autofs - Fix sparse warning: context imbalance in autofs4_d_automount() different lock contexts for basic block

Sparse complains:

fs/autofs4/root.c:409:9: sparse: context imbalance in 'autofs4_d_automount' - different lock contexts for basic block

This was introduced by commit f55fb0c24386 ("autofs4 - dont clear
DCACHE_NEED_AUTOMOUNT on rootless mount")

The function autofs4_d_automount can be left with the (&sbi->fs_lock)
held if sbi->version <= 4 and simple_empty(dentry) == false so the
warning seems valid.

--> Add an spin_unlock in this case before we jump to done

Unfortunately compile tested only.

Reported-by: Fengguang Wu <[e-mail]>
Signed-off-by: Peter Huewe <[e-mail]>
Acked-by: Ian Kent <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/autofs4/root.c

···
 				goto done;
 			}
 		} else {
-			if (!simple_empty(dentry))
+			if (!simple_empty(dentry)) {
+				spin_unlock(&sbi->fs_lock);
 				goto done;
+			}
 		}
 		ino->flags |= AUTOFS_INF_PENDING;
 		spin_unlock(&sbi->fs_lock);