xfs: avoid taking the ilock unnessecarily in xfs_qm_dqattach (b4d05e30) · Commits · 戴 / test

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@lst.de> Reviewed-by:

Mark Tinguely <tinguely@sgi.com> Reviewed-by:

Dave Chinner <dchinner@redhat.com> Signed-off-by:

Ben Myers <bpm@sgi.com>

fs/xfs/xfs_qm.c

+21 −5

Original line number	Diff line number	Diff line
		@@ -483,6 +483,23 @@ 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
		@@ -500,11 +517,7 @@ 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));
		@@ -575,6 +588,9 @@ 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);

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