Revert "ceph: fix dentry leak in splice_dentry()"

This reverts commit 8b8f53af1e.

splice_dentry() is used by three places. For two places, req->r_dentry
is passed to splice_dentry(). In the case of error, req->r_dentry does
not get updated. So splice_dentry() should not drop reference.

Cc: stable@vger.kernel.org # 4.18+
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/inode.c

@@ -1132,8 +1132,12 @@ 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 */
+		dn = realdn;
+		/*
+		 * Caller should release 'dn' in the case of error.
+		 * If 'req->r_dentry' is passed to this function,
+		 * caller should leave 'req->r_dentry' untouched.
+		 */
 		goto out;
 	} else if (realdn) {
 		dout("dn %p (%d) spliced with %p (%d) "