NFS: Clean up list moves of struct nfs_page

In several places we're just moving the struct nfs_page from one list to
another by first removing from the existing list, then adding to the new
one.
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/direct.c

@@ -664,8 +664,7 @@ static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 
 	list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
 		if (!nfs_pageio_add_request(&desc, req)) {
-			nfs_list_remove_request(req);
-			nfs_list_add_request(req, &failed);
+			nfs_list_move_request(req, &failed);
 			spin_lock(&cinfo.inode->i_lock);
 			dreq->flags = 0;
 			if (desc.pg_error < 0)

fs/nfs/pagelist.c

@@ -768,8 +768,7 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 	pageused = 0;
 	while (!list_empty(head)) {
 		req = nfs_list_entry(head->next);
-		nfs_list_remove_request(req);
-		nfs_list_add_request(req, &hdr->pages);
+		nfs_list_move_request(req, &hdr->pages);
 
 		if (!last_page || last_page != req->wb_page) {
 			pageused++;
@@ -961,8 +960,7 @@ static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 	}
 	if (!nfs_can_coalesce_requests(prev, req, desc))
 		return 0;
-	nfs_list_remove_request(req);
-	nfs_list_add_request(req, &mirror->pg_list);
+	nfs_list_move_request(req, &mirror->pg_list);
 	mirror->pg_count += req->wb_bytes;
 	return 1;
 }
@@ -994,8 +992,7 @@ nfs_pageio_cleanup_request(struct nfs_pageio_descriptor *desc,
 {
 	LIST_HEAD(head);
 
-	nfs_list_remove_request(req);
-	nfs_list_add_request(req, &head);
+	nfs_list_move_request(req, &head);
 	desc->pg_completion_ops->error_cleanup(&head);
 }
 
@@ -1237,9 +1234,8 @@ int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
 	while (!list_empty(&hdr->pages)) {
 		struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 
-		nfs_list_remove_request(req);
 		if (!nfs_pageio_add_request(desc, req))
-			nfs_list_add_request(req, &failed);
+			nfs_list_move_request(req, &failed);
 	}
 	nfs_pageio_complete(desc);
 	if (!list_empty(&failed)) {

include/linux/nfs_page.h

@@ -164,6 +164,16 @@ nfs_list_add_request(struct nfs_page *req, struct list_head *head)
 	list_add_tail(&req->wb_list, head);
 }
 
+/**
+ * nfs_list_move_request - Move a request to a new list
+ * @req: request
+ * @head: head of list into which to insert the request.
+ */
+static inline void
+nfs_list_move_request(struct nfs_page *req, struct list_head *head)
+{
+	list_move_tail(&req->wb_list, head);
+}
 
 /**
  * nfs_list_remove_request - Remove a request from its wb_list