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

To: <xfs@xxxxxxxxxxx>
Subject: [PATCH] xfs_showargs() reports group *and* project quotas enabled
From: "Alex Elder" <aelder@xxxxxxx>
Date: Wed, 26 Aug 2009 12:46:12 -0500
In-reply-to: <1AB9A794DBDDF54A8A81BE2296F7BDFE83ABD0@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Thread-index: AcoltcsPUBDDeXVES1uPr8Op+gTAWwAAfu7gAC853UA=
Thread-topic: [PATCH 0/7] inode allocation cleanups
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.

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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