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Date: Wed, 22 Jun 2011 21:16:33 -0600
From: Andreas Dilger <adilger@...ger.ca>
To: Eric Sandeen <sandeen@...hat.com>
Cc: ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] ext4: refactor duplicated block placement code
On 2011-06-22, at 12:37 PM, Eric Sandeen wrote:
> 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.
>
> Signed-off-by: Eric Sandeen <sandeen@...hat.com>
> ---
>
> ext4.h | 1
> extents.c | 37 ---------------------------------
> inode.c | 69 +++++++++++++++++++++++++++++++++++++-------------------------
> 3 files changed, 44 insertions(+), 63 deletions(-)
>
> I don't know that I like the new function name too much,
> I'm open to suggestions...
What about ext4_goal_block_from_inode() or ext4_start_block_from_inode() or
ext4_inode_to_{goal,start}_block()? One of last ones might be good since
it makes it clear this function is related to other ext4_inode_*() functions.
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 1921392..1d79fbc 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1812,6 +1812,7 @@ extern int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
> struct kstat *stat);
> extern void ext4_evict_inode(struct inode *);
> extern void ext4_clear_inode(struct inode *);
> +ext4_fsblk_t ext4_inode_group_start(struct inode *);
> extern int ext4_sync_inode(handle_t *, struct inode *);
> extern void ext4_dirty_inode(struct inode *, int);
> extern int ext4_change_inode_journal_flag(struct inode *, int);
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 5199bac..23cf7dd 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_group_start(inode);
> }
>
> /*
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index a5763e3..5784809 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -466,6 +466,47 @@ no_block:
> return p;
> }
>
> +ext4_fsblk_t ext4_inode_group_start(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;
> +}
> +
> /**
> * ext4_find_near - find a place for allocation with sufficient locality
> * @inode: owner
> @@ -491,11 +532,6 @@ 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--) {
> @@ -511,28 +547,7 @@ 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_group_start(inode);
> }
>
> /**
> --
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Cheers, Andreas
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