balloc.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 895 行 · 第 1/2 页

			goto fail_access;
		goto repeat;
	}

	BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for bitmap block");
	fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
	if (fatal) {
		*errp = fatal;
		goto fail;
	}
	return goal;

fail_access:
	BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
	ext3_journal_release_buffer(handle, bitmap_bh, credits);
fail:
	return -1;
}

static int ext3_has_free_blocks(struct ext3_sb_info *sbi)
{
	int free_blocks, root_blocks;

	free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
	root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
	if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
		sbi->s_resuid != current->fsuid &&
		(sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
		return 0;
	}
	return 1;
}

/*
 * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
 * it is profitable to retry the operation, this function will wait
 * for the current or commiting transaction to complete, and then
 * return TRUE.
 */
int ext3_should_retry_alloc(struct super_block *sb, int *retries)
{
	if (!ext3_has_free_blocks(EXT3_SB(sb)) || (*retries)++ > 3)
		return 0;

	jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);

	return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
}

/*
 * ext3_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
ext3_new_block(handle_t *handle, struct inode *inode, unsigned long goal,
		u32 *prealloc_count, u32 *prealloc_block, int *errp)
{
	struct buffer_head *bitmap_bh = NULL;	/* bh */
	struct buffer_head *gdp_bh;		/* bh2 */
	int group_no;				/* i */
	int ret_block;				/* j */
	int bgi;				/* blockgroup iteration index */
	int target_block;			/* tmp */
	int fatal = 0, err;
	int performed_allocation = 0;
	int free_blocks;
	struct super_block *sb;
	struct ext3_group_desc *gdp;
	struct ext3_super_block *es;
	struct ext3_sb_info *sbi;
#ifdef EXT3FS_DEBUG
	static int goal_hits, goal_attempts;
#endif
	*errp = -ENOSPC;
	sb = inode->i_sb;
	if (!sb) {
		printk("ext3_new_block: nonexistent device");
		return 0;
	}

	/*
	 * Check quota for allocation of this block.
	 */
	if (DQUOT_ALLOC_BLOCK(inode, 1)) {
		*errp = -EDQUOT;
		return 0;
	}

	sbi = EXT3_SB(sb);
	es = EXT3_SB(sb)->s_es;
	ext3_debug("goal=%lu.\n", goal);

	if (!ext3_has_free_blocks(sbi)) {
		*errp = -ENOSPC;
		goto out;
	}

	/*
	 * First, test whether the goal block is free.
	 */
	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)) /
			EXT3_BLOCKS_PER_GROUP(sb);
	gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
	if (!gdp)
		goto io_error;

	free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
	if (free_blocks > 0) {
		ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) %
				EXT3_BLOCKS_PER_GROUP(sb));
		bitmap_bh = read_block_bitmap(sb, group_no);
		if (!bitmap_bh)
			goto io_error;
		ret_block = ext3_try_to_allocate(sb, handle, group_no,
					bitmap_bh, ret_block, &fatal);
		if (fatal)
			goto out;
		if (ret_block >= 0)
			goto allocated;
	}

	/*
	 * Now search the rest of the groups.  We assume that 
	 * i and gdp correctly point to the last group visited.
	 */
	for (bgi = 0; bgi < EXT3_SB(sb)->s_groups_count; bgi++) {
		group_no++;
		if (group_no >= EXT3_SB(sb)->s_groups_count)
			group_no = 0;
		gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
		if (!gdp) {
			*errp = -EIO;
			goto out;
		}
		free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
		if (free_blocks <= 0)
			continue;

		brelse(bitmap_bh);
		bitmap_bh = read_block_bitmap(sb, group_no);
		if (!bitmap_bh)
			goto io_error;
		ret_block = ext3_try_to_allocate(sb, handle, group_no,
						bitmap_bh, -1, &fatal);
		if (fatal)
			goto out;
		if (ret_block >= 0) 
			goto allocated;
	}

	/* No space left on the device */
	*errp = -ENOSPC;
	goto out;

allocated:

	ext3_debug("using block group %d(%d)\n",
			group_no, gdp->bg_free_blocks_count);

