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ext4: factor out block group accounting into functions

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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: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2011-09-09 18:40:51 -04:00
parent 7137d7a48e
commit 49f7f9af4b
1 changed files with 48 additions and 32 deletions
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80
fs/ext4/balloc.c
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@ -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