linux-ext4 - Re: update uninitialized-block-groups.patch and mballoc-core.patch

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Date:	Thu, 04 Oct 2007 00:34:16 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
CC:	Andreas Dilger <adilger@...sterfs.com>,
	Avantika Mathur <mathur@...ux.vnet.ibm.com>,
	Mingming Cao <cmm@...ibm.com>,
	linux-ext4 <linux-ext4@...r.kernel.org>
Subject: Re: update uninitialized-block-groups.patch and mballoc-core.patch



Aneesh Kumar K.V wrote:
> 
> 
> Andreas Dilger wrote:
>> On Oct 03, 2007  15:30 +0530, Aneesh Kumar K.V wrote:
>>> +    if (block_group == sbi->s_gdb_count - 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
>>> +         */
>>> +        free_blocks = ext4_blocks_count(sbi->s_es) -
>>> +                le32_to_cpu(sbi->s_es->s_first_data_block) -
>>> +                (EXT4_BLOCKS_PER_GROUP(sb) * sbi->s_groups_count) -
>>> +                bit_max;
>>
>> Did you verify that subtracting s_first_data_block is indeed the right
>> thing to do.  I _think_ yes, but I didn't look at it very closely when
>> I wrote it late last night.
>>
> 
> yes s_first_data_block is always decremented to find total number of 
> blocks occupied by the reset of the group. But now looking at it again i 
> guess i need to have




diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 8613914..34b1e11 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -50,7 +50,7 @@ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
 {
 	unsigned long start;
 	int bit, bit_max;
-	unsigned free_blocks;
+	unsigned free_blocks, group_blocks;
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 
 	if (bh) {
@@ -96,14 +96,15 @@ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
 		 * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
 		 * to make sure we calculate the right free blocks
 		 */
-		free_blocks = ext4_blocks_count(sbi->s_es) -
-				le32_to_cpu(sbi->s_es->s_first_data_block) -
-				(EXT4_BLOCKS_PER_GROUP(sb) * sbi->s_groups_count) -
-				bit_max;
+		group_blocks = ext4_blocks_count(sbi->s_es) -
+			le32_to_cpu(sbi->s_es->s_first_data_block) -
+			(EXT4_BLOCKS_PER_GROUP(sb) * (sbi->s_groups_count -1));
 	} else {
-		free_blocks = EXT4_BLOCKS_PER_GROUP(sb) - bit_max;
+		group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
 	}
 
+	free_blocks = group_blocks - bit_max;
+
 	if (bh) {
 		for (bit = 0; bit < bit_max; bit++)
 			ext4_set_bit(bit, bh->b_data);
@@ -123,8 +124,7 @@ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
 		 * blocksize * 8 ( which is the size of bitmap ), set rest of the
 		 * block bitmap to 1
 		 */
-		mark_bitmap_end(EXT4_BLOCKS_PER_GROUP(sb),
-					sb->s_blocksize * 8, bh->b_data);
+		mark_bitmap_end(group_blocks, sb->s_blocksize * 8, bh->b_data);
 	}
 
 	return free_blocks - sbi->s_itb_per_group - 2;
-
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