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1// SPDX-License-Identifier: GPL-2.02/*3 * linux/fs/ext2/balloc.c4 *5 * Copyright (C) 1992, 1993, 1994, 19956 * Remy Card (card@masi.ibp.fr)7 * Laboratoire MASI - Institut Blaise Pascal8 * Universite Pierre et Marie Curie (Paris VI)9 *10 * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 199311 * Big-endian to little-endian byte-swapping/bitmaps by12 * David S. Miller (davem@caip.rutgers.edu), 199513 */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 routines25 */26 27/*28 * The free blocks are managed by bitmaps. A file system contains several29 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap30 * block for inodes, N blocks for the inode table and data blocks.31 *32 * The file system contains group descriptors which are located after the33 * super block. Each descriptor contains the number of the bitmap block and34 * the free blocks count in the block. The descriptors are loaded in memory35 * when a file system is mounted (see ext2_fill_super).36 */37 38 39struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,40 unsigned int block_group,41 struct buffer_head ** bh)42{43 unsigned long group_desc;44 unsigned long offset;45 struct ext2_group_desc * desc;46 struct ext2_sb_info *sbi = EXT2_SB(sb);47 48 if (block_group >= sbi->s_groups_count) {49 WARN(1, "block_group >= groups_count - "50 "block_group = %d, groups_count = %lu",51 block_group, sbi->s_groups_count);52 53 return NULL;54 }55 56 group_desc = block_group >> EXT2_DESC_PER_BLOCK_BITS(sb);57 offset = block_group & (EXT2_DESC_PER_BLOCK(sb) - 1);58 if (!sbi->s_group_desc[group_desc]) {59 WARN(1, "Group descriptor not loaded - "60 "block_group = %d, group_desc = %lu, desc = %lu",61 block_group, group_desc, offset);62 return NULL;63 }64 65 desc = (struct ext2_group_desc *) sbi->s_group_desc[group_desc]->b_data;66 if (bh)67 *bh = sbi->s_group_desc[group_desc];68 return desc + offset;69}70 71static int ext2_valid_block_bitmap(struct super_block *sb,72 struct ext2_group_desc *desc,73 unsigned int block_group,74 struct buffer_head *bh)75{76 ext2_grpblk_t offset;77 ext2_grpblk_t next_zero_bit;78 ext2_fsblk_t bitmap_blk;79 ext2_fsblk_t group_first_block;80 ext2_grpblk_t max_bit;81 82 group_first_block = ext2_group_first_block_no(sb, block_group);83 max_bit = ext2_group_last_block_no(sb, block_group) - group_first_block;84 85 /* check whether block bitmap block number is set */86 bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);87 offset = bitmap_blk - group_first_block;88 if (offset < 0 || offset > max_bit ||89 !ext2_test_bit(offset, bh->b_data))90 /* bad block bitmap */91 goto err_out;92 93 /* check whether the inode bitmap block number is set */94 bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);95 offset = bitmap_blk - group_first_block;96 if (offset < 0 || offset > max_bit ||97 !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 if (offset < 0 || offset > max_bit ||105 offset + EXT2_SB(sb)->s_itb_per_group - 1 > max_bit)106 goto err_out;107 next_zero_bit = ext2_find_next_zero_bit(bh->b_data,108 offset + EXT2_SB(sb)->s_itb_per_group,109 offset);110 if (next_zero_bit >= offset + EXT2_SB(sb)->s_itb_per_group)111 /* good bitmap for inode tables */112 return 1;113 114err_out:115 ext2_error(sb, __func__,116 "Invalid block bitmap - "117 "block_group = %d, block = %lu",118 block_group, bitmap_blk);119 return 0;120}121 122/*123 * Read the bitmap for a given block_group,and validate the124 * bits for block/inode/inode tables are set in the bitmaps125 *126 * Return buffer_head on success or NULL in case of failure.127 */128static struct buffer_head *129read_block_bitmap(struct super_block *sb, unsigned int block_group)130{131 struct ext2_group_desc * desc;132 struct buffer_head * bh = NULL;133 ext2_fsblk_t bitmap_blk;134 int ret;135 136 desc = ext2_get_group_desc(sb, block_group, NULL);137 if (!desc)138 return NULL;139 bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);140 bh = sb_getblk(sb, bitmap_blk);141 if (unlikely(!bh)) {142 ext2_error(sb, __func__,143 "Cannot read block bitmap - "144 "block_group = %d, block_bitmap = %u",145 block_group, le32_to_cpu(desc->bg_block_bitmap));146 return NULL;147 }148 ret = bh_read(bh, 0);149 if (ret > 0)150 return bh;151 if (ret < 0) {152 brelse(bh);153 ext2_error(sb, __func__,154 "Cannot read block bitmap - "155 "block_group = %d, block_bitmap = %u",156 block_group, le32_to_cpu(desc->bg_block_bitmap));157 return NULL;158 }159 160 ext2_valid_block_bitmap(sb, desc, block_group, bh);161 /*162 * file system mounted not to panic on error, continue with corrupt163 * bitmap164 */165 return bh;166}167 168static void group_adjust_blocks(struct super_block *sb, int group_no,169 struct ext2_group_desc *desc, struct buffer_head *bh, int count)170{171 if (count) {172 struct ext2_sb_info *sbi = EXT2_SB(sb);173 unsigned free_blocks;174 175 spin_lock(sb_bgl_lock(sbi, group_no));176 free_blocks = le16_to_cpu(desc->bg_free_blocks_count);177 desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);178 spin_unlock(sb_bgl_lock(sbi, group_no));179 mark_buffer_dirty(bh);180 }181}182 183/*184 * The reservation window structure operations185 * --------------------------------------------186 * Operations include:187 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.188 *189 * We use a red-black tree to represent per-filesystem reservation190 * windows.191 *192 */193 194/**195 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map196 * @root: root of per-filesystem reservation rb tree197 * @verbose: verbose mode198 * @fn: function which wishes to dump the reservation map199 *200 * If verbose is turned on, it will print the whole block reservation201 * windows(start, end). Otherwise, it will only print out the "bad" windows,202 * those windows that overlap with their immediate neighbors.203 */204#if 1205static void __rsv_window_dump(struct rb_root *root, int verbose,206 const char *fn)207{208 struct rb_node *n;209 struct ext2_reserve_window_node *rsv, *prev;210 int bad;211 212restart:213 n = rb_first(root);214 bad = 0;215 prev = NULL;216 217 printk("Block Allocation Reservation Windows Map (%s):\n", fn);218 while (n) {219 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);220 if (verbose)221 printk("reservation window 0x%p "222 "start: %lu, end: %lu\n",223 rsv, rsv->rsv_start, rsv->rsv_end);224 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {225 printk("Bad reservation %p (start >= end)\n",226 rsv);227 bad = 1;228 }229 if (prev && prev->rsv_end >= rsv->rsv_start) {230 printk("Bad reservation %p (prev->end >= start)\n",231 rsv);232 bad = 1;233 }234 if (bad) {235 if (!verbose) {236 printk("Restarting reservation walk in verbose mode\n");237 verbose = 1;238 goto restart;239 }240 }241 n = rb_next(n);242 prev = rsv;243 }244 printk("Window map complete.\n");245 BUG_ON(bad);246}247#define rsv_window_dump(root, verbose) \248 __rsv_window_dump((root), (verbose), __func__)249#else250#define rsv_window_dump(root, verbose) do {} while (0)251#endif252 253/**254 * goal_in_my_reservation()255 * @rsv: inode's reservation window256 * @grp_goal: given goal block relative to the allocation block group257 * @group: the current allocation block group258 * @sb: filesystem super block259 *260 * Test if the given goal block (group relative) is within the file's261 * own block reservation window range.262 *263 * If the reservation window is outside the goal allocation group, return 0;264 * grp_goal (given goal block) could be -1, which means no specific265 * goal block. In this case, always return 1.266 * If the goal block is within the reservation window, return 1;267 * otherwise, return 0;268 */269static int270goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,271 unsigned int group, struct super_block * sb)272{273 ext2_fsblk_t group_first_block, group_last_block;274 275 group_first_block = ext2_group_first_block_no(sb, group);276 group_last_block = ext2_group_last_block_no(sb, group);277 278 if ((rsv->_rsv_start > group_last_block) ||279 (rsv->_rsv_end < group_first_block))280 return 0;281 if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)282 || (grp_goal + group_first_block > rsv->_rsv_end)))283 return 0;284 return 1;285}286 287/**288 * search_reserve_window()289 * @root: root of reservation tree290 * @goal: target allocation block291 *292 * Find the reserved window which includes the goal, or the previous one293 * if the goal is not in any window.294 * Returns NULL if there are no windows or if all windows start after the goal.295 */296static struct ext2_reserve_window_node *297search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)298{299 struct rb_node *n = root->rb_node;300 struct ext2_reserve_window_node *rsv;301 302 if (!n)303 return NULL;304 305 do {306 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);307 308 if (goal < rsv->rsv_start)309 n = n->rb_left;310 else if (goal > rsv->rsv_end)311 n = n->rb_right;312 else313 return rsv;314 } while (n);315 /*316 * We've fallen off the end of the tree: the goal wasn't inside317 * any particular node. OK, the previous node must be to one318 * side of the interval containing the goal. If it's the RHS,319 * we need to back up one.320 */321 if (rsv->rsv_start > goal) {322 n = rb_prev(&rsv->rsv_node);323 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);324 }325 return rsv;326}327 328/*329 * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.330 * @sb: super block331 * @rsv: reservation window to add332 *333 * Must be called with rsv_lock held.334 */335void ext2_rsv_window_add(struct super_block *sb,336 struct ext2_reserve_window_node *rsv)337{338 struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;339 struct rb_node *node = &rsv->rsv_node;340 ext2_fsblk_t start = rsv->rsv_start;341 342 struct rb_node ** p = &root->rb_node;343 struct rb_node * parent = NULL;344 struct ext2_reserve_window_node *this;345 346 while (*p)347 {348 parent = *p;349 this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);350 351 if (start < this->rsv_start)352 p = &(*p)->rb_left;353 else if (start > this->rsv_end)354 p = &(*p)->rb_right;355 else {356 rsv_window_dump(root, 1);357 BUG();358 }359 }360 361 rb_link_node(node, parent, p);362 rb_insert_color(node, root);363}364 365/**366 * rsv_window_remove() -- unlink a window from the reservation rb tree367 * @sb: super block368 * @rsv: reservation window to remove369 *370 * Mark the block reservation window as not allocated, and unlink it371 * from the filesystem reservation window rb tree. Must be called with372 * rsv_lock held.373 */374static void rsv_window_remove(struct super_block *sb,375 struct ext2_reserve_window_node *rsv)376{377 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;378 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;379 rsv->rsv_alloc_hit = 0;380 rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);381}382 383/*384 * rsv_is_empty() -- Check if the reservation window is allocated.385 * @rsv: given reservation window to check386 *387 * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.388 */389static inline int rsv_is_empty(struct ext2_reserve_window *rsv)390{391 /* a valid reservation end block could not be 0 */392 return (rsv->_rsv_end == EXT2_RESERVE_WINDOW_NOT_ALLOCATED);393}394 395/**396 * ext2_init_block_alloc_info()397 * @inode: file inode structure398 *399 * Allocate and initialize the reservation window structure, and400 * link the window to the ext2 inode structure at last401 *402 * The reservation window structure is only dynamically allocated403 * and