block: add a bvec_set_virt helper

A small wrapper around bvec_set_page for callers that have a virtual
address.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20230203150634.3199647-4-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/bvec.h

@@ -62,6 +62,18 @@ static inline void bvec_set_folio(struct bio_vec *bv, struct folio *folio,
 	bvec_set_page(bv, &folio->page, len, offset);
 }
 
+/**
+ * bvec_set_virt - initialize a bvec based on a virtual address
+ * @bv:		bvec to initialize
+ * @vaddr:	virtual address to set the bvec to
+ * @len:	length of the bvec
+ */
+static inline void bvec_set_virt(struct bio_vec *bv, void *vaddr,
+		unsigned int len)
+{
+	bvec_set_page(bv, virt_to_page(vaddr), len, offset_in_page(vaddr));
+}
+
 struct bvec_iter {
 	sector_t		bi_sector;	/* device address in 512 byte
 						   sectors */