NFS: Refactor nfs_lock_and_join_requests()

Refactor nfs_lock_and_join_requests() in order to separate out the
subrequest merging into its own function nfs_lock_and_join_group()
that can be used by O_DIRECT.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

1 files changed, 24 insertions, 2 deletions

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index b9805d1dac75..f61f96603df7 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -131,6 +131,25 @@ nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx)
 EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait);
 
 /*
+ * nfs_page_lock_head_request - page lock the head of the page group
+ * @req: any member of the page group
+ */
+struct nfs_page *
+nfs_page_group_lock_head(struct nfs_page *req)
+{
+	struct nfs_page *head = req->wb_head;
+
+	while (!nfs_lock_request(head)) {
+		int ret = nfs_wait_on_request(head);
+		if (ret < 0)
+			return ERR_PTR(ret);
+	}
+	if (head != req)
+		kref_get(&head->wb_kref);
+	return head;
+}
+
+/*
  * nfs_unroll_locks -  unlock all newly locked reqs and wait on @req
  * @head: head request of page group, must be holding head lock
  * @req: request that couldn't lock and needs to wait on the req bit lock
@@ -186,14 +205,16 @@ nfs_page_group_lock_subreq(struct nfs_page *head, struct nfs_page *subreq)
  * @head: head request of page group
  *
  * This is a helper function for nfs_lock_and_join_requests which
- * must be called with the head request and page group both locked.
- * On error, it returns with the page group unlocked.
+ * must be called with the head request locked.
  */
 int nfs_page_group_lock_subrequests(struct nfs_page *head)
 {
 	struct nfs_page *subreq;
 	int ret;
 
+	ret = nfs_page_group_lock(head);
+	if (ret < 0)
+		return ret;
 	/* lock each request in the page group */
 	for (subreq = head->wb_this_page; subreq != head;
 			subreq = subreq->wb_this_page) {
@@ -201,6 +222,7 @@ int nfs_page_group_lock_subrequests(struct nfs_page *head)
 		if (ret < 0)
 			return ret;
 	}
+	nfs_page_group_unlock(head);
 	return 0;
 }