linked to ext2 inode the first time the open file404 * needs a new block. So, before every ext2_new_block(s) call, for405 * regular files, we should check whether the reservation window406 * structure exists or not. In the latter case, this function is called.407 * Fail to do so will result in block reservation being turned off for that408 * open file.409 *410 * This function is called from ext2_get_blocks_handle(), also called411 * when setting the reservation window size through ioctl before the file412 * is open for write (needs block allocation).413 *414 * Needs truncate_mutex protection prior to calling this function.415 */416void ext2_init_block_alloc_info(struct inode *inode)417{418 struct ext2_inode_info *ei = EXT2_I(inode);419 struct ext2_block_alloc_info *block_i;420 struct super_block *sb = inode->i_sb;421 422 block_i = kmalloc(sizeof(*block_i), GFP_KERNEL);423 if (block_i) {424 struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;425 426 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;427 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;428 429 /*430 * if filesystem is mounted with NORESERVATION, the goal431 * reservation window size is set to zero to indicate432 * block reservation is off433 */434 if (!test_opt(sb, RESERVATION))435 rsv->rsv_goal_size = 0;436 else437 rsv->rsv_goal_size = EXT2_DEFAULT_RESERVE_BLOCKS;438 rsv->rsv_alloc_hit = 0;439 block_i->last_alloc_logical_block = 0;440 block_i->last_alloc_physical_block = 0;441 }442 ei->i_block_alloc_info = block_i;443}444 445/**446 * ext2_discard_reservation()447 * @inode: inode448 *449 * Discard(free) block reservation window on last file close, or truncate450 * or at last iput().451 *452 * It is being called in three cases:453 * ext2_release_file(): last writer closes the file454 * ext2_clear_inode(): last iput(), when nobody links to this file.455 * ext2_truncate(): when the block indirect map is about to change.456 */457void ext2_discard_reservation(struct inode *inode)458{459 struct ext2_inode_info *ei = EXT2_I(inode);460 struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;461 struct ext2_reserve_window_node *rsv;462 spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;463 464 if (!block_i)465 return;466 467 rsv = &block_i->rsv_window_node;468 if (!rsv_is_empty(&rsv->rsv_window)) {469 spin_lock(rsv_lock);470 if (!rsv_is_empty(&rsv->rsv_window))471 rsv_window_remove(inode->i_sb, rsv);472 spin_unlock(rsv_lock);473 }474}475 476/**477 * ext2_free_blocks() -- Free given blocks and update quota and i_blocks478 * @inode: inode479 * @block: start physical block to free480 * @count: number of blocks to free481 */482void ext2_free_blocks(struct inode * inode, ext2_fsblk_t block,483 unsigned long count)484{485 struct buffer_head *bitmap_bh = NULL;486 struct buffer_head * bh2;487 unsigned long block_group;488 unsigned long bit;489 unsigned long i;490 unsigned long overflow;491 struct super_block * sb = inode->i_sb;492 struct ext2_sb_info * sbi = EXT2_SB(sb);493 struct ext2_group_desc * desc;494 struct ext2_super_block * es = sbi->s_es;495 unsigned freed = 0, group_freed;496 497 if (!ext2_data_block_valid(sbi, block, count)) {498 ext2_error (sb, "ext2_free_blocks",499 "Freeing blocks not in datazone - "500 "block = %lu, count = %lu", block, count);501 goto error_return;502 }503 504 ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);505 506do_more:507 overflow = 0;508 block_group = (block - le32_to_cpu(es->s_first_data_block)) /509 EXT2_BLOCKS_PER_GROUP(sb);510 bit = (block - le32_to_cpu(es->s_first_data_block)) %511 EXT2_BLOCKS_PER_GROUP(sb);512 /*513 * Check to see if we are freeing blocks across a group514 * boundary.515 */516 if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {517 overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);518 count -= overflow;519 }520 brelse(bitmap_bh);521 bitmap_bh = read_block_bitmap(sb, block_group);522 if (!bitmap_bh)523 goto error_return;524 525 desc = ext2_get_group_desc (sb, block_group, &bh2);526 if (!desc)527 goto error_return;528 529 if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||530 in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||531 in_range (block, le32_to_cpu(desc->bg_inode_table),532 sbi->s_itb_per_group) ||533 in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),534 sbi->s_itb_per_group)) {535 ext2_error (sb, "ext2_free_blocks",536 "Freeing blocks in system zones - "537 "Block = %lu, count = %lu",538 block, count);539 goto error_return;540 }541 542 for (i = 0, group_freed = 0; i < count; i++) {543 if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),544 bit + i, bitmap_bh->b_data)) {545 ext2_error(sb, __func__,546 "bit already cleared for block %lu", block + i);547 } else {548 group_freed++;549 }550 }551 552 mark_buffer_dirty(bitmap_bh);553 if (sb->s_flags & SB_SYNCHRONOUS)554 sync_dirty_buffer(bitmap_bh);555 556 group_adjust_blocks(sb, block_group, desc, bh2, group_freed);557 freed += group_freed;558 559 if (overflow) {560 block += count;561 count = overflow;562 goto do_more;563 }564error_return:565 brelse(bitmap_bh);566 if (freed) {567 percpu_counter_add(&sbi->s_freeblocks_counter, freed);568 dquot_free_block_nodirty(inode, freed);569 mark_inode_dirty(inode);570 }571}572 573/**574 * bitmap_search_next_usable_block()575 * @start: the starting block (group relative) of the search576 * @bh: bufferhead contains the block group bitmap577 * @maxblocks: the ending block (group relative) of the reservation578 *579 * The bitmap search --- search forward through the actual bitmap on disk until580 * we find a bit free.581 */582static ext2_grpblk_t583bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,584 ext2_grpblk_t maxblocks)585{586 ext2_grpblk_t next;587 588 next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);589 