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 * @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 = ext2_group_last_block_no(sb, group);
 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 * @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 (!ext2_data_block_valid(sbi, block, count)) {
 494                ext2_error (sb, "ext2_free_blocks",
 495                            "Freeing blocks not in datazone - "
 496                            "block = %lu, count = %lu", block, count);
 497                goto error_return;
 498        }
 499
 500        ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
 501
 502do_more:
 503        overflow = 0;
 504        block_group = (block - le32_to_cpu(es->s_first_data_block)) /
 505                      EXT2_BLOCKS_PER_GROUP(sb);
 506        bit = (block - le32_to_cpu(es->s_first_data_block)) %
 507                      EXT2_BLOCKS_PER_GROUP(sb);
 508        /*
 509         * Check to see if we are freeing blocks across a group
 510         * boundary.
 511         */
 512        if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
 513                overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
 514                count -= overflow;
 515        }
 516        brelse(bitmap_bh);
 517        bitmap_bh = read_block_bitmap(sb, block_group);
 518        if (!bitmap_bh)
 519                goto error_return;
 520
 521        desc = ext2_get_group_desc (sb, block_group, &bh2);
 522        if (!desc)
 523                goto error_return;
 524
 525        if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
 526            in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
 527            in_range (block, le32_to_cpu(desc->bg_inode_table),
 528                      sbi->s_itb_per_group) ||
 529            in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
 530                      sbi->s_itb_per_group)) {
 531                ext2_error (sb, "ext2_free_blocks",
 532                            "Freeing blocks in system zones - "
 533                            "Block = %lu, count = %lu",
 534                            block, count);
 535                goto error_return;
 536        }
 537
 538        for (i = 0, group_freed = 0; i < count; i++) {
 539                if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 540                                                bit + i, bitmap_bh->b_data)) {
 541                        ext2_error(sb, __func__,
 542                                "bit already cleared for block %lu", block + i);
 543                } else {
 544                        group_freed++;
 545                }
 546        }
 547
 548        mark_buffer_dirty(bitmap_bh);
 549        if (sb->s_flags & SB_SYNCHRONOUS)
 550                sync_dirty_buffer(bitmap_bh);
 551
 552        group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
 553        freed += group_freed;
 554
 555        if (overflow) {
 556                block += count;
 557                count = overflow;
 558                goto do_more;
 559        }
 560error_return:
 561        brelse(bitmap_bh);
 562        if (freed) {
 563                percpu_counter_add(&sbi->s_freeblocks_counter, freed);
 564                dquot_free_block_nodirty(inode, freed);
 565                mark_inode_dirty(inode);
 566        }
 567}
 568
 569/**
 570 * bitmap_search_next_usable_block()
 571 * @start:              the starting block (group relative) of the search
 572 * @bh:                 bufferhead contains the block group bitmap
 573 * @maxblocks:          the ending block (group relative) of the reservation
 574 *
 575 * The bitmap search --- search forward through the actual bitmap on disk until
 576 * we find a bit free.
 577 */
 578static ext2_grpblk_t
 579bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
 580                                        ext2_grpblk_t maxblocks)
 581{
 582        ext2_grpblk_t next;
 583
 584        next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
 585        if (next >= maxblocks)
 586                return -1;
 587        return next;
 588}
 589
 590/**
 591 * find_next_usable_block()
 592 * @start:              the starting block (group relative) to find next
 593 *                      allocatable block in bitmap.
 594 * @bh:                 bufferhead contains the block group bitmap
 595 * @maxblocks:          the ending block (group relative) for the search
 596 *
 597 * Find an allocatable block in a bitmap.  We perform the "most
 598 * appropriate allocation" algorithm of looking for a free block near
 599 * the initial goal; then for a free byte somewhere in the bitmap;
 600 * then for any free bit in the bitmap.
 601 */
 602static ext2_grpblk_t
 603find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
 604{
 605        ext2_grpblk_t here, next;
 606        char *p, *r;
 607
 608        if (start > 0) {
 609                /*
 610                 * The goal was occupied; search forward for a free 
 611                 * block within the next XX blocks.
 612                 *
 613                 * end_goal is more or less random, but it has to be
 614                 * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
 615                 * next 64-bit boundary is simple..
