[PATCH] ocfs2: skip uninitialized lockres in ocfs2_mark_lockres_freeing()

[Joseph Qi]

A hard readonly mount skips ocfs2_dlm_init(), so the per-osb lock
resources are never initialized and osb->cconn stays NULL.  Before
commit 550842cc60987 ("ocfs2: fix freeing uninitialized resource on
ocfs2_dlm_shutdown") ocfs2_dismount_volume() only called
ocfs2_dlm_shutdown() when osb->cconn was set.  It now calls it
unconditionally, so unmounting a hard readonly mount drops the osb
locks and takes the never initialized l_lock in
ocfs2_mark_lockres_freeing().  With lockdep enabled this triggers:

INFO: trying to register non-static key.
The code is fine but needs lockdep annotation, or maybe
you didn't initialize this object before use?
turning off the locking correctness validator.

ocfs2_drop_lock() and ocfs2_lock_res_free() already skip lock
resources without OCFS2_LOCK_INITIALIZED.  Add the same check to
ocfs2_mark_lockres_freeing(), which is reachable before them through
ocfs2_simple_drop_lockres(), so an uninitialized lockres is never
touched.

Fixes: 550842cc60987 ("ocfs2: fix freeing uninitialized resource on ocfs2_dlm_shutdown")
Reported-by: ZW Tang <tangzw515@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
---
 fs/ocfs2/dlmglue.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index a23dd8f86c89..cf3318b0d3a8 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -3525,6 +3525,10 @@ void ocfs2_mark_lockres_freeing(struct ocfs2_super *osb,
 	struct ocfs2_mask_waiter mw;
 	unsigned long flags, flags2;
 
+	/* We didn't get anywhere near actually using this lockres. */
+	if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED))
+		return;
+
 	ocfs2_init_mask_waiter(&mw);
 
 	spin_lock_irqsave(&lockres->l_lock, flags);
-- 
2.39.3