if (next >= maxblocks)590 return -1;591 return next;592}593 594/**595 * find_next_usable_block()596 * @start: the starting block (group relative) to find next597 * allocatable block in bitmap.598 * @bh: bufferhead contains the block group bitmap599 * @maxblocks: the ending block (group relative) for the search600 *601 * Find an allocatable block in a bitmap. We perform the "most602 * appropriate allocation" algorithm of looking for a free block near603 * the initial goal; then for a free byte somewhere in the bitmap;604 * then for any free bit in the bitmap.605 */606static ext2_grpblk_t607find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)608{609 ext2_grpblk_t here, next;610 char *p, *r;611 612 if (start > 0) {613 /*614 * The goal was occupied; search forward for a free 615 * block within the next XX blocks.616 *617 * end_goal is more or less random, but it has to be618 * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the619 * next 64-bit boundary is simple..620 */621 ext2_grpblk_t end_goal = (start + 63) & ~63;622 if (end_goal > maxblocks)623 end_goal = maxblocks;624 here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);625 if (here < end_goal)626 return here;627 ext2_debug("Bit not found near goal\n");628 }629 630 here = start;631 if (here < 0)632 here = 0;633 634 p = ((char *)bh->b_data) + (here >> 3);635 r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));636 next = (r - ((char *)bh->b_data)) << 3;637 638 if (next < maxblocks && next >= here)639 return next;640 641 here = bitmap_search_next_usable_block(here, bh, maxblocks);642 return here;643}644 645/**646 * ext2_try_to_allocate()647 * @sb: superblock648 * @group: given allocation block group649 * @bitmap_bh: bufferhead holds the block bitmap650 * @grp_goal: given target block within the group651 * @count: target number of blocks to allocate652 * @my_rsv: reservation window653 *654 * Attempt to allocate blocks within a give range. Set the range of allocation655 * first, then find the first free bit(s) from the bitmap (within the range),656 * and at last, allocate the blocks by claiming the found free bit as allocated.657 *658 * To set the range of this allocation:659 * if there is a reservation window, only try to allocate block(s)660 * from the file's own reservation window;661 * Otherwise, the allocation range starts from the give goal block,662 * ends at the block group's last block.663 *664 * If we failed to allocate the desired block then we may end up crossing to a665 * new bitmap.666 */667static int668ext2_try_to_allocate(struct super_block *sb, int group,669 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,670 unsigned long *count,671 struct ext2_reserve_window *my_rsv)672{673 ext2_fsblk_t group_first_block = ext2_group_first_block_no(sb, group);674 ext2_fsblk_t group_last_block = ext2_group_last_block_no(sb, group);675 ext2_grpblk_t start, end;676 unsigned long num = 0;677 678 start = 0;679 end = group_last_block - group_first_block + 1;680 /* we do allocation within the reservation window if we have a window */681 if (my_rsv) {682 if (my_rsv->_rsv_start >= group_first_block)683 start = my_rsv->_rsv_start - group_first_block;684 if (my_rsv->_rsv_end < group_last_block)685 end = my_rsv->_rsv_end - group_first_block + 1;686 if (grp_goal < start || grp_goal >= end)687 grp_goal = -1;688 }689 BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));690 691 if (grp_goal < 0) {692 grp_goal = find_next_usable_block(start, bitmap_bh, end);693 if (grp_goal < 0)694 goto fail_access;695 if (!my_rsv) {696 int i;697 698 for (i = 0; i < 7 && grp_goal > start &&699 !ext2_test_bit(grp_goal - 1,700 bitmap_bh->b_data);701 i++, grp_goal--)702 ;703 }704 }705 706 for (; num < *count && grp_goal < end; grp_goal++) {707 if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),708 grp_goal, bitmap_bh->b_data)) {709 if (num == 0)710 continue;711 break;712 }713 num++;714 }715 716 if (num == 0)717 goto fail_access;718 719 *count = num;720 return grp_goal - num;721fail_access:722 return -1;723}724 725/**726 * find_next_reservable_window - Find a reservable space within the given range.727 * @search_head: The list to search.728 * @my_rsv: The reservation we're currently using.729 * @sb: The super block.730 * @start_block: The first block we consider to start the real search from731 * @last_block: The maximum block number that our goal reservable space732 * could start from.733 *734 * It does not allocate the reservation window: alloc_new_reservation()735 * will do the work later.736 *737 * We search the given range, rather than the whole reservation double738 * linked list, (start_block, last_block) to find a free region that is739 * of my size and has not been reserved.740 *741 * @search_head is not necessarily the list head of the whole filesystem.742 * We have both head and @start_block to assist the search for the743 * reservable space. The list starts from head, but we will shift to744 * the place where start_block is, then start from there, when looking745 * for a reservable space.746 *747 * @last_block is normally the last block in this group. The search will end748 * when we found the start of next possible reservable space is out749 * of this boundary. This could handle the cross boundary reservation750 * window request.751 *752 * Return: -1 if we could not find a range of sufficient size. If we could,753 * return 0 and fill in @my_rsv with the range information.754 */755static int find_next_reservable_window(756 struct ext2_reserve_window_node *search_head,757 struct ext2_reserve_window_node *my_rsv,758 struct super_block * sb,759 ext2_fsblk_t start_block,760 ext2_fsblk_t last_block)761{762 struct rb_node *next;763 struct ext2_reserve_window_node *rsv, *prev;764 ext2_fsblk_t cur;765 