From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Fri, 15 May 2015 01:42:01 +0000 (-0700)
Subject: 3.14-stable patches
X-Git-Tag: v3.10.79~29
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ba471a37642059e06351703803bda76233356a5f;p=thirdparty%2Fkernel%2Fstable-queue.git

3.14-stable patches

added patches:
	ocfs2-dlm-fix-race-between-purge-and-get-lock-resource.patch
---

diff --git a/queue-3.14/ocfs2-dlm-fix-race-between-purge-and-get-lock-resource.patch b/queue-3.14/ocfs2-dlm-fix-race-between-purge-and-get-lock-resource.patch
new file mode 100644
index 00000000000..521489f4a98
--- /dev/null
+++ b/queue-3.14/ocfs2-dlm-fix-race-between-purge-and-get-lock-resource.patch
@@ -0,0 +1,62 @@
+From b1432a2a35565f538586774a03bf277c27fc267d Mon Sep 17 00:00:00 2001
+From: Junxiao Bi <junxiao.bi@oracle.com>
+Date: Tue, 5 May 2015 16:24:02 -0700
+Subject: ocfs2: dlm: fix race between purge and get lock resource
+
+From: Junxiao Bi <junxiao.bi@oracle.com>
+
+commit b1432a2a35565f538586774a03bf277c27fc267d upstream.
+
+There is a race window in dlm_get_lock_resource(), which may return a
+lock resource which has been purged.  This will cause the process to
+hang forever in dlmlock() as the ast msg can't be handled due to its
+lock resource not existing.
+
+    dlm_get_lock_resource {
+        ...
+        spin_lock(&dlm->spinlock);
+        tmpres = __dlm_lookup_lockres_full(dlm, lockid, namelen, hash);
+        if (tmpres) {
+             spin_unlock(&dlm->spinlock);
+             >>>>>>>> race window, dlm_run_purge_list() may run and purge
+                              the lock resource
+             spin_lock(&tmpres->spinlock);
+             ...
+             spin_unlock(&tmpres->spinlock);
+        }
+    }
+
+Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
+Cc: Joseph Qi <joseph.qi@huawei.com>
+Cc: Mark Fasheh <mfasheh@suse.com>
+Cc: Joel Becker <jlbec@evilplan.org>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ fs/ocfs2/dlm/dlmmaster.c |   13 +++++++++++++
+ 1 file changed, 13 insertions(+)
+
+--- a/fs/ocfs2/dlm/dlmmaster.c
++++ b/fs/ocfs2/dlm/dlmmaster.c
+@@ -726,6 +726,19 @@ lookup:
+ 	if (tmpres) {
+ 		spin_unlock(&dlm->spinlock);
+ 		spin_lock(&tmpres->spinlock);
++
++		/*
++		 * Right after dlm spinlock was released, dlm_thread could have
++		 * purged the lockres. Check if lockres got unhashed. If so
++		 * start over.
++		 */
++		if (hlist_unhashed(&tmpres->hash_node)) {
++			spin_unlock(&tmpres->spinlock);
++			dlm_lockres_put(tmpres);
++			tmpres = NULL;
++			goto lookup;
++		}
++
+ 		/* Wait on the thread that is mastering the resource */
+ 		if (tmpres->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
+ 			__dlm_wait_on_lockres(tmpres);