# \[PATCH 01/15\] bvec: add a bvec\_virt helper

- From: Christoph Hellwig \<hch@lst.de\>
- Date: 2021-08-04 09:59:43 
- List: linux-raid
- Page: https://ratatoskr.run/linux-raid/2021/08/6404272
- Thread: https://ratatoskr.run/linux-block/2021/08/6404270/t.md

```text
Add a helper to get the virtual address for a bvec.  This avoids that
all callers need to know about the page + offset representation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/bvec.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index f9fa43b940ff..0e9bdd42dafb 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -229,4 +229,16 @@ static inline void memzero_bvec(struct bio_vec *bvec)
 	memzero_page(bvec->bv_page, bvec->bv_offset, bvec->bv_len);
 }
 
+/**
+ * bvec_virt - return the virtual address for a bvec
+ * @bvec: bvec to return the virtual address for
+ *
+ * Note: the caller must ensure that @bvec->bv_page is not a highmem page.
+ */
+static inline void *bvec_virt(struct bio_vec *bvec)
+{
+	WARN_ON_ONCE(PageHighMem(bvec->bv_page));
+	return page_address(bvec->bv_page) + bvec->bv_offset;
+}
+
 #endif /* __LINUX_BVEC_H */
-- 
2.30.2

```