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Commit ab680bb7 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Ben Myers
Browse files

xfs: simplify xfs_qm_dqattach_grouphint 



No need to play games with the qlock now that the freelist lock nests inside
it.  Also clean up various outdated comments.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarBen Myers <bpm@sgi.com>
parent bf72de31

fs/xfs/xfs_qm.c

+16 −48
Original line number Diff line number Diff line
@@ -650,11 +650,7 @@ xfs_qm_dqattach_one( 


/*

 * Given a udquot and gdquot, attach a ptr to the group dquot in the

 * udquot as a hint for future lookups. The idea sounds simple, but the

 * execution isn't, because the udquot might have a group dquot attached

 * already and getting rid of that gets us into lock ordering constraints.

 * The process is complicated more by the fact that the dquots may or may not

 * be locked on entry.

 * udquot as a hint for future lookups.

 */

STATIC void

xfs_qm_dqattach_grouphint(
@@ -665,45 +661,21 @@ xfs_qm_dqattach_grouphint( 


	xfs_dqlock(udq);



	if ((tmp = udq->q_gdquot)) {

		if (tmp == gdq) {

			xfs_dqunlock(udq);

			return;

		}

	tmp = udq->q_gdquot;

	if (tmp) {

		if (tmp == gdq)

			goto done;



		udq->q_gdquot = NULL;

		/*

		 * We can't keep any dqlocks when calling dqrele,

		 * because the freelist lock comes before dqlocks.

		 */

		xfs_dqunlock(udq);

		/*

		 * we took a hard reference once upon a time in dqget,

		 * so give it back when the udquot no longer points at it

		 * dqput() does the unlocking of the dquot.

		 */

		xfs_qm_dqrele(tmp);



		xfs_dqlock(udq);

		xfs_dqlock(gdq);



	} else {

		ASSERT(XFS_DQ_IS_LOCKED(udq));

		xfs_dqlock(gdq);

	}



	ASSERT(XFS_DQ_IS_LOCKED(udq));

	ASSERT(XFS_DQ_IS_LOCKED(gdq));

	/*

	 * Somebody could have attached a gdquot here,

	 * when we dropped the uqlock. If so, just do nothing.

	 */

	if (udq->q_gdquot == NULL) {

	xfs_dqlock(gdq);

	XFS_DQHOLD(gdq);

		udq->q_gdquot = gdq;

	}



	xfs_dqunlock(gdq);



	udq->q_gdquot = gdq;

done:

	xfs_dqunlock(udq);

}
@@ -770,16 +742,12 @@ xfs_qm_dqattach_locked( 
		ASSERT(ip->i_gdquot);



		/*

		 * We may or may not have the i_udquot locked at this point,

		 * but this check is OK since we don't depend on the i_gdquot to

		 * be accurate 100% all the time. It is just a hint, and this

		 * will succeed in general.

		 */

		if (ip->i_udquot->q_gdquot == ip->i_gdquot)

			goto done;

		/*

		 * Attach i_gdquot to the gdquot hint inside the i_udquot.

		 * We do not have i_udquot locked at this point, but this check

		 * is OK since we don't depend on the i_gdquot to be accurate

		 * 100% all the time. It is just a hint, and this will

		 * succeed in general.

		 */

		if (ip->i_udquot->q_gdquot != ip->i_gdquot)

			xfs_qm_dqattach_grouphint(ip->i_udquot, ip->i_gdquot);

	}