 616                 */
 617                ext2_grpblk_t end_goal = (start + 63) & ~63;
 618                if (end_goal > maxblocks)
 619                        end_goal = maxblocks;
 620                here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
 621                if (here < end_goal)
 622                        return here;
 623                ext2_debug("Bit not found near goal\n");
 624        }
 625
 626        here = start;
 627        if (here < 0)
 628                here = 0;
 629
 630        p = ((char *)bh->b_data) + (here >> 3);
 631        r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
 632        next = (r - ((char *)bh->b_data)) << 3;
 633
 634        if (next < maxblocks && next >= here)
 635                return next;
 636
 637        here = bitmap_search_next_usable_block(here, bh, maxblocks);
 638        return here;
 639}
 640
 641/**
 642 * ext2_try_to_allocate()
 643 * @sb:                 superblock
 644 * @group:              given allocation block group
 645 * @bitmap_bh:          bufferhead holds the block bitmap
 646 * @grp_goal:           given target block within the group
 647 * @count:              target number of blocks to allocate
 648 * @my_rsv:             reservation window
 649 *
 650 * Attempt to allocate blocks within a give range. Set the range of allocation
 651 * first, then find the first free bit(s) from the bitmap (within the range),
 652 * and at last, allocate the blocks by claiming the found free bit as allocated.
 653 *
 654 * To set the range of this allocation:
 655 *      if there is a reservation window, only try to allocate block(s)
 656 *      from the file's own reservation window;
 657 *      Otherwise, the allocation range starts from the give goal block,
 658 *      ends at the block group's last block.
 659 *
 660 * If we failed to allocate the desired block then we may end up crossing to a
 661 * new bitmap.
 662 */
 663static int
 664ext2_try_to_allocate(struct super_block *sb, int group,
 665                        struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
 666                        unsigned long *count,
 667                        struct ext2_reserve_window *my_rsv)
 668{
 669        ext2_fsblk_t group_first_block = ext2_group_first_block_no(sb, group);
 670        ext2_fsblk_t group_last_block = ext2_group_last_block_no(sb, group);
 671        ext2_grpblk_t start, end;
 672        unsigned long num = 0;
 673
 674        start = 0;
 675        end = group_last_block - group_first_block + 1;
 676        /* we do allocation within the reservation window if we have a window */
 677        if (my_rsv) {
 678                if (my_rsv->_rsv_start >= group_first_block)
 679                        start = my_rsv->_rsv_start - group_first_block;
 680                if (my_rsv->_rsv_end < group_last_block)
 681                        end = my_rsv->_rsv_end - group_first_block + 1;
 682                if (grp_goal < start || grp_goal >= end)
 683                        grp_goal = -1;
 684        }
 685        BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
 686
 687        if (grp_goal < 0) {
 688                grp_goal = find_next_usable_block(start, bitmap_bh, end);
 689                if (grp_goal < 0)
 690                        goto fail_access;
 691                if (!my_rsv) {
 692                        int i;
 693
 694                        for (i = 0; i < 7 && grp_goal > start &&
 695                                        !ext2_test_bit(grp_goal - 1,
 696                                                        bitmap_bh->b_data);
 697                                        i++, grp_goal--)
 698                                ;
 699                }
 700        }
 701
 702        for (; num < *count && grp_goal < end; grp_goal++) {
 703                if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
 704                                        grp_goal, bitmap_bh->b_data)) {
 705                        if (num == 0)
 706                                continue;
 707                        break;
 708                }
 709                num++;
 710        }
 711
 712        if (num == 0)
 713                goto fail_access;
 714
 715        *count = num;
 716        return grp_goal - num;
 717fail_access:
 718        return -1;
 719}
 720
 721/**
 722 *      find_next_reservable_window():
 723 *              find a reservable space within the given range.
 724 *              It does not allocate the reservation window for now:
 725 *              alloc_new_reservation() will do the work later.
 726 *
 727 *      @search_head: the head of the searching list;
 728 *              This is not necessarily the list head of the whole filesystem
 729 *
 730 *              We have both head and start_block to assist the search
 731 *              for the reservable space. The list starts from head,
 732 *              but we will shift to the place where start_block is,
 733 *              then start from there, when looking for a reservable space.
 734 *
 735 *      @sb: the super block.
 736 *
 737 *      @start_block: the first block we consider to start the real search from
 738 *
 739 *      @last_block:
 740 *              the maximum block number that our goal reservable space
 741 *              could start from. This is normally the last block in this
 742 *              group. The search will end when we found the start of next
 743 *              possible reservable space is out of this boundary.
 744 *              This could handle the cross boundary reservation window
 745 *              request.
 746 *
 747 *      basically we search from the given range, rather than the whole
 748 *      reservation double linked list, (start_block, last_block)
 749 *      to find a free region that is of my size and has not
 750 *      been reserved.
