Re: [PATCH] fs/dcache.c: revamped to use a more straightforward and efficient way to operate

[Jan Kara <jack@suse.cz>]

  Hello,

  thanks for the patch. I have a few comments to it:
1) the patch should have a description in it, not only an email subject
2) usually, if an 'if' branch ends with return, as is the case in your
   patch, we don't use 'else' for the other branch...

BTW: I'm not convinced your code would be faster (or slower) than the
original one but you're right it will be easier to read...

								Honza

> Signed-off-by: Denis Cheng <crquan@gmail.com>
> ---
>  fs/dcache.c |   39 ++++++++++++++++++---------------------
>  1 files changed, 18 insertions(+), 21 deletions(-)
> 
> diff --git a/fs/dcache.c b/fs/dcache.c
> index 678d39d..05ed44a 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -1138,29 +1138,26 @@ struct dentry * d_alloc_anon(struct inode *inode)
>  	
>  	spin_lock(&dcache_lock);
>  	res = __d_find_alias(inode, 0);
> -	if (!res) {
> -		/* attach a disconnected dentry */
> -		res = tmp;
> -		tmp = NULL;
> -		spin_lock(&res->d_lock);
> -		res->d_sb = inode->i_sb;
> -		res->d_parent = res;
> -		res->d_inode = inode;
> -		res->d_flags |= DCACHE_DISCONNECTED;
> -		res->d_flags &= ~DCACHE_UNHASHED;
> -		list_add(&res->d_alias, &inode->i_dentry);
> -		hlist_add_head(&res->d_hash, &inode->i_sb->s_anon);
> -		spin_unlock(&res->d_lock);
> -
> -		inode = NULL; /* don't drop reference */
> -	}
> -	spin_unlock(&dcache_lock);
> -
> -	if (inode)
> +	if (unlikely(res)) {
> +		spin_unlock(&dcache_lock);
>  		iput(inode);
> -	if (tmp)
>  		dput(tmp);
> -	return res;
> +		return res;
> +	} else {
> +		/* attach a disconnected dentry */
> +		spin_lock(&tmp->d_lock);
> +		tmp->d_sb = inode->i_sb;
> +		tmp->d_parent = tmp;
> +		tmp->d_inode = inode;
> +		tmp->d_flags |= DCACHE_DISCONNECTED;
> +		tmp->d_flags &= ~DCACHE_UNHASHED;
> +		list_add(&tmp->d_alias, &inode->i_dentry);
> +		hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon);
> +		spin_unlock(&tmp->d_lock);
> +
> +		spin_unlock(&dcache_lock);
> +		return tmp;
> +	}
>  }
>  
>  
> -- 
> 1.5.3.2
> 
> -
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-- 
Jan Kara <jack@suse.cz>
SuSE CR Labs