From bc79491bf671b8a1d6603e0367963341339f943f Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Fri, 6 Jun 2025 07:46:02 +0200
Subject: [PATCH] fs: constify file ptr in backing_file_user_path()

Add internal helper backing_file_set_user_path() for the only
two cases that need to modify user path.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/backing-file.c  |  4 ++--
 fs/file_table.c    | 13 ++++++++-----
 fs/internal.h      |  1 +
 include/linux/fs.h |  2 +-
 4 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/fs/backing-file.c b/fs/backing-file.c
index 763fbe9b72b2..8c7396bff121 100644
--- a/fs/backing-file.c
+++ b/fs/backing-file.c
@@ -41,7 +41,7 @@ struct file *backing_file_open(const struct path *user_path, int flags,
 		return f;
 
 	path_get(user_path);
-	*backing_file_user_path(f) = *user_path;
+	backing_file_set_user_path(f, user_path);
 	error = vfs_open(real_path, f);
 	if (error) {
 		fput(f);
@@ -65,7 +65,7 @@ struct file *backing_tmpfile_open(const struct path *user_path, int flags,
 		return f;
 
 	path_get(user_path);
-	*backing_file_user_path(f) = *user_path;
+	backing_file_set_user_path(f, user_path);
 	error = vfs_tmpfile(real_idmap, real_parentpath, f, mode);
 	if (error) {
 		fput(f);
diff --git a/fs/file_table.c b/fs/file_table.c
index c04ed94cdc4b..8ac2fbbd4f6d 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -52,17 +52,20 @@ struct backing_file {
 	};
 };
 
-static inline struct backing_file *backing_file(struct file *f)
-{
-	return container_of(f, struct backing_file, file);
-}
+#define backing_file(f) container_of(f, struct backing_file, file)
 
-struct path *backing_file_user_path(struct file *f)
+struct path *backing_file_user_path(const struct file *f)
 {
 	return &backing_file(f)->user_path;
 }
 EXPORT_SYMBOL_GPL(backing_file_user_path);
 
+void backing_file_set_user_path(struct file *f, const struct path *path)
+{
+	backing_file(f)->user_path = *path;
+}
+EXPORT_SYMBOL_GPL(backing_file_set_user_path);
+
 static inline void file_free(struct file *f)
 {
 	security_file_free(f);
diff --git a/fs/internal.h b/fs/internal.h
index 213bf3226213..3860b022e57c 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -101,6 +101,7 @@ extern void chroot_fs_refs(const struct path *, const struct path *);
 struct file *alloc_empty_file(int flags, const struct cred *cred);
 struct file *alloc_empty_file_noaccount(int flags, const struct cred *cred);
 struct file *alloc_empty_backing_file(int flags, const struct cred *cred);
+void backing_file_set_user_path(struct file *f, const struct path *path);
 
 static inline void file_put_write_access(struct file *file)
 {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a4fd649e2c3f..c745aee9c88a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2813,7 +2813,7 @@ struct file *dentry_open_nonotify(const struct path *path, int flags,
 				  const struct cred *cred);
 struct file *dentry_create(const struct path *path, int flags, umode_t mode,
 			   const struct cred *cred);
-struct path *backing_file_user_path(struct file *f);
+struct path *backing_file_user_path(const struct file *f);
 
 /*
  * When mmapping a file on a stackable filesystem (e.g., overlayfs), the file
-- 
2.34.1