diff options
Diffstat (limited to 'fs/ext2/balloc.c')
| -rw-r--r-- | fs/ext2/balloc.c | 699 |
1 files changed, 699 insertions, 0 deletions
diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c new file mode 100644 index 0000000..6591abe --- /dev/null +++ b/fs/ext2/balloc.c @@ -0,0 +1,699 @@ +/* + * linux/fs/ext2/balloc.c + * + * Copyright (C) 1992, 1993, 1994, 1995 + * Remy Card (card@masi.ibp.fr) + * Laboratoire MASI - Institut Blaise Pascal + * Universite Pierre et Marie Curie (Paris VI) + * + * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993 + * Big-endian to little-endian byte-swapping/bitmaps by + * David S. Miller (davem@caip.rutgers.edu), 1995 + */ + +#include <linux/config.h> +#include "ext2.h" +#include <linux/quotaops.h> +#include <linux/sched.h> +#include <linux/buffer_head.h> + +/* + * balloc.c contains the blocks allocation and deallocation routines + */ + +/* + * The free blocks are managed by bitmaps. A file system contains several + * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap + * block for inodes, N blocks for the inode table and data blocks. + * + * The file system contains group descriptors which are located after the + * super block. Each descriptor contains the number of the bitmap block and + * the free blocks count in the block. The descriptors are loaded in memory + * when a file system is mounted (see ext2_read_super). + */ + + +#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1) + +struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb, + unsigned int block_group, + struct buffer_head ** bh) +{ + unsigned long group_desc; + unsigned long offset; + struct ext2_group_desc * desc; + struct ext2_sb_info *sbi = EXT2_SB(sb); + + if (block_group >= sbi->s_groups_count) { + ext2_error (sb, "ext2_get_group_desc", + "block_group >= groups_count - " + "block_group = %d, groups_count = %lu", + block_group, sbi->s_groups_count); + + return NULL; + } + + group_desc = block_group >> EXT2_DESC_PER_BLOCK_BITS(sb); + offset = block_group & (EXT2_DESC_PER_BLOCK(sb) - 1); + if (!sbi->s_group_desc[group_desc]) { + ext2_error (sb, "ext2_get_group_desc", + "Group descriptor not loaded - " + "block_group = %d, group_desc = %lu, desc = %lu", + block_group, group_desc, offset); + return NULL; + } + + desc = (struct ext2_group_desc *) sbi->s_group_desc[group_desc]->b_data; + if (bh) + *bh = sbi->s_group_desc[group_desc]; + return desc + offset; +} + +/* + * Read the bitmap for a given block_group, reading into the specified + * slot in the superblock's bitmap cache. + * + * Return buffer_head on success or NULL in case of failure. + */ +static struct buffer_head * +read_block_bitmap(struct super_block *sb, unsigned int block_group) +{ + struct ext2_group_desc * desc; + struct buffer_head * bh = NULL; + + desc = ext2_get_group_desc (sb, block_group, NULL); + if (!desc) + goto error_out; + bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap)); + if (!bh) + ext2_error (sb, "read_block_bitmap", + "Cannot read block bitmap - " + "block_group = %d, block_bitmap = %u", + block_group, le32_to_cpu(desc->bg_block_bitmap)); +error_out: + return bh; +} + +/* + * Set sb->s_dirt here because the superblock was "logically" altered. We + * need to recalculate its free blocks count and flush it out. + */ +static int reserve_blocks(struct super_block *sb, int count) +{ + struct ext2_sb_info *sbi = EXT2_SB(sb); + struct ext2_super_block *es = sbi->s_es; + unsigned free_blocks; + unsigned root_blocks; + + free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter); + root_blocks = le32_to_cpu(es->s_r_blocks_count); + + if (free_blocks < count) + count = free_blocks; + + if (free_blocks < root_blocks + count && !capable(CAP_SYS_RESOURCE) && + sbi->s_resuid != current->fsuid && + (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) { + /* + * We are too close to reserve and we are not privileged. + * Can we allocate anything at all? + */ + if (free_blocks > root_blocks) + count = free_blocks - root_blocks; + else + return 0; + } + + percpu_counter_mod(&sbi->s_freeblocks_counter, -count); + sb->s_dirt = 1; + return count; +} + +static void release_blocks(struct super_block *sb, int count) +{ + if (count) { + struct ext2_sb_info *sbi = EXT2_SB(sb); + + percpu_counter_mod(&sbi->s_freeblocks_counter, count); + sb->s_dirt = 1; + } +} + +static int group_reserve_blocks(struct ext2_sb_info *sbi, int group_no, + struct ext2_group_desc *desc, struct buffer_head *bh, int count) +{ + unsigned free_blocks; + + if (!desc->bg_free_blocks_count) + return 0; + + spin_lock(sb_bgl_lock(sbi, group_no)); + free_blocks = le16_to_cpu(desc->bg_free_blocks_count); + if (free_blocks < count) + count = free_blocks; + desc->bg_free_blocks_count = cpu_to_le16(free_blocks - count); + spin_unlock(sb_bgl_lock(sbi, group_no)); + mark_buffer_dirty(bh); + return count; +} + +static void group_release_blocks(struct super_block *sb, int group_no, + struct ext2_group_desc *desc, struct buffer_head *bh, int count) +{ + if (count) { + struct ext2_sb_info *sbi = EXT2_SB(sb); + unsigned free_blocks; + + spin_lock(sb_bgl_lock(sbi, group_no)); + free_blocks = le16_to_cpu(desc->bg_free_blocks_count); + desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count); + spin_unlock(sb_bgl_lock(sbi, group_no)); + sb->s_dirt = 1; + mark_buffer_dirty(bh); + } +} + +/* Free given blocks, update quota and i_blocks field */ +void ext2_free_blocks (struct inode * inode, unsigned long block, + unsigned long count) +{ + struct buffer_head *bitmap_bh = NULL; + struct buffer_head * bh2; + unsigned long block_group; + unsigned long bit; + unsigned long i; + unsigned long overflow; + struct super_block * sb = inode->i_sb; + struct ext2_sb_info * sbi = EXT2_SB(sb); + struct ext2_group_desc * desc; + struct ext2_super_block * es = sbi->s_es; + unsigned freed = 0, group_freed; + + if (block < le32_to_cpu(es->s_first_data_block) || + block + count < block || + block + count > le32_to_cpu(es->s_blocks_count)) { + ext2_error (sb, "ext2_free_blocks", + "Freeing blocks not in datazone - " + "block = %lu, count = %lu", block, count); + goto error_return; + } + + ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1); + +do_more: + overflow = 0; + block_group = (block - le32_to_cpu(es->s_first_data_block)) / + EXT2_BLOCKS_PER_GROUP(sb); + bit = (block - le32_to_cpu(es->s_first_data_block)) % + EXT2_BLOCKS_PER_GROUP(sb); + /* + * Check to see if we are freeing blocks across a group + * boundary. + */ + if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) { + overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb); + count -= overflow; + } + brelse(bitmap_bh); + bitmap_bh = read_block_bitmap(sb, block_group); + if (!bitmap_bh) + goto error_return; + + desc = ext2_get_group_desc (sb, block_group, &bh2); + if (!desc) + goto error_return; + + if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) || + in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) || + in_range (block, le32_to_cpu(desc->bg_inode_table), + sbi->s_itb_per_group) || + in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table), + sbi->s_itb_per_group)) + ext2_error (sb, "ext2_free_blocks", + "Freeing blocks in system zones - " + "Block = %lu, count = %lu", + block, count); + + for (i = 0, group_freed = 0; i < count; i++) { + if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group), + bit + i, bitmap_bh->b_data)) { + ext2_error(sb, __FUNCTION__, + "bit already cleared for block %lu", block + i); + } else { + group_freed++; + } + } + + mark_buffer_dirty(bitmap_bh); + if (sb->s_flags & MS_SYNCHRONOUS) + sync_dirty_buffer(bitmap_bh); + + group_release_blocks(sb, block_group, desc, bh2, group_freed); + freed += group_freed; + + if (overflow) { + block += count; + count = overflow; + goto do_more; + } +error_return: + brelse(bitmap_bh); + release_blocks(sb, freed); + DQUOT_FREE_BLOCK(inode, freed); +} + +static int grab_block(spinlock_t *lock, char *map, unsigned size, int goal) +{ + int k; + char *p, *r; + + if (!ext2_test_bit(goal, map)) + goto got_it; + +repeat: + if (goal) { + /* + * The goal was occupied; search forward for a free + * block within the next XX blocks. + * + * end_goal is more or less random, but it has to be + * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the + * next 64-bit boundary is simple.. + */ + k = (goal + 63) & ~63; + goal = ext2_find_next_zero_bit(map, k, goal); + if (goal < k) + goto got_it; + /* + * Search in the remainder of the current group. + */ + } + + p = map + (goal >> 3); + r = memscan(p, 0, (size - goal + 7) >> 3); + k = (r - map) << 3; + if (k < size) { + /* + * We have succeeded in finding a free byte in the block + * bitmap. Now search backwards to find the start of this + * group of free blocks - won't take more than 7 iterations. + */ + for (goal = k; goal && !ext2_test_bit (goal - 1, map); goal--) + ; + goto got_it; + } + + k = ext2_find_next_zero_bit ((u32 *)map, size, goal); + if (k < size) { + goal = k; + goto got_it; + } + return -1; +got_it: + if (ext2_set_bit_atomic(lock, goal, (void *) map)) + goto repeat; + return goal; +} + +/* + * ext2_new_block uses a goal block to assist allocation. If the goal is + * free, or there is a free block within 32 blocks of the goal, that block + * is allocated. Otherwise a forward search is made for a free block; within + * each block group the search first looks for an entire free byte in the block + * bitmap, and then for any free bit if that fails. + * This function also updates quota and i_blocks field. + */ +int ext2_new_block(struct inode *inode, unsigned long goal, + u32 *prealloc_count, u32 *prealloc_block, int *err) +{ + struct buffer_head *bitmap_bh = NULL; + struct buffer_head *gdp_bh; /* bh2 */ + struct ext2_group_desc *desc; + int group_no; /* i */ + int ret_block; /* j */ + int group_idx; /* k */ + int target_block; /* tmp */ + int block = 0; + struct super_block *sb = inode->i_sb; + struct ext2_sb_info *sbi = EXT2_SB(sb); + struct ext2_super_block *es = sbi->s_es; + unsigned group_size = EXT2_BLOCKS_PER_GROUP(sb); + unsigned prealloc_goal = es->s_prealloc_blocks; + unsigned group_alloc = 0, es_alloc, dq_alloc; + int nr_scanned_groups; + + if (!prealloc_goal--) + prealloc_goal = EXT2_DEFAULT_PREALLOC_BLOCKS - 1; + if (!prealloc_count || *prealloc_count) + prealloc_goal = 0; + + if (DQUOT_ALLOC_BLOCK(inode, 1)) { + *err = -EDQUOT; + goto out; + } + + while (prealloc_goal && DQUOT_PREALLOC_BLOCK(inode, prealloc_goal)) + prealloc_goal--; + + dq_alloc = prealloc_goal + 1; + es_alloc = reserve_blocks(sb, dq_alloc); + if (!es_alloc) { + *err = -ENOSPC; + goto out_dquot; + } + + ext2_debug ("goal=%lu.\n", goal); + + if (goal < le32_to_cpu(es->s_first_data_block) || + goal >= le32_to_cpu(es->s_blocks_count)) + goal = le32_to_cpu(es->s_first_data_block); + group_no = (goal - le32_to_cpu(es->s_first_data_block)) / group_size; + desc = ext2_get_group_desc (sb, group_no, &gdp_bh); + if (!desc) { + /* + * gdp_bh may still be uninitialised. But group_release_blocks + * will not touch it because group_alloc is zero. + */ + goto io_error; + } + + group_alloc = group_reserve_blocks(sbi, group_no, desc, + gdp_bh, es_alloc); + if (group_alloc) { + ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) % + group_size); + brelse(bitmap_bh); + bitmap_bh = read_block_bitmap(sb, group_no); + if (!bitmap_bh) + goto io_error; + + ext2_debug("goal is at %d:%d.\n", group_no, ret_block); + + ret_block = grab_block(sb_bgl_lock(sbi, group_no), + bitmap_bh->b_data, group_size, ret_block); + if (ret_block >= 0) + goto got_block; + group_release_blocks(sb, group_no, desc, gdp_bh, group_alloc); + group_alloc = 0; + } + + ext2_debug ("Bit not found in block group %d.