2 files changed, 69 insertions, 41 deletions

diff --git a/block/blk-merge.c b/block/blk-merge.c
index b92f5b0866b..a104593e70c 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -38,72 +38,84 @@ void blk_recalc_rq_sectors(struct request *rq, int nsect)
 	}
 }
 
-void blk_recalc_rq_segments(struct request *rq)
+static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
+					     struct bio *bio,
+					     unsigned int *seg_size_ptr)
 {
-	int nr_phys_segs;
 	unsigned int phys_size;
 	struct bio_vec *bv, *bvprv = NULL;
-	int seg_size;
-	int cluster;
-	struct req_iterator iter;
-	int high, highprv = 1;
-	struct request_queue *q = rq->q;
+	int cluster, i, high, highprv = 1;
+	unsigned int seg_size, nr_phys_segs;
+	struct bio *fbio;
 
-	if (!rq->bio)
-		return;
+	if (!bio)
+		return 0;
 
+	fbio = bio;
 	cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
 	seg_size = 0;
 	phys_size = nr_phys_segs = 0;
-	rq_for_each_segment(bv, rq, iter) {
-		/*
-		 * the trick here is making sure that a high page is never
-		 * considered part of another segment, since that might
-		 * change with the bounce page.
-		 */
-		high = page_to_pfn(bv->bv_page) > q->bounce_pfn;
-		if (high || highprv)
-			goto new_segment;
-		if (cluster) {
-			if (seg_size + bv->bv_len > q->max_segment_size)
-				goto new_segment;
-			if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
-				goto new_segment;
-			if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
+	for_each_bio(bio) {
+		bio_for_each_segment(bv, bio, i) {
+			/*
+			 * the trick here is making sure that a high page is
+			 * never considered part of another segment, since that
+			 * might change with the bounce page.
+			 */
+			high = page_to_pfn(bv->bv_page) > q->bounce_pfn;
+			if (high || highprv)
 				goto new_segment;
+			if (cluster) {
+				if (seg_size + bv->bv_len > q->max_segment_size)
+					goto new_segment;
+				if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
+					goto new_segment;
+				if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
+					goto new_segment;
+
+				seg_size += bv->bv_len;
+				bvprv = bv;
+				continue;
+			}
+new_segment:
+			if (nr_phys_segs == 1 && seg_size >
+			    fbio->bi_seg_front_size)
+				fbio->bi_seg_front_size = seg_size;
 
-			seg_size += bv->bv_len;
+			nr_phys_segs++;
 			bvprv = bv;
-			continue;
+			seg_size = bv->bv_len;
+			highprv = high;
 		}
-new_segment:
-		if (nr_phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
-			rq->bio->bi_seg_front_size = seg_size;
-
-		nr_phys_segs++;
-		bvprv = bv;
-		seg_size = bv->bv_len;
-		highprv = high;
 	}
 
-	if (nr_phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
+	if (seg_size_ptr)
+		*seg_size_ptr = seg_size;
+
+	return nr_phys_segs;
+}
+
+void blk_recalc_rq_segments(struct request *rq)
+{
+	unsigned int seg_size = 0, phys_segs;
+
+	phys_segs = __blk_recalc_rq_segments(rq->q, rq->bio, &seg_size);
+
+	if (phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
 		rq->bio->bi_seg_front_size = seg_size;
 	if (seg_size > rq->biotail->bi_seg_back_size)
 		rq->biotail->bi_seg_back_size = seg_size;
 
-	rq->nr_phys_segments = nr_phys_segs;
+	rq->nr_phys_segments = phys_segs;
 }
 
 void blk_recount_segments(struct request_queue *q, struct bio *bio)
 {
-	struct request rq;
 	struct bio *nxt = bio->bi_next;
-	rq.q = q;
-	rq.bio = rq.biotail = bio;
+
 	bio->bi_next = NULL;
-	blk_recalc_rq_segments(&rq);
+	bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, NULL);
 	bio->bi_next = nxt;
-	bio->bi_phys_segments = rq.nr_phys_segments;
 	bio->bi_flags |= (1 << BIO_SEG_VALID);
 }
 EXPORT_SYMBOL(blk_recount_segments);
diff --git a/block/genhd.c b/block/genhd.c
index e1eadcc9546..a9ec910974c 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -256,6 +256,22 @@ void blkdev_show(struct seq_file *seqf, off_t offset)
 }
 #endif /* CONFIG_PROC_FS */
 
+/**
+ * register_blkdev - register a new block device
+ *
+ * @major: the requested major device number [1..255]. If @major=0, try to
+ *         allocate any unused major number.
+ * @name: the name of the new block device as a zero terminated string
+ *
+ * The @name must be unique within the system.
+ *
+ * The return value depends on the @major input parameter.
+ *  - if a major device number was requested in range [1..255] then the
+ *    function returns zero on success, or a negative error code
+ *  - if any unused major number was requested with @major=0 parameter
+ *    then the return value is the allocated major number in range
+ *    [1..255] or a negative error code otherwise
+ */
 int register_blkdev(unsigned int major, const char *name)
 {
 	struct blk_major_name **n, *p;