[dm-devel] [PATCH] dm-writecache
Christoph Hellwig
hch at infradead.org
Mon Mar 12 07:50:29 UTC 2018
On Thu, Mar 08, 2018 at 10:26:17PM -0500, Mikulas Patocka wrote:
> > no business having this around.
>
> It's the default setting of the flag wc->writeback_fua (it can be changed
> with target parameters). The flag selects whether the target uses FUA
> requests when doing writeback or whether it uses non-FUA requests and
> FLUSH afterwards. For some block devices, FUA is faster, for some
> nonFUA+FLUSH is faster.
So just use true as the default flag, adding a name for it in addition
to the field it is assigned to makes no sense at all.
> > > +#ifndef bio_set_dev
> > > +#define bio_set_dev(bio, dev) ((bio)->bi_bdev = (dev))
> > > +#endif
> > > +#ifndef timer_setup
> > > +#define timer_setup(t, c, f) setup_timer(t, c, (unsigned long)(t))
> > > +#endif
> >
> > no business in mainline.
>
> People removed dax support for ramdisk in 4.15.
>
> If I need to test it on non-x86 architecture, I need ramdisk as a fake dax
> device - and that only works up to 4.14. These defines are for 4.14
> compatibility.
So add them when you backport, or use the existing automated backport
frameworks. But do not add dead code to an upstream submission.
> > > +#if defined(CONFIG_X86_64)
> > > +#define NT_STORE(dest, src) \
> > > +do { \
> > > + typeof(src) val = (src); \
> > > + memcpy_flushcache(&(dest), &val, sizeof(src)); \
> > > +} while (0)
> > > +#define COMMIT_FLUSHED() wmb()
> > > +#else
> > > +#define NT_STORE(dest, src) WRITE_ONCE(dest, src)
> > > +#define FLUSH_RANGE dax_flush
> > > +#define COMMIT_FLUSHED() do { } while (0)
> > > +#endif
> >
> > Please use proper APIs for this, this has no business in a driver.
> >
> > And that's it for now. This is clearly not submission ready, and I
> > should got back to my backlog of other things.
>
> Why is memcpy_flushcache and dax_flush "improper"? What should I use
> instead of them?
They are proper and should be used directly instead of through your
hacky macros.
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