Re: [PATCH] pass XFS_IGET_BULKSTAT to xfs_iget for handle operations

From: Eric Sandeen <sandeen@sandeen.net>
To: Christoph Hellwig <hch@infradead.org>
Cc: Mario Becroft <mb@gem.win.co.nz>, xfs@oss.sgi.com
Subject: Re: [PATCH] pass XFS_IGET_BULKSTAT to xfs_iget for handle operations
Date: Thu, 01 Jan 2009 16:31:31 -0600	[thread overview]
Message-ID: <495D4443.6010104@sandeen.net> (raw)
In-Reply-To: <20090101192116.GA6986@infradead.org>

Christoph Hellwig wrote:
> NFS clients or users of the handle ioctls can pass us arbitrary inode
> numbers through the exportfs interface.  Make sure we use the
> XFS_IGET_BULKSTAT so that these don't cause shutdowns due to the corruption
> checks.  Also translate the EINVAL we get back for invalid inode clusters
> into an ESTALE which is more appropinquate, and remove the useless check
> for a NULL inode on a successfull xfs_iget return.
> 
> I have a testcase to reproduce this using the handle interface which
> I will submit to xfsqa.
> 
> 
> Reported-by: Mario Becroft <mb@gem.win.co.nz>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Eric Sandeen <sandeen@sandeen.net>

> Index: xfs/fs/xfs/linux-2.6/xfs_export.c
> ===================================================================
> --- xfs.orig/fs/xfs/linux-2.6/xfs_export.c	2009-01-01 20:06:06.145674550 +0100
> +++ xfs/fs/xfs/linux-2.6/xfs_export.c	2009-01-01 20:14:59.673658382 +0100
> @@ -126,11 +126,26 @@ xfs_nfs_get_inode(
>  	if (ino == 0)
>  		return ERR_PTR(-ESTALE);
>  
> -	error = xfs_iget(mp, NULL, ino, 0, XFS_ILOCK_SHARED, &ip, 0);
> -	if (error)
> +	/*
> +	 * The XFS_IGET_BULKSTAT means that an invalid inode number is just
> +	 * fine and not an indication of a corrupted filesystem.  Because
> +	 * clients can send any kind of invalid file handle, e.g. after
> +	 * a restore on the server we have to deal with this case gracefully.
> +	 */
> +	error = xfs_iget(mp, NULL, ino, XFS_IGET_BULKSTAT,
> +			 XFS_ILOCK_SHARED, &ip, 0);
> +	if (error) {
> +		/*
> +		 * EINVAL means the inode cluster doesn't exist anymore.
> +		 * This implies the filehandle is stale, so we should
> +		 * translate it here.
> +		 * We don't use ESTALE directly down the chain to not
> +		 * confuse applications using bulkstat that expect EINVAL.
> +		 */
> +		if (error == EINVAL)
> +			error = ESTALE;
>  		return ERR_PTR(-error);
> -	if (!ip)
> -		return ERR_PTR(-EIO);
> +	}
>  
>  	if (ip->i_d.di_gen != generation) {
>  		xfs_iput_new(ip, XFS_ILOCK_SHARED);
> 
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