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, 14 insertions, 1 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b126c6f68e27..a4b13b8a9d09 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -637,10 +637,23 @@ static inline void blk_queue_bounce(struct request_queue *q, struct bio **bio)
 }
 #endif /* CONFIG_MMU */
 
-#define rq_for_each_bio(_bio, rq)       \
+struct req_iterator {
+        int i;
+        struct bio *bio;
+};
+
+/* This should not be used directly - use rq_for_each_segment */
+#define __rq_for_each_bio(_bio, rq)     \
         if ((rq->bio))                  \
                 for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
 
+#define rq_for_each_segment(bvl, _rq, _iter)                    \
+        __rq_for_each_bio(_iter.bio, _rq)                       \
+                bio_for_each_segment(bvl, _iter.bio, _iter.i)
+
+#define rq_iter_last(rq, _iter)                                 \
+                (_iter.bio->bi_next == NULL && _iter.i == _iter.bio->bi_vcnt-1)
+
 extern int blk_register_queue(struct gendisk *disk);
 extern void blk_unregister_queue(struct gendisk *disk);
 extern void register_disk(struct gendisk *dev);