int size = my_rsv->rsv_goal_size;766 767 /* TODO: make the start of the reservation window byte-aligned */768 /* cur = *start_block & ~7;*/769 cur = start_block;770 rsv = search_head;771 if (!rsv)772 return -1;773 774 while (1) {775 if (cur <= rsv->rsv_end)776 cur = rsv->rsv_end + 1;777 778 /* TODO?779 * in the case we could not find a reservable space780 * that is what is expected, during the re-search, we could781 * remember what's the largest reservable space we could have782 * and return that one.783 *784 * For now it will fail if we could not find the reservable785 * space with expected-size (or more)...786 */787 if (cur > last_block)788 return -1; /* fail */789 790 prev = rsv;791 next = rb_next(&rsv->rsv_node);792 rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);793 794 /*795 * Reached the last reservation, we can just append to the796 * previous one.797 */798 if (!next)799 break;800 801 if (cur + size <= rsv->rsv_start) {802 /*803 * Found a reserveable space big enough. We could804 * have a reservation across the group boundary here805 */806 break;807 }808 }809 /*810 * we come here either :811 * when we reach the end of the whole list,812 * and there is empty reservable space after last entry in the list.813 * append it to the end of the list.814 *815 * or we found one reservable space in the middle of the list,816 * return the reservation window that we could append to.817 * succeed.818 */819 820 if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))821 rsv_window_remove(sb, my_rsv);822 823 /*824 * Let's book the whole available window for now. We will check the825 * disk bitmap later and then, if there are free blocks then we adjust826 * the window size if it's larger than requested.827 * Otherwise, we will remove this node from the tree next time828 * call find_next_reservable_window.829 */830 my_rsv->rsv_start = cur;831 my_rsv->rsv_end = cur + size - 1;832 my_rsv->rsv_alloc_hit = 0;833 834 if (prev != my_rsv)835 ext2_rsv_window_add(sb, my_rsv);836 837 return 0;838}839 840/**841 * alloc_new_reservation - Allocate a new reservation window.842 * @my_rsv: The reservation we're currently using.843 * @grp_goal: The goal block relative to the start of the group.844 * @sb: The super block.845 * @group: The group we are trying to allocate in.846 * @bitmap_bh: The block group block bitmap.847 *848 * To make a new reservation, we search part of the filesystem reservation849 * list (the list inside the group). We try to allocate a new850 * reservation window near @grp_goal, or the beginning of the851 * group, if @grp_goal is negative.852 *853 * We first find a reservable space after the goal, then from there,854 * we check the bitmap for the first free block after it. If there is855 * no free block until the end of group, then the whole group is full,856 * we failed. Otherwise, check if the free block is inside the expected857 * reservable space, if so, we succeed.858 *859 * If the first free block is outside the reservable space, then start860 * from the first free block, we search for next available space, and861 * go on.862 *863 * on succeed, a new reservation will be found and inserted into the864 * list. It contains at least one free block, and it does not overlap865 * with other reservation windows.866 *867 * Return: 0 on success, -1 if we failed to find a reservation window868 * in this group869 */870static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,871 ext2_grpblk_t grp_goal, struct super_block *sb,872 unsigned int group, struct buffer_head *bitmap_bh)873{874 struct ext2_reserve_window_node *search_head;875 ext2_fsblk_t group_first_block, group_end_block, start_block;876 ext2_grpblk_t first_free_block;877 struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;878 unsigned long size;879 int ret;880 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;881 882 group_first_block = ext2_group_first_block_no(sb, group);883 group_end_block = ext2_group_last_block_no(sb, group);884 885 if (grp_goal < 0)886 start_block = group_first_block;887 else888 start_block = grp_goal + group_first_block;889 890 size = my_rsv->rsv_goal_size;891 892 if (!rsv_is_empty(&my_rsv->rsv_window)) {893 /*894 * if the old reservation is cross group boundary895 * and if the goal is inside the old reservation window,896 * we will come here when we just failed to allocate from897 * the first part of the window. We still have another part898 * that belongs to the next group. In this case, there is no899 * point to discard our window and try to allocate a new one900 * in this group(which will fail). we should901 * keep the reservation window, just simply move on.902 *903 * Maybe we could shift the start block of the reservation904 * window to the first block of next group.905 */906 907 if ((my_rsv->rsv_start <= group_end_block) &&908 (my_rsv->rsv_end > group_end_block) &&909 (start_block >= my_rsv->rsv_start))910 return -1;911 912 if ((my_rsv->rsv_alloc_hit >913 (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {914 /*915 * if the previously allocation hit ratio is916 * greater than 1/2, then we double the size of917 * the reservation window the next time,918 * otherwise we keep the same size window919 */920 size = size * 2;921 if (size > EXT2_MAX_RESERVE_BLOCKS)922 size = EXT2_MAX_RESERVE_BLOCKS;923 my_rsv->rsv_goal_size= size;924 }925 }926 927 spin_lock(rsv_lock);928 /*929 * shift the search start to the window near the goal block930 */931 search_head = search_reserve_window(fs_rsv_root, start_block);932 933 /*934 * find_next_reservable_window() simply finds a reservable window935 * inside the given range(start_block, group_end_block).936 *937 * To make sure the reservation window has a free bit inside it, we938 * need to check the bitmap after we found a reservable