 751 *
 752 */
 753static int find_next_reservable_window(
 754                                struct ext2_reserve_window_node *search_head,
 755                                struct ext2_reserve_window_node *my_rsv,
 756                                struct super_block * sb,
 757                                ext2_fsblk_t start_block,
 758                                ext2_fsblk_t last_block)
 759{
 760        struct rb_node *next;
 761        struct ext2_reserve_window_node *rsv, *prev;
 762        ext2_fsblk_t cur;
 763        int size = my_rsv->rsv_goal_size;
 764
 765        /* TODO: make the start of the reservation window byte-aligned */
 766        /* cur = *start_block & ~7;*/
 767        cur = start_block;
 768        rsv = search_head;
 769        if (!rsv)
 770                return -1;
 771
 772        while (1) {
 773                if (cur <= rsv->rsv_end)
 774                        cur = rsv->rsv_end + 1;
 775
 776                /* TODO?
 777                 * in the case we could not find a reservable space
 778                 * that is what is expected, during the re-search, we could
 779                 * remember what's the largest reservable space we could have
 780                 * and return that one.
 781                 *
 782                 * For now it will fail if we could not find the reservable
 783                 * space with expected-size (or more)...
 784                 */
 785                if (cur > last_block)
 786                        return -1;              /* fail */
 787
 788                prev = rsv;
 789                next = rb_next(&rsv->rsv_node);
 790                rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
 791
 792                /*
 793                 * Reached the last reservation, we can just append to the
 794                 * previous one.
 795                 */
 796                if (!next)
 797                        break;
 798
 799                if (cur + size <= rsv->rsv_start) {
 800                        /*
 801                         * Found a reserveable space big enough.  We could
 802                         * have a reservation across the group boundary here
 803                         */
 804                        break;
 805                }
 806        }
 807        /*
 808         * we come here either :
 809         * when we reach the end of the whole list,
 810         * and there is empty reservable space after last entry in the list.
 811         * append it to the end of the list.
 812         *
 813         * or we found one reservable space in the middle of the list,
 814         * return the reservation window that we could append to.
 815         * succeed.
 816         */
 817
 818        if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
 819                rsv_window_remove(sb, my_rsv);
 820
 821        /*
 822         * Let's book the whole available window for now.  We will check the
 823         * disk bitmap later and then, if there are free blocks then we adjust
 824         * the window size if it's larger than requested.
 825         * Otherwise, we will remove this node from the tree next time
 826         * call find_next_reservable_window.
 827         */
 828        my_rsv->rsv_start = cur;
 829        my_rsv->rsv_end = cur + size - 1;
 830        my_rsv->rsv_alloc_hit = 0;
 831
 832        if (prev != my_rsv)
 833                ext2_rsv_window_add(sb, my_rsv);
 834
 835        return 0;
 836}
 837
 838/**
 839 *      alloc_new_reservation()--allocate a new reservation window
 840 *
 841 *              To make a new reservation, we search part of the filesystem
 842 *              reservation list (the list that inside the group). We try to
 843 *              allocate a new reservation window near the allocation goal,
 844 *              or the beginning of the group, if there is no goal.
 845 *
 846 *              We first find a reservable space after the goal, then from
 847 *              there, we check the bitmap for the first free block after
 848 *              it. If there is no free block until the end of group, then the
 849 *              whole group is full, we failed. Otherwise, check if the free
 850 *              block is inside the expected reservable space, if so, we
 851 *              succeed.
 852 *              If the first free block is outside the reservable space, then
 853 *              start from the first free block, we search for next available
 854 *              space, and go on.
 855 *
 856 *      on succeed, a new reservation will be found and inserted into the list
 857 *      It contains at least one free block, and it does not overlap with other
 858 *      reservation windows.
 859 *
 860 *      failed: we failed to find a reservation window in this group
 861 *
 862 *      @my_rsv: the reservation
 863 *
 864 *      @grp_goal: The goal (group-relative).  It is where the search for a
 865 *              free reservable space should start from.
 866 *              if we have a goal(goal >0 ), then start from there,
 867 *              no goal(goal = -1), we start from the first block
 868 *              of the group.
