[PATCH 2/2] block: add a bvec_phys helper

[Christoph Hellwig <hch@lst.de>]

Get callers out of poking into bvec internals a bit more.  Not a huge win
right now, but with the proposed new DMA mapping API we might end up with
a lot more of this otherwise.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/m68k/emu/nfblock.c |  2 +-
 block/bio.c             |  2 +-
 block/blk-merge.c       |  6 ++----
 block/blk.h             |  4 ++--
 include/linux/bvec.h    | 15 +++++++++++++++
 5 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/arch/m68k/emu/nfblock.c b/arch/m68k/emu/nfblock.c
index 8eea7ef9115146..874fe958877388 100644
--- a/arch/m68k/emu/nfblock.c
+++ b/arch/m68k/emu/nfblock.c
@@ -71,7 +71,7 @@ static void nfhd_submit_bio(struct bio *bio)
 		len = bvec.bv_len;
 		len >>= 9;
 		nfhd_read_write(dev->id, 0, dir, sec >> shift, len >> shift,
-				page_to_phys(bvec.bv_page) + bvec.bv_offset);
+				bvec_phys(&bvec));
 		sec += len;
 	}
 	bio_endio(bio);
diff --git a/block/bio.c b/block/bio.c
index e9e809a63c5975..a3b1b2266c50be 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -953,7 +953,7 @@ bool bvec_try_merge_hw_page(struct request_queue *q, struct bio_vec *bv,
 		bool *same_page)
 {
 	unsigned long mask = queue_segment_boundary(q);
-	phys_addr_t addr1 = page_to_phys(bv->bv_page) + bv->bv_offset;
+	phys_addr_t addr1 = bvec_phys(bv);
 	phys_addr_t addr2 = page_to_phys(page) + offset + len - 1;
 
 	if ((addr1 | mask) != (addr2 | mask))
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 515173342eb757..93779fc6dfb1c3 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -255,8 +255,7 @@ static bool bvec_split_segs(const struct queue_limits *lim,
 	unsigned seg_size = 0;
 
 	while (len && *nsegs < max_segs) {
-		seg_size = get_max_segment_size(lim, page_to_phys(bv->bv_page) +
-						bv->bv_offset + total_len);
+		seg_size = get_max_segment_size(lim, bvec_phys(bv) + total_len);
 		seg_size = min(seg_size, len);
 
 		(*nsegs)++;
@@ -492,8 +491,7 @@ static unsigned blk_bvec_map_sg(struct request_queue *q,
 	while (nbytes > 0) {
 		unsigned offset = bvec->bv_offset + total;
 		unsigned len = min(get_max_segment_size(&q->limits,
-				   page_to_phys(bvec->bv_page) + offset),
-				   nbytes);
+				   bvec_phys(bvec) + total), nbytes);
 		struct page *page = bvec->bv_page;
 
 		/*
diff --git a/block/blk.h b/block/blk.h
index 47dadd2439b1ca..8e8936e97307c6 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -98,8 +98,8 @@ static inline bool biovec_phys_mergeable(struct request_queue *q,
 		struct bio_vec *vec1, struct bio_vec *vec2)
 {
 	unsigned long mask = queue_segment_boundary(q);
-	phys_addr_t addr1 = page_to_phys(vec1->bv_page) + vec1->bv_offset;
-	phys_addr_t addr2 = page_to_phys(vec2->bv_page) + vec2->bv_offset;
+	phys_addr_t addr1 = bvec_phys(vec1);
+	phys_addr_t addr2 = bvec_phys(vec2);
 
 	/*
 	 * Merging adjacent physical pages may not work correctly under KMSAN
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index bd1e361b351c5a..0b9a56fc0faaf5 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -280,4 +280,19 @@ static inline void *bvec_virt(struct bio_vec *bvec)
 	return page_address(bvec->bv_page) + bvec->bv_offset;
 }
 
+/**
+ * bvec_phys - return the physical address for a bvec
+ * @bvec: bvec to return the physical address for
+ */
+static inline phys_addr_t bvec_phys(const struct bio_vec *bvec)
+{
+	/*
+	 * Note this open codes page_to_phys because page_to_phys is defined in
+	 * <asm/io.h>, which we don't want to pull in here.  If it ever moves to
+	 * a sensible place we should start using it.
+	 */
+	return ((phys_addr_t)page_to_pfn(bvec->bv_page) << PAGE_SHIFT) +
+		bvec->bv_offset;
+}
+
 #endif /* __LINUX_BVEC_H */
-- 
2.43.0