Gitweb: http://git.kernel.org/linus/5bb87a33b2cfb8e7ef3383718274094bdff266a3
Commit: 5bb87a33b2cfb8e7ef3383718274094bdff266a3
Parent: a4edd1da20af79b2e92efeee3ca94831c8024d61
Author: Christoph Hellwig <hch@lst.de>
AuthorDate: Mon Jan 19 02:03:19 2009 +0100
Committer: Christoph Hellwig <hch@brick.lst.de>
CommitDate: Mon Jan 19 02:03:19 2009 +0100
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>
---
fs/xfs/quota/xfs_dquot.c | 24 ++++++++++++++----------
fs/xfs/quota/xfs_dquot.h | 10 ++++++++++
2 files changed, 24 insertions(+), 10 deletions(-)
diff --git a/fs/xfs/quota/xfs_dquot.c b/fs/xfs/quota/xfs_dquot.c
index d68b4e1..ebdf3c8 100644
--- a/fs/xfs/quota/xfs_dquot.c
+++ b/fs/xfs/quota/xfs_dquot.c
@@ -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);
}
}
diff --git a/fs/xfs/quota/xfs_dquot.h b/fs/xfs/quota/xfs_dquot.h
index 7e45533..d443e93 100644
--- a/fs/xfs/quota/xfs_dquot.h
+++ b/fs/xfs/quota/xfs_dquot.h
@@ -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
--
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