 869 *
 870 *      @sb: the super block
 871 *      @group: the group we are trying to allocate in
 872 *      @bitmap_bh: the block group block bitmap
 873 *
 874 */
 875static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
 876                ext2_grpblk_t grp_goal, struct super_block *sb,
 877                unsigned int group, struct buffer_head *bitmap_bh)
 878{
 879        struct ext2_reserve_window_node *search_head;
 880        ext2_fsblk_t group_first_block, group_end_block, start_block;
 881        ext2_grpblk_t first_free_block;
 882        struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
 883        unsigned long size;
 884        int ret;
 885        spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
 886
 887        group_first_block = ext2_group_first_block_no(sb, group);
 888        group_end_block = ext2_group_last_block_no(sb, group);
 889
 890        if (grp_goal < 0)
 891                start_block = group_first_block;
 892        else
 893                start_block = grp_goal + group_first_block;
 894
 895        size = my_rsv->rsv_goal_size;
 896
 897        if (!rsv_is_empty(&my_rsv->rsv_window)) {
 898                /*
 899                 * if the old reservation is cross group boundary
 900                 * and if the goal is inside the old reservation window,
 901                 * we will come here when we just failed to allocate from
 902                 * the first part of the window. We still have another part
 903                 * that belongs to the next group. In this case, there is no
 904                 * point to discard our window and try to allocate a new one
 905                 * in this group(which will fail). we should
 906                 * keep the reservation window, just simply move on.
 907                 *
 908                 * Maybe we could shift the start block of the reservation
 909                 * window to the first block of next group.
 910                 */
 911
 912                if ((my_rsv->rsv_start <= group_end_block) &&
 913                                (my_rsv->rsv_end > group_end_block) &&
 914                                (start_block >= my_rsv->rsv_start))
 915                        return -1;
 916
 917                if ((my_rsv->rsv_alloc_hit >
 918                     (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
 919                        /*
 920                         * if the previously allocation hit ratio is
 921                         * greater than 1/2, then we double the size of
 922                         * the reservation window the next time,
 923                         * otherwise we keep the same size window
 924                         */
 925                        size = size * 2;
 926                        if (size > EXT2_MAX_RESERVE_BLOCKS)
 927                                size = EXT2_MAX_RESERVE_BLOCKS;
 928                        my_rsv->rsv_goal_size= size;
 929                }
 930        }
 931
 932        spin_lock(rsv_lock);
 933        /*
 934         * shift the search start to the window near the goal block
 935         */
 936        search_head = search_reserve_window(fs_rsv_root, start_block);
 937
 938        /*
 939         * find_next_reservable_window() simply finds a reservable window
 940         * inside the given range(start_block, group_end_block).
 941         *
 942         * To make sure the reservation window has a free bit inside it, we
 943         * need to check the bitmap after we found a reservable window.
 944         */
 945retry:
 946        ret = find_next_reservable_window(search_head, my_rsv, sb,
 947                                                start_block, group_end_block);
 948
 949        if (ret == -1) {
 950                if (!rsv_is_empty(&my_rsv->rsv_window))
 951                        rsv_window_remove(sb, my_rsv);
 952                spin_unlock(rsv_lock);
 953                return -1;
 954        }
 955
 956        /*
 957         * On success, find_next_reservable_window() returns the
 958         * reservation window where there is a reservable space after it.
 959         * Before we reserve this reservable space, we need
 960         * to make sure there is at least a free block inside this region.
 961         *
 962         * Search the first free bit on the block bitmap.  Search starts from
 963         * the start block of the reservable space we just found.
 964         */
 965        spin_unlock(rsv_lock);
 966        first_free_block = bitmap_search_next_usable_block(
 967                        my_rsv->rsv_start - group_first_block,
 968                        bitmap_bh, group_end_block - group_first_block + 1);
 969
 970        if (first_free_block < 0) {
 971                /*
 972                 * no free block left on the bitmap, no point
 973                 * to reserve the space. return failed.
 974                 */
 975                spin_lock(rsv_lock);
 976                if (!rsv_is_empty(&my_rsv->rsv_window))
 977                        rsv_window_remove(sb, my_rsv);
 978                spin_unlock(rsv_lock);
 979                return -1;              /* failed */
 980        }
 981
 982        start_block = first_free_block + group_first_block;
 983        /*
 984         * check if the first free block is within the
 985         * free space we just reserved
 986         */
 987        if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
 988                return 0;               /* success */
 989        /*
 990         * if the first free bit we found is out of the reservable space
 991         * continue search for next reservable space,
 992         * start from where the free block is,
 993         * we also shift the list head to where we stopped last time
 994         */
 995        search_head = my_rsv;
 996        spin_lock(rsv_lock);
 997        goto retry;
 998}
 999
1000/**
1001 * try_to_extend_reservation()
1002 * @my_rsv:             given reservation window
1003 * @sb:                 super block
1004 * @size:               the delta to extend
1005 *
1006 * Attempt to expand the reservation window large enough to have
1007 * required number of free blocks
1008 *
1009 * Since ext2_try_to_allocate() will always allocate blocks within
1010 * the reservation window range, if the window size is too small,
1011 * multiple blocks allocation has to stop at the end of the reservation
1012 * window. To make this more efficient, given the total number of
1013 * blocks needed and the current size of the window, we try to
1014 * expand the reservation window size if necessary on a best-effort
1015 * basis before ext2_new_blocks() tries to allocate blocks.
