Re: [PATCH 1/3] replace PAGECACHE_TAG_* definition with enumeration

From: Dave Hansen
Date: Mon Jun 02 2014 - 12:48:11 EST


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?
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