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Date: Tue, 28 Jun 2011 09:14:32 -0500
From: Eric Sandeen <sandeen@...hat.com>
To: "Theodore Ts'o" <tytso@....edu>
CC: Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH -v3] ext4: refactor duplicated block placement code
On 6/28/11 9:05 AM, Theodore Ts'o wrote:
> From: "Theodore Ts'o" <tytso@....edu>
I kind of wish you'd keep me on the From: even if you did
move the change to a new file.
Thanks,
-Eric
> I found that ext4_ext_find_goal() and ext4_find_near()
> share the same code for returning a coloured start block
> based on i_block_group.
>
> We can refactor this into a common function so that they
> don't diverge in the future.
>
> Thanks to adilger for suggesting the new function name.
>
> Signed-off-by: Eric Sandeen <sandeen@...hat.com>
> Signed-off-by: "Theodore Ts'o" <tytso@....edu>
> ---
>
> Moved new code to balloc.c, and rebased patch to take into account the
> fs/ext4/indirect.c reorganization. -- Ted
>
> fs/ext4/balloc.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
> fs/ext4/ext4.h | 1 +
> fs/ext4/extents.c | 37 +------------------------------------
> fs/ext4/indirect.c | 28 +---------------------------
> 4 files changed, 51 insertions(+), 63 deletions(-)
>
> diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
> index 264f694..f8224ad 100644
> --- a/fs/ext4/balloc.c
> +++ b/fs/ext4/balloc.c
> @@ -620,3 +620,51 @@ unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
>
> }
>
> +/**
> + * ext4_inode_to_goal_block - return a hint for block allocation
> + * @inode: inode for block allocation
> + *
> + * Return the ideal location to start allocating blocks for a
> + * newly created inode.
> + */
> +ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
> +{
> + struct ext4_inode_info *ei = EXT4_I(inode);
> + ext4_group_t block_group;
> + ext4_grpblk_t colour;
> + int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
> + ext4_fsblk_t bg_start;
> + ext4_fsblk_t last_block;
> +
> + block_group = ei->i_block_group;
> + if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
> + /*
> + * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
> + * block groups per flexgroup, reserve the first block
> + * group for directories and special files. Regular
> + * files will start at the second block group. This
> + * tends to speed up directory access and improves
> + * fsck times.
> + */
> + block_group &= ~(flex_size-1);
> + if (S_ISREG(inode->i_mode))
> + block_group++;
> + }
> + bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
> + last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
> +
> + /*
> + * If we are doing delayed allocation, we don't need take
> + * colour into account.
> + */
> + if (test_opt(inode->i_sb, DELALLOC))
> + return bg_start;
> +
> + if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
> + colour = (current->pid % 16) *
> + (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
> + else
> + colour = (current->pid % 16) * ((last_block - bg_start) / 16);
> + return bg_start + colour;
> +}
> +
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index ddaf504..49d2cea 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1743,6 +1743,7 @@ extern unsigned ext4_init_block_bitmap(struct super_block *sb,
> 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 */
> extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *,
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index eb63c7b..f331e50 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -114,12 +114,6 @@ static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
> struct ext4_ext_path *path,
> ext4_lblk_t block)
> {
> - struct ext4_inode_info *ei = EXT4_I(inode);
> - ext4_fsblk_t bg_start;
> - ext4_fsblk_t last_block;
> - ext4_grpblk_t colour;
> - ext4_group_t block_group;
> - int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
> int depth;
>
> if (path) {
> @@ -161,36 +155,7 @@ static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
> }
>
> /* OK. use inode's group */
> - block_group = ei->i_block_group;
> - if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
> - /*
> - * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
> - * block groups per flexgroup, reserve the first block
> - * group for directories and special files. Regular
> - * files will start at the second block group. This
> - * tends to speed up directory access and improves
> - * fsck times.
> - */
> - block_group &= ~(flex_size-1);
> - if (S_ISREG(inode->i_mode))
> - block_group++;
> - }
> - bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
> - last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
> -
> - /*
> - * If we are doing delayed allocation, we don't need take
> - * colour into account.
> - */
> - if (test_opt(inode->i_sb, DELALLOC))
> - return bg_start;
> -
> - if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
> - colour = (current->pid % 16) *
> - (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
> - else
> - colour = (current->pid % 16) * ((last_block - bg_start) / 16);
> - return bg_start + colour + block;
> + return ext4_inode_to_goal_block(inode);
> }
>
> /*
> diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
> index c3e85a8..6c27111 100644
> --- a/fs/ext4/indirect.c
> +++ b/fs/ext4/indirect.c
> @@ -207,11 +207,6 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
> struct ext4_inode_info *ei = EXT4_I(inode);
> __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
> __le32 *p;
> - ext4_fsblk_t bg_start;
> - ext4_fsblk_t last_block;
> - ext4_grpblk_t colour;
> - ext4_group_t block_group;
> - int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
>
> /* Try to find previous block */
> for (p = ind->p - 1; p >= start; p--) {
> @@ -227,28 +222,7 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
> * It is going to be referred to from the inode itself? OK, just put it
> * into the same cylinder group then.
> */
> - block_group = ei->i_block_group;
> - if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
> - block_group &= ~(flex_size-1);
> - if (S_ISREG(inode->i_mode))
> - block_group++;
> - }
> - bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
> - last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
> -
> - /*
> - * If we are doing delayed allocation, we don't need take
> - * colour into account.
> - */
> - if (test_opt(inode->i_sb, DELALLOC))
> - return bg_start;
> -
> - if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
> - colour = (current->pid % 16) *
> - (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
> - else
> - colour = (current->pid % 16) * ((last_block - bg_start) / 16);
> - return bg_start + colour;
> + return ext4_inode_to_goal_block(inode);
> }
>
> /**
--
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