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>
diff --git a/drivers/block/ps3disk.c b/drivers/block/ps3disk.c
index aa8b890..8953e7c 100644
--- a/drivers/block/ps3disk.c
+++ b/drivers/block/ps3disk.c
@@ -91,30 +91,30 @@
 				   struct request *req, int gather)
 {
 	unsigned int offset = 0;
-	struct bio *bio;
-	sector_t sector;
+	struct req_iterator iter;
 	struct bio_vec *bvec;
-	unsigned int i = 0, j;
+	unsigned int i = 0;
 	size_t size;
 	void *buf;
 
-	rq_for_each_bio(bio, req) {
-		sector = bio->bi_sector;
+	rq_for_each_segment(bvec, req, iter) {
+		unsigned long flags;
 		dev_dbg(&dev->sbd.core,
 			"%s:%u: bio %u: %u segs %u sectors from %lu\n",
-			__func__, __LINE__, i, bio_segments(bio),
-			bio_sectors(bio), sector);
-		bio_for_each_segment(bvec, bio, j) {
+			__func__, __LINE__, i, bio_segments(iter.bio),
+			bio_sectors(iter.bio),
+			(unsigned long)iter.bio->bi_sector);
+
 			size = bvec->bv_len;
-			buf = __bio_kmap_atomic(bio, j, KM_IRQ0);
+			buf = bvec_kmap_irq(bvec, &flags);
 			if (gather)
 				memcpy(dev->bounce_buf+offset, buf, size);
 			else
 				memcpy(buf, dev->bounce_buf+offset, size);
 			offset += size;
-			flush_kernel_dcache_page(bio_iovec_idx(bio, j)->bv_page);
-			__bio_kunmap_atomic(bio, KM_IRQ0);
-		}
+			flush_kernel_dcache_page(bvec->bv_page);
+			bvec_kunmap_irq(bvec, &flags);
+
 		i++;
 	}
 }
@@ -130,12 +130,13 @@
 
 #ifdef DEBUG
 	unsigned int n = 0;
-	struct bio *bio;
+	struct bio_vec *bv;
+	struct req_iterator iter;
 
-	rq_for_each_bio(bio, req)
+	rq_for_each_segment(bv, req, iter)
 		n++;
 	dev_dbg(&dev->sbd.core,
-		"%s:%u: %s req has %u bios for %lu sectors %lu hard sectors\n",
+		"%s:%u: %s req has %u bvecs for %lu sectors %lu hard sectors\n",
 		__func__, __LINE__, op, n, req->nr_sectors,
 		req->hard_nr_sectors);
 #endif