Ocfs2 devel - Feb 2009 - [PATCH 0/7] OCFS2 locking fixes and lockdep annotations

Hi,

  the first four patches in this series fix locking problems in OCFS2 quota code
(three of
them can lead to potential deadlocks). The fifth patch reorders ip_alloc_sem for
directories
to be acquired before localalloc locks. Mark would you please merge these?
  The last two patches implement lockdep annotations for OCFS2 cluster locks. We
annotate all
the cluster locks except for special ones like open lock or local quota file
lock - these are
not held by any particular process and thus lockdep cannot properly track them.
I can still hit
some lockdep warnings with it (I'll report them separately) but I think the
patch is already in
a decent state and I don't expect major changes. Please consider merging
these lockdep patches.
  Happy testing. As always, comments are welcome.

										Honza

It is not possible to get a read lock and then try to get the same write lock
in one thread as that can block on downconvert being requested by other node
leading to deadlock. So first drop the quota lock for reading and only after
that get it for writing.

Signed-off-by: Jan Kara <jack at suse.cz>
---
 fs/ocfs2/quota_global.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index 1ed0f7c..edfa60c 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -421,6 +421,7 @@ int ocfs2_global_read_dquot(struct dquot *dquot)
 	OCFS2_DQUOT(dquot)->dq_originodes = dquot->dq_dqb.dqb_curinodes;
 	if (!dquot->dq_off) {	/* No real quota entry? */
 		/* Upgrade to exclusive lock for allocation */
+		ocfs2_qinfo_unlock(info, 0);
 		err = ocfs2_qinfo_lock(info, 1);
 		if (err < 0)
 			goto out_qlock;
@@ -435,7 +436,8 @@ int ocfs2_global_read_dquot(struct dquot *dquot)
 out_qlock:
 	if (ex)
 		ocfs2_qinfo_unlock(info, 1);
-	ocfs2_qinfo_unlock(info, 0);
+	else
+		ocfs2_qinfo_unlock(info, 0);
 out:
 	if (err < 0)
 		mlog_errno(err);
-- 
1.6.0.2