[PATCH 3/3] bvec: make the bvec_iter helpers inline functions

[Christoph Hellwig]

The macros are impossible to follow due to the lack of visual type
information and all the braces.  Replace them with inline helpers to
improve on that.  Because the calling conventions are a bit problematic
with a lot of passing structures by value, all the helpers are marked
as __always_inline so that they are force inlined.

Signed-off-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Bart Van Assche <bvanassche at acm.org>
Reviewed-by: Caleb Sander Mateos <csander at purestorage.com>
---
 include/linux/bvec.h | 101 +++++++++++++++++++++++++++----------------
 1 file changed, 64 insertions(+), 37 deletions(-)

diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index d36dd476feda..f4c7ec282ac9 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -104,51 +104,78 @@ struct bvec_iter_all {
 	unsigned	done;
 };
 
-/*
- * various member access, note that bio_data should of course not be used
- * on highmem page vectors
- */
-#define __bvec_iter_bvec(bvec, iter)	(&(bvec)[(iter).bi_idx])
+static __always_inline const struct bio_vec *
+__bvec_iter_bvec(const struct bio_vec *bvecs, const struct bvec_iter iter)
+{
+	return bvecs + iter.bi_idx;
+}
 
 /* multi-page (mp_bvec) helpers */
-#define mp_bvec_iter_page(bvec, iter)				\
-	(__bvec_iter_bvec((bvec), (iter))->bv_page)
+static __always_inline struct page *
+mp_bvec_iter_page(const struct bio_vec *bvecs, const struct bvec_iter iter)
+{
+	return __bvec_iter_bvec(bvecs, iter)->bv_page;
+}
 
-#define mp_bvec_iter_len(bvec, iter)				\
-	min((iter).bi_size,					\
-	    __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
+static __always_inline unsigned int
+mp_bvec_iter_len(const struct bio_vec *bvecs, const struct bvec_iter iter)
+{
+	return min(__bvec_iter_bvec(bvecs, iter)->bv_len - iter.bi_bvec_done,
+			iter.bi_size);
+}
 
-#define mp_bvec_iter_offset(bvec, iter)				\
-	(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
+static __always_inline unsigned int
+mp_bvec_iter_offset(const struct bio_vec *bvecs, const struct bvec_iter iter)
+{
+	return __bvec_iter_bvec(bvecs, iter)->bv_offset + iter.bi_bvec_done;
+}
 
-#define mp_bvec_iter_page_idx(bvec, iter)			\
-	(mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE)
+static __always_inline unsigned int
+mp_bvec_iter_page_idx(const struct bio_vec *bvecs, const struct bvec_iter iter)
+{
+	return mp_bvec_iter_offset(bvecs, iter) / PAGE_SIZE;
+}
 
-#define mp_bvec_iter_bvec(bvec, iter)				\
-((struct bio_vec) {						\
-	.bv_page	= mp_bvec_iter_page((bvec), (iter)),	\
-	.bv_len		= mp_bvec_iter_len((bvec), (iter)),	\
-	.bv_offset	= mp_bvec_iter_offset((bvec), (iter)),	\
-})
+static __always_inline struct bio_vec
+mp_bvec_iter_bvec(const struct bio_vec *bvecs, const struct bvec_iter iter)
+{
+	return (struct bio_vec) {
+		.bv_page	= mp_bvec_iter_page(bvecs, iter),
+		.bv_len		= mp_bvec_iter_len(bvecs, iter),
+		.bv_offset	= mp_bvec_iter_offset(bvecs, iter),
+	};
+}
 
 /* For building single-page bvec in flight */
- #define bvec_iter_offset(bvec, iter)				\
-	(mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE)
-
-#define bvec_iter_len(bvec, iter)				\
-	min_t(unsigned, mp_bvec_iter_len((bvec), (iter)),		\
-	      PAGE_SIZE - bvec_iter_offset((bvec), (iter)))
-
-#define bvec_iter_page(bvec, iter)				\
-	(mp_bvec_iter_page((bvec), (iter)) +			\
-	 mp_bvec_iter_page_idx((bvec), (iter)))
-
-#define bvec_iter_bvec(bvec, iter)				\
-((struct bio_vec) {						\
-	.bv_page	= bvec_iter_page((bvec), (iter)),	\
-	.bv_len		= bvec_iter_len((bvec), (iter)),	\
-	.bv_offset	= bvec_iter_offset((bvec), (iter)),	\
-})
+static __always_inline unsigned int
+bvec_iter_offset(const struct bio_vec *bvecs, const struct bvec_iter iter)
+{
+	return mp_bvec_iter_offset(bvecs, iter) % PAGE_SIZE;
+}
+
+static __always_inline unsigned int
+bvec_iter_len(const struct bio_vec *bvecs, const struct bvec_iter iter)
+{
+	return min(mp_bvec_iter_len(bvecs, iter),
+			PAGE_SIZE - bvec_iter_offset(bvecs, iter));
+}
+
+static __always_inline struct page *
+bvec_iter_page(const struct bio_vec *bvecs, const struct bvec_iter iter)
+{
+	return mp_bvec_iter_page(bvecs, iter) +
+		mp_bvec_iter_page_idx(bvecs, iter);
+}
+
+static __always_inline struct bio_vec
+bvec_iter_bvec(const struct bio_vec *bvecs, const struct bvec_iter iter)
+{
+	return (struct bio_vec) {
+		.bv_page	= bvec_iter_page(bvecs, iter),
+		.bv_len		= bvec_iter_len(bvecs, iter),
+		.bv_offset	= bvec_iter_offset(bvecs, iter),
+	};
+}
 
 static inline bool bvec_iter_advance(const struct bio_vec *bv,
 		struct bvec_iter *iter, unsigned bytes)
-- 
2.53.0