[RFC PATCH 11/16] bvec: convert to using pfn_t internally

[Logan Gunthorpe <logang-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>]

With bv_page fenced off, we can now convert it to a pfn_t fairly simply.
Everything should work the same with the exception of a BUG_ON
for potentially unmappable pfns.

A couple of initializers that assign {NULL} to a bio_vec had to also be
changed to {} to prevent a warning seeing pfn_t is actually a struct.

Signed-off-by: Logan Gunthorpe <logang-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
Signed-off-by: Stephen Bates <sbates-pv7U853sEMVWk0Htik3J/w@public.gmane.org>
---
 block/blk-integrity.c |  4 ++--
 block/blk-merge.c     |  6 +++---
 include/linux/bvec.h  | 13 +++++++++----
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/block/blk-integrity.c b/block/blk-integrity.c
index 857138a..2ba66f7 100644
--- a/block/blk-integrity.c
+++ b/block/blk-integrity.c
@@ -40,7 +40,7 @@
  */
 int blk_rq_count_integrity_sg(struct request_queue *q, struct bio *bio)
 {
-	struct bio_vec iv, ivprv = { NULL };
+	struct bio_vec iv, ivprv = {};
 	unsigned int segments = 0;
 	unsigned int seg_size = 0;
 	struct bvec_iter iter;
@@ -86,7 +86,7 @@ EXPORT_SYMBOL(blk_rq_count_integrity_sg);
 int blk_rq_map_integrity_sg(struct request_queue *q, struct bio *bio,
 			    struct scatterlist *sglist)
 {
-	struct bio_vec iv, ivprv = { NULL };
+	struct bio_vec iv, ivprv = {};
 	struct scatterlist *sg = NULL;
 	unsigned int segments = 0;
 	struct bvec_iter iter;
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 65dcee9..93e87fe 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -245,7 +245,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
 					     struct bio *bio,
 					     bool no_sg_merge)
 {
-	struct bio_vec bv, bvprv = { NULL };
+	struct bio_vec bv, bvprv = {};
 	int cluster, prev = 0;
 	unsigned int seg_size, nr_phys_segs;
 	struct bio *fbio, *bbio;
@@ -347,7 +347,7 @@ EXPORT_SYMBOL(blk_recount_segments);
 static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
 				   struct bio *nxt)
 {
-	struct bio_vec end_bv = { NULL }, nxt_bv;
+	struct bio_vec end_bv = {}, nxt_bv;
 
 	if (!blk_queue_cluster(q))
 		return 0;
@@ -430,7 +430,7 @@ static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio,
 			     struct scatterlist *sglist,
 			     struct scatterlist **sg)
 {
-	struct bio_vec bvec, bvprv = { NULL };
+	struct bio_vec bvec, bvprv = {};
 	struct bvec_iter iter;
 	int cluster = blk_queue_cluster(q), nsegs = 0;
 
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index b53b879..d950288 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -22,12 +22,13 @@
 
 #include <linux/kernel.h>
 #include <linux/bug.h>
+#include <linux/pfn_t.h>
 
 /*
  * was unsigned short, but we might as well be ready for > 64kB I/O pages
  */
 struct bio_vec {
-	struct page	*bv_page;
+	pfn_t		bv_pfn;
 	unsigned int	bv_len;
 	unsigned int	bv_offset;
 };
@@ -45,12 +46,13 @@ struct bvec_iter {
 
 static inline struct page *bvec_page(const struct bio_vec *bvec)
 {
-	return bvec->bv_page;
+	BUG_ON(!pfn_t_is_always_mappable(bvec->bv_pfn));
+	return pfn_t_to_page(bvec->bv_pfn);
 }
 
 static inline void bvec_set_page(struct bio_vec *bvec, struct page *page)
 {
-	bvec->bv_page = page;
+	bvec->bv_pfn = page_to_pfn_t(page);
 }
 
 /*
@@ -59,6 +61,9 @@ static inline void bvec_set_page(struct bio_vec *bvec, struct page *page)
  */
 #define __bvec_iter_bvec(bvec, iter)	(&(bvec)[(iter).bi_idx])
 
+#define bvec_iter_pfn_t(bvec, iter)				\
+	(__bvec_iter_bvec((bvec), (iter))->bv_pfn)
+
 #define bvec_iter_page(bvec, iter)				\
 	(bvec_page(__bvec_iter_bvec((bvec), (iter))))
 
@@ -71,7 +76,7 @@ static inline void bvec_set_page(struct bio_vec *bvec, struct page *page)
 
 #define bvec_iter_bvec(bvec, iter)				\
 ((struct bio_vec) {						\
-	.bv_page	= bvec_iter_page((bvec), (iter)),	\
+	.bv_pfn		= bvec_iter_pfn_t((bvec), (iter)),	\
 	.bv_len		= bvec_iter_len((bvec), (iter)),	\
 	.bv_offset	= bvec_iter_offset((bvec), (iter)),	\
 })
-- 
2.1.4