ceph: fix dentry leak in splice_dentry()

In any case, d_splice_alias() does not drop reference of original
dentry.
Signed-off-by: N"Yan, Zheng" <zyan@redhat.com>
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

fs/ceph/inode.c

@@ -1135,6 +1135,7 @@ static struct dentry *splice_dentry(struct dentry *dn, struct inode *in)
 	if (IS_ERR(realdn)) {
 		pr_err("splice_dentry error %ld %p inode %p ino %llx.%llx\n",
 		       PTR_ERR(realdn), dn, in, ceph_vinop(in));
+		dput(dn);
 		dn = realdn; /* note realdn contains the error */
 		goto out;
 	} else if (realdn) {