block: introduce mp_bvec_for_each_page() for iterating over page

Ming Lei · axboe · commit 594b9a89af8e · 2019-02-28T05:56:03.000-07:00
mp_bvec_for_each_segment() is a bit big for the iteration, so introduce
a light-weight helper for iterating over pages, then 32bytes stack
space can be saved.

Signed-off-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
@@ -188,4 +188,9 @@ static inline void mp_bvec_last_segment(const struct bio_vec *bvec,
 	}
 }
 
+#define mp_bvec_for_each_page(pg, bv, i)				\
+	for (i = (bv)->bv_offset / PAGE_SIZE;				\
+		(i <= (((bv)->bv_offset + (bv)->bv_len - 1) / PAGE_SIZE)) && \
+		(pg = bvec_nth_page((bv)->bv_page, i)); i += 1)
+
 #endif /* __LINUX_BVEC_ITER_H */

Original file line number	Diff line number	Diff line change
`@@ -188,4 +188,9 @@ static inline void mp_bvec_last_segment(const struct bio_vec *bvec,`
`188`	`188`	`}`
`189`	`189`	`}`
`190`	`190`
	`191`	`+#define mp_bvec_for_each_page(pg, bv, i) \`
	`192`	`+ for (i = (bv)->bv_offset / PAGE_SIZE; \`
	`193`	`+ (i <= (((bv)->bv_offset + (bv)->bv_len - 1) / PAGE_SIZE)) && \`
	`194`	`+ (pg = bvec_nth_page((bv)->bv_page, i)); i += 1)`
	`195`	`+`
`191`	`196`	`#endif /* __LINUX_BVEC_ITER_H */`