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

To: Alex Elder <aelder@xxxxxxx>
Subject: Re: [PATCH] xfs_showargs() reports group *and* project quotas enabled
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Wed, 26 Aug 2009 18:14:47 -0400
Cc: xfs@xxxxxxxxxxx
In-reply-to: <1AB9A794DBDDF54A8A81BE2296F7BDFE83ABD9@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
References: <1AB9A794DBDDF54A8A81BE2296F7BDFE83ABD0@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> <1AB9A794DBDDF54A8A81BE2296F7BDFE83ABD9@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
User-agent: Mutt/1.5.19 (2009-01-05)
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@xxxxxx>

> 
> Signed-off-by: Alex Elder <aelder@xxxxxxx>
> 
> ---
>  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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