From: Theodore Ts'o Subject: [PATCH, RFC 05/12] ext4: factor out block group accounting into functions Date: Sat, 19 Mar 2011 17:28:30 -0400 Message-ID: <1300570117-24048-6-git-send-email-tytso@mit.edu> References: <1300570117-24048-1-git-send-email-tytso@mit.edu> Cc: Theodore Ts'o To: linux-ext4@vger.kernel.org Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:52240 "EHLO test.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757599Ab1CSVhX (ORCPT ); Sat, 19 Mar 2011 17:37:23 -0400 In-Reply-To: <1300570117-24048-1-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: 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" --- 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