On Sun, Oct 14, 2018 at 10:24:33AM -0700, Christoph Hellwig wrote:
> On Fri, Oct 12, 2018 at 05:07:37PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> >
> > Create a RFR_TO_SRC_EOF flag to explicitly declare that the caller wants
> > the remap implementation to remap to the end of the source file, once
> > the files are locked.
>
> The name looks like a cat threw up on your keyboard :)
Yeah... :(
> From reading the code this seems to ask for a whole file remap, right?
Nope. In the original btrfs clonerange ioctl, length == 0 meant "to EOF".
If you made a call like this:
struct btrfs_ioctl_clone_range_args x = {
.src_offset = 16384,
.src_length = 0,
.dest_offset = 0,
.src_fd = whatever,
};
ftruncate(dest_fd, 0);
ioctl(dest_fd, BTRFS_IOC_CLONE, &x);
Then dest_fd ends up with the contents of [16k...EOF] from src_fd.
It's annoying to have the magic length number (and no flags?) but we're
stuck with this quirk of the interface.
> Why not put that in the name to make it more descriptive?
I'm all ears for better suggestions. :)
--D