\n", group_no); + + /* + * Now search the rest of the groups. We assume that + * i and desc correctly point to the last group visited. + */ + nr_scanned_groups = 0; +retry: + for (group_idx = 0; !group_alloc && + group_idx < sbi->s_groups_count; group_idx++) { + group_no++; + if (group_no >= sbi->s_groups_count) + group_no = 0; + desc = ext2_get_group_desc(sb, group_no, &gdp_bh); + if (!desc) + goto io_error; + group_alloc = group_reserve_blocks(sbi, group_no, desc, + gdp_bh, es_alloc); + } + if (!group_alloc) { + *err = -ENOSPC; + goto out_release; + } + brelse(bitmap_bh); + bitmap_bh = read_block_bitmap(sb, group_no); + if (!bitmap_bh) + goto io_error; + + ret_block = grab_block(sb_bgl_lock(sbi, group_no), bitmap_bh->b_data, + group_size, 0); + if (ret_block < 0) { + /* + * If a free block counter is corrupted we can loop inifintely. + * Detect that here. + */ + nr_scanned_groups++; + if (nr_scanned_groups > 2 * sbi->s_groups_count) { + ext2_error(sb, "ext2_new_block", + "corrupted free blocks counters"); + goto io_error; + } + /* + * Someone else grabbed the last free block in this blockgroup + * before us. Retry the scan. + */ + group_release_blocks(sb, group_no, desc, gdp_bh, group_alloc); + group_alloc = 0; + goto retry; + } + +got_block: + ext2_debug("using block group %d(%d)\n", + group_no, desc->bg_free_blocks_count); + + target_block = ret_block + group_no * group_size + + le32_to_cpu(es->s_first_data_block); + + if (target_block == le32_to_cpu(desc->bg_block_bitmap) || + target_block == le32_to_cpu(desc->bg_inode_bitmap) || + in_range(target_block, le32_to_cpu(desc->bg_inode_table), + sbi->s_itb_per_group)) + ext2_error (sb, "ext2_new_block", + "Allocating block in system zone - " + "block = %u", target_block); + + if (target_block >= le32_to_cpu(es->s_blocks_count)) { + ext2_error (sb, "ext2_new_block", + "block(%d) >= blocks count(%d) - " + "block_group = %d, es == %p ", ret_block, + le32_to_cpu(es->s_blocks_count), group_no, es); + goto io_error; + } + block = target_block; + + /* OK, we _had_ allocated something */ + ext2_debug("found bit %d\n", ret_block); + + dq_alloc--; + es_alloc--; + group_alloc--; + + /* + * Do block preallocation now if required. + */ + write_lock(&EXT2_I(inode)->i_meta_lock); + if (group_alloc && !*prealloc_count) { + unsigned n; + + for (n = 0; n < group_alloc && ++ret_block < group_size; n++) { + if (ext2_set_bit_atomic(sb_bgl_lock(sbi, group_no), + ret_block, + (void*) bitmap_bh->b_data)) + break; + } + *prealloc_block = block + 1; + *prealloc_count = n; + es_alloc -= n; + dq_alloc -= n; + group_alloc -= n; + } + write_unlock(&EXT2_I(inode)->i_meta_lock); + + mark_buffer_dirty(bitmap_bh); + if (sb->s_flags & MS_SYNCHRONOUS) + sync_dirty_buffer(bitmap_bh); + + ext2_debug ("allocating block %d. ", block); + + *err = 0; +out_release: + group_release_blocks(sb, group_no, desc, gdp_bh, group_alloc); + release_blocks(sb, es_alloc); +out_dquot: + DQUOT_FREE_BLOCK(inode, dq_alloc); +out: + brelse(bitmap_bh); + return block; + +io_error: + *err = -EIO; + goto out_release; +} + +unsigned long ext2_count_free_blocks (struct super_block * sb) +{ + struct ext2_group_desc * desc; + unsigned long desc_count = 0; + int i; +#ifdef EXT2FS_DEBUG + unsigned long bitmap_count, x; + struct ext2_super_block *es; + + lock_super (sb); + es = EXT2_SB(sb)->s_es; + desc_count = 0; + bitmap_count = 0; + desc = NULL; + for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) { + struct buffer_head *bitmap_bh; + desc = ext2_get_group_desc (sb, i, NULL); + if (!desc) + continue; + desc_count += le16_to_cpu(desc->bg_free_blocks_count); + bitmap_bh = read_block_bitmap(sb, i); + if (!bitmap_bh) + continue; + + x = ext2_count_free(bitmap_bh, sb->s_blocksize); + printk ("group %d: stored = %d, counted = %lu\n", + i, le16_to_cpu(desc->bg_free_blocks_count), x); + bitmap_count += x; + brelse(bitmap_bh); + } + printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n", + (long)le32_to_cpu(es->s_free_blocks_count), + desc_count, bitmap_count); + unlock_super (sb); + return bitmap_count; +#else + for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) { + desc = ext2_get_group_desc (sb, i, NULL); + if (!desc) + continue; + desc_count += le16_to_cpu(desc->bg_free_blocks_count); + } + return desc_count; +#endif +} + +static inline int +block_in_use(unsigned long block, struct super_block *sb, unsigned char *map) +{ + return ext2_test_bit ((block - + le32_to_cpu(EXT2_SB(sb)->s_es->s_first_data_block)) % + EXT2_BLOCKS_PER_GROUP(sb), map); +} + +static inline int test_root(int a, int b) +{ + int num = b; + + while (a > num) + num *= b; + return num == a; +} + +static int ext2_group_sparse(int group) +{ + if (group <= 1) + return 1; + return (test_root(group, 3) || test_root(group, 5) || + test_root(group, 7)); +} + +/** + * ext2_bg_has_super - number of blocks used by the superblock in group + * @sb: superblock for filesystem + * @group: group number to check + * + * Return the number of blocks used by the superblock (primary or backup) + * in this group. Currently this will be only 0 or 1. + */ +int ext2_bg_has_super(struct super_block *sb, int group) +{ + if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&& + !ext2_group_sparse(group)) + return 0; + return 1; +} + +/** + * ext2_bg_num_gdb - number of blocks used by the group table in group + * @sb: superblock for filesystem + * @group: group number to check + * + * Return the number of blocks used by the group descriptor table + * (primary or backup) in this group. In the future there may be a + * different number of descriptor blocks in each group. + */ +unsigned long ext2_bg_num_gdb(struct super_block *sb, int group) +{ + if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&& + !ext2_group_sparse(group)) + return 0; + return EXT2_SB(sb)->s_gdb_count; +} + +#ifdef CONFIG_EXT2_CHECK +/* Called at mount-time, super-block is locked */ +void ext2_check_blocks_bitmap (struct super_block * sb) +{ + struct buffer_head *bitmap_bh = NULL; + struct ext2_super_block * es; + unsigned long desc_count, bitmap_count, x, j; + unsigned long desc_blocks; + struct ext2_group_desc * desc; + int i; + + es = EXT2_SB(sb)->s_es; + desc_count = 0; + bitmap_count = 0; + desc = NULL; + for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) { + desc = ext2_get_group_desc (sb, i, NULL); + if (!desc) + continue; + desc_count += le16_to_cpu(desc->bg_free_blocks_count); + brelse(bitmap_bh); + bitmap_bh = read_block_bitmap(sb, i); + if (!bitmap_bh) + continue; + + if (ext2_bg_has_super(sb, i) && + !ext2_test_bit(0, bitmap_bh->b_data)) + ext2_error(sb, __FUNCTION__, + "Superblock in group %d is marked free", i); + + desc_blocks = ext2_bg_num_gdb(sb, i); + for (j = 0; j < desc_blocks; j++) + if (!ext2_test_bit(j + 1, bitmap_bh->b_data)) + ext2_error(sb, __FUNCTION__, + "Descriptor block #%ld in group " + "%d is marked free", j, i); + + if (!block_in_use(le32_to_cpu(desc->bg_block_bitmap), + sb, bitmap_bh->b_data)) + ext2_error(sb, "ext2_check_blocks_bitmap", + "Block bitmap for group %d is marked free", + i); + + if (!block_in_use(le32_to_cpu(desc->bg_inode_bitmap), + sb, bitmap_bh->b_data)) + ext2_error(sb, "ext2_check_blocks_bitmap", + "Inode bitmap for group %d is marked free", + i); + + for (j = 0; j < EXT2_SB(sb)->s_itb_per_group; j++) + if (!block_in_use(le32_to_cpu(desc->bg_inode_table) + j, + sb, bitmap_bh->b_data)) + ext2_error (sb, "ext2_check_blocks_bitmap", + "Block #%ld of the inode table in " + "group %d is marked free", j, i); + + x = ext2_count_free(bitmap_bh, sb->s_blocksize); + if (le16_to_cpu(desc->bg_free_blocks_count) != x) + ext2_error (sb, "ext2_check_blocks_bitmap", + "Wrong free blocks count for group %d, " + "stored = %d, counted = %lu", i, + le16_to_cpu(desc->bg_free_blocks_count), x); + bitmap_count += x; + } + if (le32_to_cpu(es->s_free_blocks_count) != bitmap_count) + ext2_error (sb, "ext2_check_blocks_bitmap", + "Wrong free blocks count in super block, " + "stored = %lu, counted = %lu", + (unsigned long)le32_to_cpu(es->s_free_blocks_count), + bitmap_count); + brelse(bitmap_bh); +} +#endif |
