp_goal + group_first_block;
 919
 920        size = my_rsv->rsv_goal_size;
 921
 922        if (!rsv_is_empty(&my_rsv->rsv_window)) {
 923                /*
 924                 * if the old reservation is cross group boundary
 925                 * and if the goal is inside the old reservation window,
 926                 * we will come here when we just failed to allocate from
 927                 * the first part of the window. We still have another part
 928                 * that belongs to the next group. In this case, there is no
 929                 * point to discard our window and try to allocate a new one
 930                 * in this group(which will fail). we should
 931                 * keep the reservation window, just simply move on.
 932                 *
 933                 * Maybe we could shift the start block of the reservation
 934                 * window to the first block of next group.
 935                 */
 936
 937                if ((my_rsv->rsv_start <= group_end_block) &&
 938                                (my_rsv->rsv_end > group_end_block) &&
 939                                (start_block >= my_rsv->rsv_start))
 940                        return -1;
 941
 942                if ((my_rsv->rsv_alloc_hit >
 943                     (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
 944                        /*
 945                         * if the previously allocation hit ratio is
 946                         * greater than 1/2, then we double the size of
 947                         * the reservation window the next time,
 948                         * otherwise we keep the same size window
 949                         */
 950                        size = size * 2;
 951                        if (size > EXT2_MAX_RESERVE_BLOCKS)
 952                                size = EXT2_MAX_RESERVE_BLOCKS;
 953                        my_rsv->rsv_goal_size= size;
 954                }
 955        }
 956
 957        spin_lock(rsv_lock);
 958        /*
 959         * shift the search start to the window near the goal block
 960         */
 961        search_head = search_reserve_window(fs_rsv_root, start_block);
 962
 963        /*
 964         * find_next_reservable_window() simply finds a reservable window
 965         * inside the given range(start_block, group_end_block).
 966         *
 967         * To make sure the reservation window has a free bit inside it, we
 968         * need to check the bitmap after we found a reservable window.
 969         */
 970retry:
 971        ret = find_next_reservable_window(search_head, my_rsv, sb,
 972                                                start_block, group_end_block);
 973
 974        if (ret == -1) {
 975                if (!rsv_is_empty(&my_rsv->rsv_window))
 976                        rsv_window_remove(sb, my_rsv);
 977                spin_unlock(rsv_lock);
 978                return -1;
 979        }
 980
 981        /*
 982         * On success, find_next_reservable_window() returns the
 983         * reservation window where there is a reservable space after it.
 984         * Before we reserve this reservable space, we need
 985         * to make sure there is at least a free block inside this region.
 986         *
 987         * Search the first free bit on the block bitmap.  Search starts from
 988         * the start block of the reservable space we just found.
 989         */
 990        spin_unlock(rsv_lock);
 991        first_free_block = bitmap_search_next_usable_block(
 992                        my_rsv->rsv_start - group_first_block,
 993                        bitmap_bh, group_end_block - group_first_block + 1);
 994
 995        if (first_free_block < 0) {
 996                /*
 997                 * no free block left on the bitmap, no point
 998                 * to reserve the space. return failed.
 999                 */
1000                spin_lock(rsv_lock);
1001                if (!rsv_is_empty(&my_rsv->rsv_window))
1002                        rsv_window_remove(sb, my_rsv);
1003                spin_unlock(rsv_lock);
1004                return -1;              /* failed */
1005        }
1006
1007        start_block = first_free_block + group_first_block;
1008        /*
1009         * check if the first free block is within the
1010         * free space we just reserved
1011         */
1012        if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
1013                return 0;               /* success */
1014        /*
1015         * if the first free bit we found is out of the reservable space
1016         * continue search for next reservable space,
1017         * start from where the free block is,
1018         * we also shift the list head to where we stopped last time
1019         */
1020        search_head = my_rsv;
1021        spin_lock(rsv_lock);
1022        goto retry;
1023}
1024
1025/**
1026 * try_to_extend_reservation()
1027 * @my_rsv:             given reservation window
1028 * @sb:                 super block
1029 * @size:               the delta to extend
1030 *
1031 * Attempt to expand the reservation window large enough to have
1032 * required number of free blocks
1033 *
1034 * Since ext2_try_to_allocate() will always allocate blocks within
1035 * the reservation window range, if the window size is too small,
1036 * multiple blocks allocation has to stop at the end of the reservation
1037 * window. To make this more efficient, given the total number of
1038 * blocks needed and the current size of the window, we try to
1039 * expand the reservation window size if necessary on a best-effort
1040 * basis before ext2_new_blocks() tries to allocate blocks.
