dm writecache: fix smatch warning about invalid return from writecache_map

There's a smatch warning "inconsistent returns '&wc->lock'" in
dm-writecache. The reason for the warning is that writecache_map()
doesn't drop the lock on the impossible path.

Fix this warning by adding wc_unlock() after the BUG statement (so
that it will be compiled-away anyway).

Fixes: df699cc16ea5e ("dm writecache: report invalid return from writecache_map helpers")
Reported-by: kernel test robot <[email protected]>
Reported-by: Dan Carpenter <[email protected]>
Signed-off-by: Mikulas Patocka <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index ead008ea38f2..03fe2c5d5e32 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -1598,7 +1598,8 @@ done:
 
 	default:
 		BUG();
-		return -1;
+		wc_unlock(wc);
+		return DM_MAPIO_KILL;
 	}
 }