linux-ext4 - Re: [PATCH 2/2] Ext3: use unlikely to improve the efficiency of the kernel

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Date:	Mon, 14 Jan 2013 15:22:05 +0100
From:	Jan Kara <jack@...e.cz>
To:	shilong wang <wangshilong1991@...il.com>
Cc:	Jan Kara <jack@...e.cz>, linux-fsdevel@...r.kernel.org,
	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/2] Ext3: use unlikely to improve the efficiency of
 the kernel

On Sat 12-01-13 01:36:17, shilong wang wrote:
> From: Wang Shilong <wangsl-fnst@...fujitsu.com>
> 
> Because the function 'sb_getblk' seldomly fails to return
> NULL value,it will be better to use unlikely to check it.
  Thanks. I've merged the patch. Here also applies my comment about line
wrapping from the previous patch...

								Honza
> 
> Signed-off-by: Wang Shilong <wangsl-fnst@...fujitsu.com>
> ---
>  fs/ext3/inode.c  |    6 +++---
>  fs/ext3/resize.c |    6 +++---
>  fs/ext3/xattr.c  |    2 +-
>  3 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
> index 61bc8bd..7338a76 100644
> --- a/fs/ext3/inode.c
> +++ b/fs/ext3/inode.c
> @@ -1083,7 +1083,7 @@ struct buffer_head *ext3_getblk(handle_t
> *handle, struct inode *inode,
>  	if (!err && buffer_mapped(&dummy)) {
>  		struct buffer_head *bh;
>  		bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
> -		if (!bh) {
> +		if (unlikely(!bh)) {
>  			*errp = -EIO;
>  			goto err;
>  		}
> @@ -2734,7 +2734,7 @@ static int __ext3_get_inode_loc(struct inode *inode,
>  		return -EIO;
> 
>  	bh = sb_getblk(inode->i_sb, block);
> -	if (!bh) {
> +	if (unlikely(!bh)) {
>  		ext3_error (inode->i_sb, "ext3_get_inode_loc",
>  				"unable to read inode block - "
>  				"inode=%lu, block="E3FSBLK,
> @@ -2788,7 +2788,7 @@ static int __ext3_get_inode_loc(struct inode *inode,
> 
>  			bitmap_bh = sb_getblk(inode->i_sb,
>  					le32_to_cpu(desc->bg_inode_bitmap));
> -			if (!bitmap_bh)
> +			if (unlikely(!bitmap_bh))
>  				goto make_io;
> 
>  			/*
> diff --git a/fs/ext3/resize.c b/fs/ext3/resize.c
> index 0f814f3..704e8ce 100644
> --- a/fs/ext3/resize.c
> +++ b/fs/ext3/resize.c
> @@ -116,7 +116,7 @@ static struct buffer_head *bclean(handle_t
> *handle, struct super_block *sb,
>  	int err;
> 
>  	bh = sb_getblk(sb, blk);
> -	if (!bh)
> +	if (unlikely(!bh))
>  		return ERR_PTR(-EIO);
>  	if ((err = ext3_journal_get_write_access(handle, bh))) {
>  		brelse(bh);
> @@ -234,7 +234,7 @@ static int setup_new_group_blocks(struct super_block *sb,
>  			goto exit_bh;
> 
>  		gdb = sb_getblk(sb, block);
> -		if (!gdb) {
> +		if (unlikely(!gdb)) {
>  			err = -EIO;
>  			goto exit_bh;
>  		}
> @@ -722,7 +722,7 @@ static void update_backups(struct super_block *sb,
>  			break;
> 
>  		bh = sb_getblk(sb, group * bpg + blk_off);
> -		if (!bh) {
> +		if (unlikely(!bh)) {
>  			err = -EIO;
>  			break;
>  		}
> diff --git a/fs/ext3/xattr.c b/fs/ext3/xattr.c
> index d22ebb7..9f57470 100644
> --- a/fs/ext3/xattr.c
> +++ b/fs/ext3/xattr.c
> @@ -813,7 +813,7 @@ inserted:
>  			ea_idebug(inode, "creating block %d", block);
> 
>  			new_bh = sb_getblk(sb, block);
> -			if (!new_bh) {
> +			if (unlikely(!new_bh)) {
>  getblk_failed:
>  				ext3_free_blocks(handle, inode, block, 1);
>  				error = -EIO;
> -- 
> 1.7.7.6
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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