window.939 */940retry:941 ret = find_next_reservable_window(search_head, my_rsv, sb,942 start_block, group_end_block);943 944 if (ret == -1) {945 if (!rsv_is_empty(&my_rsv->rsv_window))946 rsv_window_remove(sb, my_rsv);947 spin_unlock(rsv_lock);948 return -1;949 }950 951 /*952 * On success, find_next_reservable_window() returns the953 * reservation window where there is a reservable space after it.954 * Before we reserve this reservable space, we need955 * to make sure there is at least a free block inside this region.956 *957 * Search the first free bit on the block bitmap. Search starts from958 * the start block of the reservable space we just found.959 */960 spin_unlock(rsv_lock);961 first_free_block = bitmap_search_next_usable_block(962 my_rsv->rsv_start - group_first_block,963 bitmap_bh, group_end_block - group_first_block + 1);964 965 if (first_free_block < 0) {966 /*967 * no free block left on the bitmap, no point968 * to reserve the space. return failed.969 */970 spin_lock(rsv_lock);971 if (!rsv_is_empty(&my_rsv->rsv_window))972 rsv_window_remove(sb, my_rsv);973 spin_unlock(rsv_lock);974 return -1; /* failed */975 }976 977 start_block = first_free_block + group_first_block;978 /*979 * check if the first free block is within the980 * free space we just reserved981 */982 if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)983 return 0; /* success */984 /*985 * if the first free bit we found is out of the reservable space986 * continue search for next reservable space,987 * start from where the free block is,988 * we also shift the list head to where we stopped last time989 */990 search_head = my_rsv;991 spin_lock(rsv_lock);992 goto retry;993}994 995/**996 * try_to_extend_reservation()997 * @my_rsv: given reservation window998 * @sb: super block999 * @size: the delta to extend1000 *1001 * Attempt to expand the reservation window large enough to have1002 * required number of free blocks1003 *1004 * Since ext2_try_to_allocate() will always allocate blocks within1005 * the reservation window range, if the window size is too small,1006 * multiple blocks allocation has to stop at the end of the reservation1007 * window. To make this more efficient, given the total number of1008 * blocks needed and the current size of the window, we try to1009 * expand the reservation window size if necessary on a best-effort1010 * basis before ext2_new_blocks() tries to allocate blocks.1011 */1012static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,1013 struct super_block *sb, int size)1014{1015 struct ext2_reserve_window_node *next_rsv;1016 struct rb_node *next;1017 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;1018 1019 if (!spin_trylock(rsv_lock))1020 return;1021 1022 next = rb_next(&my_rsv->rsv_node);1023 1024 if (!next)1025 my_rsv->rsv_end += size;1026 else {1027 next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);1028 1029 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)1030 my_rsv->rsv_end += size;1031 else1032 my_rsv->rsv_end = next_rsv->rsv_start - 1;1033 }1034 spin_unlock(rsv_lock);1035}1036 1037/**1038 * ext2_try_to_allocate_with_rsv()1039 * @sb: superblock1040 * @group: given allocation block group1041 * @bitmap_bh: bufferhead holds the block bitmap1042 * @grp_goal: given target block within the group1043 * @count: target number of blocks to allocate1044 * @my_rsv: reservation window1045 *1046 * This is the main function used to allocate a new block and its reservation1047 * window.1048 *1049 * Each time when a new block allocation is need, first try to allocate from1050 * its own reservation. If it does not have a reservation window, instead of1051 * looking for a free bit on bitmap first, then look up the reservation list to1052 * see if it is inside somebody else's reservation window, we try to allocate a1053 * reservation window for it starting from the goal first. Then do the block1054 * allocation within the reservation window.1055 *1056 * This will avoid keeping on searching the reservation list again and1057 * again when somebody is looking for a free block (without1058 * reservation), and there are lots of free blocks, but they are all1059 * being reserved.1060 *1061 * We use a red-black tree for the per-filesystem reservation list.1062 */1063static ext2_grpblk_t1064ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,1065 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,1066 struct ext2_reserve_window_node * my_rsv,1067 unsigned long *count)1068{1069 ext2_fsblk_t group_first_block, group_last_block;1070 ext2_grpblk_t ret = 0;1071 unsigned long num = *count;1072 1073 /*1074 * we don't deal with reservation when1075 * filesystem is mounted without reservation1076 * or the file is not a regular file1077 * or last attempt to allocate a block with reservation turned on failed1078 */1079 if (my_rsv == NULL) {1080 return ext2_try_to_allocate(sb, group, bitmap_bh,1081 grp_goal, count, NULL);1082 }1083 /*1084 * grp_goal is a group relative block number (if there is a goal)1085 * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)1086 * first block is a filesystem wide block number1087 * first block is the block number of the first block in this group1088 */1089 group_first_block = ext2_group_first_block_no(sb, group);1090 group_last_block = ext2_group_last_block_no(sb, group);1091 1092 /*1093 * Basically we will allocate a new block from inode's reservation1094 * window.1095 *1096 * We need to allocate a new reservation window, if:1097 * a) inode does not have a reservation window; or1098 * b) last attempt to allocate a block from existing reservation1099 * failed; or1100 * c) we come here with a goal and with a reservation window1101 *1102 * We do not need to allocate a new reservation window if we come here1103 * at the beginning with