1041 */
1042static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
1043                        struct super_block *sb, int size)
1044{
1045        struct ext2_reserve_window_node *next_rsv;
1046        struct rb_node *next;
1047        spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
1048
1049        if (!spin_trylock(rsv_lock))
1050                return;
1051
1052        next = rb_next(&my_rsv->rsv_node);
1053
1054        if (!next)
1055                my_rsv->rsv_end += size;
1056        else {
1057                next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
1058
1059                if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1060                        my_rsv->rsv_end += size;
1061                else
1062                        my_rsv->rsv_end = next_rsv->rsv_start - 1;
1063        }
1064        spin_unlock(rsv_lock);
1065}
1066
1067/**
1068 * ext2_try_to_allocate_with_rsv()
1069 * @sb:                 superblock
1070 * @group:              given allocation block group
1071 * @bitmap_bh:          bufferhead holds the block bitmap
1072 * @grp_goal:           given target block within the group
1073 * @count:              target number of blocks to allocate
1074 * @my_rsv:             reservation window
1075 *
1076 * This is the main function used to allocate a new block and its reservation
1077 * window.
1078 *
1079 * Each time when a new block allocation is need, first try to allocate from
1080 * its own reservation.  If it does not have a reservation window, instead of
1081 * looking for a free bit on bitmap first, then look up the reservation list to
1082 * see if it is inside somebody else's reservation window, we try to allocate a
1083 * reservation window for it starting from the goal first. Then do the block
1084 * allocation within the reservation window.
1085 *
1086 * This will avoid keeping on searching the reservation list again and
1087 * again when somebody is looking for a free block (without
1088 * reservation), and there are lots of free blocks, but they are all
1089 * being reserved.
1090 *
1091 * We use a red-black tree for the per-filesystem reservation list.
1092 */
1093static ext2_grpblk_t
1094ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
1095                        struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
1096                        struct ext2_reserve_window_node * my_rsv,
1097                        unsigned long *count)
1098{
1099        ext2_fsblk_t group_first_block, group_last_block;
1100        ext2_grpblk_t ret = 0;
1101        unsigned long num = *count;
1102
1103        /*
1104         * we don't deal with reservation when
1105         * filesystem is mounted without reservation
1106         * or the file is not a regular file
1107         * or last attempt to allocate a block with reservation turned on failed
1108         */
1109        if (my_rsv == NULL) {
1110                return ext2_try_to_allocate(sb, group, bitmap_bh,
1111                                                grp_goal, count, NULL);
1112        }
1113        /*
1114         * grp_goal is a group relative block number (if there is a goal)
1115         * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
1116         * first block is a filesystem wide block number
1117         * first block is the block number of the first block in this group
1118         */
1119        group_first_block = ext2_group_first_block_no(sb, group);
1120        group_last_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
1121
1122        /*
1123         * Basically we will allocate a new block from inode's reservation
1124         * window.
1125         *
1126         * We need to allocate a new reservation window, if:
1127         * a) inode does not have a reservation window; or
1128         * b) last attempt to allocate a block from existing reservation
1129         *    failed; or
1130         * c) we come here with a goal and with a reservation window
1131         *
1132         * We do not need to allocate a new reservation window if we come here
1133         * at the beginning with a goal and the goal is inside the window, or
1134         * we don't have a goal but already have a reservation window.
1135         * then we could go to allocate from the reservation window directly.
1136         */
1137        while (1) {
1138                if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1139                        !goal_in_my_reservation(&my_rsv->rsv_window,
1140                                                grp_goal, group, sb)) {
1141                        if (my_rsv->rsv_goal_size < *count)
1142                                my_rsv->rsv_goal_size = *count;
1143                        ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1144                                                        group, bitmap_bh);
1145                        if (ret < 0)
1146                                break;                  /* failed */
1147
1148                        if (!goal_in_my_reservation(&my_rsv->rsv_window,
1149                                                        grp_goal, group, sb))
1150                                grp_goal = -1;
1151                } else if (grp_goal >= 0) {
1152                        int curr = my_rsv->rsv_end -
1153                                        (grp_goal + group_first_block) + 1;
1154
1155                        if (curr < *count)
1156                                try_to_extend_reservation(my_rsv, sb,
1157                                                        *count - curr);
1158                }
1159
1160                if ((my_rsv->rsv_start > group_last_block) ||
1161                                (my_rsv->rsv_end < group_first_block)) {
1162                        rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
1163                        BUG();
1164                }
1165                ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
1166                                           &num, &my_rsv->rsv_window);
1167                if (ret >= 0) {
1168                        my_rsv->rsv_alloc_hit += num;
1169                        *count = num;
1170                        break;                          /* succeed */
1171                }
1172                num = *count;
1173        }
1174        return ret;
1175}
1176
1177/**
1178 * ext2_has_free_blocks()
1179 * @sbi:                in-core super block structure.
