Re: [PATCH 1/6] filemap: make the folio order calculation shareable

[Matthew Wilcox]

On Fri, Sep 15, 2023 at 09:51:23AM +0000, Daniel Gomez wrote:
> To make the code that clamps the folio order in the __filemap_get_folio
> routine reusable to others, move and merge it to the fgf_set_order
> new subroutine (mapping_size_order), so when mapping the size at a
> given index, the order calculated is already valid and ready to be
> used when order is retrieved from fgp_flags with FGF_GET_ORDER.
> 
> Signed-off-by: Daniel Gomez <da.gomez@xxxxxxxxxxx>
> ---
>  fs/iomap/buffered-io.c  |  6 ++++--
>  include/linux/pagemap.h | 42 ++++++++++++++++++++++++++++++++++++-----
>  mm/filemap.c            |  8 --------
>  3 files changed, 41 insertions(+), 15 deletions(-)

That seems like a lot of extra code to add in order to avoid copying
six lines of code and one comment into the shmem code.

It's not wrong, but it seems like a bad tradeoff to me.