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Date: Sat, 19 Mar 2011 17:28:30 -0400
From: Theodore Ts'o <tytso@....edu>
To: linux-ext4@...r.kernel.org
Cc: Theodore Ts'o <tytso@....edu>
Subject: [PATCH, RFC 05/12] 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: "Theodore Ts'o" <tytso@....edu>
---
fs/ext4/balloc.c | 80 ++++++++++++++++++++++++++++++++---------------------
1 files changed, 48 insertions(+), 32 deletions(-)
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index adf96b8..c608fda 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -21,6 +21,9 @@
#include "ext4_jbd2.h"
#include "mballoc.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
*/
@@ -81,14 +84,30 @@ 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) {
@@ -108,35 +127,6 @@ 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;
@@ -174,7 +164,8 @@ 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);
}
@@ -741,3 +732,28 @@ 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;
+}
--
1.7.3.1
--
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