Re: [amir73il:ovl_copy_file_range 3/6] fs/read_write.c:1499 copy_file_fs_cmp() error: we previously assumed 'f_out->f_op' could be null (see line 1496)

On Tue, Jul 14, 2026 at 9:16 AM Dan Carpenter <[email protected]> wrote:
>
> tree:   https://github.com/amir73il/linux ovl_copy_file_range
> head:   4421f88f42bb20b8a6f9fd56c5c877a1088d0e00
> commit: b86e287575a3f81b04ef92b5bb46f87329fc314f [3/6] fs: add support for copy file range from another fs
> config: i386-randconfig-141-20260714 (https://download.01.org/0day-ci/archive/20260714/[email protected]/config)
> compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
> smatch: v0.5.0-9185-gbcc58b9c
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <[email protected]>
> | Reported-by: Dan Carpenter <[email protected]>
> | Closes: https://lore.kernel.org/r/[email protected]/
>
> New smatch warnings:
> fs/read_write.c:1499 copy_file_fs_cmp() error: we previously assumed 'f_out->f_op' could be null (see line 1496)

I think this assumption was wrong and the extra f_out->f_op test can
be avoided here
>
> Old smatch warnings:
> fs/read_write.c:1631 vfs_copy_file_range() error: we previously assumed 'file_out->f_op->copy_file_range' could be null (see line 1614)
>
> vim +1499 fs/read_write.c
>
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1491  static int copy_file_fs_cmp(struct file *f_in, struct file *f_out,
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1492                              unsigned int flags)
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1493  {
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1494          if (flags & COPY_FILE_SPLICE)
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1495                  return FS_COPY_SPLICE;
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13 @1496          else if (f_out->f_op && f_out->f_op->copy_file_range &&
>                                                                  ^^^^^^^^^^^
> if ->f_op is NULL
>
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1497                   f_out->f_op->copy_file_range == f_in->f_op->copy_file_range)
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1498                  return FS_COPY_SAME_FS;
> b86e287575a3f8 Amir Goldstein 2026-07-13 @1499          else if (f_out->f_op->fop_flags & FOP_CROSS_FS_COPY)
>                                                                  ^^^^^^^^^^^^^^^^^^^^^^
> then we are toasted.
>
> b86e287575a3f8 Amir Goldstein 2026-07-13  1500                  return FS_COPY_FROM_OTHER_FS;
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1501          else if (file_inode(f_in)->i_sb == file_inode(f_out)->i_sb)
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1502                  return FS_COPY_SAME_SB;
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1503          else
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1504                  return FS_COPY_CROSS_FS;
> cd6e8d0dbe33ef Amir Goldstein 2026-07-13  1505  }
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
>