[PATCH 5.10 05/34] nfs: fold nfs_page_group_lock_subrequests into nfs_lock_and_join_requests

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

5.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christoph Hellwig <hch@lst.de>

commit 25edbcac6e32eab345e470d56ca9974a577b878b upstream.

Fold nfs_page_group_lock_subrequests into nfs_lock_and_join_requests to
prepare for future changes to this code, and move the helpers to write.c
as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/nfs/pagelist.c        |   77 -----------------------------------------------
 fs/nfs/write.c           |   74 +++++++++++++++++++++++++++++++++++++++++----
 include/linux/nfs_page.h |    1 
 3 files changed, 68 insertions(+), 84 deletions(-)

--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -168,83 +168,6 @@ nfs_page_group_lock_head(struct nfs_page
 }
 
 /*
- * 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
- *
- * This is a helper function for nfs_lock_and_join_requests
- * returns 0 on success, < 0 on error.
- */
-static void
-nfs_unroll_locks(struct nfs_page *head, struct nfs_page *req)
-{
-	struct nfs_page *tmp;
-
-	/* relinquish all the locks successfully grabbed this run */
-	for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
-		if (!kref_read(&tmp->wb_kref))
-			continue;
-		nfs_unlock_and_release_request(tmp);
-	}
-}
-
-/*
- * nfs_page_group_lock_subreq -  try to lock a subrequest
- * @head: head request of page group
- * @subreq: request to lock
- *
- * 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.
- */
-static int
-nfs_page_group_lock_subreq(struct nfs_page *head, struct nfs_page *subreq)
-{
-	int ret;
-
-	if (!kref_get_unless_zero(&subreq->wb_kref))
-		return 0;
-	while (!nfs_lock_request(subreq)) {
-		nfs_page_group_unlock(head);
-		ret = nfs_wait_on_request(subreq);
-		if (!ret)
-			ret = nfs_page_group_lock(head);
-		if (ret < 0) {
-			nfs_unroll_locks(head, subreq);
-			nfs_release_request(subreq);
-			return ret;
-		}
-	}
-	return 0;
-}
-
-/*
- * nfs_page_group_lock_subrequests -  try to lock the subrequests
- * @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 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) {
-		ret = nfs_page_group_lock_subreq(head, subreq);
-		if (ret < 0)
-			return ret;
-	}
-	nfs_page_group_unlock(head);
-	return 0;
-}
-
-/*
  * nfs_page_set_headlock - set the request PG_HEADLOCK
  * @req: request that is to be locked
  *
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -547,6 +547,57 @@ void nfs_join_page_group(struct nfs_page
 }
 
 /*
+ * 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
+ *
+ * This is a helper function for nfs_lock_and_join_requests
+ * returns 0 on success, < 0 on error.
+ */
+static void
+nfs_unroll_locks(struct nfs_page *head, struct nfs_page *req)
+{
+	struct nfs_page *tmp;
+
+	/* relinquish all the locks successfully grabbed this run */
+	for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
+		if (!kref_read(&tmp->wb_kref))
+			continue;
+		nfs_unlock_and_release_request(tmp);
+	}
+}
+
+/*
+ * nfs_page_group_lock_subreq -  try to lock a subrequest
+ * @head: head request of page group
+ * @subreq: request to lock
+ *
+ * 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.
+ */
+static int
+nfs_page_group_lock_subreq(struct nfs_page *head, struct nfs_page *subreq)
+{
+	int ret;
+
+	if (!kref_get_unless_zero(&subreq->wb_kref))
+		return 0;
+	while (!nfs_lock_request(subreq)) {
+		nfs_page_group_unlock(head);
+		ret = nfs_wait_on_request(subreq);
+		if (!ret)
+			ret = nfs_page_group_lock(head);
+		if (ret < 0) {
+			nfs_unroll_locks(head, subreq);
+			nfs_release_request(subreq);
+			return ret;
+		}
+	}
+	return 0;
+}
+
+/*
  * nfs_lock_and_join_requests - join all subreqs to the head req
  * @page: the page used to lookup the "page group" of nfs_page structures
  *
@@ -565,7 +616,7 @@ static struct nfs_page *
 nfs_lock_and_join_requests(struct page *page)
 {
 	struct inode *inode = page_file_mapping(page)->host;
-	struct nfs_page *head;
+	struct nfs_page *head, *subreq;
 	struct nfs_commit_info cinfo;
 	int ret;
 
@@ -579,16 +630,27 @@ nfs_lock_and_join_requests(struct page *
 	if (IS_ERR_OR_NULL(head))
 		return head;
 
+	ret = nfs_page_group_lock(head);
+	if (ret < 0)
+		goto out_unlock;
+
 	/* lock each request in the page group */
-	ret = nfs_page_group_lock_subrequests(head);
-	if (ret < 0) {
-		nfs_unlock_and_release_request(head);
-		return ERR_PTR(ret);
+	for (subreq = head->wb_this_page;
+	     subreq != head;
+	     subreq = subreq->wb_this_page) {
+		ret = nfs_page_group_lock_subreq(head, subreq);
+		if (ret < 0)
+			goto out_unlock;
 	}
 
-	nfs_join_page_group(head, &cinfo, inode);
+	nfs_page_group_unlock(head);
 
+	nfs_join_page_group(head, &cinfo, inode);
 	return head;
+
+out_unlock:
+	nfs_unlock_and_release_request(head);
+	return ERR_PTR(ret);
 }
 
 static void nfs_write_error(struct nfs_page *req, int error)
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -144,7 +144,6 @@ extern  int nfs_wait_on_request(struct n
 extern	void nfs_unlock_request(struct nfs_page *req);
 extern	void nfs_unlock_and_release_request(struct nfs_page *);
 extern	struct nfs_page *nfs_page_group_lock_head(struct nfs_page *req);
-extern	int nfs_page_group_lock_subrequests(struct nfs_page *head);
 extern void nfs_join_page_group(struct nfs_page *head,
 				struct nfs_commit_info *cinfo,
 				struct inode *inode);