linux-kernel - Re: [PATCH v8 11/32] vfs: make do

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Message-ID: <20121030161429.GD24618@fieldses.org>
Date:	Tue, 30 Oct 2012 12:14:29 -0400
From:	"J. Bruce Fields" <bfields@...ldses.org>
To:	Jeff Layton <jlayton@...hat.com>
Cc:	viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org,
	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
	michael.brantley@...haw.com, hch@...radead.org, miklos@...redi.hu,
	pstaubach@...grid.com
Subject: Re: [PATCH v8 11/32] vfs: make do_unlinkat retry on ESTALE errors

On Sat, Oct 27, 2012 at 08:33:18AM -0400, Jeff Layton wrote:
> Signed-off-by: Jeff Layton <jlayton@...hat.com>
> ---
>  fs/namei.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index 7c9bb50..467b9f1 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -3446,9 +3446,13 @@ static long do_unlinkat(int dfd, const char __user *pathname)
>  	struct filename *name;
>  	struct dentry *dentry;
>  	struct nameidata nd;
> -	struct inode *inode = NULL;
> +	struct inode *inode;
> +	unsigned int try = 0;
> +	unsigned int lookup_flags = LOOKUP_PARENT;
>  
> -	name = user_path_parent(dfd, pathname, &nd, 0);
> +retry:
> +	inode = NULL;

So, you fail after "inode" was set (say vfs_unlink returned an error)
the first time, then before "inode" was set (lookup_hash returns an
error), and you end up incorrectly doing another iput() the second time
through if you don't reset inode here?

(I think I made the same mistake in another patch, actually....)

--b.

> +	name = user_path_parent(dfd, pathname, &nd, try);
>  	if (IS_ERR(name))
>  		return PTR_ERR(name);
>  
> @@ -3486,6 +3490,10 @@ exit2:
>  exit1:
>  	path_put(&nd.path);
>  	putname(name);
> +	if (retry_estale(error, try++)) {
> +		lookup_flags |= LOOKUP_REVAL;
> +		goto retry;
> +	}
>  	return error;
>  
>  slashes:
> -- 
> 1.7.11.7
> 
> --
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