linux-kernel - Re: [PATCH] fs: Eliminate a local variable to make the code more clear

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Date:   Tue, 8 Sep 2020 13:06:56 +0000
From:   Hao Lee <haolee.swjtu@...il.com>
To:     viro@...iv.linux.org.uk
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fs: Eliminate a local variable to make the code more
 clear

ping

On Wed, Jul 29, 2020 at 03:21:28PM +0000, Hao Lee wrote:
> The dentry local variable is introduced in 'commit 84d17192d2afd ("get
> rid of full-hash scan on detaching vfsmounts")' to reduce the length of
> some long statements for example
> mutex_lock(&path->dentry->d_inode->i_mutex). We have already used
> inode_lock(dentry->d_inode) to do the same thing now, and its length is
> acceptable. Furthermore, it seems not concise that assign path->dentry
> to local variable dentry in the statement before goto. So, this function
> would be more clear if we eliminate the local variable dentry.
> 
> The function logic is not changed.
> 
> Signed-off-by: Hao Lee <haolee.swjtu@...il.com>
> ---
>  fs/namespace.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/namespace.c b/fs/namespace.c
> index 4a0f600a3328..fcb93586fcc9 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -2187,20 +2187,19 @@ static int attach_recursive_mnt(struct mount *source_mnt,
>  static struct mountpoint *lock_mount(struct path *path)
>  {
>  	struct vfsmount *mnt;
> -	struct dentry *dentry = path->dentry;
>  retry:
> -	inode_lock(dentry->d_inode);
> -	if (unlikely(cant_mount(dentry))) {
> -		inode_unlock(dentry->d_inode);
> +	inode_lock(path->dentry->d_inode);
> +	if (unlikely(cant_mount(path->dentry))) {
> +		inode_unlock(path->dentry->d_inode);
>  		return ERR_PTR(-ENOENT);
>  	}
>  	namespace_lock();
>  	mnt = lookup_mnt(path);
>  	if (likely(!mnt)) {
> -		struct mountpoint *mp = get_mountpoint(dentry);
> +		struct mountpoint *mp = get_mountpoint(path->dentry);
>  		if (IS_ERR(mp)) {
>  			namespace_unlock();
> -			inode_unlock(dentry->d_inode);
> +			inode_unlock(path->dentry->d_inode);
>  			return mp;
>  		}
>  		return mp;
> @@ -2209,7 +2208,7 @@ static struct mountpoint *lock_mount(struct path *path)
>  	inode_unlock(path->dentry->d_inode);
>  	path_put(path);
>  	path->mnt = mnt;
> -	dentry = path->dentry = dget(mnt->mnt_root);
> +	path->dentry = dget(mnt->mnt_root);
>  	goto retry;
>  }
>  
> -- 
> 2.24.1
>