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Commit 49f7f9af authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: factor out block group accounting into functions 



This makes it easier to understand how ext4_init_block_bitmap() works,
and it will assist when we split out ext4_free_blocks_after_init() in
the next commit.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 7137d7a4

fs/ext4/balloc.c

+48 −32
Original line number Diff line number Diff line
@@ -23,6 +23,9 @@ 


#include <trace/events/ext4.h>



static unsigned int num_base_meta_blocks(struct super_block *sb,

					 ext4_group_t block_group);



/*

 * balloc.c contains the blocks allocation and deallocation routines

 */
@@ -83,14 +86,30 @@ static int ext4_group_used_meta_blocks(struct super_block *sb, 
	return used_blocks;

}



static unsigned int num_blocks_in_group(struct super_block *sb,

					ext4_group_t block_group)

{

	if (block_group == ext4_get_groups_count(sb) - 1) {

		/*

		 * Even though mke2fs always initializes the first and

		 * last group, just in case some other tool was used,

		 * we need to make sure we calculate the right free

		 * blocks.

		 */

		return ext4_blocks_count(EXT4_SB(sb)->s_es) -

			ext4_group_first_block_no(sb, block_group);

	} else

		return EXT4_BLOCKS_PER_GROUP(sb);

}



/* Initializes an uninitialized block bitmap if given, and returns the

 * number of blocks free in the group. */

unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,

		 ext4_group_t block_group, struct ext4_group_desc *gdp)

{

	int bit, bit_max;

	unsigned int bit, bit_max = num_base_meta_blocks(sb, block_group);

	ext4_group_t ngroups = ext4_get_groups_count(sb);

	unsigned free_blocks, group_blocks;

	unsigned group_blocks = num_blocks_in_group(sb, block_group);

	struct ext4_sb_info *sbi = EXT4_SB(sb);



	if (bh) {
@@ -110,35 +129,6 @@ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh, 
		memset(bh->b_data, 0, sb->s_blocksize);

	}



	/* Check for superblock and gdt backups in this group */

	bit_max = ext4_bg_has_super(sb, block_group);



	if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||

	    block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *

			  sbi->s_desc_per_block) {

		if (bit_max) {

			bit_max += ext4_bg_num_gdb(sb, block_group);

			bit_max +=

				le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);

		}

	} else { /* For META_BG_BLOCK_GROUPS */

		bit_max += ext4_bg_num_gdb(sb, block_group);

	}



	if (block_group == ngroups - 1) {

		/*

		 * Even though mke2fs always initialize first and last group

		 * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need

		 * to make sure we calculate the right free blocks

		 */

		group_blocks = ext4_blocks_count(sbi->s_es) -

			ext4_group_first_block_no(sb, ngroups - 1);

	} else {

		group_blocks = EXT4_BLOCKS_PER_GROUP(sb);

	}



	free_blocks = group_blocks - bit_max;



	if (bh) {

		ext4_fsblk_t start, tmp;

		int flex_bg = 0;
@@ -176,7 +166,8 @@ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh, 
		ext4_mark_bitmap_end(group_blocks, sb->s_blocksize * 8,

				     bh->b_data);

	}

	return free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp);

	return group_blocks - bit_max -

		ext4_group_used_meta_blocks(sb, block_group, gdp);

}
@@ -620,6 +611,31 @@ unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group) 


}



/*

 * This function returns the number of file system metadata blocks at

 * the beginning of a block group, including the reserved gdt blocks.

 */

static unsigned int num_base_meta_blocks(struct super_block *sb,

					 ext4_group_t block_group)

{

	struct ext4_sb_info *sbi = EXT4_SB(sb);

	int num;



	/* Check for superblock and gdt backups in this group */

	num = ext4_bg_has_super(sb, block_group);



	if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||

	    block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *

			  sbi->s_desc_per_block) {

		if (num) {

			num += ext4_bg_num_gdb(sb, block_group);

			num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);

		}

	} else { /* For META_BG_BLOCK_GROUPS */

		num += ext4_bg_num_gdb(sb, block_group);

	}

	return num;

}

/**

 *	ext4_inode_to_goal_block - return a hint for block allocation

 *	@inode: inode for block allocation