On Mon, Oct 29, 2018 at 7:41 PM Olga Kornievskaia
<olga.kornievskaia@xxxxxxxxx> wrote:
>
> From: Olga Kornievskaia <kolga@xxxxxxxxxx>
>
> If a filesystem does not support cross device or cross file system
> type copy offload functionality, then this patch provides a fallback
The flaw in this statement is that in the common case, filesystem that does
not support copy_file_range, doesn't have copy_file_range() file operation,
so in fact, patch [1/12] has already implemented
"generic cross-device copy_file_range() support for most filesystems"
This is why the order of this patch in the series is awkward.
Please see my suggestion in comment to patch [1/12].
> to a page cache based physical data copy. This means the
> copy_file_range() systemcall will never fail with EXDEV, and so in
> future userspace will not need to detect or provide a fallback for
> failed cross-device copies anymore.
>
> Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx>
> ---
> fs/read_write.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 7a912e3..cff59bd 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1597,7 +1597,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> if (file_out->f_op->copy_file_range) {
> ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
> pos_out, len, flags);
> - if (ret != -EOPNOTSUPP)
> + if (ret != -EOPNOTSUPP && ret != -EXDEV)
> goto done;
> }
>
> --
> 1.8.3.1
>
