block: factor out a bvec_set_page helper

Add a helper to initialize a bvec based of a page pointer.  This will help
removing various open code bvec initializations.
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/20230203150634.3199647-2-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/bio-integrity.c

@@ -124,23 +124,18 @@ int bio_integrity_add_page(struct bio *bio, struct page *page,
 			   unsigned int len, unsigned int offset)
 {
 	struct bio_integrity_payload *bip = bio_integrity(bio);
-	struct bio_vec *iv;
 
 	if (bip->bip_vcnt >= bip->bip_max_vcnt) {
 		printk(KERN_ERR "%s: bip_vec full\n", __func__);
 		return 0;
 	}
 
-	iv = bip->bip_vec + bip->bip_vcnt;
-
 	if (bip->bip_vcnt &&
 	    bvec_gap_to_prev(&bdev_get_queue(bio->bi_bdev)->limits,
 			     &bip->bip_vec[bip->bip_vcnt - 1], offset))
 		return 0;
 
-	iv->bv_page = page;
-	iv->bv_len = len;
-	iv->bv_offset = offset;
+	bvec_set_page(&bip->bip_vec[bip->bip_vcnt], page, len, offset);
 	bip->bip_vcnt++;
 
 	return len;

block/bio.c

@@ -1029,10 +1029,7 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio,
 	if (bio->bi_vcnt >= queue_max_segments(q))
 		return 0;
 
-	bvec = &bio->bi_io_vec[bio->bi_vcnt];
-	bvec->bv_page = page;
-	bvec->bv_len = len;
-	bvec->bv_offset = offset;
+	bvec_set_page(&bio->bi_io_vec[bio->bi_vcnt], page, len, offset);
 	bio->bi_vcnt++;
 	bio->bi_iter.bi_size += len;
 	return len;
@@ -1108,15 +1105,10 @@ EXPORT_SYMBOL_GPL(bio_add_zone_append_page);
 void __bio_add_page(struct bio *bio, struct page *page,
 		unsigned int len, unsigned int off)
 {
-	struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt];
-
 	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
 	WARN_ON_ONCE(bio_full(bio, len));
 
-	bv->bv_page = page;
-	bv->bv_offset = off;
-	bv->bv_len = len;
-
+	bvec_set_page(&bio->bi_io_vec[bio->bi_vcnt], page, len, off);
 	bio->bi_iter.bi_size += len;
 	bio->bi_vcnt++;
 }

include/linux/bvec.h

@@ -34,6 +34,21 @@ struct bio_vec {
 	unsigned int	bv_offset;
 };
 
+/**
+ * bvec_set_page - initialize a bvec based off a struct page
+ * @bv:		bvec to initialize
+ * @page:	page the bvec should point to
+ * @len:	length of the bvec
+ * @offset:	offset into the page
+ */
+static inline void bvec_set_page(struct bio_vec *bv, struct page *page,
+		unsigned int len, unsigned int offset)
+{
+	bv->bv_page = page;
+	bv->bv_len = len;
+	bv->bv_offset = offset;
+}
+
 struct bvec_iter {
 	sector_t		bi_sector;	/* device address in 512 byte
 						   sectors */