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

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Message-ID: <CA+PpKP=cz4n2zzv4NrJ_Yg=PHqpfCHYnAhgUD2BLTUJmQSrizg@mail.gmail.com>
Date:   Fri, 14 Aug 2020 14:01:50 +0800
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 11:21 PM Hao Lee <haolee.swjtu@...il.com> 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
>