nfs: fold nfs_page_group_lock_subrequests into nfs_lock_and_join_requests

jira VULN-136536
cve-pre CVE-2025-39697
commit-author Christoph Hellwig <hch@lst.de>
commit 25edbca
upstream-diff Used linux-6.6.y backport
  9a1963404cc2eef69d2f8a42861bdf63d087dd5d for the clean cherry pick

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>
(cherry picked from commit 9a1963404cc2eef69d2f8a42861bdf63d087dd5d)
	Signed-off-by: Marcin Wcisło <marcin.wcislo@conclusive.pl>

Author: pvts-mat

fs/nfs/pagelist.c

@@ -205,83 +205,6 @@ nfs_page_group_lock_head(struct nfs_page *req)
 	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
- *
- * 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

fs/nfs/write.c

@@ -547,6 +547,57 @@ void nfs_join_page_group(struct nfs_page *head, struct nfs_commit_info *cinfo,
 	nfs_destroy_unlinked_subrequests(destroy_list, head, inode);
 }
 
+/*
+ * 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
  * @folio: the folio used to lookup the "page group" of nfs_page structures
@@ -565,7 +616,7 @@ void nfs_join_page_group(struct nfs_page *head, struct nfs_commit_info *cinfo,
 static struct nfs_page *nfs_lock_and_join_requests(struct folio *folio)
 {
 	struct inode *inode = folio_file_mapping(folio)->host;
-	struct nfs_page *head;
+	struct nfs_page *head, *subreq;
 	struct nfs_commit_info cinfo;
 	int ret;
 
@@ -579,16 +630,28 @@ static struct nfs_page *nfs_lock_and_join_requests(struct folio *folio)
 	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_init_cinfo_from_inode(&cinfo, inode);
+	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)

include/linux/nfs_page.h

@@ -156,7 +156,6 @@ extern  int nfs_wait_on_request(struct nfs_page *);
 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);