ovl: port ovl_create_tmpfile() to new ovl_override_creator_creds cleanup guard

This clearly indicates the double-credential override and makes the code
a lot easier to grasp with one glance.

Link: https://patch.msgid.link/20251117-work-ovl-cred-guard-prepare-v2-2-bd1c97a36d7b@kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index c61976180a83e0f7bdb5f36b621fd50c8bab8a7a..68f6617b6a77af1bef12cb60585f35aeef195661 100644 (file)
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -1381,7 +1381,6 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
 static int ovl_create_tmpfile(struct file *file, struct dentry *dentry,
                              struct inode *inode, umode_t mode)
 {
-       const struct cred *new_cred __free(put_cred) = NULL;
        struct path realparentpath;
        struct file *realfile;
        struct ovl_file *of;
@@ -1390,33 +1389,34 @@ static int ovl_create_tmpfile(struct file *file, struct dentry *dentry,
        int flags = file->f_flags | OVL_OPEN_FLAGS;
        int err;
 
-       scoped_class(override_creds_ovl, old_cred, dentry->d_sb) {
-               new_cred = ovl_setup_cred_for_create(dentry, inode, mode, old_cred);
-               if (IS_ERR(new_cred))
-                       return PTR_ERR(new_cred);
-
-               ovl_path_upper(dentry->d_parent, &realparentpath);
-               realfile = backing_tmpfile_open(&file->f_path, flags, &realparentpath,
-                                               mode, current_cred());
-               err = PTR_ERR_OR_ZERO(realfile);
-               pr_debug("tmpfile/open(%pd2, 0%o) = %i\n", realparentpath.dentry, mode, err);
-               if (err)
-                       return err;
+       with_ovl_creds(dentry->d_sb) {
+               scoped_class(ovl_override_creator_creds, cred, dentry, inode, mode) {
+                       if (IS_ERR(cred))
+                               return PTR_ERR(cred);
+
+                       ovl_path_upper(dentry->d_parent, &realparentpath);
+                       realfile = backing_tmpfile_open(&file->f_path, flags, &realparentpath,
+                                                       mode, current_cred());
+                       err = PTR_ERR_OR_ZERO(realfile);
+                       pr_debug("tmpfile/open(%pd2, 0%o) = %i\n", realparentpath.dentry, mode, err);
+                       if (err)
+                               return err;
 
-               of = ovl_file_alloc(realfile);
-               if (!of) {
-                       fput(realfile);
-                       return -ENOMEM;
-               }
+                       of = ovl_file_alloc(realfile);
+                       if (!of) {
+                               fput(realfile);
+                               return -ENOMEM;
+                       }
 
-               /* ovl_instantiate() consumes the newdentry reference on success */
-               newdentry = dget(realfile->f_path.dentry);
-               err = ovl_instantiate(dentry, inode, newdentry, false, file);
-               if (!err) {
-                       file->private_data = of;
-               } else {
-                       dput(newdentry);
-                       ovl_file_free(of);
+                       /* ovl_instantiate() consumes the newdentry reference on success */
+                       newdentry = dget(realfile->f_path.dentry);
+                       err = ovl_instantiate(dentry, inode, newdentry, false, file);
+                       if (!err) {
+                               file->private_data = of;
+                       } else {
+                               dput(newdentry);
+                               ovl_file_free(of);
+                       }
                }
        }
        return err;