xfs
[Top] [All Lists]

[PATCH 1/5] xfs: avoid taking the ilock unnessecarily in xfs_qm_dqattach

To: xfs@xxxxxxxxxxx
Subject: [PATCH 1/5] xfs: avoid taking the ilock unnessecarily in xfs_qm_dqattach
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Tue, 27 Mar 2012 10:34:46 -0400
References: <20120327143445.196524266@xxxxxxxxxxxxxxxxxxxxxx>
User-agent: quilt/0.48-1
Check if we actually need to attach a dquot before taking the ilock in
xfs_qm_dqattach.  This avoid superflous lock roundtrips for the common cases
of quota support compiled in but not activated on a filesystem and an
inode that already has the dquots attached.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>

---
 fs/xfs/xfs_qm.c |   26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

Index: xfs/fs/xfs/xfs_qm.c
===================================================================
--- xfs.orig/fs/xfs/xfs_qm.c    2012-03-26 21:11:12.000000000 +0200
+++ xfs/fs/xfs/xfs_qm.c 2012-03-27 08:04:51.765661301 +0200
@@ -476,6 +476,23 @@ done:
        xfs_dqunlock(udq);
 }
 
+static bool
+xfs_qm_need_dqattach(
+       struct xfs_inode        *ip)
+{
+       struct xfs_mount        *mp = ip->i_mount;
+
+       if (!XFS_IS_QUOTA_RUNNING(mp))
+               return false;
+       if (!XFS_IS_QUOTA_ON(mp))
+               return false;
+       if (!XFS_NOT_DQATTACHED(mp, ip))
+               return false;
+       if (ip->i_ino == mp->m_sb.sb_uquotino ||
+           ip->i_ino == mp->m_sb.sb_gquotino)
+               return false;
+       return true;
+}
 
 /*
  * Given a locked inode, attach dquot(s) to it, taking U/G/P-QUOTAON
@@ -493,11 +510,7 @@ xfs_qm_dqattach_locked(
        uint            nquotas = 0;
        int             error = 0;
 
-       if (!XFS_IS_QUOTA_RUNNING(mp) ||
-           !XFS_IS_QUOTA_ON(mp) ||
-           !XFS_NOT_DQATTACHED(mp, ip) ||
-           ip->i_ino == mp->m_sb.sb_uquotino ||
-           ip->i_ino == mp->m_sb.sb_gquotino)
+       if (!xfs_qm_need_dqattach(ip))
                return 0;
 
        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
@@ -568,6 +581,9 @@ xfs_qm_dqattach(
 {
        int                     error;
 
+       if (!xfs_qm_need_dqattach(ip))
+               return 0;
+
        xfs_ilock(ip, XFS_ILOCK_EXCL);
        error = xfs_qm_dqattach_locked(ip, flags);
        xfs_iunlock(ip, XFS_ILOCK_EXCL);

<Prev in Thread] Current Thread [Next in Thread>