[PATCH] locks: fix fasync_struct memory leak in lease upgrade/downgrade handling

[Jeff Layton <jeff.layton@primarydata.com>]

Commit 8634b51f6ca2 (locks: convert lease handling to file_lock_context)
introduced a regression in the handling of lease upgrade/downgrades.

In the event that we already have a lease on a file and are going to
either upgrade or downgrade it, we skip doing any list insertion or
deletion and skip to re-calling lm_setup on the existing lease.

As of commit 8634b51f6ca2 however, we end up calling lm_setup on the
lease that was passed in, instead of on the existing lease. This causes
us to leak the fasync_struct that was allocated in the event that there
was not already an existing one (as it always appeared that there
wasn't one).

Fixes: 8634b51f6ca2 (locks: convert lease handling to file_lock_context)
Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
---
 fs/locks.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/locks.c b/fs/locks.c
index 365c82e1b3a9..f1bad681fc1c 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1665,7 +1665,8 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
 	}
 
 	if (my_fl != NULL) {
-		error = lease->fl_lmops->lm_change(my_fl, arg, &dispose);
+		lease = my_fl;
+		error = lease->fl_lmops->lm_change(lease, arg, &dispose);
 		if (error)
 			goto out;
 		goto out_setup;
-- 
2.1.0