Re: [PATCH] xfs_showargs() reports group *and* project quotas enabled

From: Christoph Hellwig <hch@infradead.org>
To: Alex Elder <aelder@sgi.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH] xfs_showargs() reports group *and* project quotas enabled
Date: Wed, 26 Aug 2009 18:14:47 -0400	[thread overview]
Message-ID: <20090826221446.GD18119@infradead.org> (raw)
In-Reply-To: <1AB9A794DBDDF54A8A81BE2296F7BDFE83ABD9@cf--amer001e--3.americas.sgi.com>

On Wed, Aug 26, 2009 at 12:46:12PM -0500, Alex Elder wrote:
> If you enable group or project quotas on an XFS file system, then the
> mount table presented through /proc/self/mounts erroneously shows
> that both options are in effect for the file system.  The root of
> the problem is some bad logic in the xfs_showargs() function, which
> is used to format the file system type-specific options in effect
> for a file system.
> 
> The problem originated in this GIT commit:
>     Move platform specific mount option parse out of core XFS code
>     Date: 11/22/07
>     Author: Dave Chinner
>     SHA1 ID: a67d7c5f5d25d0b13a4dfb182697135b014fa478
> 
> For XFS quotas, project and group quota management are mutually
> exclusive--only one can be in effect at a time.  There are two
> parts to managing quotas:  aggregating usage information; and
> enforcing limits.  It is possible to have a quota in effect
> (aggregating usage) but not enforced.
> 
> These features are recorded on an XFS mount point using these flags:
>     XFS_PQUOTA_ACCT - Project quotas are aggregated
>     XFS_GQUOTA_ACCT - Group quotas are aggregated
>     XFS_OQUOTA_ENFD - Project/group quotas are enforced
> 
> The code in error is in fs/xfs/linux-2.6/xfs_super.c:
> 
>         if (mp->m_qflags & (XFS_PQUOTA_ACCT|XFS_OQUOTA_ENFD))
>                 seq_puts(m, "," MNTOPT_PRJQUOTA);
>         else if (mp->m_qflags & XFS_PQUOTA_ACCT)
>                 seq_puts(m, "," MNTOPT_PQUOTANOENF);
> 
>         if (mp->m_qflags & (XFS_GQUOTA_ACCT|XFS_OQUOTA_ENFD))
>                 seq_puts(m, "," MNTOPT_GRPQUOTA);
>         else if (mp->m_qflags & XFS_GQUOTA_ACCT)
>                 seq_puts(m, "," MNTOPT_GQUOTANOENF);
> 
> The problem is that XFS_OQUOTA_ENFD will be set in mp->m_qflags
> if either group or project quotas are enforced, and as a result
> both MNTOPT_PRJQUOTA and MNTOPT_GRPQUOTA will be shown as mount
> options.

Indeed.  Thanks for the detailed analysis.

Reviewed-by: Christoph Hellwig <hch@lst.de>

> 
> Signed-off-by: Alex Elder <aelder@sgi.com>
> 
> ---
>  fs/xfs/linux-2.6/xfs_super.c |   20 ++++++++++++--------
>  1 file changed, 12 insertions(+), 8 deletions(-)
> 
> Index: b/fs/xfs/linux-2.6/xfs_super.c
> ===================================================================
> --- a/fs/xfs/linux-2.6/xfs_super.c
> +++ b/fs/xfs/linux-2.6/xfs_super.c
> @@ -579,15 +579,19 @@ xfs_showargs(
>  	else if (mp->m_qflags & XFS_UQUOTA_ACCT)
>  		seq_puts(m, "," MNTOPT_UQUOTANOENF);
>  
> -	if (mp->m_qflags & (XFS_PQUOTA_ACCT|XFS_OQUOTA_ENFD))
> -		seq_puts(m, "," MNTOPT_PRJQUOTA);
> -	else if (mp->m_qflags & XFS_PQUOTA_ACCT)
> -		seq_puts(m, "," MNTOPT_PQUOTANOENF);
> +	/* Either project or group quotas can be active, not both */
>  
> -	if (mp->m_qflags & (XFS_GQUOTA_ACCT|XFS_OQUOTA_ENFD))
> -		seq_puts(m, "," MNTOPT_GRPQUOTA);
> -	else if (mp->m_qflags & XFS_GQUOTA_ACCT)
> -		seq_puts(m, "," MNTOPT_GQUOTANOENF);
> +	if (mp->m_qflags & XFS_PQUOTA_ACCT) {
> +		if (mp->m_qflags & XFS_OQUOTA_ENFD)
> +			seq_puts(m, "," MNTOPT_PRJQUOTA);
> +		else
> +			seq_puts(m, "," MNTOPT_PQUOTANOENF);
> +	} else if (mp->m_qflags & XFS_GQUOTA_ACCT) {
> +		if (mp->m_qflags & XFS_OQUOTA_ENFD)
> +			seq_puts(m, "," MNTOPT_GRPQUOTA);
> +		else
> +			seq_puts(m, "," MNTOPT_GQUOTANOENF);
> +	}
>  
>  	if (!(mp->m_qflags & XFS_ALL_QUOTA_ACCT))
>  		seq_puts(m, "," MNTOPT_NOQUOTA);
> 
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