1016 */
1017static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
1018                        struct super_block *sb, int size)
1019{
1020        struct ext2_reserve_window_node *next_rsv;
1021        struct rb_node *next;
1022        spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
1023
1024        if (!spin_trylock(rsv_lock))
1025                return;
1026
1027        next = rb_next(&my_rsv->rsv_node);
1028
1029        if (!next)
1030                my_rsv->rsv_end += size;
1031        else {
1032                next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
1033
1034                if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1035                        my_rsv->rsv_end += size;
1036                else
1037                        my_rsv->rsv_end = next_rsv->rsv_start - 1;
1038        }
1039        spin_unlock(rsv_lock);
1040}
1041
1042/**
1043 * ext2_try_to_allocate_with_rsv()
1044 * @sb:                 superblock
1045 * @group:              given allocation block group
1046 * @bitmap_bh:          bufferhead holds the block bitmap
1047 * @grp_goal:           given target block within the group
1048 * @count:              target number of blocks to allocate
1049 * @my_rsv:             reservation window
1050 *
1051 * This is the main function used to allocate a new block and its reservation
1052 * window.
1053 *
1054 * Each time when a new block allocation is need, first try to allocate from
1055 * its own reservation.  If it does not have a reservation window, instead of
1056 * looking for a free bit on bitmap first, then look up the reservation list to
1057 * see if it is inside somebody else's reservation window, we try to allocate a
1058 * reservation window for it starting from the goal first. Then do the block
1059 * allocation within the reservation window.
1060 *
1061 * This will avoid keeping on searching the reservation list again and
1062 * again when somebody is looking for a free block (without
1063 * reservation), and there are lots of free blocks, but they are all
1064 * being reserved.
1065 *
1066 * We use a red-black tree for the per-filesystem reservation list.
1067 */
1068static ext2_grpblk_t
1069ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
1070                        struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
1071                        struct ext2_reserve_window_node * my_rsv,
1072                        unsigned long *count)
1073{
1074        ext2_fsblk_t group_first_block, group_last_block;
1075        ext2_grpblk_t ret = 0;
1076        unsigned long num = *count;
1077
1078        /*
1079         * we don't deal with reservation when
1080         * filesystem is mounted without reservation
1081         * or the file is not a regular file
1082         * or last attempt to allocate a block with reservation turned on failed
1083         */
1084        if (my_rsv == NULL) {
1085                return ext2_try_to_allocate(sb, group, bitmap_bh,
1086                                                grp_goal, count, NULL);
1087        }
1088        /*
1089         * grp_goal is a group relative block number (if there is a goal)
1090         * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
1091         * first block is a filesystem wide block number
1092         * first block is the block number of the first block in this group
1093         */
1094        group_first_block = ext2_group_first_block_no(sb, group);
1095        group_last_block = ext2_group_last_block_no(sb, group);
1096
1097        /*
1098         * Basically we will allocate a new block from inode's reservation
1099         * window.
1100         *
1101         * We need to allocate a new reservation window, if:
1102         * a) inode does not have a reservation window; or
1103         * b) last attempt to allocate a block from existing reservation
1104         *    failed; or
1105         * c) we come here with a goal and with a reservation window
1106         *
1107         * We do not need to allocate a new reservation window if we come here
1108         * at the beginning with a goal and the goal is inside the window, or
1109         * we don't have a goal but already have a reservation window.
1110         * then we could go to allocate from the reservation window directly.