a goal and the goal is inside the window, or1104 * we don't have a goal but already have a reservation window.1105 * then we could go to allocate from the reservation window directly.1106 */1107 while (1) {1108 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||1109 !goal_in_my_reservation(&my_rsv->rsv_window,1110 grp_goal, group, sb)) {1111 if (my_rsv->rsv_goal_size < *count)1112 my_rsv->rsv_goal_size = *count;1113 ret = alloc_new_reservation(my_rsv, grp_goal, sb,1114 group, bitmap_bh);1115 if (ret < 0)1116 break; /* failed */1117 1118 if (!goal_in_my_reservation(&my_rsv->rsv_window,1119 grp_goal, group, sb))1120 grp_goal = -1;1121 } else if (grp_goal >= 0) {1122 int curr = my_rsv->rsv_end -1123 (grp_goal + group_first_block) + 1;1124 1125 if (curr < *count)1126 try_to_extend_reservation(my_rsv, sb,1127 *count - curr);1128 }1129 1130 if ((my_rsv->rsv_start > group_last_block) ||1131 (my_rsv->rsv_end < group_first_block)) {1132 ext2_error(sb, __func__,1133 "Reservation out of group %u range goal %d fsb[%lu,%lu] rsv[%lu, %lu]",1134 group, grp_goal, group_first_block,1135 group_last_block, my_rsv->rsv_start,1136 my_rsv->rsv_end);1137 rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);1138 return -1;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 overlaps1175 * 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 function1195 * @inode: file inode1196 * @goal: given target block(filesystem wide)1197 * @count: target number of blocks to allocate1198 * @errp: error code1199 * @flags: allocate flags1200 *1201 * ext2_new_blocks uses a goal block to assist allocation. If the goal is1202 * free, or there is a free block within 32 blocks of the goal, that block1203 * is allocated. Otherwise a forward search is made for a free block; within 1204 * each block group the search first looks for an entire free byte in the block1205 * bitmap, and then for any free bit if that fails.1206 * This function also updates quota and i_blocks field.1207 */1208ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,1209 unsigned long *count, int *errp, unsigned int flags)1210{1211 struct buffer_head *bitmap_bh = NULL;1212 struct buffer_head *gdp_bh;1213 int group_no;1214 int goal_group;1215 ext2_grpblk_t grp_target_blk; /* blockgroup relative goal block */1216 ext2_grpblk_t grp_alloc_blk; /* blockgroup-relative allocated block*/1217 ext2_fsblk_t ret_block; /* filesyetem-wide allocated block */1218 int bgi; /* blockgroup iteration index */1219 int performed_allocation = 0;1220 ext2_grpblk_t free_blocks; /* number of free blocks in a group */1221 struct super_block *sb;1222 struct ext2_group_desc *gdp;1223 struct ext2_super_block *es;1224 struct ext2_sb_info *sbi;1225 struct ext2_reserve_window_node *my_rsv = NULL;1226 struct ext2_block_alloc_info *block_i;1227 unsigned short windowsz = 0;1228 unsigned long ngroups;1229 unsigned long num = *count;1230 int ret;1231 1232 *errp = -ENOSPC;1233 sb = inode->i_sb;1234 1235 /*1236 * Check quota for allocation of this block.1237 */1238 ret = dquot_alloc_block(inode, num);1239 if (ret) {1240 *errp = ret;1241 return 0;1242 }1243 1244 sbi = EXT2_SB(sb);1245 es = EXT2_SB(sb)->s_es;1246 ext2_debug("goal=%lu.\n", goal);1247 /*1248 * Allocate a block from reservation only when the filesystem is1249 * mounted with reservation(default,-o reservation), and it's a regular1250 * file, and the desired window size is greater than 0 (One could use1251 * ioctl command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn1252 * off reservation on that particular file). Also do not use the1253 * reservation window if the caller asked us not to do it.1254 */1255 block_i = EXT2_I(inode)->i_block_alloc_info;1256 if (!(flags & EXT2_ALLOC_NORESERVE) && block_i) {1257 windowsz = block_i->rsv_window_node.rsv_goal_size;1258 if (windowsz > 0)1259 my_rsv = &block_i->rsv_window_node;1260 }1261 1262 if (!ext2_has_free_blocks(sbi)) {1263 *errp = -ENOSPC;1264 goto out;1265 }1266 1267 /*1268 * First, test whether the goal block is free.1269 */1270 if (goal < le32_to_cpu(es->s_first_data_block) ||1271 goal >= le32_to_cpu(es->s_blocks_count))1272 goal = le32_to_cpu(es->s_first_data_block);1273 group_no = (goal - le32_to_cpu(es->s_first_data_block)) /1274 EXT2_BLOCKS_PER_GROUP(sb);1275 goal_group = group_no;1276retry_alloc:1277 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);1278 if (!gdp)1279 goto io_error;1280 1281 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);1282 /*1283 * if there is not enough free blocks to make a new resevation1284 * turn off reservation for this allocation1285 */1286 if (my_rsv && (free_blocks < windowsz)1287 && (free_blocks > 0)1288 && (rsv_is_empty(&my_rsv->rsv_window)))1289 my_rsv = NULL;1290 1291 if (free_blocks > 0) {1292 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %1293 EXT2_BLOCKS_PER_GROUP(sb));1294 /*1295 * In case we retry allocation (due to fs reservation not1296 * working out or fs corruption), the bitmap_bh is non-null1297 * pointer and we have to release it before calling1298 * read_block_bitmap().1299 */1300 brelse(bitmap_bh);1301 bitmap_bh = read_block_bitmap(sb, group_no);1302 if (!bitmap_bh)1303 goto io_error;1304 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,1305 bitmap_bh, grp_target_blk,1306 my_rsv, &num);1307 if (grp_alloc_blk >= 0)1308 goto allocated;1309 }1310 1311 ngroups = EXT2_SB(sb)->s_groups_count;1312 smp_rmb();1313 1314 /*1315 * Now search the rest of the groups. We assume that1316 * group_no and gdp correctly point to the last group visited.1317 */1318 for (bgi = 0; bgi < ngroups; bgi++) {1319 group_no++;1320 if (group_no >= ngroups)1321 group_no = 0;1322 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);1323 if (!gdp)1324 goto io_error;1325 1326 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);1327 /*1328 * skip this group (and avoid loading bitmap) if there1329 * are no free blocks1330 */1331 if (!free_blocks)1332 continue;1333 /*1334 * skip this group if the number of1335 * free blocks is less than half of the reservation1336 * window size.1337 */1338 if (my_rsv && (free_blocks <= (windowsz/2)))1339 continue;1340 1341 brelse(bitmap_bh);1342 bitmap_bh = read_block_bitmap(sb, group_no);1343 if (!bitmap_bh)1344 goto io_error;1345 /*1346 * try to allocate block(s) from this group, without a goal(-1).1347 */1348 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,1349 bitmap_bh, -1, my_rsv, &num);1350 if (grp_alloc_blk >= 0)1351 goto allocated;1352 }1353 /*1354 * We may end up a bogus earlier ENOSPC error due to1355 * filesystem is "full" of reservations, but1356 * there maybe indeed free blocks available on disk1357 * In this case, we just forget about the reservations1358 * just do block allocation as without reservations.1359 */1360 if (my_rsv) {1361 my_rsv = NULL;1362 windowsz = 0;1363 group_no = goal_group;1364 goto retry_alloc;1365 }1366 /* No space left on the device */1367 *errp = -ENOSPC;1368 goto out;1369 1370allocated:1371 1372 ext2_debug("using block group %d(%d)\n",1373 group_no, gdp->bg_free_blocks_count);1374 1375 ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);1376 1377 if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||1378 in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||1379 in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),1380 EXT2_SB(sb)->s_itb_per_group) ||1381 in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),1382 EXT2_SB(sb)->s_itb_per_group)) {1383 ext2_error(sb, "ext2_new_blocks",1384 "Allocating block in system zone - "1385 "blocks from "E2FSBLK", length %lu",1386 ret_block, num);1387 /*1388 * ext2_try_to_allocate marked the blocks we allocated as in1389 * use. So we may want to selectively mark some of the blocks1390 * as free1391 */1392 num = *count;1393 goto retry_alloc;1394 }1395 1396 performed_allocation = 1;1397 1398 if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {1399 ext2_error(sb, "ext2_new_blocks",1400 "block("E2FSBLK") >= blocks count(%d) - "1401 "block_group = %d, es == %p ", ret_block,1402 le32_to_cpu(es->s_blocks_count), group_no, es);1403 goto out;1404 }1405 1406 group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);1407 percpu_counter_sub(&sbi->s_freeblocks_counter, num);1408 1409 mark_buffer_dirty(bitmap_bh);1410 if (sb->s_flags & SB_SYNCHRONOUS)1411 sync_dirty_buffer(bitmap_bh);1412 1413 *errp = 0;1414 brelse(bitmap_bh);1415 if (num < *count) {1416 dquot_free_block_nodirty(inode, *count-num);1417 mark_inode_dirty(inode);1418 *count = num;1419 }1420 return ret_block;1421 1422io_error:1423 *errp = -EIO;1424out:1425 /*1426 * Undo the block allocation1427 */1428 if (!performed_allocation) {1429 dquot_free_block_nodirty(inode, *count);1430 mark_inode_dirty(inode);1431 }1432 brelse(bitmap_bh);1433 return 0;1434}1435 1436#ifdef EXT2FS_DEBUG1437 1438unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)1439{1440 return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);1441}1442 1443#endif /* EXT2FS_DEBUG */1444 1445unsigned long ext2_count_free_blocks (struct super_block * sb)1446{1447 struct ext2_group_desc * desc;1448 unsigned long desc_count = 0;1449 int i;1450#ifdef EXT2FS_DEBUG1451 unsigned long bitmap_count, x;1452 struct ext2_super_block *es;1453 1454 es = EXT2_SB(sb)->s_es;1455 desc_count = 0;1456 bitmap_count = 0;1457 desc = NULL;1458 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {1459 struct buffer_head *bitmap_bh;1460 desc = ext2_get_group_desc (sb, i, NULL);1461 if (!desc)1462 continue;1463 desc_count += le16_to_cpu(desc->bg_free_blocks_count);1464 bitmap_bh = read_block_bitmap(sb, i);1465 if (!bitmap_bh)1466 continue;1467 1468 x = ext2_count_free(bitmap_bh, sb->s_blocksize);1469 printk ("group %d: stored = %d, counted = %lu\n",1470 i, le16_to_cpu(desc->bg_free_blocks_count), x);1471 bitmap_count += x;1472 brelse(bitmap_bh);1473 }1474 printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",1475 (long)le32_to_cpu(es->s_free_blocks_count),1476 desc_count, bitmap_count);1477 return bitmap_count;1478#else1479 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {1480 desc = ext2_get_group_desc(sb, i, NULL);1481 if (!desc)1482 continue;1483 desc_count += le16_to_cpu(desc->bg_free_blocks_count);1484 }1485 return desc_count;1486#endif1487}1488 1489static inline int test_root(int a, int b)1490{1491 int num = b;1492 1493 while (a > num)1494 num *= b;1495 return num == a;1496}1497 1498static int ext2_group_sparse(int group)1499{1500 if (group <= 1)1501 return 1;1502 return (test_root(group, 3) || test_root(group, 5) ||1503 test_root(group, 7));1504}1505 1506/**1507 * ext2_bg_has_super - number of blocks used by the superblock in group1508 * @sb: superblock for filesystem1509 * @group: group number to check1510 *1511 * Return the number of blocks used by the superblock (primary or backup)1512 * in this group. Currently this will be only 0 or 1.1513 */1514int ext2_bg_has_super(struct super_block *sb, int group)1515{1516 if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&1517 !ext2_group_sparse(group))1518 return 0;1519 return 1;1520}1521 1522/**1523 * ext2_bg_num_gdb - number of blocks used by the group table in group1524 * @sb: superblock for filesystem1525 * @group: group number to check1526 *1527 * Return the number of blocks used by the group descriptor table1528 * (primary or backup) in this group. In the future there may be a1529 * different number of descriptor blocks in each group.1530 */1531unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)1532{1533 return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;1534}1535 1536