From 4e8a301929bfa017e6ffe11e3cf78ccaf8492801 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 2 Jun 2009 14:23:59 +0200
Subject: [PATCH] ocfs2: Fix possible deadlock in ocfs2_global_read_dquot()
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@suse.cz>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
---
fs/ocfs2/quota_global.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index 1ed0f7c86869..edfa60cd155c 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);
--
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