1180 *
1181 * Check if filesystem has at least 1 free block available for allocation.
1182 */
1183static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
1184{
1185        ext2_fsblk_t free_blocks, root_blocks;
1186
1187        free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1188        root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1189        if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1190                !uid_eq(sbi->s_resuid, current_fsuid()) &&
1191                (gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
1192                 !in_group_p (sbi->s_resgid))) {
1193                return 0;
1194        }
1195        return 1;
1196}
1197
1198/*
1199 * Returns 1 if the passed-in block region is valid; 0 if some part overlaps
1200 * with filesystem metadata blocksi.
1201 */
1202int ext2_data_block_valid(struct ext2_sb_info *sbi, ext2_fsblk_t start_blk,
1203                          unsigned int count)
1204{
1205        if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
1206            (start_blk + count < start_blk) ||
1207            (start_blk > le32_to_cpu(sbi->s_es->s_blocks_count)))
1208                return 0;
1209
1210        /* Ensure we do not step over superblock */
1211        if ((start_blk <= sbi->s_sb_block) &&
1212            (start_blk + count >= sbi->s_sb_block))
1213                return 0;
1214
1215
1216        return 1;
1217}
1218
1219/*
1220 * ext2_new_blocks() -- core block(s) allocation function
1221 * @inode:              file inode
1222 * @goal:               given target block(filesystem wide)
1223 * @count:              target number of blocks to allocate
1224 * @errp:               error code
1225 *
1226 * ext2_new_blocks uses a goal block to assist allocation.  If the goal is
1227 * free, or there is a free block within 32 blocks of the goal, that block
1228 * is allocated.  Otherwise a forward search is made for a free block; within 
1229 * each block group the search first looks for an entire free byte in the block
1230 * bitmap, and then for any free bit if that fails.
1231 * This function also updates quota and i_blocks field.
1232 */
1233ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
1234                    unsigned long *count, int *errp)
1235{
1236        struct buffer_head *bitmap_bh = NULL;
1237        struct buffer_head *gdp_bh;
1238        int group_no;
1239        int goal_group;
1240        ext2_grpblk_t grp_target_blk;   /* blockgroup relative goal block */
1241        ext2_grpblk_t grp_alloc_blk;    /* blockgroup-relative allocated block*/
1242        ext2_fsblk_t ret_block;         /* filesyetem-wide allocated block */
1243        int bgi;                        /* blockgroup iteration index */
1244        int performed_allocation = 0;
1245        ext2_grpblk_t free_blocks;      /* number of free blocks in a group */
1246        struct super_block *sb;
1247        struct ext2_group_desc *gdp;
1248        struct ext2_super_block *es;
1249        struct ext2_sb_info *sbi;
1250        struct ext2_reserve_window_node *my_rsv = NULL;
1251        struct ext2_block_alloc_info *block_i;
1252        unsigned short windowsz = 0;
1253        unsigned long ngroups;
1254        unsigned long num = *count;
1255        int ret;
1256
1257        *errp = -ENOSPC;
1258        sb = inode->i_sb;
1259
1260        /*
1261         * Check quota for allocation of this block.
1262         */
1263        ret = dquot_alloc_block(inode, num);
1264        if (ret) {
1265                *errp = ret;
1266                return 0;
1267        }
1268
1269        sbi = EXT2_SB(sb);
1270        es = EXT2_SB(sb)->s_es;
1271        ext2_debug("goal=%lu.\n", goal);
1272        /*
1273         * Allocate a block from reservation only when
1274         * filesystem is mounted with reservation(default,-o reservation), and
1275         * it's a regular file, and
1276         * the desired window size is greater than 0 (One could use ioctl
1277         * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off
1278         * reservation on that particular file)
1279         */
1280        block_i = EXT2_I(inode)->i_block_alloc_info;
1281        if (block_i) {
1282                windowsz = block_i->rsv_window_node.rsv_goal_size;
1283                if (windowsz > 0)
1284                        my_rsv = &block_i->rsv_window_node;
1285        }
1286
1287        if (!ext2_has_free_blocks(sbi)) {
1288                *errp = -ENOSPC;
1289                goto out;
1290        }
1291
1292        /*
1293         * First, test whether the goal block is free.
