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From: Ian Kent <raven@themaw.net>
Newsgroups: gmane.linux.kernel
Subject: [PATCH] autofs4 - fix lockdep splat in autofs
Date: Mon, 22 Aug 2011 11:52:28 +0800
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Cc: Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>
To: Al Viro <viro@ZenIV.linux.org.uk>
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Xref: news.gmane.org gmane.linux.kernel:1182197
Archived-At: <http://permalink.gmane.org/gmane.linux.kernel/1182197>
 
From: Steven Rostedt <rostedt@goodmis.org>
 
When recursing down the locks when traversing a tree/list in
get_next_positive_dentry() or get_next_positive_subdir() a lock can
change from being nested to being a parent which breaks lockdep. This
patch tells lockdep about what we did.
 
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Ian Kent <raven@themaw.net>
---
 
 fs/autofs4/expire.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
 
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 450f529..1feb68e 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -124,6 +124,7 @@ start:
 	/* Negative dentry - try next */
 	if (!simple_positive(q)) {
 		spin_unlock(&p->d_lock);
+		lock_set_subclass(&q->d_lock.dep_map, 0, _RET_IP_);
 		p = q;
 		goto again;
 	}
@@ -186,6 +187,7 @@ again:
 	/* Negative dentry - try next */
 	if (!simple_positive(ret)) {
 		spin_unlock(&p->d_lock);
+		lock_set_subclass(&ret->d_lock.dep_map, 0, _RET_IP_);
 		p = ret;
 		goto again;
 	}