linux-kernel - Re: [PATCH 25/41] union-mount: stop lookup when directory has S

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Message-Id: <200912010410.nB14AwWh030303@agora.fsl.cs.sunysb.edu>
Date:	Mon, 30 Nov 2009 23:10:58 -0500
From:	Erez Zadok <ezk@...sunysb.edu>
To:	Valerie Aurora <vaurora@...hat.com>
Cc:	Jan Blunck <jblunck@...e.de>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christoph Hellwig <hch@...radead.org>,
	Andy Whitcroft <apw@...onical.com>,
	Scott James Remnant <scott@...onical.com>,
	Sandu Popa Marius <sandupopamarius@...il.com>,
	Jan Rekorajski <baggins@...h.mimuw.edu.pl>,
	"J. R. Okajima" <hooanon05@...oo.co.jp>,
	Arnd Bergmann <arnd@...db.de>,
	Vladimir Dronnikov <dronnikov@...il.com>,
	Felix Fietkau <nbd@...nwrt.org>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 25/41] union-mount: stop lookup when directory has S_OPAQUE flag set 

In message <1256152779-10054-26-git-send-email-vaurora@...hat.com>, Valerie Aurora writes:
> From: Jan Blunck <jblunck@...e.de>
> 
> Honor the S_OPAQUE flag in the union path lookup.

Was it intentional to have a separate patch which adds opaque directories
support, or should it be part of the larger patch #24?

> 
> Signed-off-by: Jan Blunck <jblunck@...e.de>
> Signed-off-by: Valerie Aurora <vaurora@...hat.com>
> ---
>  fs/namei.c |   17 ++++++++++++++---
>  1 files changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index b279686..8ebbf4f 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -523,6 +523,9 @@ static int __cache_lookup_build_union(struct nameidata *nd, struct qstr *name,
>  			path_put(&last);
>  		last.dentry = dentry;
>  		last.mnt = mntget(nd->path.mnt);
> +
> +		if (IS_OPAQUE(last.dentry->d_inode))
> +			break;
>  	}
>  
>  	if (last.dentry != path->dentry)
> @@ -562,7 +565,8 @@ static int cache_lookup_union(struct nameidata *nd, struct qstr *name,
>  
>  		/* only directories can be part of a union stack */
>  		if (!path->dentry->d_inode ||
> -		    !S_ISDIR(path->dentry->d_inode->i_mode))
> +		    !S_ISDIR(path->dentry->d_inode->i_mode) ||
> +		    IS_OPAQUE(path->dentry->d_inode))
>  			goto out;
>  
>  		/* Build the union stack for this part */
> @@ -804,6 +808,9 @@ static int __real_lookup_build_union(struct nameidata *nd, struct qstr *name,
>  			path_put(&last);
>  		last.dentry = next.dentry;
>  		last.mnt = mntget(next.mnt);
> +
> +		if (IS_OPAQUE(last.dentry->d_inode))
> +			break;
>  	}
>  
>  	if (last.dentry != path->dentry)
> @@ -825,7 +832,8 @@ static int real_lookup_union(struct nameidata *nd, struct qstr *name,
>  
>  	/* only directories can be part of a union stack */
>  	if (!path->dentry->d_inode ||
> -	    !S_ISDIR(path->dentry->d_inode->i_mode))
> +	    !S_ISDIR(path->dentry->d_inode->i_mode) ||
> +	    IS_OPAQUE(path->dentry->d_inode))
>  		goto out;
>  
>  	/* Build the union stack for this part */
> @@ -1111,7 +1119,7 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
>  {
>  	int err;
>  
> -	if (IS_MNT_UNION(nd->path.mnt))
> +	if (IS_MNT_UNION(nd->path.mnt) && !IS_OPAQUE(nd->path.dentry->d_inode))
>  		goto need_union_lookup;
>  
>  	path->dentry = __d_lookup(nd->path.dentry, name);
> @@ -1676,6 +1684,9 @@ static int __hash_lookup_build_union(struct nameidata *nd, struct qstr *name,
>  			path_put(&last);
>  		last.dentry = next.dentry;
>  		last.mnt = mntget(next.mnt);
> +
> +		if (IS_OPAQUE(last.dentry->d_inode))
> +			break;
>  	}
>  
>  	if (last.dentry != path->dentry)
> -- 
> 1.6.3.3
> 
> --
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Erez.
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