From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: [PATCH v3 109/110] namei: handle absolute symlinks without
 dropping out of RCU mode
Date: Fri, 15 May 2015 06:11:00 +0100
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 <1431367690-5223-109-git-send-email-viro@ZenIV.linux.org.uk>
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Cc: Neil Brown <neilb@suse.de>, Christoph Hellwig <hch@infradead.org>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
To: Linus Torvalds <torvalds@linux-foundation.org>
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On Mon, May 11, 2015 at 07:08:09PM +0100, Al Viro wrote:
> @@ -499,7 +499,7 @@ struct nameidata {
>  	struct path	root;
>  	struct inode	*inode; /* path.dentry.d_inode */
>  	unsigned int	flags;
> -	unsigned	seq, m_seq;
> +	unsigned	seq, m_seq, root_seq;
>  	int		last_type;
>  	unsigned	depth;
>  	int		total_link_count;
> @@ -780,14 +780,14 @@ static __always_inline void set_root(struct nameidata *nd)
>  static __always_inline unsigned set_root_rcu(struct nameidata *nd)
>  {
>  	struct fs_struct *fs = current->fs;
> -	unsigned seq, res;
> +	unsigned seq;
>  
>  	do {
>  		seq = read_seqcount_begin(&fs->seq);
>  		nd->root = fs->root;
> -		res = __read_seqcount_begin(&nd->root.dentry->d_seq);
> +		nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq);

nd->root_seq is also needed in LOOKUP_ROOT | LOOKUP_RCU case.  Fixed and
folded.