	BUFFER_TRACE(gdp_bh, "get_write_access");
	fatal = ext3_journal_get_write_access(handle, gdp_bh);
	if (fatal)
		goto out;

	target_block = ret_block + group_no * EXT3_BLOCKS_PER_GROUP(sb)
				+ le32_to_cpu(es->s_first_data_block);

	if (target_block == le32_to_cpu(gdp->bg_block_bitmap) ||
	    target_block == le32_to_cpu(gdp->bg_inode_bitmap) ||
	    in_range(target_block, le32_to_cpu(gdp->bg_inode_table),
		      EXT3_SB(sb)->s_itb_per_group))
		ext3_error(sb, "ext3_new_block",
			    "Allocating block in system zone - "
			    "block = %u", target_block);

	performed_allocation = 1;

#ifdef CONFIG_JBD_DEBUG
	{
		struct buffer_head *debug_bh;

		/* Record bitmap buffer state in the newly allocated block */
		debug_bh = sb_find_get_block(sb, target_block);
		if (debug_bh) {
			BUFFER_TRACE(debug_bh, "state when allocated");
			BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
			brelse(debug_bh);
		}
	}
	jbd_lock_bh_state(bitmap_bh);
	spin_lock(sb_bgl_lock(sbi, group_no));
	if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
		if (ext3_test_bit(ret_block,
				bh2jh(bitmap_bh)->b_committed_data)) {
			printk("%s: block was unexpectedly set in "
				"b_committed_data\n", __FUNCTION__);
		}
	}
	ext3_debug("found bit %d\n", ret_block);
	spin_unlock(sb_bgl_lock(sbi, group_no));
	jbd_unlock_bh_state(bitmap_bh);
#endif

	/* ret_block was blockgroup-relative.  Now it becomes fs-relative */
	ret_block = target_block;

	if (ret_block >= le32_to_cpu(es->s_blocks_count)) {
		ext3_error(sb, "ext3_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 out;
	}

	/*
	 * It is up to the caller to add the new buffer to a journal
	 * list of some description.  We don't know in advance whether
	 * the caller wants to use it as metadata or data.
	 */
	ext3_debug("allocating block %d. Goal hits %d of %d.\n",
			ret_block, goal_hits, goal_attempts);

	spin_lock(sb_bgl_lock(sbi, group_no));
	gdp->bg_free_blocks_count =
			cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - 1);
	spin_unlock(sb_bgl_lock(sbi, group_no));
	percpu_counter_mod(&sbi->s_freeblocks_counter, -1);

	BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
	err = ext3_journal_dirty_metadata(handle, gdp_bh);
	if (!fatal)
		fatal = err;

	sb->s_dirt = 1;
	if (fatal)
		goto out;

	*errp = 0;
	brelse(bitmap_bh);
	return ret_block;

io_error:
	*errp = -EIO;
out:
	if (fatal) {
		*errp = fatal;
		ext3_std_error(sb, fatal);
	}
	/*
	 * Undo the block allocation
	 */
	if (!performed_allocation)
		DQUOT_FREE_BLOCK(inode, 1);
	brelse(bitmap_bh);
	return 0;
}

unsigned long ext3_count_free_blocks(struct super_block *sb)
{
	unsigned long desc_count;
	struct ext3_group_desc *gdp;
	int i;
#ifdef EXT3FS_DEBUG
	struct ext3_super_block *es;
	unsigned long bitmap_count, x;
	struct buffer_head *bitmap_bh = NULL;

	lock_super(sb);
	es = EXT3_SB(sb)->s_es;
	desc_count = 0;
	bitmap_count = 0;
	gdp = NULL;
	for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
		gdp = ext3_get_group_desc(sb, i, NULL);
		if (!gdp)
			continue;
		desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
		brelse(bitmap_bh);
		bitmap_bh = read_block_bitmap(sb, i);
		if (bitmap_bh == NULL)
			continue;