1111         */
1112        while (1) {
1113                if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1114                        !goal_in_my_reservation(&my_rsv->rsv_window,
1115                                                grp_goal, group, sb)) {
1116                        if (my_rsv->rsv_goal_size < *count)
1117                                my_rsv->rsv_goal_size = *count;
1118                        ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1119                                                        group, bitmap_bh);
1120                        if (ret < 0)
1121                                break;                  /* failed */
1122
1123                        if (!goal_in_my_reservation(&my_rsv->rsv_window,
1124                                                        grp_goal, group, sb))
1125                                grp_goal = -1;
1126                } else if (grp_goal >= 0) {
1127                        int curr = my_rsv->rsv_end -
1128                                        (grp_goal + group_first_block) + 1;
1129
1130                        if (curr < *count)
1131                                try_to_extend_reservation(my_rsv, sb,
1132                                                        *count - curr);
1133                }
1134
1135                if ((my_rsv->rsv_start > group_last_block) ||
1136                                (my_rsv->rsv_end < group_first_block)) {
1137                        rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
1138                        BUG();
1139                }
1140                ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
1141                                           &num, &my_rsv->rsv_window);
1142                if (ret >= 0) {
1143                        my_rsv->rsv_alloc_hit += num;
1144                        *count = num;
1145                        break;                          /* succeed */
1146                }
1147                num = *count;
1148        }
1149        return ret;
1150}
1151
1152/**
1153 * ext2_has_free_blocks()
1154 * @sbi:                in-core super block structure.
1155 *
1156 * Check if filesystem has at least 1 free block available for allocation.
1157 */
1158static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
1159{
1160        ext2_fsblk_t free_blocks, root_blocks;
1161
1162        free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1163        root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1164        if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1165                !uid_eq(sbi->s_resuid, current_fsuid()) &&
1166                (gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
1167                 !in_group_p (sbi->s_resgid))) {
1168                return 0;
1169        }
1170        return 1;
1171}
1172
1173/*
1174 * Returns 1 if the passed-in block region is valid; 0 if some part overlaps
1175 * with filesystem metadata blocks.
1176 */
1177int ext2_data_block_valid(struct ext2_sb_info *sbi, ext2_fsblk_t start_blk,
1178                          unsigned int count)
1179{
1180        if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
1181            (start_blk + count - 1 < start_blk) ||
1182            (start_blk + count - 1 >= le32_to_cpu(sbi->s_es->s_blocks_count)))
1183                return 0;
1184
1185        /* Ensure we do not step over superblock */
1186        if ((start_blk <= sbi->s_sb_block) &&
1187            (start_blk + count - 1 >= sbi->s_sb_block))
1188                return 0;
1189
1190        return 1;
1191}
1192
1193/*
1194 * ext2_new_blocks() -- core block(s) allocation function
1195 * @inode:              file inode
1196 * @goal:               given target block(filesystem wide)
1197 * @count:              target number of blocks to allocate
1198 * @errp:               error code
1199 *
1200 * ext2_new_blocks uses a goal block to assist allocation.  If the goal is
1201 * free, or there is a free block within 32 blocks of the goal, that block
1202 * is allocated.  Otherwise a forward search is made for a free block; within 
1203 * each block group the search first looks for an entire free byte in the block
1204 * bitmap, and then for any free bit if that fails.
1205 * This function also updates quota and i_blocks field.
1206 */
1207ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
1208                    unsigned long *count, int *errp)
1209{
1210        struct buffer_head *bitmap_bh = NULL;
1211        struct buffer_head *gdp_bh;
1212        int group_no;
1213        int goal_group;
1214        ext2_grpblk_t grp_target_blk;   /* blockgroup relative goal block */
1215        ext2_grpblk_t grp_alloc_blk;    /* blockgroup-relative allocated block*/
1216        ext2_fsblk_t ret_block;         /* filesyetem-wide allocated block */
1217        int bgi;                        /* blockgroup iteration index */
1218        int performed_allocation = 0;
1219        ext2_grpblk_t free_blocks;      /* number of free blocks in a group */
1220        struct super_block *sb;
1221        struct ext2_group_desc *gdp;
1222        struct ext2_super_block *es;
1223        struct ext2_sb_info *sbi;
1224        struct ext2_reserve_window_node *my_rsv = NULL;
1225        struct ext2_block_alloc_info *block_i;
1226        unsigned short windowsz = 0;
1227        unsigned long ngroups;
1228        unsigned long num = *count;
1229        int ret;
1230
1231        *errp = -ENOSPC;
1232        sb = inode->i_sb;
1233
1234        /*
1235         * Check quota for allocation of this block.
1236         */
1237        ret = dquot_alloc_block(inode, num);
1238        if (ret) {
1239                *errp = ret;
1240                return 0;
1241        }
1242
1243        sbi = EXT2_SB(sb);
1244        es = EXT2_SB(sb)->s_es;
1245        ext2_debug("goal=%lu.\n", goal);
1246        /*
1247         * Allocate a block from reservation only when
1248         * filesystem is mounted with reservation(default,-o reservation), and
1249         * it's a regular file, and
1250         * the desired window size is greater than 0 (One could use ioctl
1251         * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off
1252         * reservation on that particular file)
1253         */
1254        block_i = EXT2_I(inode)->i_block_alloc_info;
1255        if (block_i) {
1256                windowsz = block_i->rsv_window_node.rsv_goal_size;
1257                if (windowsz > 0)
1258                        my_rsv = &block_i->rsv_window_node;
1259        }
1260
1261        if (!ext2_has_free_blocks(sbi)) {
1262                *errp = -ENOSPC;
1263                goto out;
1264        }
1265
1266        /*
1267         * First, test whether the goal block is free.
