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: Christoph Hellwig <hch@lst.de> Reviewed-by: Dave Chinner <david@fromorbit.com>
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@ -1383,6 +1383,12 @@ xfs_dqunlock_nonotify(
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mutex_unlock(&(dqp->q_qlock));
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}
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/*
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* Lock two xfs_dquot structures.
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*
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* To avoid deadlocks we always lock the quota structure with
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* the lowerd id first.
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*/
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void
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xfs_dqlock2(
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xfs_dquot_t *d1,
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@ -1392,18 +1398,16 @@ xfs_dqlock2(
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ASSERT(d1 != d2);
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if (be32_to_cpu(d1->q_core.d_id) >
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be32_to_cpu(d2->q_core.d_id)) {
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xfs_dqlock(d2);
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xfs_dqlock(d1);
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mutex_lock(&d2->q_qlock);
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mutex_lock_nested(&d1->q_qlock, XFS_QLOCK_NESTED);
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} else {
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xfs_dqlock(d1);
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xfs_dqlock(d2);
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}
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} else {
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if (d1) {
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xfs_dqlock(d1);
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} else if (d2) {
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xfs_dqlock(d2);
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mutex_lock(&d1->q_qlock);
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mutex_lock_nested(&d2->q_qlock, XFS_QLOCK_NESTED);
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}
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} else if (d1) {
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mutex_lock(&d1->q_qlock);
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} else if (d2) {
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mutex_lock(&d2->q_qlock);
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}
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}
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@ -97,6 +97,16 @@ typedef struct xfs_dquot {
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#define dq_hashlist q_lists.dqm_hashlist
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#define dq_flags q_lists.dqm_flags
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/*
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* Lock hierachy for q_qlock:
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* XFS_QLOCK_NORMAL is the implicit default,
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* XFS_QLOCK_NESTED is the dquot with the higher id in xfs_dqlock2
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*/
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enum {
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XFS_QLOCK_NORMAL = 0,
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XFS_QLOCK_NESTED,
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};
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#define XFS_DQHOLD(dqp) ((dqp)->q_nrefs++)
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#ifdef DEBUG
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