1294         */
1295        if (goal < le32_to_cpu(es->s_first_data_block) ||
1296            goal >= le32_to_cpu(es->s_blocks_count))
1297                goal = le32_to_cpu(es->s_first_data_block);
1298        group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1299                        EXT2_BLOCKS_PER_GROUP(sb);
1300        goal_group = group_no;
1301retry_alloc:
1302        gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1303        if (!gdp)
1304                goto io_error;
1305
1306        free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1307        /*
1308         * if there is not enough free blocks to make a new resevation
1309         * turn off reservation for this allocation
1310         */
1311        if (my_rsv && (free_blocks < windowsz)
1312                && (free_blocks > 0)
1313                && (rsv_is_empty(&my_rsv->rsv_window)))
1314                my_rsv = NULL;
1315
1316        if (free_blocks > 0) {
1317                grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1318                                EXT2_BLOCKS_PER_GROUP(sb));
1319                bitmap_bh = read_block_bitmap(sb, group_no);
1320                if (!bitmap_bh)
1321                        goto io_error;
1322                grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1323                                        bitmap_bh, grp_target_blk,
1324                                        my_rsv, &num);
1325                if (grp_alloc_blk >= 0)
1326                        goto allocated;
1327        }
1328
1329        ngroups = EXT2_SB(sb)->s_groups_count;
1330        smp_rmb();
1331
1332        /*
1333         * Now search the rest of the groups.  We assume that
1334         * group_no and gdp correctly point to the last group visited.
1335         */
1336        for (bgi = 0; bgi < ngroups; bgi++) {
1337                group_no++;
1338                if (group_no >= ngroups)
1339                        group_no = 0;
1340                gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1341                if (!gdp)
1342                        goto io_error;
1343
1344                free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1345                /*
1346                 * skip this group (and avoid loading bitmap) if there
1347                 * are no free blocks
1348                 */
1349                if (!free_blocks)
1350                        continue;
1351                /*
1352                 * skip this group if the number of
1353                 * free blocks is less than half of the reservation
1354                 * window size.
1355                 */
1356                if (my_rsv && (free_blocks <= (windowsz/2)))
1357                        continue;
1358
1359                brelse(bitmap_bh);
1360                bitmap_bh = read_block_bitmap(sb, group_no);
1361                if (!bitmap_bh)
1362                        goto io_error;
1363                /*
1364                 * try to allocate block(s) from this group, without a goal(-1).
1365                 */
1366                grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1367                                        bitmap_bh, -1, my_rsv, &num);
1368                if (grp_alloc_blk >= 0)
1369                        goto allocated;
1370        }
1371        /*
1372         * We may end up a bogus earlier ENOSPC error due to
1373         * filesystem is "full" of reservations, but
1374         * there maybe indeed free blocks available on disk
1375         * In this case, we just forget about the reservations
1376         * just do block allocation as without reservations.
