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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>
This commit is contained in:
Christoph Hellwig 2009-01-19 02:03:19 +01:00 committed by Christoph Hellwig
parent a4edd1da20
commit 5bb87a33b2
2 changed files with 24 additions and 10 deletions
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24
fs/xfs/quota/xfs_dquot.c
View File

@ -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);
}
} else {
if (d1) {
xfs_dqlock(d1);
} else if (d2) {
xfs_dqlock(d2);
mutex_lock(&d1->q_qlock);
mutex_lock_nested(&d2->q_qlock, XFS_QLOCK_NESTED);
}
} else if (d1) {
mutex_lock(&d1->q_qlock);
} else if (d2) {
mutex_lock(&d2->q_qlock);
}
}

10
fs/xfs/quota/xfs_dquot.h
View File

@ -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