Introduce rq_for_each_segment replacing rq_for_each_bio

Every usage of rq_for_each_bio wraps a usage of
bio_for_each_segment, so these can be combined into
rq_for_each_segment.

We define "struct req_iterator" to hold the 'bio' and 'index' that
are needed for the double iteration.

Signed-off-by: Neil Brown <neilb@suse.de>

Various compile fixes by me...

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 4 insertions, 6 deletions

diff --git a/drivers/block/lguest_blk.c b/drivers/block/lguest_blk.c
index 160cf14431ac..1e838ae60a60 100644
--- a/drivers/block/lguest_blk.c
+++ b/drivers/block/lguest_blk.c
@@ -142,12 +142,11 @@ static irqreturn_t lgb_irq(int irq, void *_bd)
  * return the total length. */
 static unsigned int req_to_dma(struct request *req, struct lguest_dma *dma)
 {
-        unsigned int i = 0, idx, len = 0;
-        struct bio *bio;
+        unsigned int i = 0, len = 0;
+        struct req_iterator iter;
+        struct bio_vec *bvec;
 
-        rq_for_each_bio(bio, req) {
-                struct bio_vec *bvec;
-                bio_for_each_segment(bvec, bio, idx) {
+        rq_for_each_segment(bvec, req, iter) {
                         /* We told the block layer not to give us too many. */
                         BUG_ON(i == LGUEST_MAX_DMA_SECTIONS);
                         /* If we had a zero-length segment, it would look like
@@ -160,7 +159,6 @@ static unsigned int req_to_dma(struct request *req, struct lguest_dma *dma)
                         dma->len[i] = bvec->bv_len;
                         len += bvec->bv_len;
                         i++;
-                }
         }
         /* If the array isn't full, we mark the end with a 0 length */
         if (i < LGUEST_MAX_DMA_SECTIONS)