ovl: port ovl_nlink_start() to cred guard

Use the scoped ovl cred guard.

Link: https://patch.msgid.link/20251117-work-ovl-cred-guard-v4-28-b31603935724@kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 46387aeb6be6a4970c6485326c897eb851077ed6..e61eb758349ac7d630ce09f2a6fa4178278a3f5e 100644 (file)
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -1147,7 +1147,6 @@ fail:
 int ovl_nlink_start(struct dentry *dentry)
 {
        struct inode *inode = d_inode(dentry);
-       const struct cred *old_cred;
        int err;
 
        if (WARN_ON(!inode))
@@ -1184,15 +1183,14 @@ int ovl_nlink_start(struct dentry *dentry)
        if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode))
                return 0;
 
-       old_cred = ovl_override_creds(dentry->d_sb);
        /*
         * The overlay inode nlink should be incremented/decremented IFF the
         * upper operation succeeds, along with nlink change of upper inode.
         * Therefore, before link/unlink/rename, we store the union nlink
         * value relative to the upper inode nlink in an upper inode xattr.
         */
-       err = ovl_set_nlink_upper(dentry);
-       ovl_revert_creds(old_cred);
+       with_ovl_creds(dentry->d_sb)
+               err = ovl_set_nlink_upper(dentry);
        if (err)
                goto out_drop_write;