On Mon, Jun 02, 2014 at 09:45:07AM -0700, Dave Hansen wrote:
> On 06/02/2014 09:37 AM, Naoya Horiguchi wrote:
> > On Mon, Jun 02, 2014 at 09:12:25AM -0700, Dave Hansen wrote:
> >> > On 06/01/2014 10:24 PM, Naoya Horiguchi wrote:
> >>> > > -#define PAGECACHE_TAG_DIRTY 0
> >>> > > -#define PAGECACHE_TAG_WRITEBACK 1
> >>> > > -#define PAGECACHE_TAG_TOWRITE 2
> >>> > > +enum {
> >>> > > + PAGECACHE_TAG_DIRTY,
> >>> > > + PAGECACHE_TAG_WRITEBACK,
> >>> > > + PAGECACHE_TAG_TOWRITE,
> >>> > > + __NR_PAGECACHE_TAGS,
> >>> > > +};
> >> >
> >> > Doesn't this end up exposing kernel-internal values out to a userspace
> >> > interface? Wouldn't that lock these values in to the ABI?
> > Yes, that would. I hope these PAGECACHE_TAG_* stuff is very basic
> > things and will never change drastically in the future (only added),
> > so it's unlikely to bother people about ABI breakage things.
>
> OK, so if I'm writing a userspace program, which header do I include
> pull these values in to my program?
Yes, that's necessary to consider (but I haven't done, sorry),
so I'm thinking of moving this definition to the new file
include/uapi/linux/pagecache.h and let it be imported from the
userspace programs. Is it fine?
Thanks,
Naoya Horiguchi
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