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Commit 4f2d4ac6 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Lachlan McIlroy
Browse files

xfs: lockdep annotations for xfs_dqlock2 



xfs_dqlock2 locks two xfs_dquots, which is fine as it always locks the
dquot with the lower id first.  Use mutex_lock_nested to tell lockdep
about this fact.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDave Chinner <david@fromorbit.com>
parent 080dda7f

fs/xfs/quota/xfs_dquot.c

+14 −10
Original line number Diff line number Diff line
@@ -1383,6 +1383,12 @@ xfs_dqunlock_nonotify( 
	mutex_unlock(&(dqp->q_qlock));

}



/*

 * Lock two xfs_dquot structures.

 *

 * To avoid deadlocks we always lock the quota structure with

 * the lowerd id first.

 */

void

xfs_dqlock2(

	xfs_dquot_t	*d1,
@@ -1392,18 +1398,16 @@ xfs_dqlock2( 
		ASSERT(d1 != d2);

		if (be32_to_cpu(d1->q_core.d_id) >

		    be32_to_cpu(d2->q_core.d_id)) {

			xfs_dqlock(d2);

			xfs_dqlock(d1);

			mutex_lock(&d2->q_qlock);

			mutex_lock_nested(&d1->q_qlock, XFS_QLOCK_NESTED);

		} else {

			xfs_dqlock(d1);

			xfs_dqlock(d2);

			mutex_lock(&d1->q_qlock);

			mutex_lock_nested(&d2->q_qlock, XFS_QLOCK_NESTED);

		}

	} else {

		if (d1) {

			xfs_dqlock(d1);

	} else if (d1) {

		mutex_lock(&d1->q_qlock);

	} else if (d2) {

			xfs_dqlock(d2);

		}

		mutex_lock(&d2->q_qlock);

	}

}

fs/xfs/quota/xfs_dquot.h

+10 −0
Original line number Diff line number Diff line
@@ -97,6 +97,16 @@ typedef struct xfs_dquot { 
#define dq_hashlist	q_lists.dqm_hashlist

#define dq_flags	q_lists.dqm_flags



/*

 * Lock hierachy for q_qlock:

 *	XFS_QLOCK_NORMAL is the implicit default,

 * 	XFS_QLOCK_NESTED is the dquot with the higher id in xfs_dqlock2

 */

enum {

	XFS_QLOCK_NORMAL = 0,

	XFS_QLOCK_NESTED,

};



#define XFS_DQHOLD(dqp)		((dqp)->q_nrefs++)



#ifdef DEBUG