		x = ext3_count_free(bitmap_bh, sb->s_blocksize);
		printk("group %d: stored = %d, counted = %lu\n",
			i, le16_to_cpu(gdp->bg_free_blocks_count), x);
		bitmap_count += x;
	}
	brelse(bitmap_bh);
	printk("ext3_count_free_blocks: stored = %u, computed = %lu, %lu\n",
	       le32_to_cpu(es->s_free_blocks_count), desc_count, bitmap_count);
	unlock_super(sb);
	return bitmap_count;
#else
	desc_count = 0;
	for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
		gdp = ext3_get_group_desc(sb, i, NULL);
		if (!gdp)
			continue;
		desc_count += le16_to_cpu(gdp->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 ext3_test_bit ((block -
		le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) %
			 EXT3_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;
	}
}

int ext3_group_sparse(int group)
{
	return (test_root(group, 3) || test_root(group, 5) ||
		test_root(group, 7));
}

/**
 *	ext3_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 ext3_bg_has_super(struct super_block *sb, int group)
{
	if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
	    !ext3_group_sparse(group))
		return 0;
	return 1;
}

/**
 *	ext3_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 ext3_bg_num_gdb(struct super_block *sb, int group)
{
	if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
	    !ext3_group_sparse(group))
		return 0;
	return EXT3_SB(sb)->s_gdb_count;
}

#ifdef CONFIG_EXT3_CHECK
/* Called at mount-time, super-block is locked */
void ext3_check_blocks_bitmap (struct super_block * sb)
{
	struct ext3_super_block *es;
	unsigned long desc_count, bitmap_count, x, j;
	unsigned long desc_blocks;
	struct buffer_head *bitmap_bh = NULL;
	struct ext3_group_desc *gdp;
	int i;

	es = EXT3_SB(sb)->s_es;
	desc_count = 0;
	bitmap_count = 0;
	gdp = NULL;
	for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
		gdp = ext3_get_group_desc (sb, i, NULL);
		if (!gdp)
			continue;
		desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
		brelse(bitmap_bh);
		bitmap_bh = read_block_bitmap(sb, i);
		if (bitmap_bh == NULL)
			continue;

		if (ext3_bg_has_super(sb, i) &&
				!ext3_test_bit(0, bitmap_bh->b_data))
			ext3_error(sb, __FUNCTION__,
				   "Superblock in group %d is marked free", i);

		desc_blocks = ext3_bg_num_gdb(sb, i);
		for (j = 0; j < desc_blocks; j++)
			if (!ext3_test_bit(j + 1, bitmap_bh->b_data))
				ext3_error(sb, __FUNCTION__,
					   "Descriptor block #%ld in group "
					   "%d is marked free", j, i);

		if (!block_in_use (le32_to_cpu(gdp->bg_block_bitmap),
						sb, bitmap_bh->b_data))
			ext3_error (sb, "ext3_check_blocks_bitmap",
				    "Block bitmap for group %d is marked free",
				    i);

		if (!block_in_use (le32_to_cpu(gdp->bg_inode_bitmap),
						sb, bitmap_bh->b_data))
			ext3_error (sb, "ext3_check_blocks_bitmap",
				    "Inode bitmap for group %d is marked free",
				    i);

		for (j = 0; j < EXT3_SB(sb)->s_itb_per_group; j++)
			if (!block_in_use (le32_to_cpu(gdp->bg_inode_table) + j,
							sb, bitmap_bh->b_data))
				ext3_error (sb, "ext3_check_blocks_bitmap",
					    "Block #%d of the inode table in "
					    "group %d is marked free", j, i);

		x = ext3_count_free(bitmap_bh, sb->s_blocksize);
		if (le16_to_cpu(gdp->bg_free_blocks_count) != x)
			ext3_error (sb, "ext3_check_blocks_bitmap",
				    "Wrong free blocks count for group %d, "
				    "stored = %d, counted = %lu", i,
				    le16_to_cpu(gdp->bg_free_blocks_count), x);
		bitmap_count += x;
	}
	brelse(bitmap_bh);
	if (le32_to_cpu(es->s_free_blocks_count) != bitmap_count)
		ext3_error (sb, "ext3_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);
}
#endif