balloc.c

Linux Kernel 2.6.9 for OMAP1710

		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)
{
	if (a == 0)
		return 1;
	while (1) {
		if (a == 1)
			return 1;
		if (a % b)
			return 0;
		a = a / b;
	}
}

static int ext2_group_sparse(int group)
{
	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