Re: [PATCH 09/15] vfs: pass operation flags to {clone, dedupe}_file_range implementations

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Fri, Oct 05, 2018 at 10:07:43AM +0300, Amir Goldstein wrote:
> 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>
> >
> > Pass operational flags to the per-filesystem clone and dedupe
> > implementations.  This enables the vfs to signal when it can deal with
> > short clone and short dedupe operations.
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> [...]
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -1761,7 +1761,7 @@ struct file_operations {
> >                         loff_t, size_t, unsigned int);
> >         s64 (*clone_file_range)(struct file *file_in, loff_t pos_in,
> >                                 struct file *file_out, loff_t pos_out,
> > -                               u64 count);
> > +                               u64 count, unsigned int flags);
> >         s64 (*dedupe_file_range)(struct file *file_in, loff_t pos_in,
> >                                  struct file *file_out, loff_t pos_out,
> >                                  u64 count);
> > @@ -1827,9 +1827,15 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
> >                 unsigned long, loff_t *, rwf_t);
> >  extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
> >                                    loff_t, size_t, unsigned int);
> > +/* Caller can handle a shortened operation. */
> > +#define CLONERANGE_SHORT       (1 << 0)
> > +/* End operation at the source file's EOF. */
> > +#define CLONERANGE_EOF         (1 << 1)
> > +/* Operation is actually dedupe, not clone. */
> > +#define CLONERANGE_DEDUPE      (1 << 2)
> 
> That's cool. But you know what's going to be the next step, right?
> Merging the 3 file operation interfaces into a single one.
> copy_file_range() already has the flags arg for future extensions
> and as you wrote somewhere, clone is really an optimized copy.
> ovl_copyfile() already does that internally.
> 
> So the only take away for this patch series, please use constant
> names COPYRANGE_* and also explicitly define:
> 
> /* Operation is actually clone, not copy. */
> #define COPYRANGE_CLONE      (1 << 2)
> /* Operation is actually dedupe, not copy. */
> #define COPYRANGE_DEDUPE      (1 << 3)

Yeah, I was too tired to try to throw that one on top of the flaming
garbage pile.  But I guess since I have a bunch more work to do to the
previous patch I might as well do that...

--D

> 
> Thanks,
> Amir.