1268         */
1269        if (goal < le32_to_cpu(es->s_first_data_block) ||
1270            goal >= le32_to_cpu(es->s_blocks_count))
1271                goal = le32_to_cpu(es->s_first_data_block);
1272        group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1273                        EXT2_BLOCKS_PER_GROUP(sb);
1274        goal_group = group_no;
1275retry_alloc:
1276        gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1277        if (!gdp)
1278                goto io_error;
1279
1280        free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1281        /*
1282         * if there is not enough free blocks to make a new resevation
1283         * turn off reservation for this allocation
1284         */
1285        if (my_rsv && (free_blocks < windowsz)
1286                && (free_blocks > 0)
1287                && (rsv_is_empty(&my_rsv->rsv_window)))
1288                my_rsv = NULL;
1289
1290        if (free_blocks > 0) {
1291                grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1292                                EXT2_BLOCKS_PER_GROUP(sb));
1293                /*
1294                 * In case we retry allocation (due to fs reservation not
1295                 * working out or fs corruption), the bitmap_bh is non-null
1296                 * pointer and we have to release it before calling
1297                 * read_block_bitmap().
1298                 */
1299                brelse(bitmap_bh);
1300                bitmap_bh = read_block_bitmap(sb, group_no);
1301                if (!bitmap_bh)
1302                        goto io_error;
1303                grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1304                                        bitmap_bh, grp_target_blk,
1305                                        my_rsv, &num);
1306                if (grp_alloc_blk >= 0)
1307                        goto allocated;
1308        }
1309
1310        ngroups = EXT2_SB(sb)->s_groups_count;
1311        smp_rmb();
1312
1313        /*
1314         * Now search the rest of the groups.  We assume that
1315         * group_no and gdp correctly point to the last group visited.
1316         */
1317        for (bgi = 0; bgi < ngroups; bgi++) {
1318                group_no++;
1319                if (group_no >= ngroups)
1320                        group_no = 0;
1321                gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1322                if (!gdp)
1323                        goto io_error;
1324
1325                free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1326                /*
1327                 * skip this group (and avoid loading bitmap) if there
1328                 * are no free blocks
1329                 */
1330                if (!free_blocks)
1331                        continue;
1332                /*
1333                 * skip this group if the number of
1334                 * free blocks is less than half of the reservation
1335                 * window size.
1336                 */
1337                if (my_rsv && (free_blocks <= (windowsz/2)))
1338                        continue;
1339
1340                brelse(bitmap_bh);
1341                bitmap_bh = read_block_bitmap(sb, group_no);
1342                if (!bitmap_bh)
1343                        goto io_error;
1344                /*
1345                 * try to allocate block(s) from this group, without a goal(-1).
1346                 */
1347                grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1348                                        bitmap_bh, -1, my_rsv, &num);
1349                if (grp_alloc_blk >= 0)
1350                        goto allocated;
1351        }
1352        /*
1353         * We may end up a bogus earlier ENOSPC error due to
1354         * filesystem is "full" of reservations, but
1355         * there maybe indeed free blocks available on disk
1356         * In this case, we just forget about the reservations
1357         * just do block allocation as without reservations.
