ceph: voluntarily drop Lx cap for link/rename requests

MDS need to xlock inode's linklock when handling link/rename requests.
Voluntarily dropping CEPH_CAP_AUTH_EXCL avoids a cap revoke message.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/dir.c

@@ -983,7 +983,7 @@ static int ceph_link(struct dentry *old_dentry, struct inode *dir,
 	req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
 	req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
 	/* release LINK_SHARED on source inode (mds will lock it) */
-	req->r_old_inode_drop = CEPH_CAP_LINK_SHARED;
+	req->r_old_inode_drop = CEPH_CAP_LINK_SHARED | CEPH_CAP_LINK_EXCL;
 	err = ceph_mdsc_do_request(mdsc, dir, req);
 	if (err) {
 		d_drop(dentry);
@@ -1096,7 +1096,7 @@ static int ceph_rename(struct inode *old_dir, struct dentry *old_dentry,
 	req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
 	req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
 	/* release LINK_RDCACHE on source inode (mds will lock it) */
-	req->r_old_inode_drop = CEPH_CAP_LINK_SHARED;
+	req->r_old_inode_drop = CEPH_CAP_LINK_SHARED | CEPH_CAP_LINK_EXCL;
 	if (d_really_is_positive(new_dentry))
 		req->r_inode_drop = drop_caps_for_unlink(d_inode(new_dentry));
 	err = ceph_mdsc_do_request(mdsc, old_dir, req);