linux-kernel - Re: [PATCH 10/15] __d_add(): don't drop/regain ->d

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Message-ID: <1461521349.28145.2.camel@poochiereds.net>
Date:	Sun, 24 Apr 2016 14:09:09 -0400
From:	Jeff Layton <jlayton@...chiereds.net>
To:	Al Viro <viro@...IV.linux.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 10/15] __d_add(): don't drop/regain ->d_lock

On Sat, 2016-04-16 at 01:55 +0100, Al Viro wrote:
> From: Al Viro <viro@...iv.linux.org.uk>
> 
> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> ---
>  fs/dcache.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/dcache.c b/fs/dcache.c
> index e9de4d9..33cad8a 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -2363,11 +2363,19 @@ EXPORT_SYMBOL(d_rehash);
>  
>  static inline void __d_add(struct dentry *dentry, struct inode *inode)
>  {
> +	spin_lock(&dentry->d_lock);
>  	if (inode) {
> -		__d_instantiate(dentry, inode);
> +		unsigned add_flags = d_flags_for_inode(inode);
> +		hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
> +		raw_write_seqcount_begin(&dentry->d_seq);
> +		__d_set_inode_and_type(dentry, inode, add_flags);
> +		raw_write_seqcount_end(&dentry->d_seq);
> +		__fsnotify_d_instantiate(dentry);

Should the above be a new __d_instantiate_locked instead of open-coding 
it?

> +	}
> +	_d_rehash(dentry);
> +	spin_unlock(&dentry->d_lock);
> +	if (inode)
>  		spin_unlock(&inode->i_lock);
> -	}
> -	d_rehash(dentry);
>  }
>  
>  /**
-- 
Jeff Layton <jlayton@...chiereds.net>