kernel - Fix smbfs readdir and umount

* Fix a bug in smbfs's readdir that was causing an empty list and also
  a later deadlock.

* Fix a bug in smbfs's umount that was panicing the machine.

sys/vfs/smbfs/smbfs_vfsops.c

@@ -234,6 +234,9 @@ smbfs_unmount(struct mount *mp, int mntflags)
 	if (error)
 		return error;
 	smb_makescred(&scred, curthread, smp->sm_cred);
+	error = smb_share_lock(smp->sm_share, LK_EXCLUSIVE);
+	if (error)
+		goto out;
 	smb_share_put(smp->sm_share, &scred);
 	mp->mnt_data = (qaddr_t)0;
 
@@ -244,6 +247,7 @@ smbfs_unmount(struct mount *mp, int mntflags)
 	lockdestroy(&smp->sm_hashlock);
 	kfree(smp, M_SMBFSDATA);
 	mp->mnt_flag &= ~MNT_LOCAL;
+out:
 	return error;
 }
 

sys/vfs/smbfs/smbfs_vnops.c

@@ -714,7 +714,7 @@ smbfs_readdir(struct vop_readdir_args *ap)
 	}
 #endif
 	error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY | LK_FAILRECLAIM);
-	if (error) {
+	if (error == 0) {
 		error = smbfs_readvnode(vp, uio, ap->a_cred);
 		vn_unlock(vp);
 	}