1358         */
1359        if (my_rsv) {
1360                my_rsv = NULL;
1361                windowsz = 0;
1362                group_no = goal_group;
1363                goto retry_alloc;
1364        }
1365        /* No space left on the device */
1366        *errp = -ENOSPC;
1367        goto out;
1368
1369allocated:
1370
1371        ext2_debug("using block group %d(%d)\n",
1372                        group_no, gdp->bg_free_blocks_count);
1373
1374        ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
1375
1376        if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1377            in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1378            in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1379                      EXT2_SB(sb)->s_itb_per_group) ||
1380            in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1381                      EXT2_SB(sb)->s_itb_per_group)) {
1382                ext2_error(sb, "ext2_new_blocks",
1383                            "Allocating block in system zone - "
1384                            "blocks from "E2FSBLK", length %lu",
1385                            ret_block, num);
1386                /*
1387                 * ext2_try_to_allocate marked the blocks we allocated as in
1388                 * use.  So we may want to selectively mark some of the blocks
1389                 * as free
1390                 */
1391                num = *count;
1392                goto retry_alloc;
1393        }
1394
1395        performed_allocation = 1;
1396
1397        if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1398                ext2_error(sb, "ext2_new_blocks",
1399                            "block("E2FSBLK") >= blocks count(%d) - "
1400                            "block_group = %d, es == %p ", ret_block,
1401                        le32_to_cpu(es->s_blocks_count), group_no, es);
1402                goto out;
1403        }
1404
1405        group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
1406        percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1407
1408        mark_buffer_dirty(bitmap_bh);
1409        if (sb->s_flags & SB_SYNCHRONOUS)
1410                sync_dirty_buffer(bitmap_bh);
1411
1412        *errp = 0;
1413        brelse(bitmap_bh);
1414        if (num < *count) {
1415                dquot_free_block_nodirty(inode, *count-num);
1416                mark_inode_dirty(inode);
1417                *count = num;
1418        }
1419        return ret_block;
1420
1421io_error:
1422        *errp = -EIO;
1423out:
1424        /*
1425         * Undo the block allocation
1426         */
1427        if (!performed_allocation) {
1428                dquot_free_block_nodirty(inode, *count);
1429                mark_inode_dirty(inode);
1430        }
1431        brelse(bitmap_bh);
1432        return 0;
1433}
1434
1435ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
1436{
1437        unsigned long count = 1;
1438
1439        return ext2_new_blocks(inode, goal, &count, errp);
1440}
1441
1442#ifdef EXT2FS_DEBUG
1443
1444unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)
1445{
1446        return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
1447}
1448
1449#endif  /*  EXT2FS_DEBUG  */
1450
1451unsigned long ext2_count_free_blocks (struct super_block * sb)
1452{
1453        struct ext2_group_desc * desc;
1454        unsigned long desc_count = 0;
1455        int i;
1456#ifdef EXT2FS_DEBUG
1457        unsigned long bitmap_count, x;
1458        struct ext2_super_block *es;
1459
1460        es = EXT2_SB(sb)->s_es;
1461        desc_count = 0;
1462        bitmap_count = 0;
1463        desc = NULL;
1464        for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1465                struct buffer_head *bitmap_bh;
1466                desc = ext2_get_group_desc (sb, i, NULL);
1467                if (!desc)
1468                        continue;
1469                desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1470                bitmap_bh = read_block_bitmap(sb, i);
1471                if (!bitmap_bh)
1472                        continue;
1473                
1474                x = ext2_count_free(bitmap_bh, sb->s_blocksize);
1475                printk ("group %d: stored = %d, counted = %lu\n",
1476                        i, le16_to_cpu(desc->bg_free_blocks_count), x);
1477                bitmap_count += x;
1478                brelse(bitmap_bh);
1479        }
1480        printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
1481                (long)le32_to_cpu(es->s_free_blocks_count),
1482                desc_count, bitmap_count);
1483        return bitmap_count;
1484#else
1485        for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1486                desc = ext2_get_group_desc (sb, i, NULL);
1487                if (!desc)
1488                        continue;
1489                desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1490        }
1491        return desc_count;
1492#endif
1493}
1494
1495static inline int test_root(int a, int b)
1496{
1497        int num = b;
1498
1499        while (a > num)
1500                num *= b;
1501        return num == a;
1502}
1503
1504static int ext2_group_sparse(int group)
1505{
1506        if (group <= 1)
1507                return 1;
1508        return (test_root(group, 3) || test_root(group, 5) ||
1509                test_root(group, 7));
1510}
1511
1512/**
1513 *      ext2_bg_has_super - number of blocks used by the superblock in group
1514 *      @sb: superblock for filesystem
1515 *      @group: group number to check
1516 *
1517 *      Return the number of blocks used by the superblock (primary or backup)
1518 *      in this group.  Currently this will be only 0 or 1.
1519 */
1520int ext2_bg_has_super(struct super_block *sb, int group)
1521{
1522        if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1523            !ext2_group_sparse(group))
1524                return 0;
1525        return 1;
1526}
1527
1528/**
1529 *      ext2_bg_num_gdb - number of blocks used by the group table in group
1530 *      @sb: superblock for filesystem
1531 *      @group: group number to check
1532 *
1533 *      Return the number of blocks used by the group descriptor table
1534 *      (primary or backup) in this group.  In the future there may be a
1535 *      different number of descriptor blocks in each group.
1536 */
1537unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
1538{
1539        return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
1540}
1541
1542