ceph: eliminate req->r_wait_for_completion from ceph_mds_request

...and instead just pass the wait function on the stack.

Make ceph_mdsc_wait_request non-static, and add an argument for wait for
completion. Then have ceph_lock_message call ceph_mdsc_submit_request,
and ceph_mdsc_wait_request and pass in the pointer to
ceph_lock_wait_for_completion.

While we're in there, rearrange some fields in ceph_mds_request, so we
save a total of 24 bytes per.

Signed-off-by: Jeff Layton <[e-mail]>
Reviewed-by: Xiubo Li <[e-mail]>
Signed-off-by: Ilya Dryomov <[e-mail]>

fs/ceph/locks.c

···
 	req->r_args.filelock_change.length = cpu_to_le64(length);
 	req->r_args.filelock_change.wait = wait;
 
-	if (wait)
-		req->r_wait_for_completion = ceph_lock_wait_for_completion;
-
-	err = ceph_mdsc_do_request(mdsc, inode, req);
+	err = ceph_mdsc_submit_request(mdsc, inode, req);
+	if (!err)
+		err = ceph_mdsc_wait_request(mdsc, req, wait ?
+					ceph_lock_wait_for_completion : NULL);
 	if (!err && operation == CEPH_MDS_OP_GETFILELOCK) {
 		fl->fl_pid = -le64_to_cpu(req->r_reply_info.filelock_reply->pid);
 		if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)

fs/ceph/mds_client.c

···
 	return err;
 }
 
-static int ceph_mdsc_wait_request(struct ceph_mds_client *mdsc,
-				  struct ceph_mds_request *req)
+int ceph_mdsc_wait_request(struct ceph_mds_client *mdsc,
+			   struct ceph_mds_request *req,
+			   ceph_mds_request_wait_callback_t wait_func)
 {
 	int err;
 
 	/* wait */
 	dout("do_request waiting\n");
-	if (!req->r_timeout && req->r_wait_for_completion) {
-		err = req->r_wait_for_completion(mdsc, req);
+	if (wait_func) {
+		err = wait_func(mdsc, req);
 	} else {
 		long timeleft = wait_for_completion_killable_timeout(
 					&req->r_completion,
···
 	/* issue */
 	err = ceph_mdsc_submit_request(mdsc, dir, req);
 	if (!err)
-		err = ceph_mdsc_wait_request(mdsc, req);
+		err = ceph_mdsc_wait_request(mdsc, req, NULL);
 	dout("do_request %p done, result %d\n", req, err);
 	return err;
 }

fs/ceph/mds_client.h

···
 
 	union ceph_mds_request_args r_args;
 	int r_fmode;        /* file mode, if expecting cap */
-	const struct cred *r_cred;
 	int r_request_release_offset;
+	const struct cred *r_cred;
 	struct timespec64 r_stamp;
 
 	/* for choosing which mds to send this request to */
···
 	struct ceph_msg  *r_reply;
 	struct ceph_mds_reply_info_parsed r_reply_info;
 	int r_err;
-
+	u32               r_readdir_offset;
 
 	struct page *r_locked_page;
 	int r_dir_caps;
 	int r_num_caps;
-	u32               r_readdir_offset;
 
 	unsigned long r_timeout;  /* optional.  jiffies, 0 is "wait forever" */
 	unsigned long r_started;  /* start time to measure timeout against */
···
 	struct completion r_completion;
 	struct completion r_safe_completion;
 	ceph_mds_request_callback_t r_callback;
-	ceph_mds_request_wait_callback_t r_wait_for_completion;
 	struct list_head  r_unsafe_item;  /* per-session unsafe list item */
 
 	long long	  r_dir_release_cnt;
···
 extern int ceph_mdsc_submit_request(struct ceph_mds_client *mdsc,
 				    struct inode *dir,
 				    struct ceph_mds_request *req);
+int ceph_mdsc_wait_request(struct ceph_mds_client *mdsc,
+			struct ceph_mds_request *req,
+			ceph_mds_request_wait_callback_t wait_func);
 extern int ceph_mdsc_do_request(struct ceph_mds_client *mdsc,
 				struct inode *dir,
 				struct ceph_mds_request *req);