On Wed, Mar 02, 2022 at 07:29:34PM -0500, Josef Bacik wrote:
> On Wed, Mar 02, 2022 at 07:07:35PM -0500, J. Bruce Fields wrote:
> > Sorry, took me a minute to understand, myself:
> >
> > It's actually only the client behavior that changed. Previously the
> > client would reject an attempt to clone across filesystems, so the
> > server never saw such a request. After this patch, the client will go
> > ahead and send the CLONE. (Which, come to think of it, is probably the
> > right thing for the client to do.)
> >
> > So the server's probably always had a bug, and this just uncovered it.
> >
> > I'd be curious what the consequences are. And where the check should be
> > (above or below vfs_clone_file_range()?).
> >
>
> This is where I'm confused, this really shouldn't succeed
>
> loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out,
> loff_t len, unsigned int remap_flags)
> {
> loff_t ret;
>
> WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);
>
> if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
> return -EXDEV;
>
>
> loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out,
> loff_t len, unsigned int remap_flags)
> {
> loff_t ret;
>
> file_start_write(file_out);
> ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len,
> remap_flags);
>
> And even if we get past here, I imagine XFS would freak out because it can't
> find the extents (unless you're getting lucky and everything is lining up?).
> I'm super confused...
Bah, I see what you mean. Maybe there's something wrong with my setup.
I'll try some more stuff and report back....
--b.
