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Message-Id: <B18ADA2A-CB14-4D30-A091-E4ACB1C9E280@gmail.com>
Date: Wed, 20 Jul 2011 09:41:24 -0600
From: Andreas Dilger <aedilger@...il.com>
To: Yongqiang Yang <xiaoqiangnk@...il.com>
Cc: "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
"tytso@....edu" <tytso@....edu>,
Yongqiang Yang <xiaoqiangnk@...il.com>
Subject: Re: [PATCH 2/2] ext4: remove ext4_free_blocks_after_init()
On 2011-07-20, at 7:32 AM, Yongqiang Yang <xiaoqiangnk@...il.com> wrote:
> This patch removes ext4_free_blocks_after_init() and simplifies
> ext4_init_block_bitmap() a lot.
Why not use the ext4_set_bits() function, exported in another patch, to set multiple bits?
> Signed-off-by: Yongqiang Yang <xiaoqiangnk@...il.com>
> ---
> fs/ext4/balloc.c | 122 ++++++++++++++++++-----------------------------------
> fs/ext4/ext4.h | 4 +-
> 2 files changed, 43 insertions(+), 83 deletions(-)
>
> diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
> index f8224ad..2dd9820 100644
> --- a/fs/ext4/balloc.c
> +++ b/fs/ext4/balloc.c
> @@ -55,60 +55,31 @@ static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
> return 0;
> }
>
> -static int ext4_group_used_meta_blocks(struct super_block *sb,
> - ext4_group_t block_group,
> - struct ext4_group_desc *gdp)
> -{
> - ext4_fsblk_t tmp;
> - struct ext4_sb_info *sbi = EXT4_SB(sb);
> - /* block bitmap, inode bitmap, and inode table blocks */
> - int used_blocks = sbi->s_itb_per_group + 2;
> -
> - if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
> - if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp),
> - block_group))
> - used_blocks--;
> -
> - if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp),
> - block_group))
> - used_blocks--;
> -
> - tmp = ext4_inode_table(sb, gdp);
> - for (; tmp < ext4_inode_table(sb, gdp) +
> - sbi->s_itb_per_group; tmp++) {
> - if (!ext4_block_in_group(sb, tmp, block_group))
> - used_blocks -= 1;
> - }
> - }
> - return used_blocks;
> -}
> -
> -/* 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,
> +/* Initializes an uninitialized block bitmap */
> +void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
> ext4_group_t block_group, struct ext4_group_desc *gdp)
> {
> + ext4_fsblk_t start, tmp;
> int bit, bit_max;
> ext4_group_t ngroups = ext4_get_groups_count(sb);
> - unsigned free_blocks, group_blocks;
> + unsigned group_blocks;
> struct ext4_sb_info *sbi = EXT4_SB(sb);
> -
> - if (bh) {
> - J_ASSERT_BH(bh, buffer_locked(bh));
> -
> - /* If checksum is bad mark all blocks used to prevent allocation
> - * essentially implementing a per-group read-only flag. */
> - if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
> - ext4_error(sb, "Checksum bad for group %u",
> - block_group);
> - ext4_free_blks_set(sb, gdp, 0);
> - ext4_free_inodes_set(sb, gdp, 0);
> - ext4_itable_unused_set(sb, gdp, 0);
> - memset(bh->b_data, 0xff, sb->s_blocksize);
> - return 0;
> - }
> - memset(bh->b_data, 0, sb->s_blocksize);
> + int flex_bg = 0;
> +
> + J_ASSERT_BH(bh, bh && buffer_locked(bh));
> +
> + /* If checksum is bad mark all blocks used to prevent allocation
> + * essentially implementing a per-group read-only flag. */
> + if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
> + ext4_error(sb, "Checksum bad for group %u",
> + block_group);
> + ext4_free_blks_set(sb, gdp, 0);
> + ext4_free_inodes_set(sb, gdp, 0);
> + ext4_itable_unused_set(sb, gdp, 0);
> + memset(bh->b_data, 0xff, sb->s_blocksize);
> + return;
> }
> + 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);
> @@ -137,46 +108,37 @@ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
> group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
> }
>
> - free_blocks = group_blocks - bit_max;
>
> - if (bh) {
> - ext4_fsblk_t start, tmp;
> - int flex_bg = 0;
> + for (bit = 0; bit < bit_max; bit++)
> + ext4_set_bit(bit, bh->b_data);
>
> - for (bit = 0; bit < bit_max; bit++)
> - ext4_set_bit(bit, bh->b_data);
> + start = ext4_group_first_block_no(sb, block_group);
>
> - start = ext4_group_first_block_no(sb, block_group);
> + flex_bg = EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG);
>
> - if (EXT4_HAS_INCOMPAT_FEATURE(sb,
> - EXT4_FEATURE_INCOMPAT_FLEX_BG))
> - flex_bg = 1;
> + /* Set bits for block and inode bitmaps, and inode table */
> + tmp = ext4_block_bitmap(sb, gdp);
> + if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
> + ext4_set_bit(tmp - start, bh->b_data);
>
> - /* Set bits for block and inode bitmaps, and inode table */
> - tmp = ext4_block_bitmap(sb, gdp);
> - if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
> - ext4_set_bit(tmp - start, bh->b_data);
> + tmp = ext4_inode_bitmap(sb, gdp);
> + if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
> + ext4_set_bit(tmp - start, bh->b_data);
>
> - tmp = ext4_inode_bitmap(sb, gdp);
> - if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
> + tmp = ext4_inode_table(sb, gdp);
> + for (; tmp < ext4_inode_table(sb, gdp) +
> + sbi->s_itb_per_group; tmp++) {
> + if (!flex_bg ||
> + ext4_block_in_group(sb, tmp, block_group))
> ext4_set_bit(tmp - start, bh->b_data);
> -
> - tmp = ext4_inode_table(sb, gdp);
> - for (; tmp < ext4_inode_table(sb, gdp) +
> - sbi->s_itb_per_group; tmp++) {
> - if (!flex_bg ||
> - ext4_block_in_group(sb, tmp, block_group))
> - ext4_set_bit(tmp - start, bh->b_data);
> - }
> - /*
> - * Also if the number of blocks within the group is
> - * less than the blocksize * 8 ( which is the size
> - * of bitmap ), set rest of the block bitmap to 1
> - */
> - 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);
> + /*
> + * Also if the number of blocks within the group is
> + * less than the blocksize * 8 ( which is the size
> + * of bitmap ), set rest of the block bitmap to 1
> + */
> + ext4_mark_bitmap_end(group_blocks, sb->s_blocksize * 8,
> + bh->b_data);
> }
>
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 62cee2b..eacaad2 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1741,12 +1741,10 @@ extern struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
> extern int ext4_should_retry_alloc(struct super_block *sb, int *retries);
> struct buffer_head *ext4_read_block_bitmap(struct super_block *sb,
> ext4_group_t block_group);
> -extern unsigned ext4_init_block_bitmap(struct super_block *sb,
> +extern void ext4_init_block_bitmap(struct super_block *sb,
> struct buffer_head *bh,
> ext4_group_t group,
> struct ext4_group_desc *desc);
> -#define ext4_free_blocks_after_init(sb, group, desc) \
> - ext4_init_block_bitmap(sb, NULL, group, desc)
> ext4_fsblk_t ext4_inode_to_goal_block(struct inode *);
>
> /* dir.c */
> --
> 1.7.5.1
>
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