Re: [RFC v0 1/4] vfs: add copy_range syscall and vfs entry point

From: Eric Wong
Date: Wed May 15 2013 - 15:44:12 EST


Zach Brown <zab@xxxxxxxxxx> wrote:
> This adds a syscall and vfs entry point for clone_range which offloads
> data copying between existing files.
>
> The syscall is a thin wrapper around the vfs entry point. Its arguments
> are inspired by sys_splice().

Why introduce a new syscall instead of extending sys_splice?

Perhaps adding a new SPLICE_F_COPYRANGE flag to avoid compatibility
problems with userspace which may expect ESPIPE when given two non-pipes
would be useful.

If the user doesn't need a out offset, then sendfile() should also be
able to transparently utilize COPY/CLONE_RANGE, too.
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