Re: [PATCH 10/15] vfs: make cloning to source file eof more explicit

[Amir Goldstein <amir73il@gmail.com>]

On Fri, Oct 5, 2018 at 3:46 AM Darrick J. Wong <darrick.wong@oracle.com> wrote:
>
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> Use the new CLONE_RANGE_EOF flag to explicitly declare that the caller
> wants the clone implementation to set *len appropriately once the files
> are locked.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/read_write.c |   14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
>
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 7cfff497263b..4eaea52f70a8 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1747,11 +1747,12 @@ int vfs_clone_file_prep(struct file *file_in, loff_t pos_in,
>
>         isize = i_size_read(inode_in);
>
> -       /* Zero length dedupe exits immediately; reflink goes to EOF. */
> -       if (*len == 0) {
> -               if (is_dedupe || pos_in == isize)
> -                       return 0;
> -               if (pos_in > isize)
> +       /*
> +        * If the caller asked to go all the way to the end of the source file,
> +        * set *len now that we have the file locked.
> +        */
> +       if ((flags & CLONERANGE_EOF) && *len == 0) {
> +               if (pos_in >= isize)
>                         return -EINVAL;

Slight change of behavior with clone of 0 bytes at EOF.
Is that intentional?
Does not change behavior through the entire series?
Please drop a work about this in commit message.

Thanks,
Amir.