1377         */
1378        if (my_rsv) {
1379                my_rsv = NULL;
1380                windowsz = 0;
1381                group_no = goal_group;
1382                goto retry_alloc;
1383        }
1384        /* No space left on the device */
1385        *errp = -ENOSPC;
1386        goto out;
1387
1388allocated:
1389
1390        ext2_debug("using block group %d(%d)\n",
1391                        group_no, gdp->bg_free_blocks_count);
1392
1393        ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
1394
1395        if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1396            in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1397            in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1398                      EXT2_SB(sb)->s_itb_per_group) ||
1399            in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1400                      EXT2_SB(sb)->s_itb_per_group)) {
1401                ext2_error(sb, "ext2_new_blocks",
1402                            "Allocating block in system zone - "
1403                            "blocks from "E2FSBLK", length %lu",
1404                            ret_block, num);
1405                /*
1406                 * ext2_try_to_allocate marked the blocks we allocated as in
1407                 * use.  So we may want to selectively mark some of the blocks
1408                 * as free
1409                 */
1410                goto retry_alloc;
1411        }
1412
1413        performed_allocation = 1;
1414
1415        if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1416                ext2_error(sb, "ext2_new_blocks",
1417                            "block("E2FSBLK") >= blocks count(%d) - "
1418                            "block_group = %d, es == %p ", ret_block,
1419                        le32_to_cpu(es->s_blocks_count), group_no, es);
1420                goto out;
1421        }
1422
1423        group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
1424        percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1425
1426        mark_buffer_dirty(bitmap_bh);
1427        if (sb->s_flags & SB_SYNCHRONOUS)
1428                sync_dirty_buffer(bitmap_bh);
1429
1430        *errp = 0;
1431        brelse(bitmap_bh);
1432        if (num < *count) {
1433                dquot_free_block_nodirty(inode, *count-num);
1434                mark_inode_dirty(inode);
1435                *count = num;
1436        }
1437        return ret_block;
1438
1439io_error:
1440        *errp = -EIO;
1441out:
1442        /*
1443         * Undo the block allocation
1444         */
1445        if (!performed_allocation) {
1446                dquot_free_block_nodirty(inode, *count);
1447                mark_inode_dirty(inode);
1448        }
1449        brelse(bitmap_bh);
1450        return 0;
1451}
1452
1453ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
1454{
1455        unsigned long count = 1;
1456
1457        return ext2_new_blocks(inode, goal, &count, errp);
1458}
1459
1460#ifdef EXT2FS_DEBUG
1461
1462unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)
1463{
1464        return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
1465}
1466
1467#endif  /*  EXT2FS_DEBUG  */
1468
1469unsigned long ext2_count_free_blocks (struct super_block * sb)
1470{
1471        struct ext2_group_desc * desc;
1472        unsigned long desc_count = 0;
1473        int i;
1474#ifdef EXT2FS_DEBUG
1475        unsigned long bitmap_count, x;
1476        struct ext2_super_block *es;
1477
1478        es = EXT2_SB(sb)->s_es;
1479        desc_count = 0;
1480        bitmap_count = 0;
1481        desc = NULL;
1482        for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1483                struct buffer_head *bitmap_bh;
1484                desc = ext2_get_group_desc (sb, i, NULL);
1485                if (!desc)
1486                        continue;
1487                desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1488                bitmap_bh = read_block_bitmap(sb, i);
1489                if (!bitmap_bh)
1490                        continue;
1491                
1492                x = ext2_count_free(bitmap_bh, sb->s_blocksize);
1493                printk ("group %d: stored = %d, counted = %lu\n",
1494                        i, le16_to_cpu(desc->bg_free_blocks_count), x);
1495                bitmap_count += x;
1496                brelse(bitmap_bh);
1497        }
1498        printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
1499                (long)le32_to_cpu(es->s_free_blocks_count),
1500                desc_count, bitmap_count);
1501        return bitmap_count;
1502#else
1503        for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1504                desc = ext2_get_group_desc (sb, i, NULL);
1505                if (!desc)
1506                        continue;
1507                desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1508        }
1509        return desc_count;
1510#endif
1511}
1512
1513static inline int test_root(int a, int b)
1514{
1515        int num = b;
1516
1517        while (a > num)
1518                num *= b;
1519        return num == a;
1520}
1521
1522static int ext2_group_sparse(int group)
1523{
1524        if (group <= 1)
1525                return 1;
1526        return (test_root(group, 3) || test_root(group, 5) ||
1527                test_root(group, 7));
1528}
1529
1530/**
1531 *      ext2_bg_has_super - number of blocks used by the superblock in group
1532 *      @sb: superblock for filesystem
1533 *      @group: group number to check
1534 *
1535 *      Return the number of blocks used by the superblock (primary or backup)
1536 *      in this group.  Currently this will be only 0 or 1.
1537 */
1538int ext2_bg_has_super(struct super_block *sb, int group)
1539{
1540        if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1541            !ext2_group_sparse(group))
1542                return 0;
1543        return 1;
1544}
1545
1546/**
1547 *      ext2_bg_num_gdb - number of blocks used by the group table in group
1548 *      @sb: superblock for filesystem
1549 *      @group: group number to check
1550 *
1551 *      Return the number of blocks used by the group descriptor table
1552 *      (primary or backup) in this group.  In the future there may be a
1553 *      different number of descriptor blocks in each group.
1554 */
1555unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
1556{
1557        return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
1558}
1559
1560