Re: [PATCH] mtd: fix mtd_blkdevs problem with caches on some architectures (2.6.31)

[Andrew Morton <akpm@linux-foundation.org>]

On Sun, 22 Nov 2009 16:55:21 +0300 Ilya Loginov <isloginov@gmail.com> wrote:

> +#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
> +# error	"You should to define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform."
> +#endif
> +#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
> +static inline void bio_flush_dcache_pages(struct bio *bi)
> +{
> +	int i;
> +	struct bio_vec* bvec;
> +
> +	bio_for_each_segment(bvec, bi, i)
> +		flush_dcache_page(bvec->bv_page);
> +}
> +#else
> +static inline void bio_flush_dcache_pages(struct bio *bi)
> +{
> +}
> +#endif
> +
>  extern struct bio *bio_copy_user(struct request_queue *, struct rq_map_data *,
>  				 unsigned long, unsigned int, int, gfp_t);
>  extern struct bio *bio_copy_user_iov(struct request_queue *,
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 69103e0..9b5214c 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -740,6 +740,24 @@ struct req_iterator {
>  #define rq_iter_last(rq, _iter)					\
>  		(_iter.bio->bi_next == NULL && _iter.i == _iter.bio->bi_vcnt-1)
>  
> +#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
> +# error	"You should to define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform."
> +#endif
> +#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
> +static inline void rq_flush_dcache_pages(struct request *rq)
> +{
> +	struct req_iterator iter;
> +	struct bio_vec* bvec;
> +
> +	rq_for_each_segment(bvec, rq, iter)
> +		flush_dcache_page(bvec->bv_page);
> +}
> +#else
> +static inline void rq_flush_dcache_pages(struct request *rq)
> +{
> +}
> +#endif

I don't think the non-stub versions of these should be inlined.  They
will generate quite a lot of code and they're pretty heavyweight. 
Better to implement them in block/ somewhere, and EXPORT_SYMBOL().