/* * 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 "ext2.h" #include <linux/quotaops.h> #include <linux/sched.h> #include <linux/buffer_head.h> #include <linux/capability.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; } #ifdef EXT2FS_DEBUG static int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0}; unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars) { unsigned int i; unsigned long sum = 0; if (!map) return (0); for (i = 0; i < numchars; i++) sum += nibblemap[map->b_data[i] & 0xf] + nibblemap[(map->b_data[i] >> 4) & 0xf]; return (sum); } #endif /* EXT2FS_DEBUG */ 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; 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); 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; }